Full text of "Family #15, Gramineae"

See other formats

ILL

URXoir«<

JUL 1 9 1982

The person charging this material is re-
sponsible for its return to the library from
which it was withdrawn on or before the
Latest Date stamped below.

Theft, mutilation, and underlining of books are reasons

for disciplinary action and may result in dismissal from

the University.

To renew call Telephone Center, 333-#4DO

UNIVERSITY Of lUlbiai&aiBRARY AT URBANA-CHAMPAIGN

L161— O-1096

FIELDIANA
Botany

Published by Field Museum of Natural History
New Strii's, Xu. I

FLORA COSTARICENSIS

WILLIAM BURGER, Editor

FAMILY #15, GRAMINEAE
RICHARD W. POHL

BIOLOGY
101

JUN 1 6 1981

December 19, 1980
Publication 1313

Families of seed plants known or expected to occur in Costa Rica and adjacent
areas, listed alphabetically and numbered according to the sequence of Engler's
Syllabus der Pflanzenfamilien, edition 11, reworked by L. Diels (1936).

200

136
67

117

184

119

166

185

127

153

194

145

133

189

106

115

154

114

207

203

151

138

120

144

169

146

161

208

186

116

168

206

118

112

135

205

178

156

130

143

172

Acanthaceae

Actinidiaceae

Aizoaceae

Alismataceae

Amaranthaceae

Amaryllidaceae

Anacardiaceae

Anonaceae

Apocynaceae

Aquifoliaceae

Araceae

Araliaceae

Araucariaceae

Aristolochiaceae

Asclepiadaceae

Balanophoraceae

Balsammaceae

Basellaceae

Batidaceae

Begoniaceae

Berberidaceae

Betulaceae

Bignoniaceae

Bixaceae

Bombacaceae

Boraginaceae

Bromeliaceae

Brunelliaceae

Burmanniaceae

Burseraceae

Butomaceae

Buxaceae

Cactaceae

Caesalpiniaeeae,

see Leguminosae
Callitrichaceae
Campanulaceae
Cannaceae
Capparidaceae
Caprifoliaceae
Caricaceae
Caryocaraceae
Caryophyllaceae
Casuarinaceae
Celastraceae
Ceratophyllaceae
Chenopodiaceae
Chloranthaceae
Cistaceae
Clethraceae
Cochlospermaceae
Combretaceae
Commelinaceae
Compositae
Connaraceae
Convolvulaceae
Coriariaceae
Cornaceae
Crasaulaceae
Cruciferae
Cucurbitaceae
Cunoniaceae
Cupressaceae
Cycadaceae
Cyclanthaceae
Cyperaceae
Cyrillaceae
Dichapetalaceae
Dillemaceae
Dioscoreaceae
Dipsacaceae
Droseraceae
Ebenaceae
Elaeagnaceae
Elaocarpaceae
Elatinaceae
Ericaceae
Eriocaulaceae

102

Erythroxylaceae

Papaveraceae

113

Euphorbiaceae

150

Pasaifloraceae

Fabaceae,

195

Pedal iaceae

see Leguminosae

Phytolaccaceae

Fagaceae

Pinaceae

148

Flacourtiaceae

Piperaceae

Fumariaceae,

171

Pyrolaceae

see Papaveraceae

201

Plantaginaceae

45
183

Garryaceae
Gentianaceae

176
3

Plumbaginaceae
Podocarpaceae

Geraniaceae

Podostemonaceae

198

Gesneriaceae

187

Polemoniaceae

Gnetaceae

111

Polygalaceae

Gramineae

Polygonaceae

142

Guttiferae

Pontederiaceae

Haemodoraceae

Portulacaceae

165

Halorrhagaceae

Potamogetonaceae

Hamamelidaceae

175

Primulaceae

Hernandiaceae

Proteaceae

124

Hippocastanaceae

158

Punicaceae

121

Hippocrateaceae

140

Quiinaceae

101

Humiriaceae,

Rafflesiaceae

see Linaceae

Ranunculaceae

Hydrocharitaceae

Resedaceae

188

Hydrophyllaceae

128

Rhamnaceae

142

Hypericaceae,

160

Rhizophoraceae

see Guttiferae

Rosaceae

123

Icacinaceae

202

Rubiaceae

Iridaceae

104

Rutaceae

Juglandaceae

126

Sabiaceae

Juncaceae

Salicaceae

Krameriaceae

125

Sapindaceae

191

Labiatae

177

Sapotaceae

Lacistemaceae

Saxifragaceae

Lauraceae

193

Scrophulariaceae

159

Lecythidaceae

105

Simarubaceae

Leguminosae

192

Solanaceae

Lemnaceae

122

Staphyleaceae

199

Lentibulariaceae

134

Sterculiaceae

Liliaceae

180

Styracaceae

101

Linaceae

179

Symplocaceae

152

Loasaceae

Taxaceae

182

Loganiaceae

141

Theaceae

Loranthaceae

173

Theophrastaceae

157

Lythraceae

155

Thymelaeaceae

Magnoliaceae

131

Til iaceae

108

Malpighiaceae

Tovariaceae

132

Malvaceae

109

Trigoniaceae

Marantaceae

Triuridaceae

139

Marcgraviaceae

100

Tropaeolaceae

196

Martyniaceae

149

Turneraceae

Mayacaceae

Typhaceae

163

Melastomataceae

Ulmaceae

107

Mel iaceae

167

Umbelliferae

Menispermaceae

Urticaceae

Mimosaceae,

204

Valerianaceae

see Leguminosae

Velloziaceae

Monimiaceae

190

Verbenaceae

170

Monotropaceae

147

Violaceae

Moraceae

129

Vitaceae

Moringaceae

110

Vochyaiaceae

Musaceae

Xyridaceae

Myricaceae

Zingiberaceae

Myristicaceae

103

Zygophyllaceae

174

Myrsinaceae

162

Myrtaceae

Najadaceae

Nyctaginaceae

Nymphaeaceae

137

Ochnaceae

Olacaceae

181

Oleaceae

164

Onagraceae

Opiliaceae

Orchidaceae

197

Orobanchaceae

Oxalidaceae

Palmae

JUN161981

FLORA COSTARICENSIS
FAMILY #15, GRAMINEAE

FIELDIANA
Botany

Published by Field Museum of Natural History

New Series, No. 4

FLORA COSTARICENSIS

WILLIAM BURGER, Editor

Curator, Vascular Plants

Field Museum of Natural History

FAMILY #15, GRAMINEAE
RICHARD W. POHL

Research Associate in Botany
Field Museum of Natural History
Distinguished Professor
Botany, Iowa State University

Accepted for publication Nov. 20, 1978.

This publication was supported in part by NSF grant DEB74-08575.

December 19, 1980

Publication 1313

Library of Congress Catalog Card Number: 79-55875

US ISSN 0015-0746
PRINTED IN THE UNITED STATES OF AMERICA

CONTENTS

Acknowledgements 1

Abbreviations 2

Gramineae (Poaceae), Grass Family 3

Classification of the Grass Family 7

Index . .596

ACKNOWLEDGEMENTS

Working toward the completion of a taxonomic treatment of the
grasses of Costa Rica, field work began in 1966. It has been aided by so
many people and agencies that it is difficult to know how to express
appreciation to them all. Financial support for all of the field work and
for expenses connected with herbarium study were furnished by the
National Science Foundation under grants GB-7307X and GB-32085.
The author received salary for six months in 1968 under a Faculty
Improvement Leave Grant from Iowa State University. The facilities
of the Iowa State University Herbarium, supported by the Sciences
and Humanities Research Institute, were used throughout the term of
my studies.

My study of Costa Rican grasses began while I was an instructor in a
course on tropical grasses given by the Organization for Tropical
Studies during the summer of 1966. The organization has since that
time furnished aid in many ways, including logistic support and the use
of its bases in Costa Rica. My special thanks go to Sr. Jorge Cam-
pabadal, Resident Director of the O.T.S. in San Jose, for the many
ways in which he made my field work easier and more productive. Dr.
Rafael Rodriguez C. of the Department of Biology of the University of
Costa Rica furnished laboratory space and equipment for the 1968-
1969 year, and has given generously of his time and counsel during the
entire time of the field work. The Museo Nacional de Costa Rica and
Sr. Luis Diego Gomez P. furnished facilities, the use of the herbarium,
and the use of a field vehicle. The family of Mr. Werner Hagnauer of
Finca la Pacifica at Canas furnished not only food, shelter, and a kindly
atmosphere, but much sagacious counsel on field travel in Guanacaste.
Dr. Gerrit Davidse, currently of the Missouri Botanical Garden in St.
Louis, was my field companion in Costa Rica from June, 1968 to May,
1969. Much of the success of the field program is due to his indefatiga-
ble efforts. He is also responsible for many of the hundreds of chromo-
some counts that we obtained from Central American grasses, which
are reported in the text.

2 FIELDIANA: BOTANY

Field Museum has furnished access to its herbarium and library, and
allowed the use of its field vehicles in Costa Rica. My special thanks are
due to Louis Williams and William Burger of the Museum. During my
many visits to the U.S. National Herbarium, Dr. Thomas Soderstrom
and Dr. Cleofe Calderon furnished facilities, access to literature, and
aid in identifications.

Finally, like all field biologists in Costa Rica, I owe a great deal to
the friendly and courteous people of that beautiful land. They have
helped in many ways, ranging from extricating my jeep from a ditch to
offering interest and information about the plants that I was studying.

ILLUSTRATIONS

The majority of the illustrations of grasses in this publication are the
work of Judy Appenzeller LaMotte (JEA). Most of the remainder are
taken from the illustrations of various publications of Agnes Chase and
A. S. Hitchcock, the originals of which are now in the Hunt Center for
Botanical Documentation and are used with the kind permission of that
institution. Scale lines for spikelets are 1 mm. long; for larger
structures, 1 cm. long.

ABBREVIATIONS

BREM tlbersee-Museum, Bremen, Federal Republic of Germany
CATIE Centro Agronomico Tropical de Investigation y Ensenanza,

Turrialba

CIA Carretera Interamericana (Interamerican Highway)
CR Herbario Nacional, Museo Nacional de Costa Rica, San Jose

F Field Museum of Natural History

IICA Institute Interamericana de Ciencias Agricolas, Turrialba
ISC Iowa State University Herbarium, Ames, Iowa
JEA Judy Appenzeller LaMotte, artist
US United States National Herbarium, Smithsonian Institution,

Washington, D.C.

GRAMINEAE (POACEAE). GRASS FAMILY

REFERENCES: N. L. Bor, The grasses of Burma, Ceylon, India and
Pakistan (excluding Bambuseae). XVIII + 767 pp. Pergamon Press.
London. 1960. A. Burkart (ed.) & collaborators, Flora Ilustrada de
Entre Rios (Argentina), Parte II: Gramineas. V + 551 pp. Coleccion
Cientifica del I.N.T.A., Tomo VI, II. Buenos Aires. 1969. E. G.
Camus, Les Bambusees. Texte, 215 pp. Lechevalier. Paris. 1913. +
Atlas of 101 plates. Not dated. W. D. Clayton, Flora of Tropical East
Africa, Gramineae, Part 1:1-176. Government Bookshops. London.
1970. E. Fournier, Mexicanas Plantas, Pars Secunda. Gramineae. 160
pp. Typographeo Reipublicae. Paris. 1881. J. S. Gamble, The Bam-
buseae of British India, Ann. Roy. Bot. Gard. (Calcutta). 1896. Re-
print by Micro Methods Ltd. & Johnson Reprint Corp. 1966. A. S.
Hitchcock, The grasses of Central America, Contr. U.S. Natl. Herb.
23(9):XVI + 557-762. U.S. Govt. Printing Office. Washington, D.C.
1930. A. S. Hitchcock, Manual of the grasses of the West Indies, Misc.
Publ. 243, U.S. Dept. Agric. 439 pp. Govt. Printing Office.
Washington, D.C. 1936. C. E. Hubbard, Flora of Tropical Africa. (A.
W. Hill, ed.) 10(1): 192 pp. L. Reeve. Ashford. 1937. H. Jacques-Felix,
Les Graminees (Poaceae) D' Afrique Tropicale I. Generalites,
Classification Description des Genres. XI + 345 pp. Ins. Recherches
Agron. Trop. Paris. 1962. A. S. Maroto, Los Forrajes de Costa Rica.
606 pp. Universidad de Costa Rica. San Jose. 1955. F. A. McClure,
Genera of bamboos native to the New World (Gramineae: Bam-
busoideae, Smithsonian Contr. Bot. 9:XI + 148. Smithsonian Inst.
Press. Washington, D.C. 1973. New York Bot. Gard. ed. 1912-1939.
North American Flora 17:77-638, Family Poaceae. Parts 1, 2, 3 by G.
V. Nash, 1912-15 pp. 77-288; Parts 4, 5, 6, 7 by A. S. Hitchcock,
1935-37, pp. 289-354; Part 8, by A. S. Hitchcock, J. R. Swallen, &
Agnes Chase, 1939, pp. 543-638. H. Pittier, Ensayo sobre Plantas
Usuales de Costa Rica, ed. 2. Revised by R. Rodriguez C. 264 pp. + 50
plates. Editorial Universitaria. San Jose. 1957. B. Rosengurtt, B. R.
Arrillaga de Maffei, & P. Izaguirre de Artucio. Gramineas Uruguayas.

4 FIELDIANA: BOTANY

VII + 489 pp. Universidad de la Republica. Montevideo. 1970. 0.
Stapf, Flora of Tropical Africa. (D. Prain, ed.) IX. Gramineae
(Maydeae-Paniceae). VI + 1,132pp. L. Reeve. London 1917-1934. G.
L. Stebbins, Jr., & B. Crampton, A suggested revision of the grass
genera of North America, Recent Advances in Botany, pp. 133-145.
1961. J. R. Swallen, The grasses of the Yucatan Peninsula, Appendix
to Contr. Amer. Archaeol., No. 12. Carnegie Inst. Wash. Publ.
436:323-355. 1934. J. R. Swallen, Botany of the Maya Area: Miscel-
laneous Papers IX: The grasses of British Honduras and the Peten,
Guatemala, Carnegie Inst. Wash. Publ. 461:141-189. 1936. J. R. Swal-
len, Flora of Panama: Gramineae, Ann. Missouri Bot. Gard. 30:104-
280. 1943. J. R. Swallen, Flora of Guatemala, Part II: Grasses of
Guatemala (Bamboos by F. A. McClure), Fieldiana, Bot. 24, Pt. II:IX
+ 390 pp. 1955.

Mostly herbaceous plants, occasionally shrubby or treelike, as in the bamboos. Root
systems fibrous, mostly lacking in characters of systematic importance, in large part of
adventitious origin from the basal nodes, the primary root soon dying. Stems conspicu-
ously jointed, mostly with hollow internodes and solid nodes; aerial stems (culms) mostly
terminating in inflorescences; plants also producing young vegetative stems (innova-
tions) from the base. Plants variously clump-forming (caespitose) or with stolons or
rhizomes. Branches ordinarily 1 per node, the base subtended by a highly modified
bracteal leaf, the prophyllum, attached to the base of the branch and tending to hold
together the main stem and the branch. Foliage leaves alternate, spaced 180 deg. apart
on the stem. Each leaf consists of three major parts, these being the sheath that sur-
rounds the internode and which usually has overlapping edges; the ligule, a small mem-
branaceous or hairy rim or projection at the juncture of the sheath and the leaf blade;
and the usually flat, linear, parallel- veined leaf blade. In addition to these structures, the
following are sometimes seen. The flange, or dewlap, is a triangular outpouched area
between the summit of the sheath and the blade proper. It permits upward and down-
ward motion of the blade. The collar is the line of union between the lower surface of the
blade and the sheath. Auricles are rounded or pointed projections of the base of the blade
or the summit of the sheath. In bamboos and their relatives and a few other grasses, a
narrow stalk is intercalated between the base of the blade proper and the summit of the
sheath. This is the pseudopetiole, morphologically a portion of the leaf blade and not a
true petiole.

Grass inflorescences are extremely variable, and difficult to confine to a simple system
of nomenclature. Since grasses do not have naked individual flowers, the terminology
ordinarily used for inflorescences does not well fit their flowering structures. While
authors have ordinarily used standard inflorescence names in describing grasses, it
should be borne in mind that such usage always implies that the flowering unit is a
spikelet, not an individual flower. I have used the terms panicle, spike, and raceme in the
usual sense, but have added a new term, RAME, to indicate an unbranched axis that
bears both sessile and pedicellate spikelets. This term is convenient to indicate the
flowering axes of the Tribe Andropogoneae, where one of each pair of spikelets may be
sessile and the other pedicellate. Inflorescences are often terminal on the culms of

BURGER: FLORA COSTARICENSIS 5

grasses, but in many cases axillary ones are also produced. In one genus (Pariana)
naked inflorescences arise from the soil level, and in a few grasses (C Moris chl&ridea,
the genus Amphicarpum) entirely subterranean inflorescences occur.

The spikelet is the basic unit of the grass inflorescence. It is a small axis (rachilla)
bearing alternate overlapping bracts distichously. It is never secondarily branched,
thereby differing from other inflorescence structures. Usually spikelets are borne on
slender stalks, the pedicels. The lowermost two (rarely one) bracts of the spikelet
(glumes) are sterile.

Successive nodes of the rachilla above the glumes bear flowering units called florets.
The floret consists of an outer bract, the lemma, attached to the rachilla itself, an inner
bract, the palea, attached to the flower axis, and the included flower. The lemma and
palea together are sometimes called the anthoecium (anthecium). The lemma may bear a
projecting midrib, the awn. Rarely lateral nerves (vascular bundles) may also be ex-
tended into awns, as in Aristida. The inner floral bract, the palea, is the homologue of
the prophyllum found on vegetative parts of the plant. In spikelets with several florets,
disarticulation often takes place at the apex of each rachilla internode, so that the
disseminules are individual florets. In the Subfamily Panicoideae, in general, and in
various other genera, the entire spikelet is shed from the plant as a unit.

Grass flowers are very small, and lack a conspicuous perianth. The vestiges of the
perianth are small fleshy or scale-like bodies called lodicules. Two lodicules are present
in all the grass subfamilies with the exception of the Bambusoideae. They are placed at
the base of the ovary on the side toward the lemma, and serve, by their rapid swelling,
to force the lemma outward and permit the exposure of the anthers and stigmas at
anthesis. The shape, number, and vasculation, or lack of it, of the lodicules are char-
acteristic of the various subfamilies of the Gramineae. In the Subfamily Pooideae, the
lodicules are more or less pointed, flattened except near the swollen base, and non-
vascular. In the Subfamilies Chloridoideae, Oryzoideae, and Panicoideae, the lodicules
are thick, fleshy, truncate, and possess vascular traces. In the Bambusoideae, three
lodicules are ordinarily present. They are flat, ovate, pointed, and have conspicuous
forking vascular traces. A great majority of grasses have three stamens, with elongated
flexuous filaments and large, versatile anthers. A few isolated species have one or two
anthers, and the Bambusoideae ordinarily have six, or rarely other numbers. The
gynoecium in most grasses, with the exception of the Bambusoideae, has two style
branches bearing enlarged plumose stigmas. A third carpel is represented only by a
vascular bundle in the ovary wall. In the Bambusoideae, most species have a single style
bearing three rather small stigmas. With rare exceptions, grasses have some or all of the
flowers perfect. A few monoecious or dioecious grasses occur in widely disparate groups
of grasses.

The fruit in grasses is generally a caryopsis, a single-seeded dry indehiscent grain
with the pericarp and seed united. In a few genera, notably Sporobolus, the pericarp
gelatinizes and separates from the seed. In the bamboos, various types of specialized
grass fruits occur.

While true grass spikelets never rebranch, some bamboos and their herbaceous rela-
tives have complex bracted structures which branch secondarily into the true spikelets.
Such structures are designated as pseudospikelets.

The duration of the life of grasses is usually designated as annual or
perennial. While this distinction is fairly usable in the temperate zone,

6 FIELDIANA: BOTANY

it does not work well in the tropics, where frost or drought does not
often occur to terminate the life of the individual. In instances where it
seems impossible to determine the life span of plants of a species, I
have indicated this by the statement "duration indefinite." In the
tropics, stoloniferous grasses frequently fall into this category.

Measurements given in this work are derived primarily from Cen-
tral American specimens. It is possible that material from other areas
might yield larger or smaller values. Plane shapes of structures are
designated according to the International Association for Plant Tax-
onomy chart (Taxon 11:145-156. 1962). According to this system, a
shape is designated by a general class, followed by a ratio indicating
the length to width proportions, as for example: ovate 4:1; obovate
3-7:1.

The abbreviations CIA, for Carretera Interamericana (the Pan
American Highway), and P.&D., for collections of Pohl & Davidse, are
often used in the discussions under the species.

Chromosome numbers cited in the text are mostly derived from
counts made by the author and Dr. Gerrit Davidse and published
in the following series of papers: R. W. Pohl & G. Davidse, Chromo-
some numbers of Costa Rican grasses, Brittonia 23:293-324. 1971. G.
Davidse & R. W. Pohl, Chromosome numbers and notes on some Cen-
tral American grasses, Canad. J. Bot. 50:273-283. 1972; Chromosome
numbers, meiotic behavior, and notes on some grasses from Central
America and the West Indies, Canad. J. Bot. 50:1441-1452. 1972;
Chromosome numbers, meiotic behavior, and notes on tropical Ameri-
can grasses (Gramineae), Canad. J. Bot. 52:317-328. 1974.

CLASSIFICATION OF THE GRASS FAMILY

For many years, the standard classification of the Gramineae used in
most works of American origin was that of A. S. Hitchcock. This
system featured the use of two large subfamilies, the Festucoideae and
Panicoideae, and a rather limited number of inclusive tribes. Studies in
grass morphology, anatomy, cytology, ecology, and physiology indi-
cate that this system did not make sufficient allowance for the wide-
spread and frequent occurrence of convergent evolution in external
form. A number of newer systems of classification, utilizing a much
wider range of data in the formulation of the major categories, have
been proposed in recent years. The system used for this work is based
largely on the one proposed for the American temperate zone elements
of the family by G. L. Stebbins and Beecher Crampton. I have
modified this system in detail, but the general outline follows the work
of the above authors. While the system has much higher phylogenetic
and predictive value than older arrangements, it does not lend itself to
use for routine identification. I have therefore constructed artificial
keys to assist in identification, and the arrangement in the text is
strictly alphabetical.

The following brief summary will serve to indicate the principal
characteristics of each of the six subfamilies recognized in this treat-
ment, and indicate the Costa Rican genera belonging to each one.

SUBFAMILY I. BAMBUSOIDEAE

This subfamily includes the bamboos and a number of herbaceous
grasses, mostly found in moist forests of the tropics, which resemble
the bamboos in their leaf epidermal and cross-sectional anatomy, the
number and nature of lodicules, the number of stamens and stigmas.
The bamboos are readily recognized by their woody stems, and all of
these grasses possess at least short pseudopetioles. The following gen-
era occur in Costa Rica:

Woody bamboos. — Arthrostylidium, Aulonemia, Bambusa,

FIELDIANA: BOTANY

Chusquea, Elytrostachys, Merostachys, Rhipidocladum, Swallen-
ochloa. A number of other genera are cultivated, including species of
Phyllostachys, Yushania, and Bambusa.

Herbaceous bamboos: Cryptochloa, Lithachne, Olyra, Pariana,
Raddia, Pharus, Streptochaeta, Streptogyna.

The treatment of the bamboos in this work is necessarily tentative.
Many of the species bloom only after long intervals of years, and some
have never been observed to bloom in our area. Much more field and
herbarium work will have to be done before a definitive treatment of
the Central American bamboos can be produced.

SUBFAMILY II. ORYZOIDEAE

This is a relatively small subfamily, allied to the bambusoids by
anatomical characteristics and chromosome numbers. Their spikelets
have very reduced or vestigial glumes, usually appearing as a minute
cupule at the apex of the pedicel. There is only one fertile floret. All are
plants of wet ground or water. The following genera occur in Costa
Rica: Leersia, Luziola, Oryza.

SUBFAMILY III. POOIDEAE (FESTUCOIDEAE)

This is a large subfamily, containing many of the grasses of the
temperate and cold regions of the world. In Central America, rela-
tively few of them occur, and these mostly at high elevations. They are
characterized by rather simple leaf anatomy, reduced embryo struc-
ture, and the possession of large chromosomes in multiples of seven.
The following genera occur in Costa Rica, some of them as introduc-
tions in upland pastures: Aciachne, Agropyron, Agrostis, Aira,
Anthoxanthum, Avena, Briza, Brachy podium, Bromus, Calama-
grostis, Cinna, Cynosurus, Dactylis, Deschampsia, Festuca, Gly-
ceria, Hierochloe, Holcus, Lolium, Lorenzochloa, Nassella, Phalaris,
Poa, Polypogon, Secale, Stipa, Triniochloa, Trisetum, Vulpia.

SUBFAMILY IV. ARUNDINOIDEAE

This subfamily contains numerous large, reedlike grasses, often
with plumelike, fuzzy panicles. Other genera included here are placed
largely on anatomical grounds. Costa Rican representatives are:
Aristida, Arundo, Cortaderia, Danthonia, Gynerium, Orthoclada,
Phragmites, Zeugites.

SUBFAMILY V. CHLORIDOIDEAE (ERAGROSTOIDEAE)

This is an abundant subfamily of warm climates. They are funda-
mentally characterized by microscopic characters, including the elabo-

BURGER: FLORA COSTARICENSIS 9

rately structured leaf cross-section, featuring a number of quasi-
independent units, the cells of each radiating around a single vascular
bundle. In many, the lemmas have three strong vascular bundles, in
contrast to the five or more faint bundles in lemmas of most pooid
grasses. The following genera occur in Costa Rica, mostly at low or
middle elevations: Aegopogon, Bouteloua, Chloris, Cynodon, Dac-
tyloctenium, Eleusine, Eragrostis, Gouinia, Gymnopogon, Jouvea,
Leptochloa, Muhlenbergia, Pentarraphis, Pereilema, Spartina, Spor-
obolus, Triplasis, Uniola, Zoysia.

SUBFAMILY VI. PANICOIDEAE

This is by far the largest subfamily of warm climate grasses, forming
a significant portion of the grass cover in tropical regions. Spikelets,
with rare exceptions, are dorsally compressed, have a single perfect
flower, and disarticulate below the glumes. Genera occurring in Costa
Rica are the following: Acroceras, Andropogon, Anthephora, Arthra-
xon, Arundinella, Axonopus, Bothriochloa, Brachiaria, Cenchms,
Chaetium, Coelorachis, Coix, Cymbopogon, Diectomis, Digitaria,
Echinochloa, Echinolaena, Eremochloa, Eriochloa, Eriochrysis,
Euclasta, Hackelochloa, Homolepis, Hymenachne, Hyparrhenia,
Hypogynium, Ichnanthus, Imperata, Isachne, Ischaemum, Ixo-
phorus, Lasiacis, Leptocoryphium, Melinis, Mesosetum, Oplis-
menus, Panicum, Paratheria, Paspalidium, Paspalum, Penni-
setum, Polytrias, Pseudechinolaena, Rhynchelytrum, Rottboellia,
Saccharum, Sacciolepis, Schizachyrium, Setaria, Sorghastrum, Sor-
ghum, Stenotaphrum, Thrasya, Trachypogon, Tripsacum, Urochloa,
Vetiveria, Zea.

MASTER KEY

la. Culms at least 2 m. tall, woody and perennial; foliage leaves usually borne on

secondary branches; rarely blooming KEY I

Ib. Culms herbaceous, usually less than 2 m. tall; foliage leaves on main culms as well

as branches; blooming annually 2

2a. All or some spikelets borne partially or completely concealed, in spiny burs,
or bony rachis joints, or bead-like or horn-like structures, or detachable fasci-
cles of hard bracts, or completely hidden in leaf sheaths with only the stamens

and stigmas visible KEY II

2b. Spikelets borne in the open, in panicles, racemes, rames, or spike-like

inflorescences 3

3a. Leaf blades separated from sheaths by slender pseudopetiole, 5 mm. -several cm.

long KEY III

3b. Leaf blades attached directly to sheaths, or with short pseudopetioles not more
than 1-3 mm. long 4

10 FIELDIANA: BOTANY

4a. Spikelets disarticulating above the glumes which remain attached to pedicels

as visible bracts KEY IV

4b. Spikelets disarticulating completely from the pedicels, no glumes remaining

on the plant, or at the most a minute nerveless cupule 5

5a. Spikelets all falling as single units, without attached accessory structures

KEY V

5b. Spikelets, or some of them, falling in clusters or with attached rachis, pedicels, or
sterile, bristle-like branches KEY VI

KEY I

GIANT GRASSES; CULMS 2-30 M. TALL, OFTEN WOODY OR SOLID

la. Culm internodes solid, without central lumen 2

Ib. Culm internodes with small or large central lumen 4

2a. Leaf blades 1-several m. long, borne on main culm; culms pithy, not ex-
tremely woody 3

2b. Leaf blades usually less than 20 cm. long, mostly borne on small lateral

branches, main culms naked or bearing bladeless sheaths Chusquea

3a. Leaf blades distributed along culms; spikelets single-flowered, disarticulating
below glumes; cultivated crop (sugar cane; cana de azucar); pith sweet

Saccharum officinarum

3b. Leaf blades borne in a large, fan-shaped cluster at the apex of culm; spikelets
2-flowered, disarticulating above the glumes; wild plants, usually growing on river

banks; pith not sweet Gynerium sagittatum

4a. Leaf blades 1-2 m. long, cordate-clasping at base, borne on main culm, often
yellow-striped; culms thin-walled; plants cultivated for ornament, rarely

escaping to the wild Arundo donax

4b. Leaf blades usually 20 cm. long or shorter, not cordate-clasping, mostly with

short pseudopetioles; wild or cultivated plants 5

5a. Culms with thorny branches Bambusa

5b. Culms lacking thorny branches 6

6a. Culms barely woody, internodes slender (1 cm. or less), green, and soft (can

be crushed with the fingers) 7

6b. Culms definitely woody, of various diameters 9

7a. Culms with glistening, viscid band at nodes; plants rarely blooming

Aulonemia

7b. Culms not viscid; plants annual bloomers 8

8a. Spikelets alike, black and shiny when mature, placed at an angle to
pedicel; disarticulation below glumes; leaf blades sessile, without pseudo-
petioles Lasiacis

8b. Spikelets unisexual, of 2 kinds, not black, aligned with pedicel; disarticulation

above glumes; leaf blades with short pseudopetiole Olyra

9a. Bamboos of various habits, in forested or savanna habitats below 3,000 m. eleva-
tion; lumen of internodes usually large and with definite boundary membrane;

branches 2-many per node 10

9b. Small, shrubby bamboos of paramos above 3,000 m. elevation; central lumen of

BURGER: FLORA COSTARICENSIS 11

culm internodes small, lacking definite boundary membrane; branches stiff and

erect, usually 3-5 per node Suxillenochloa

lOa. Branches at midculm nodes numerous, arising from edges of flat, triangular

plate-like meristem that is closely appressed to main culm 11

lOb. Branches at midculm nodes not arising from flat plate, of varying number . 12
lla. Midculm sheaths with a narrow reflexed blade that is constricted at its base and

much narrower than sheath apex Merostachys

lib. Midculm sheaths with an erect blade that is as wide as the sheath apex and not

constricted at the base Rhipidocladum

12a. Primary midculm branches solitary, soon branched near the base; auricular
bristles very prominent, up to 8 cm. long on the main culm sheaths

Elytrostachys
12b. Primary midculm branches 2-several per node; auricular bristles short . 13

13a. Branches 3-many per node, arising above the node at the apex of a prominent bulge
that continues down to the node; internodes cylindrical in cross-section; wild plants

Arthrostylidium

13b. Primary branches usually 2 per node; internodes D-shaped in cross-section; culti-
vated bamboos, used for hedges, banana props, etc Phyllostachys

KEY II

GRASSES WITH VARIOUSLY CONCEALED OR HIGHLY MODIFIED SPIKELETS

la. Low, stoloniferous grass of mountain pastures; spikelets concealed within sheaths,

only stigmas and stamens protruding Pennisetum clandestinum

Ib. Grasses of various statures; spikelets not all concealed in leaf sheaths 2

2a. Inflorescence a spike of densely spiny, readily detached burs, each concealing

1-several spikelets Cenchrus

2b. Inflorescence not bearing spiny burs 3

3a. Inflorescence an unbranched spike bearing fascicles of coriaceous flat bracts which
conceal spikelets, fascicles readily detached from zigzag rachis

Anthephora hermaphrodita

3b. Inflorescence rachis without detachable fascicles 4

4a. Low stoloniferous or rhizomatous widely spreading plants 5

4b. Plants not stoloniferous or rhizomatous; culms erect 6

5a. Sheaths strongly flattened and keeled; plants stoloniferous on moist soil; spikelets
sunken into one side of flattened, corky, club-shaped erect rachis; spikelets

perfect-flowered Stenotaphrum secundatum

5b. Sheaths not keeled; plants stoloniferous or rhizomatous, forming mats or mounds
on coastal sand dunes or mud flats; plants dioecious; pistillate plants bearing rigid,

pointed horns containing caryopses, in clusters at tips of the culms Jouvea

6a. Pistillate spikelets borne in single spheroidal beads on tips of axillary pedun-
cles; staminate inflorescence a short cluster of spikelets protruding from

opening of bead Coix laeryma-jobi

6b. Pistillate spikelets borne in exposed spikes or on axillary cobs concealed in

leaf sheaths, never in beadlike structures 7

7a. Staminate spikelets borne on terminal panicle; pistillate spikelets borne on a thick

12 FIELDIANA: BOTANY

axillary spike (cob), completely covered with leaf sheaths, styles protruding as

"silks" Zea mays

7b. Staminate and pistillate spikelets borne together on 1-several spikes, basal portion
of each spike composed of a series of hard, bony internodes, each containing a
single pistillate spikelet, internodes separating when mature; terminal portion of
spike with flattened, non-disarticulating rachis, each node bearing a pair of stami-
nate spikelets Tripsacum

KEY III

LEAF BLADES WITH PSEUDOPETIOLES AT LEAST 5 MM. LONG

la. Spikelets laterally compressed, with 2-many florets 2

Ib. Spikelets not compressed, with a single floret 3

2a. Spikelets 2-flowered; flowers perfect Orthoclada laxa

2b. Spikelets several-many flowered; lowermost flower pistillate, the others

staminate Zeugites

3a. Veins of leaf blades diverging from midrib, running straight to lateral leaf margins;

lemmas awnless; inflorescence a panicle Pharus

3b. Veins of leaf blades running from base to tip of blades, parallel to midrib; spikelets
with a long, coiled awn; inflorescence a spike Streptochaeta

KEY IV

SPIKELETS WITH I-MANY FLORETS; GLUMES EVIDENT, WITH A MIDRIB;
DlSARTICULATION ABOVE THE GLUMES, WHICH REMAIN ON THE PEDICELS

la. Spikelets with 1 floret 2

Ib. Spikelets with 2-many florets, some of which may be staminate or sterile ... 23

2a. Spikelets unisexual, the two kinds different in appearance 3

2b. Spikelets with perfect flowers, all alike 7

3a. Leaf blades with veins running from base to tip 4

3b. Leaf blades broad, with veins running from midrib to lateral margins; fertile lemma

bearing hooked hairs Pharus

4a. Fertile floret broad and flat at apex, obpyramidal, hard and bony

Lithachne pauciflora

4b. Fertile floret acute-tipped, elliptical 5

5a. Inflorescence with usually less than 5 spikelets; low grasses of rain forests, less
than 30 cm. tall; leaf blades short, crowded; leafy culms resembling the pinnately

compound leaves of some legumes 6

5b. Inflorescence with many spikelets; plants small or up to 3-4 m. tall; leaves not

crowded, lanceolate to linear Olyra

6a. Leaf blades hirsute Raddia costaricensis

6b. Leaf blades glabrous Cryptochloa

7a. Dwarf paramo plants, less than 5 cm. tall, forming flat, circular mats, with stiff,
short leaves less than 1.5 cm. long; inflorescences of 1-7 spikelets, mostly hidden
among the leaves 8

BURGER: FLORA COSTARICENSIS 13

7b. Plants large or small, of various habitats; inflorescences with many spikelets, sup-
ported above foliage on peduncle 9

8a. Leaf blades sharp-pointed; first glume 3-5-nerved Aciachne pulvinata

8b. Leaf blades with boat-shaped tips; first glume 1-nerved

Muhlenbergia calcicola

9a. Floret hard, smooth, usuaUy awned 10

9b. Floret soft-textured, awned or awnless 16

lOa. Floret awnless, laterally compressed, with 2 minute rudimentary florets at-
tached below it and closely appressed to it, the three falling as a unit from

glumes Phalaris

lOb. Floret awned, without rudimentary florets below, terete or nearly so . . 1L

lla. Lemma bearing 3 awns, lateral 2 often smaller Aristida

lib. Lemma bearing single awn 12

12a. Awn attached to back of lemma below tip Triniochloa stipoides

12b. Awn attached at tip of lemma 13

13a. Palea exposed between edges of lemma Lorenzochloa

13b. Palea concealed by overlapping margins of cylindrical lemma 14

14a. Floret plump, swollen near apex, the readily deciduous awn attached eccen-
trically Nassella

14b. Floret slender-cylindrical, firmly attached awn attached at center of apex . 15
15a. Awn glabrous, curved, not strongly twisted above base; in savannas at low eleva-
tions Aristida

15b. Awn hairy below, straight but geniculate, strongly twisted above the base; upper

elevations in mountains Stipa icku

16a. Fertile spikelets surrounded by cluster of bristles (abortive spikelets)

Pereilema
16b. Spikelets not surrounded by bristles 17

17a. Inflorescence a panicle 19

17b. Inflorescence of several-many 1-sided spikes or racemes 18

18a. Stoloniferous or rhizomatous plants; spikes digitate; lemmas awnless; com-
mon weed Cynodon

18b. Tufted plants; spikes racemose; lemmas awned; rare, Boruca

Gymnopogon fastigiatus

19a. Both glumes longer than floret 20

19b. One or both glumes shorter than floret 21

20a. Rachilla prolonged behind palea of the floret as a thin, often hairy bristle;

callus hairs often long and abundant, rarely short or scanty 58

20b. Rachilla not prolonged behind palea; callus hairs usually short or minute . 59

21a. Awn arising from the back of lemma below tip Triniochloa stipoides

21b. Awn absent or arising from tip of lemma 22

22a. Lemmas 1-nerved, awnless; ovary wall gelatinous and swollen when wet, the

seed extruding from burst ovary Sporobolux

22b. Lemmas 3-nerved, usually awned; ovary wall not becoming gelatinous, seed

not extruding Muhlenbergia

23a. Inflorescence a single balanced or 1-sided spike or raceme 24

14 FIELDIANA: BOTANY

23b. Inflorescence a panicle, or group of spikes or racemes borne on common pedun-
cle 29

24a. Florets becoming entangled into single group by the elongated, stiff,

spirally-coiled styles; stigmas 3 Streptogyna americana

24b. Florets not becoming entangled by styles; stigmas 2 25

25a. Spikelets on short, erect, hairy pedicels Brachypodium mexicanum

25b. Spikelets sessile 26

26a. Spikelets 2-flowered; keels of lemmas with row of short, stiff, spreading hairs;

cultivated, upper elevations, rare Secale cereale

26b. Spikelets with more than 2 flowers; keels of lemmas without spreading

hairs 27

27a. Spikelets placed edgewise to rachis, only exterior glume present; flowers perfect;

upper elevation pastures Lolium perenne

27b. Spikelets placed flatwise to rachis; both glumes present 28

28a. Flowers staminate; wiry stoloniferous seashore plants Jouvea

28b. Flowers perfect; caespitose alpine plants; Cerro Chirripo Grande

Agropyron

29a. Tall, stout, reedlike grasses, culms usually 2-12 m. tall; panicles large, plumelike,
spikelets silky because of abundant long hairs attached to lemmas or rachillas

(glabrous in staminate Gynerium) 30

29b. Grasses of various statures, but usually less than 2 m. tall; inflorescences not

silky-hairy 33

30a. Culms solid; leaves all in fan-shaped cluster near top of culms; spikelets with 2
florets, the staminate ones glabrous; panicles more than 1 m. long on larger

plants Gynerium sagittatum

30b. Culms hollow; leaves basal or along culms; spikelets with more than 2

florets 31

31a. Lemmas hairy 32

31b. Lemmas glabrous; rachilla internodes long-hairy Phragmites australis

32a. Leaf blade bases very broad, conspicuously clasping; leaves spaced evenly
along culms; blades often yellow-striped; flowers perfect; cultivated for orna-
ment, or escaped Arundo donax

32b. Leaf blades narrow; leaves aggregated into basal cluster, the culms few-
leaved; flowers functionally unisexual; usually paramo plants, one species

rarely cultivated Cortaderia

33a. One or both glumes much shorter than spikelet 42

33b. Both glumes at least three-fourths as long as spikelet 34

34a. Lower 1 or 2 florets much longer than terminal floret and either staminate or

sterile 35

34b. Lower florets about as long as upper florets, all perfect-flowered and similar

to lowermost 37

35a. Spikelets 3-flowered, 1 or both of lower florets with awns and either staminate or

sterile; plants with sweet odor of coumarin 36

35b. Spikelets 2-flowered, lower floret staminate, awnless; upper floret perfect, with

conspicuous geniculate awn; plants not sweet-scented Arundinella

36a. Glumes very unequal; both of the 2 lower florets sterile

Anthoxanthum odoratum

BURGER: FLORA COSTARICENSIS 15

36b. Glumes equal; at least 1 of lower florets staminate HierochloU

37a. Spikelets 2 cm. or more long; glumes many-nerved; annual crop, persisting after

cultivation in mountain fields Avena saliva

37b. Spikelets less than 2 cm. long; glumes 1-5-nerved 38

38a. Lemmas with 3 conspicuous nerves; spikelets nearly sessile, arranged in 2
rows along lower sides of the simple, elongated panicle branches; lemmas

awnless or short-awned Leptochloa

38b. Lemmas with 5 or more nerves; spikelets variously arranged, mostly in open

panicles, not along lower sides of simple panicle branches 39

39a. Florets 4-5; lemmas nearly awnless, bidentate at tip; rare introduction in high-
elevation pastures Danthonia decumbens

39b. Florets 2-3; lemmas awned, the awn from the back or between teeth; plants of

upper elevations 40

40a. Awn attached above middle of lemma Trisetum

40b. Awn attached near base of lemma 41

4 la. Rachilla extending above base of upper floret as a minute hairy bristle; perennial

Deschampsia
41b. Rachilla not extending beyond second floret; diminutive annual

Aira caryophyllea

42a. Lemmas with 3 conspicuous nerves 43

42b. Lemmas with 5 or more inconspicuous nerves, or rarely only the midrib

visible 50

43a. Spikelets with single fertile floret, a differently shaped rudimentary floret above

it 44

43b. Spikelets with several-many similar florets 45

44a. Inflorescence of 1-several whorls of spikes; second floret with evident

lemma 60

44b. Inflorescence a raceme of spikes; second floret much reduced, lemma scarcely

wider than awn; rare, Boruca savannas Gymnopogon fastigiatus

45a. Spikelets sessile, pectinately arranged in short, thick, 1-sided spikes borne in 1 or 2

whorls 46

45b. Spikelets borne on pedicels, either in panicles, or racemosely along slender

branches attached to central rachis 47

46a. Rachis of each spike extended beyond spikelets as naked tip; second glume

bearing short, divergent awn Dactyloctenium aegyptium

46b. Rachis covered with spikelets to its tip; glumes not bearing awns

Eleusine indica
47 a. Palea long-hairy on its upper half; tip of lemma split, the short awn arising between

2 teeth; sandy Caribbean beaches Triplosis

47b. Palea not long-hairy; tip of lemma various; plants not confined to sandy beaches . 48

48a. Primary panicle branches elongated and simple, spikelets arranged in 2 rows

along the lower side, on very short pedicels; lemmas awned or awnless . 49

48b. Primary panicle branches at least in part with secondary branches; spikelets

not arranged in rows along lower sides; some of pedicels at least half as long

as spikelets; lemmas awnless Erogrostis

49a. Glumes several-nerved; lemmas long-awned, spikelets 1-2 cm. long

Gouinia virgata

16 FIELDIANA: BOTANY

49b. Glumes 1-nerved; lemmas short-awned or awnless; spikelets less than 5 mm. long

Leptochloa

50a. Spikelets all alike 51

50b. Spikelets paired, one of each pair sterile, containing only empty lemmas, its
rachilla not disarticulating; the other fertile, its lemmas 1-nerved, rachilla
disarticulating; panicle dense, spikelike; introduced in upper elevation

pastures Cynosurus cristatus

51a. Leaf sheaths with united edges, at least for basal third of their length 52

51b. Leaf sheaths with overlapping edges 54

52a. Lemmas blunt-tipped, nerves running parallel to the midrib

Glyceria plicata

52b. Lemmas acute or awned, nerves converging toward the midrib 53

53a. Spikelets 2 cm. or more long, all on evident pedicels Bromus

53b. Spikelets less than 1 cm. long, subsessile, crowded in dense fascicles at tips of the

few, rigid panicle branches Dactylis glomerata

54a. Plants tall, stout, extensively stoloniferous; on coastal sand dunes; spikelets

strongly compressed and keeled Uniola pittieri

54b. Plants not stoloniferous; growing at middle and upper elevations; spikelets
not strongly compressed and keeled 55

55a. Lemmas nearly circular in outline, spreading at right angles to rachilla, awnless

and without evident nerves Briza minor

55b. Lemmas longer than wide, acute or awned at tip, placed at acute angles to

rachilla 56

56a. Lemmas awned or acuminate; callus never bearing cottony hairs; leaf blades

with acuminate tips 57

56b. Lemmas awnless, blunt or acute, pubescent on nerves or with a tuft of cot-
tony hairs on callus; leaf blades with blunt, boat-shaped tips Poa

57a. Anther 1, usually not exserted from the cleistogamous florets; small caespitose

annuals, leaf blades usually 1-2 mm. wide Vulpia

57b. Anthers 3, usually exserted during anthesis; leaf blades mostly 3 mm. or more

wide; caespitose perennials, often tall Festuca

58a. Low, delicate grasses with abundant tufts of capillary basal leaves; panicles

open, delicate; spikelets 2 mm. or less long; anthers 3 . Agrostis bacillata

58b. Coarse grasses, lacking capillary basal foliage; leaf blades elongated, often

stiff and involute; panicles dense or spikelike; spikelets mostly more than

4 mm. long; anthers 1, 2, or 3 Calamagrostis

59a. Lemmas plainly 3-nerved, tapering to an acuminate apex; panicle dense, cylindri-
cal, dark gray; rare; Chirripo Grande Muhlenbergia nigra

59b. Lemmas faintly 5-nerved, awnless or with dorsal awn; panicles open or dense;

plants widespread at upper elevations Agrostis

60a. Culm internodes solid, pithy; spikelets arranged in 2 evident rows along
rachis; fertile lemma greenish or tan, bearing an awn as long as or longer than

body; plants widespread Chloris

60b. Culm internodes hollow; spikelets 2-rowed but overlapping and forming a
single file; fertile lemma chocolate brown, nearly awnless; plants of sandy
Caribbean beaches Eustachys petraea

BURGER: FLORA COSTARICENSIS 17

KEYV

SPIKELETS DISARTICULATING FROM THE PEDICELS INDIVIDUALLY,
WITHOUT ATTACHED RACHIS OR BRISTLES

la. Spikelets all alike in appearance, usually with perfect flowers 3

Ib. Spikelets of 2 unlike kinds, frequently some abortive or unisexual 2

2a. Inflorescence a single erect rame, bearing pairs of unlike spikelets; 1 of each
pair long-awned, detachable, and perfect-flowered, the other awnless, persis-
tent, and staminate; grasses of dry savannas Trachypogon

2b. Inflorescence a panicle or raceme; spikelets awnless, all unisexual; plants of

moist or marshy areas 43

3a. Spikelets when mature covered with hooked spines

Pseudoechinolaena polystachya

3b. Spikelets not covered with hooked spines 4

4a. Spikelets laterally compressed 5

4b. Spikelets dorsally compressed or terete 17

5a. Spikelets borne in single raceme or spike 6

5b. Spikelets borne in panicle or cluster of spikes 8

6a. First glume missing, second glume leathery, its lower margins united; floret

1 Zoysia

6b. First glume present; margins of glumes not united; sterile lemma present

below fertile floret 7

7a. Spike erect, slender; first glume about as long as spikelet . . Mesosetum pittieri
7b. Spike strongly reflexed, short and thick; first glume twice as long as rest of

spikelet, tuberculate-hispid Echinolaena gracilis

8a. Spikelets sessile, in slender or dense spikes 9

8b. Spikelets pedicellate, in open or dense panicles 10

9a. Spikelets awned, in very slender spikes; delicate annual weed; Meseta Central

Arthraxon qvartinianus
9b. Spikelets awnless, densely imbricated in stiff, short spikes; wiry perennial; coral

beaches north of Limdn Spartina spartinae

lOa. Spikelets concealed by long pinkish or silvery hairs Rhynchelytrum repens

lOb. Spikelets not concealed by hairs 11

11 a. Spikelets with 2 bracts only (lemma and palea), glumes missing; lemma awnless

Leersia

lib. Spikelets with 4 or more bracts; lemmas awned or awnless 12

12a. Leaf blades borne on pseudopetioles Zeugites

12b. Leaf blades lacking pseudopetioles 13

13a. Spikelets with numerous florets; tall, stout, stoloniferous grasses of sea beaches

Uniola pittieri

13b. Spikelets with 1-2 florets; not sea beach grasses 14

14a. Glumes longer than florets 15

14b. "Glumes" (actually sterile lemmas) much shorter than floret Oryza

15a. Foliage densely velvety-hairy; florets 2 Holcus lanatus

15b. Foliage not velvety; floret 1 16

16a. Glumes and lemma awned; rachilla not prolonged . . . Polypogon elongatus

18 FIELDIANA: BOTANY

16b. Glumes and lemma awnless; rachilla prolonged behind palea

Cinna poaeformis

17a. Spikelets covered with long, dense, silky hairs 18

17b. Spikelets glabrous or pubescent, but not silky-hairy 20

18a. Inflorescence golden-brown Eriochrysis cayanensis

18b. Inflorescence white or grayish 19

19a. Both glumes longer than thin, delicate floret Imperata

19b. First glume much shorter than stiff, dark-colored floret Digitaria insularis

20a. Leaf blades broad, longitudinally pleated Setaria

20b. Leaf blades never pleated 21

21a. Each spikelet subtended by 1 or more stiff bristles (sterile branchlets); inflores-
cence a panicle 22

21b. Spikelets not subtended by sterile bristles, every branchlet ending in a spikelet;

inflorescence a panicle or group of racemes 23

22a. Each spikelet subtended by a single bristle; spikelets with a broad papery

wing when mature Ixophorus unisetus

22b. Each spikelet subtended by several-many bristles; spikelets never winged

Setaria

23a. Inflorescence a single 1-sided raceme on each peduncle 24

23b. Inflorescence of several-many racemes, or a panicle 25

24a. Spikelets in 2 or 4 longitudinal rows, their sterile lemmas facing outward; first

glume present or absent Paspalum

24b. Spikelets in single longitudinal row, paired so that sterile lemmas of each 2
successive spikelets are facing each other; first glume present . . . Thrasya

25a. Spikelets awnless, with hardened knob-like protrusion at base, formed of first
glume and rachilla joint Eriochloa

25b. Spikelets awned or awnless, without basal knob-like protrusion; first glume evident

or missing 26

26a. Spikelets awned or awn-tipped 27

26b. Spikelets blunt or acute, never awned 30

27a. Foliage densely covered with sticky hairs; plants aromatic . Melinis minutiflora

27b. Foliage not sticky-hairy; plants not aromatic 28

28a. Plants decumbent or stoloniferous; leaf blades short, lanceolate or elliptical

Oplismenus
28b. Plants not stoloniferous; leaf blades linear 29

29a. Spikelets narrow, with pointed basal callus; both glumes long-awned

Chaetium bromoides

29b. Spikelets ovoid, blunt at base; glumes not long-awned Echinochloa

30a. Spikelets with 2 fertile florets, nearly spherical Isachne

30b. Spikelets with a perfect terminal floret, lower floret staminate or sterile . 31

31a. Spikelets borne in panicles 36

31b. Spikelets borne in 1-sided spikelike racemes, all on lower sides of flattened or

triangular rachises 32

32a. Backs of fertile lemma and second glume turned toward rachis 33

32b. Backs of fertile lemma and second glume turned away from rachis 35

33a. Fertile floret soft and flexible, edges of lemma thin, exposed Digitaria

BURGER: FLORA COSTARICENSIS 19

33b. Fertile floret rigid, edges of lemma inrolled and concealed 34

34a. Fertile lemma smooth; spikelets plano-convex; first glume small or absent

Paspalum
34b. Fertile lemma transversely corrugated; spikelets with rounded edges; first

glume well developed 44

35a. First glume well developed; spikelet with 3 bracts below fertile floret; fertile

lemma corrugated Brachiaria

35b. First glume absent; spikelet with 2 bracts below fertile floret; fertile lemma smooth

Axonopus
36a. Spikelets with 2 bracts below fertile floret, first glume missing

Leptocoryphium lanatum

36b. Spikelets with 3 bracts below fertile floret, first glume present 37

37a. Spikelets placed very obliquely on tip of pedicel, rotund, turning black when
mature; second glume and florets with minute tufts of hairs at tip; some species

with woody culms Lasiacis

37b. Spikelets not obliquely placed on pedicel; florets lacking tufts of hairs at tip; culms

not woody 38

38a. Fertile lemma with small, fleshy blisters, which leave scar-like depressions in

drying, along its edges at base Ichnanthus

38b. Fertile lemma lacking blisters or scars along its edges 39

39a. Panicles dense, cylindrical and spikelike 40

39b. Panicles more or less open, not spikelike 41

40a. Spikelets strongly inflated or bulging on second glume side; blades narrow;

culms less than 1 m. tall Sacciolepis

40b. Spikelets not inflated; blades very wide, with prominent cordate bases; culms

usually 2-3 m. tall Hymenachne

41a. Both glumes as long as the pointed spikelet Homolepis aturensis

41b. First glume shorter than spikelet 42

42a. Fertile lemma with a laterally flattened, beaklike tip . Acroceras zizanioides

42b. Fertile lemma rounded to tip, without beak Panicum

43a. Leaf blades linear, elongated, acuminate, lacking pseudopetioles; aquatic or marsh

plants Luziola

43b. Leaf blades narrowly triangular, blunt-tipped, less than 5 x longer than wide,

borne on short pseudopetioles Olyra

44a. Leaf blades ovate, 4-5 times longer than wide, base cordate; racemes divari-
cate, few; rachis of each raceme terminating in a spikelet Urochloa

44b. Leaf blades linear, many times longer than wide, not cordate; racemes ap-
pressed to rachis, many; rachis of each raceme terminating in a flattened
sterile tip Paspalidium

KEY VI

SPIKELETS ALL OR SOME FALLING IN CLUSTERS OF Two OR MORE, OR ATTACHED TO
RACHIS INTERNODES, PEDICELS, OR BRISTLES (REDUCED BRANCHLETS OR ABORTIVE

SPIKELETS)

la. Inflorescences usually arising directly from soil on short, leafless peduncles, club
shaped, disarticulating into individual internodes, each bearing 3 flattened bracts,

20 FIELDIANA: BOTANY

each with 2 minute staminate spikelets, and concealing within them a slender
rachis and a solitary sessile pistillate spikelet; rain forests, Caribbean lowlands

Pariana parvispica
Ib. Inflorescences all borne on leafy culms, various but never as in la 2

2a. Inflorescence a slender simple panicle, each branch reduced to single stiff
unbranched bristle that falls from rachis at maturity, bearing a single appressed
permanently attached spikelet near its base Paratheria

2b. Inflorescence various, but never with simple deciduous branches, each bear-
ing solitary spikelet 3

3a. Inflorescence a dense cylindrical bristly panicle; each spikelet or spikelet group
surrounded by ring of long stiff bristles (reduced branchlets), with which it falls

from the persistent rachis Pennisetum

3b. Spikelets not surrounded by elongated bristles; inflorescence a panicle or group of

spikes, rames, or spikelet fascicles 4

4a. Rachis of individual spike or rame disarticulating into individual internodes at

maturity, each carrying spikelets with it 9

4b. Rachis remaining intact, spikelet groups falling from it, or entire inflores-
cence falling 5

5a. Inflorescence a single cylindrical or flattened spike or rame, without visible

branches 6

5b. Inflorescence a raceme of spikelet fascicles or short 1-sided spikes 7

6a. Rachis flattened, corky, spikelets acute, sunken into 1 side of the rachis;
leaves subopposite in pairs; sheaths strongly keeled

Stenotaphrum secundatum
6b. Rachis thin, truncate spikelets closely overlapping and surrounding it; leaves

alternate Eremochloa ophiuroides

7a. Spikelets borne in short, 1-sided spikes of more than 3 spikelets Bouteloua

7b. Spikelets borne in fascicles of 1-3, often with short attached bristles 8

8a. Spikelets 1-2 in each cluster, accompanied by bristles (reduced or abortive

spikelets) Pentarraphis annua

8b. Spikelets 3 in each cluster, all pedicellate; sterile bristles absent

Aegopogon cenchroides

9a. Sessile spikelets laterally compressed, glumes keeled 10

9b. All spikelets dorsally compressed or spherical, glumes not keeled 12

lOa. Spikelets awnless, members of each pair equal; inflorescence a large ter-
minal panicle of verticillate rames; plants up to 2 m. tall, in dense, hard

clumps Vetiveria zizanioides

lOb. Spikelets awned, the pedicellate one absent or different from the sessile one;

inflorescence not a large panicle 11

lla. Spikelets solitary, the lowermost ones sometimes accompanied with a minute
pedicel; low, creeping plants with short, cordate leaf blades

Arthraxon quartinianus
lib. Spikelets paired, dimorphic, pedicellate ones enlarged and flattened; plants erect;

leaf blades linear Diectomis

12a. Inflorescence silky-hairy, abundant hairs exceeding and concealing spike-
lets 13

12b. Inflorescence not silky-hairy, spikelets easily visible 14

BURGER: FLORA COSTARICENSIS 21

13a. Inflorescence open, pyramidal; hairs white Saccharum officinarum

13b. Inflorescence dense, cylindrical (like Typha); hairs golden-brown

Eriochrysis cayanensis
14a. Spikelets, or some of them, sunken into hollows of thickened cylindrical

rachis 15

14b. Spikelets never sunken into thin or partially thickened rachis internodes . 17
15a. Spikelets all unisexual, lower part of each inflorescence made up of a series of bony
cylindrical internodes, each containing single pistillate spikelet; upper portion flat-
tened, bearing paired staminate spikelets Tripsacum

15b. Sessile spikelet of each pair with a perfect flower; inflorescence not as in 14a . 16
16a. Rachis internode united with edge of the pedicel; pedicellate spikelets sterile;

foliage bristly-hispid, irritating to touch Rottboellia exaltata

16b. Rachis internode not united with pedicel, pedicellate spikelet sometimes with

a flower; foliage not bristly Coelorachis aurita

17a. Rames 1 on each peduncle (but culms sometimes bearing several to many pedun-
cles, interspersed with bracts) 18

17b. Rames 2-many on each peduncle, forming an inflorescence 21

18a. Low, creeping stoloniferous grass; spikelets equal, in pairs or trios, at each

node of rachis Polytrias amaura

18b. Plants not low and creeping; spikelets in pairs, the sessile one fertile, usually

awned, the pedicellate spikelet much reduced and sterile 19

19a. Sessile spikelets spherical, 1-2 mm. in diameter, hard, black, rough and ridged,

awnless Hackelochloa granularis

19b. Sessile spikelets ovate, acute, never spherical, awned or awnless 20

20a. Sessile spikelets perfect-flowered, usually awned; pedicellate spikelets re-
duced, sterile Schizachyrium

20b. Sessile spikelets pistillate, awnless; pedicellate spikelets staminate, awnless,

as large as sessile ones Hypogynium virgatum

21a. One spikelet of each pair sessile 22

2 1 b. Both spikelets of each pair pedicellate and usually alike: pedicels of unequal length

Ischaemum

22a. First glume strongly cross-wrinkled; lower floret staminate . . Ischaemum
22b. First glume not cross-wrinkled; lower floret sterile, represented by an empty

lemma 23

23a. Rachis segment and pedicels with thick margins and a very thin, translucent center

line; first glume of sessile spikelets 5-9-nerved 24

23b. Rachis segments and pedicels not thin in center; first glumes of sessile spikelets

usually 2-5-nerved 25

24a. First glume of sessile spikelets with conspicuous circular pit in the center,
rames sessile in fan-shaped cluster, spikelet-bearing to their bases

Bothriochloa
24b. First glume of sessile spikelets lacking a pit; rames borne individually on

slender weak peduncles along central rachis Euclasta

25a. Foliage strongly lemon-scented; plants very rarely blooming

Cymbopogon citratus
25b. Foliage not lemon-scented; annual bloomers 26

22 FIELDIANA: BOTANY

26a. Individual rames of numerous pairs of spikelets 28

26b. Individual rames numerous, of 1-7 segments (spikelet pairs), borne on lateral
branches of large terminal, bractless panicle 27

27a. Pedicellate spikelets present but awnless Sorghum

27b. Pedicellate spikelets absent, only hairy pedicels present Sorghastrum

28a. All pairs of spikelets of each rame alike, each with a fertile sessile spikelet

Andropogon

28b. Lowermost 1 or 2 pairs of spikelets of each rame awnless, staminate or
sterile, others with perfect-flowered, awned sessile spikelets and awnless
or rudimentary pedicellate spikelets Hyparrhenia

ACIACHNE Bentham

REFERENCES: Agnes Chase, Aciachne, a cleistogamous grass of the
high Andes, J. Wash. Acad. Sci. 14:364-366. 1924. J. Reeder & C.
Reeder, Parodiella, a new genus of grasses from the high Andes, Bol.
Soc. Argent. Bot. 12:268-283. 1968.

Low, pungent cushion grasses of high altitudes. Inflorescence a short spike of 1-3
spikelets, mostly hidden among the leaves. Glumes obtuse, equal, stiff, the first 3-5-
nerved, the second 5-nerved; nerves evident; disarticulation above the glumes; floret 1;
lemma faintly 3-nerved, indurate, smooth and shining, tapering into a short, stiff, awn-
like tip; callus blunt; palea about as long as the body of the lemma; lodicules 3, dimorphic,
the broader pair each 1-nerved; third lodicule solitary, spatulate, nerveless.

One species, restricted to the paramos of high mountains, mostly in
the Andes. The genus is closely related to Lorenzochloa, which occurs
in similar habitats. (Pooideae: Stipeae.)

Aciachne pulvinata Bentham, in Hook., Icon. PL 14:44, pi. 1362.
1880. Figure 1.

Perennial, forming low cushions, 1-3 cm. high; culms much-branched; internodes very
short, concealed by the densely overlapping sheaths; sheaths thin, hyaline, 3-5-nerved,
somewhat gaping; ligule stiff, erect, truncate, scabrid on the back, ca. 0.7 mm. long,
decurrent onto the sheath margins; blades numerous, forming a pungent fan-shaped
cluster near the culm apex, folded, 4-10 mm. long, terete, glabrous beneath, erect or
slightly recurved, with a pungent tip; upper surface with abundant short, peg-like hairs;
blade in cross-section with a thick, continuous sclerenchyma layer covering the entire
external surface and the edges of the upper epidermis; vascular bundles 3; mesophyll
somewhat radially arranged, densely packed; prophylla prominent, stiff, the keels ex-
serted as 2 pungent teeth. Inflorescence scarcely exceeding the foliage, a short spike of
1-3 spikelets. Glumes obtuse, stiff, evidently nerved; lemma stiff, faintly 3-nerved,
smooth and shining, tapering to a short awnlike tip; palea nearly as long as the lemma;
anthers 3; style branches 2, separate. Chromosome number 2n = 22 (Reeder & Reeder,
1968).

The only Central American collection of this species is the following:
Prov. San Jose: Valle de los Conejos, Chirripo Massiv, 3,500 m., 16

FIG. 1. Aciachne pulvinata. A, portion of a matted plant; B, spikelet; C, floret.

24 FIELDIANA: BOTANY

March 1971. H. Kuhbier 0393 (BREM, CR, ISC). High mountains of
southern Costa Rica; Venezuela, Peru, and Bolivia.

The occurrence of Aciachne along with two other xeromorphic
grasses of Andean distribution, Lorenzochloa erectifolia and Stipa
hans-meyeri, on the high paramos of Chirripo Grande in Costa Rica,
poses a difficult question as to the manner of migration of these and
many other high-altitude paramo plants that occur in both Central
America and the Andes.

ACROCERAS Stapf in Prain

Sprawling annuals and perennials, the culms rooting at the lower nodes; inflorescence
a panicle. Spikelets large, apiculate, the glumes and sterile lemma with pronounced
crest-like keels at their tips; first glume nearly as long as the spikelet, 3-5-nerved; second
glume and sterile lemma equal, 5-nerved; sterile lemma with a well-developed palea;
fertile lemma rigid, smooth, with a laterally flattened herbaceous green beak, a circular
depressed area on the back above the base; margins of lemma thickened but not involute;
palea flat, rigid, with a small flattened bidentate herbaceous beak at its tip; rachilla thick
and indurate, with definite internodes between the glumes and between the second
glume and the sterile lemma.

Acroceras is a small genus of tropical grasses, widespread in Africa
and Asia. Acroceras zizanioides appears to be the only species found in
the Americas, where it may have been introduced. The genus is some-
what similar to the endemic American Lasiacis, but the resemblances
may be coincidental. (Panicoideae: Paniceae.)

Acroceras zizanioides (H.B.K.) Dandy, J. Bot. 69:54. 1931. A.
oryzoides Stapf in Prain, Fl. Trop. Africa 9:622. 1920. Panicum
oryzoides Swartz, Prodr. Veg. Ind. Occ. 23. 1788, not P. oryzoides
Ard., Animadv. Spec. Alt. 16, pi. 5. 1764. P. zizanioides H.B.K. , Nov.
Gen. & Sp. 1:100. 1816. Figure 2.

Duration indefinite; plants sprawling or scrambling, rooting at the lower nodes; culms
up to 2 m. long, the tips ascending; branching freely at lower nodes; culms glabrous,
smooth, thick-walled, hollow; nodes glabrous or papillose-hispid. Sheaths shorter than
the internodes, glabrous or papillose-hispid, especially near the apex; exposed margin of
sheath papillose-hispid; ligule 0.2-0.5 mm. long, membranaceous; blades cordate at the
base above a short pseudopetiole, glabrous or nearly so, sometimes papillose-hispid on
the basal lobes of the blade, collar, and midrib above the base. Inflorescence terminal on
the main culm or on leafy branches; panicles open, with few rather simple ascending
branches, 9-35 cm. long, 2-10 cm. wide, mostly 2-4 times longer than wide. Spikelets
mostly paired, one short pedicellate and the other longer pedicellate, on angular
pedicels, appressed along the main panicle branches; Spikelets dorsally compressed,
elliptic-ovate, 5.5-6.6 mm. long, glabrous; first glume 4.0-5.4 mm. long, ovate, 3-5-
nerved, clasping the second glume; second glume 5-6 mm. long, 5-nerved; lower (sterile)
lemma 4.5-5.4 mm. long, 5-nerved; palea 3.5-4.0 mm. long; anthers purple, 2 mm. long;

FIG. 2. Acroceras zizanioides. A, spikelet; B, fertile floret; C, panicle.

26 FIELDIANA: BOTANY

fertile floret 4.5-5.0 mm. long, palea with 2 marginal triangular membranaceous flanges
just above the base. Chromosome number from Costa Rican specimens, n = 18.

Common on shaded riverbanks and forest margins, shaded road-
sides; mostly below 100 m. but occasionally to 1,100 m.; Caribbean and
Pacific slopes; June to December, possibly yearlong. Southern Mexico
to northern Argentina; West Indies; Tropical Africa.

AEGOPOGON Humboldt & Bonpland ex Willdenow

REFERENCE: A. A. Beetle, The genus Aegopogon Humb. & Bonpl. ,
Univ. of Wyoming Publications XIII:17-23. 1948.

Delicate sprawling or stoloniferous grasses; inflorescence a unilateral raceme of de-
tachable triads of spikelets, the triads borne on short persistent branchlets, in 2 rows
along 2 sides of a triquetrous rachis; triad deciduous as a group, with a short segment of
the branch below as a hairy stipe; each triad with 1 short-pedicellate or subsessile fertile
spikelet and 2 longer-pedicellate sterile or staminate ones; fertile spikelet 1-flowered;
glumes equal, shorter than the floret, awned from a bifid apex; lemma 5-lobed, the 2
marginal lobes nerveless, membranaceous, the 3 prominent nerves each extending into
an awn, the 2 lateral awns much shorter than the central one; palea about as long as the
lemma, the nerves extending into awns; rachilla not extended beyond the floret.

Aegopogon is a small genus of American grasses, found in warm, dry
regions from the southwestern United States to South America. It is
most closely related to Pentarraphis and Bouteloua. (Chloridoideae:
Chlorideae.)

KEY TO SPECIES OF Aegopogon

la. Glumes oblong, narrow, lateral lobes acute; ligules 1.5-4.5 mm. long

Ae. cenchroides

Ib. Glumes flabellate, lateral lobes broadly rounded; ligules 0.7-1.5 mm. long

Ae. tenellus

Aegopogon cenchroides Humb. & Bonpl. ex Willd., Sp. PL 899.
1806. Figure 3.

Duration indefinite; plants sprawling, the culms rooting at the nodes, forming large
patches; erect portions of culms 3-30 cm. long; branching abundant from the trailing
culms; prophylla pointed, ciliate on the keels, 7-15 mm. long; culms 0.2-0.3 mm. thick,
hollow, glabrous; sheaths much shorter than the internodes, glabrous to puberulent;
ligules 1.5-4.5 mm. long, membranaceous; blades 2-10 cm. long, 1-2 mm. wide, glabrous,
scabrous, or puberulent; peduncle slender, exserted 3-10 cm.; inflorescences solitary,
terminal on the erect culm branches, 2-9 cm. long; spikelet triads in 2 rows, but usually
oriented in one direction; stalk of the spikelet triad ca. 0.2 mm. long, bearded; pedicel of
fertile spikelet ca. 0.3 mm. long, those of the sterile pair 0.4-0.7 mm. long; sterile
spikelets range from nearly as long as the fertile one to minute rudiments; fertile
spikelet 3.7-5.5 mm. long, excluding the central awn; glumes subequal, 3-9 mm., nar-
rowly oblong, the apex bifid, the lobes acute, the awn making up half or more of the total

FIG. 3. Aegopogon cenchroides. A, inflorescence; B, triad of spikelets.

28 FIELDIANA: BOTANY

length; lemma glabrous, membranaceous, lanceolate, the undivided portion 1.5-2.5 mm.
long, the lateral awns 1.5-2.5 mm. long, the central awn 3.5-8.5 mm. long; palea 2.5-5.2
mm. long, including keel awns up to 1 mm. long; anthers 3, 0.5-2.0 mm. long, yellow.
Chromosome numbers, from Costa Rican material, n = 20, 40. Hexaploids with n = 30
are also known.

Road embankments and open slopes, mid elevations from 1,400-
2,700 m., volcanoes of the Meseta Central; Cordillera de Talamanca.
June to December. Mexico to Colombia and Venezuela.

The spikelets are extremely variable in awning and in the degree of
development of the two sterile lateral spikelets, which range from
sterile rudiments to a few which are either staminate or pistillate. The
extreme morphological variability of our material does not appear to
be correlated with the ploidy level. This small genus obviously needs
further study.

Aegopogon tenellus (DC.) Trin., Gram. Unifl. 164. 1824. Lamarckia
tenella DC., Cat. Hort. Monspel. 120. 1813.

Duration indefinite; culms sprawling and rooting at the nodes, the erect flowering
portions 10-30 cm. long; branching abundant from the decumbent portions; prophylla
10-12 mm. long, ciliate on the keels; culms 0.5 mm. or less thick, hollow, glabrous; nodes
dark colored, glabrous; sheaths shorter than the internodes, glabrous or sparingly hir-
sute; ligule a lacerate membrane, 0.7-1.5 mm. long; blades 1-7 cm. long, 1-2 mm. wide,
glabrous or puberulent; inflorescence a unilateral raceme of spikelet triads, 2-5 cm. long,
linear; pedicels of spikelets 1.0-1.5 mm. long, bearded; spikelets laterally compressed,
4.5-5.5 mm. long, excluding the central awn; glumes 4.0-4.5 mm. long, 1-nerved, flabel-
late, with a broad cordate apex, the midrib occasionally bearded near the base; un-
divided portion of lemma ca. 2.5 mm. long; lateral awns ca. 2.5 mm. long, the central one
ca. 11 mm.; palea ca. 4.5 mm. long, including awns ca. 2 mm. long; anthers 3, 0.6 mm.
long, tan.

The above measurements are taken from well-developed spikelets.
Many specimens show much reduced spikelets , often with reduced
awns (var. abortivus (Fourn.) Beetle). This species is known from
Costa Rica only by the following specimen: Prov. de San Jose, Vicinity
of Santa Maria de Dota, alt. 1,500-1,800 m., Standley 41720. Southern
Arizona to Costa Rica.

AGROPYRON Gaertner

Caespitose or rhizomatous perennial grasses; inflorescence a solitary terminal bal-
anced spike, the spikelets solitary at each node of the thin rachis and laterally appressed
to it. Glumes equal, several-many-nerved; florets several; disarticulation above the
glumes and between the florets; lemmas 5-7-nerved, awnless or awned from the tip;
palea nearly as long as the lemma.

BURGER: FLORA COSTARICENSIS 29

A large genus in temperate and cold regions of both Old and New
Worlds, much rarer in the southern hemisphere. The genus is closely
related to Elymus, Triticwn, Secale, Hordeum, etc. (Pooideae:
Triticeae). Compare also Brachy podium, which has similar inflores-
cence and spikelets, but the individual spikelets on short pedicels.

Agropyron attenuatum (H.B.K.) Roem. & Schult., Syst. Veg.
2:751. 1817. Triticum attenuatum H.B.K. , Nov. Gen. & Sp. 1:180.
1816. Figure 4.

Perennial, 1-2 m. tall; culms erect, unbranched, the bases decumbent or rhizomatous;
internodes glabrous, 2-3 mm. thick, thin-walled; nodes dark, contracted; sheaths mostly
overlapping, striate, slightly puberulent near the apex; ligule firm, membranaceous, 0.7
mm. long, continuous with the membranaceous sheath margin; blades up to 20 cm. long,
2-5 mm. wide, glabrous or puberulent above and below; uppermost blade reduced. Spike
11-14 cm. long, 5 mm. wide, the spikelets longer than the internodes and overlapping;
rachis internodes thin, flat, scabrid on the angles, 6-7 mm. long. Spikelets 15-17 mm.
long, laterally compressed; glumes equal, lanceolate or narrowly ovate, acute, flat,
overlapping on the abaxial side of the spikelet, 11 mm. long, 5-7-nerved; florets 3-5, the
terminal one rudimentary; lemmas lanceolate, 9-13 mm. long, rounded on the back,
scabrid; awn lacking or up to 1.5 mm. long; palea 9-10 mm. long, scabrid on the keels;
rachilla segments thick, 2.5-2.8 mm. long, the scar of disarticulation very oblique;
anthers 3, 2.5 mm. long, yellow; ovary with a large deltoid pubescent appendage.

Rare, paramos near summit of Chirripo Grande. This is the only
North American locality for this species, previously known only from
the Andes of Ecuador, Peru, and Bolivia. November-April.

This species can easily be confused with Brachypodium mexi-
canum, which occurs in the same area. The Brachypodium has short
pedicels, 1-3 mm. long, whereas the spikelets of Agropyron are sessile
or nearly so.

AGROSTIS Linnaeus

Mostly perennial grasses of temperate climates; plants caespitose, rhizomatous, or
stoloniferous. Inflorescence a terminal panicle; spikelets numerous, small, laterally com-
pressed; glumes nearly equal or the first slightly longer than the second, both exceeding
the single floret; disarticulation above the glumes; lemma thin, faintly 3-5-nerved, the tip
blunt or narrow, sometimes minutely toothed; callus often minutely bearded; lemma
occasionally bearing a straight or geniculate awn; palea in various species absent, min-
ute, or well developed; rachilla in one of our species (A. bacillata) produced behind the
palea as a minute bristle, otherwise absent; anthers 3.

Agrostis is a large genus of temperate and cold climates, in the
tropics confined to high altitudes. The spikelets are similar to those of
Calamagrostis, which differs in the possession of abundant callus hairs
and a prolonged, usually hairy rachilla. (Pooideae: Agrostideae.)

FIG. 4. Agropyron attenuatum. A, spike; B, spikelet; C, a single floret.

BURGER: FLORA COSTARICENSIS 31

KEY TO SPECIES OF Agrostis

la. Rachilla extended beyond base of palea as a bristle; lemmas awned or awnless

A. bacillata

Ib. Rachilla not evident beyond base of the palea 2

2a. Palea at least half as long as lemma 3

2b. Palea absent or less than half as long as lemma 5

3a. Ligule of innovations less than 1 mm. long, those of culm leaves up to 2 mm.

A. tennis

3b. Ligules mostly 3-8 mm. long 4

4a. Erect, rhizomatous plants A. gigantea

4b. Trailing, mat-forming stoloniferous plants A. stolonifera var. palustris

5a. Panicles narrow or spikelike, 5-10 x longer than wide, usually less than 1 cm. wide;

basal leaf blades capillary, less than 1 mm. wide 6

5b. Panicles open or diffuse, branches spreading, at least during flowering 7

6a. Panicles dense, the rachis mostly concealed; pedicels shorter than spikelets;
palea absent; awn twisted and geniculate; Cordillera de Talamanca

A. tolitcensis

6b. Panicles narrow but loose, rachis partly exposed; pedicels once to twice as long
as spikelets; palea ca. 1 mm. long; awn straight; around summit of Volcan Poas

A. pittieri

7a. Plants with abundant basal foliage, leaf blades narrow, flat or folded; palea absent;

awn present or absent 8

7b. Plants lacking conspicuous basal foliage; panicles very lax and much-branched; palea

minute; awn minute or absent A. perennans

8a. Spikelets ca. 2 mm. long; lemma 1.2-1.4 mm. long, awnless or with a minute awn

just below apex A. turrialbae

8b. Spikelets 2.9-3.7 mm. long; lemma 1.7-2. 2 mm. long; awn inserted below middle
of back, twisted and geniculate, exserted A. subpatens

Agrostis bacillata Hack., Oesterr. Bot. Z. 52:59. 1902. Figure 7.

Delicate, densely tufted perennial, 10-30 (-50) cm. tall; foliage mostly basal; culms
erect, unbranched, glabrous, ca. 0.2-0.3 mm. thick, with 1-2 shorter internodes above
the base, the terminal internode (peduncle) the longest; nodes purple; sheaths nearly as
long as the internodes; ligule a thin white membrane, 1.7-4.3 mm. long, tapering to an
acute apex; leaf blades 2-15 cm. long, 0.2-0.3 mm. thick as folded, stiffish and erect,
minutely scaberulous on the lower surface, tightly folded; upper surface with a few
coarse ridges. Peduncle exserted 2-6 cm.; inflorescence solitary, terminal, an open cylin-
drical delicate panicle, 4-11 cm. long, 3-5 cm. wide; branches delicate, mostly paired, thin
and flexuous, bearing spikelets on their outer half; pedicels spreading, longer than the
spikelets. Spikelets 1.8-2.0 mm. long, the glumes equal or the second slightly shorter
than the first, spreading apart at the tips, 3-nerved, ovate 4.5:1 as folded, acute, usually
purple, the keel slightly scabrid; lemma ovate-obovate 3:1 as folded, 5-nerved, the apex
blunt; a thin awn sometimes present, 0.3-0.6 mm. long, inserted on the back of the
lemma ca. one-third below its tip; palea 1.1-1.4 mm. long; anthers 3, purple, 0.8-1.0 mm.
long; rachilla prolonged behind the palea as a slender naked bristle, 1.1-1.4 mm. long.
Chromosome number n = 14 from a Costa Rican specimen.

32 FIELDIANA: BOTANY

PaYamos above 3,000 m. elev.; Asuncidn, Cerro de las Vueltas, Chir-
rip<5 Grande, above Llano Grande on Irazii. Apparently blooming
yearlong. Endemic to Costa Rica. The type, Pittier 10477, was col-
lected on the Cerro de la Muerte.

This species is unusual in the genus Agrostis by its possession of a
rachilla internode extended beyond the floret. In this it resembles
species of Calamagrostis, which differ in having unequal glumes and
prominent callus hairs.

Agrostis gigantea Roth, Tent. Fl. Germ. 1:31. 1788. Agrostis alba
Auth., non L.

Vigorous rhizomatous perennial; plants 40-120 cm. tall, erect or the culm bases de-
cumbent in wet sites; culms unbranched or branched from the lower nodes, glabrous,
hollow; nodes glabrous; sheaths glabrous; ligule a thin white membrane, usually 3-6 mm.
long, lacerate at the tip. Peduncle slender, exserted; inflorescence a solitary terminal
panicle, 8-25 cm. long, 3-15 cm. wide, ovoid-pyramidal, usually rather open; branches
fascicled, of various lengths; spikelets clustered, the pedicels usually shorter than the
spikelet. Spikelets 2-3 mm. long; first glume ovate, acute, 1-nerved, longer than the
similar second glume; glumes scabrous on the keel; lemma ca. 2 mm. long, ovate, acute,
faintly 3-5-nerved; callus minutely bearded, tip blunt, usually awnless; palea ca. half as
long as the lemma, with 2 faint vascular bundles; anthers 3, yellow, 1.0-1.5 mm. long.

Moist pastures and roadsides; volcanoes of the Meseta Central,
above 2,000 m. Blooming yearlong.

This species is a cool-climate pasture grass of European origin. Its
occurrence in dairy pastures on the volcanoes suggests that it was
introduced in pasture seed mixtures, along with other European
species. Two similar species, A. stolonifera and A. tennis, occur in the
same types of habitats. This species has consistently been called A.
alba in American literature for many years. However, European au-
thors universally reject that name. The panicles have a reddish or
brownish tinge when well developed, hence the English common
name, "redtop."

Agrostis perennans (Walt.) Tuckerm., Amer. J. Sci. 45:44. 1843.
Cornucopiae perennans Walt., Fl. Carol. 74. 1788. An extensive
synonymy is given in Hitchcock, Man. Gr. U.S., ed. 2. 1950. Figure 5.

Weak, somewhat decumbent caespitose perennial; culms up 100 cm. long, unbranched
or branching only from the base; internodes glabrous, hollow, 0.7-1.0 mm. thick; sheaths
glabrous, ridged, shorter than the elongated internodes; ligule a thin, lacerate mem-
brane, decurrent on the sheath margins, 2-5 mm. long; leaf blades flat, 6-13 cm. long,
1.5-3.0 mm. wide, ridged, scaberulous. Peduncle slender, exserted 8-15 cm.; inflores-
cence a solitary terminal panicle, 11-15 cm. long, 6-11 cm. wide, open and delicate,
ovoid-pyramidal; branches up to 7 per node, including some solitary elongated pedicels;

FIG. 5. Agrostis perennans. A, panicle; B, spikelets; C, floret.

FIG. 6. Agrostis species. A. turrialbae: A, panicle; A. tolucensis: B, plant, C, spikelet,
D, floret; A pittieri: E, panicle, F, spikelet, G, floret.

BURGER: FLORA COSTARICENSIS 35

branches delicate, flexuous, rebranching at or below the middle; pedicels all spreading,
longer than the spikelets. First glume 2.2-2.9 mm. long, 1-nerved, ovate, caudate, the
tip slightly keeled; midrib scabrous; second glume similar, shorter, 1.9-2.3 mm. long;
lemma ovate, 1.7-1.8 mm. long, very faintly nerved; callus appearing glabrous except
under high magnification, tip erose or bifid, occasionally with a minute awn from the bifid
apex; palea minute, nerveless; anthers 3, purple, 0.8-1.0 mm. long.

Forests and paramos, 2,900-3,300 m. elevation, Asuncion, La Geor-
gina, and other scattered localities on the Cordillera de Talamanca.
June to August.

Our plants seem similar to the woodland phase of A. perennans from
the United States; however, three of our specimens for which we have
chromosome counts indicate a number of n = 14, whereas counts from
temperate North America shown = 21. A single count from Mexico by
Dr. Reeder also indicates n = 14. Agrostis laxissima Swallen from
Guatemala appears very similar to our plants, but has a well-developed
awn. Agrostis turrialbae, which is regarded as endemic to Costa Rica,
is similar to A. perennans, differing in the possession of abundant
basal foliage. Its chromosome number is not yet known. This complex
of species needs detailed morphological and cytological study.

Agrostis pittieri Hack., Oesterr. Bot. Z. 52:60. 1902. Figure 6.

Perennial, 30-60 cm. tall, in dense tufts with numerous intravaginal innovations; culms
erect, 0.5-1.0 mm. thick, the internodes glabrous; culm nodes purple; internodes 3, 2
shorter internodes at the base of the culm, the peduncle longer; foliage mostly basal;
sheaths glabrous or slightly scaberulous toward the apex; ligule a thin membrane,
2.5-3.5 mm. long; basal blades 7-15 cm. long, 0.6-1.0 mm. wide, folded, minutely
scaberulous on the lower surface, coarsely ridged above; culm blades usually shorter and
not folded. Inflorescence a solitary terminal panicle, 9-11 cm. long, narrow but loose,
0.5-1.0 cm. wide, relatively few-flowered; branches slender, erect, 2-many from each
node; pedicels erect, scabrous, 1-2 x as long as the spikelet. Spikelets laterally com-
pressed; glumes 1-nerved, purplish toward the tips, scabrous on the keels; first glume
2.9-3.9 mm. long; second slightly shorter, 2.8-3.4 mm. long; lemma 1.9-2.0 mm. long,
ovate, thin, faintly nerved, 4-toothed at the apex; callus minutely bearded; awn 2.0-3.0
mm. long, straight, inserted at or just below the middle of the lemma; palea a minute
nerveless scale, 0.7-1.1 mm. long; anthers 3, purple, 1.2-1.5 mm. long. Chromosome
number n = 21 from a collection from Poas.

This species is endemic around the crater of Volcan Poas, above
2,500 m. It occurs in meadows, on road embankments, on cinders near
the crater, and in openings of the cloud forest. Blooming yearlong.

Agrostis stolonifera L., Sp. PL 62. 1753, var. palustris (Huds.)
Farwell, Rep. Michigan Acad. Sci. 21:351. 1919. A. palustris Huds.,
Fl. Angl. 27. 1762.

36 FIELDIANA: BOTANY

Perennial; low, creeping, spreading extensively by slender, elongated stolons, form-
ing a dense leafy mat; branching frequent; stems hollow, glabrous; sheaths glabrous;
ligule a thin membrane, up to 8 mm. long; blades 6-20 cm. long, 3-7 mm. wide. Inflores-
cence solitary, terminal on the trailing stems; panicle slender, contracted, 6-12 cm. long,
1-2 cm. wide, the branches ascending, the rachis usually hidden by the densely clustered
short-pedicellate spikelets. Spikelets 2-3 mm. long; first glume ovate, acute, scabrous on
the keel; second glume similar but slightly shorter; lemma ca. 1.5 mm. long, ovate,
acute, faintly nerved; palea ca. two-thirds as long, anthers 3, ca. 1 mm. long, yellow.

This European grass has been collected in moist pastures of
Hacienda Central de Volcan Turrialba, at 2,600 m. elevation. Like A.
gigantea and A. tennis, which occur in similar habitats, it was proba-
bly introduced from Europe in pasture seed mixtures. It produces a
lush, soft turf and is much used in temperate climates for golf greens.
This group of European species is difficult to interpret, the species
being highly variable, with several chromosome numbers and some
reported hybridity. The English common name is "creeping bent."

Agrostis subpatens Hitchc., N. Amer. Fl. 17:527. 1937. Figure 7.

Perennial, in dense tufts; plants 20-50 cm. tall; culms erect; internodes 0.5-1.0 mm.
thick, hollow, thin-walled, glabrous; culm nodes 2, purple, glabrous; sheaths nearly as
long as the internodes, glabrous; ligule a thin white membrane, 3-5 mm. long; foliage
mostly basal, the basal blades numerous, erect, tightly folded, ca. 0.6 mm. wide,
scaberulous beneath, 5-15 cm. long; culm blades wider, 1-2 mm. wide, flat, up to 15 cm.
long. Peduncle exserted up to 5 cm.; inflorescence a solitary, terminal, narrowly ovoid,
purple panicle, 8-9 cm. long, the length 2-4 x the width; branches clustered, up to 7 per
node, spreading at least during anthesis, scabrous, bearing spikelets mostly near the
outer ends; pedicels spreading, scabrous, 1-2 x as long as the purple spikelets. First
glume 2.9-3.7 mm. long, acute, ovate 6:1 as folded, scabrous on the keel; second glume
similar but slightly shorter, 2.5-3.5 mm. long; lemma 1.7-2.2 mm. long, ovate, 4-toothed
at the apex; awn inserted below the middle, usually about one-fourth above the base,
twisted below, geniculate, exserted near the tips of the glumes; palea absent; anthers 3,
purple, 1.0-1.5 mm. long; caryopsis 1.3-1.4 mm. long, narrowly ovate, amber.

Open paramos above 3,000 m. elevation; frequent at Asuncion and
Buena Vista; Villa Mills; Irazii; Chirripo Grande. Endemic to Costa
Rica, the type from Cerro de la Muerte, Pittier 10470.

This species is very similar to A pittieri which occurs on Poas. It
differs in its more open panicle, lack of a palea, and longer awns.
Despite the close resemblance, the single chromosome counts for these
species indicate that A. pittieri is hexaploid, with n = 21, whereas A.
subpatens is tetraploid with n = 14.

Agrostis tenuis Sibth., Fl. Oxon. 36. 1794.

Perennial, 10-70 cm. tall; plants erect or decumbent in some forms, spreading by
rhizomes or stolons; culms branching from the base, hollow, glabrous; sheaths glabrous;
ligule a short membrane, 0.2-2.0 mm. long, usually less than 1 mm.; leaf blades flat,

FIG. 7. Agrostis species. A. subpatens: A, panicle and basal foliage; B, leaf base and
ligule; C, spikelet and floret; A. bacillata: D, spikelets; E, plant and floret.

38 FIELDIANA: BOTANY

glabrous or scaberulous, up to 15 cm. long, 1-5 mm. wide. Peduncle exserted; inflores-
cence a solitary terminal panicle, ovoid-pyramidal, up to 20 cm. long, open and delicate,
the branches naked below; pedicels short. Spikelets 2.0-3.5 mm. long; glumes ovate,
acute, the first slightly longer than the second; lemma two-thirds to three-fourths as long
as the glumes, ovate, blunt, faintly 3-5-nerved, rarely with an awn; palea one-half or
more as long as the lemma; anthers 3, 1.0-1.5 mm. long.

Rare or overlooked, moist pastures on the south slopes of Volcan
Turrialba and Volcan Irazu. This species was introduced from Europe,
probably as a pasture grass and appears to persist in pastures over
2,000 m. elevation. Certain strains are "bent grasses," forming dense
turf by the spreading stolons.

Agrostis tolucensis H.B.K., Nov. Gen. & Sp. 1:135. 1816. A.
hoffmannii Mez, Repert. Sp. Nov. 18:3. 1922. Figure 6.

Dwarf perennial; plants erect, in dense small tufts; culms slender, ca. 0.5 mm. thick,
hollow, glabrous, 8-32 cm. tall; nodes 1-3, purple, the lower internodes shorter; sheaths
about as long as the internodes, glabrous; ligule 2.8-4.5 mm. long, a thin white mem-
brane, its margins decurrent onto the sheath; foliage mostly basal, the numerous basal
blades 0.7-1.0 mm. wide, tightly folded, 5-10 cm. long, erect, scaberulous; culm blades
wider, 1-2 mm. wide, flat, scaberulous on both surfaces, coarsely ridged above, 2-9 cm.
long. Peduncle included or exserted up to 8 cm. Inflorescence a solitary spikelike termi-
nal panicle, very narrow and dense, 3-10 cm. long, 3-8 mm. wide, the branches fascicled,
erect, short, rarely to 2 cm. long, spikelet-bearing to the base; pedicels erect, mostly
scabrous, from very short to about as long as the spikelet; inflorescence purple or
lead-colored. First glume 2.3-3.6 mm. long, acute, 1-nerved, ovate 6:1 as folded, scab-
rous on the keel, usually purple; second glume similar but slightly shorter, 2.1-3.2 mm.
long; lemma 2.0-2.8 mm. long, ovate, the apex 4-toothed; awn twisted and geniculate,
inserted on the lower third of the lemma, 2.0-2.8 mm. long; palea absent; callus minutely
barbed; anthers 3, purple, ca. 1 mm. long. Chromosome number n = 14 from a specimen
from Irazii.

Paramos, 3,000-3,400 m.; Asuncion, Las Vueltas, Villa Mills, Irazu,
Turrialba; probably blooming yearlong. Mexico to Chile.

This species, A. pittieri, and A. subpatens are all very similar in
spikelet structure and appear to be closely related. The group merits
further study.

Agrostis turrialbae Mez, Rep. Sp. Nov. 18:4. 1922. Figure 6.

Perennial, 10-40 cm. tall; culms erect or the bases decumbent and rooting when grow-
ing in very wet sites; culms unbranched or somewhat branched from the base, 0.5-1.0
mm. thick, glabrous, hollow; nodes 1-2, purple, glabrous; foliage mostly from near the
base, the terminal internodes much longer than the lower; sheaths glabrous; ligule a
thin, white membrane, 1.5-3.5 mm. long; leaf blades thin, flat, 5-10 cm. long, 1-2 mm.
wide, the margins scabrid, surfaces glabrous or minutely scaberulous. Inflorescence
solitary, terminal; peduncle slender, exserted up to 10 cm.; inflorescence a very open,
delicate, elliptical or narrowly pyramidal panicle, 4-12 cm. long, 2-6 cm. wide; branches

BURGER: FLORA COSTARICENSIS 39

fascicled, up to 6 per node, sometimes a few very elongated solitary pedicels with the
branches; branches branching once or twice, mostly on the outer half; pedicels longer
than the spikelets, diverging strongly from the branches; rachis, branches, and pedicels
usually shiny, glabrous or slightly scabrous. Spikelets purplish; first glume ovate, acute,
scabrous on the keel, 2.0-2.1 mm. long; second glume similar, 1.8-2.0 mm. long, both
apparently 1-nerved; lemma ovate, 1.2-1.4 mm. long, rather blunt, sometimes with a
minute abortive awn on the back just below the summit; callus minutely bearded; palea
absent; anthers 3, purple, 0.7 mm. long; caryopsis narrowly elliptical, amber. Chromo-
some number n = 14 from Pinette 1297 from the Cerro de la Muerte.

Moist areas in paramos, mostly above 3,000 m. elevation; Turrialba,
Irazu, Las Vueltas, Cerro de la Muerte. February to August. Endemic
to Costa Rica.

This species has been identified from material available to me and
from the original description and a purported portion of the type in
US. The latter specimen, collected by Pittier, unfortunately has lost all
of its spikelets, but resembles our specimens in other features. The
original description by Mez indicates that the spikelets have long
paleas. None of our specimens possesses a palea, but Mez may have
been in error in his original observations.

AIRA Linnaeus

Caespitose annual grasses; inflorescence a terminal panicle; spikelets small; laterally
compressed; glumes equal, longer than the concealed florets, hyaline, 1-nerved, rounded
on the back; florets 2; disarticulation above the glumes and beneath the second floret;
lemmas rounded on the back, tapering to 2 acuminate teeth; awns geniculate, twisted
below, inserted on the lower part of the backs of the lemmas; rachilla not extended
beyond the palea of the second floret.

Aira is a genus of the temperate zone of the Old World, represented
in the western hemisphere only by introductions. The genus is related
to Deschampsia and Trisetum. (Pooideae: Aveneae.)

Aira caryophyllea L., Sp. PI. 66. 1753. Figure 8.

Diminutive caespitose annual; culms 4-15 cm. long, erect or decumbent at the base,
branching from the base only, 0.5 mm. thick, hollow, glabrous; nodes glabrous; blades
usually 1-2 per culm, borne on the lower half of the culm, 1-2 cm. long, less than 1 mm.
wide; ligules pointed, 2-4 mm. long, membranaceous, decurrent on the sheaths; blades
mostly withered at flowering time. Peduncle glabrous, slender, elongated, 4-7 cm. long;
panicle very open, pyramidal, about as wide as long, 2-3.5 cm. long, with few branches,
the spikelets clustered near their tips; pedicels 1-several times as long as the spikelets.
Spikelets 2.5-3.0 mm. long; glumes equal or the first slightly longer; florets equal; lem-
mas lanceolate, brownish, roughened above, 2. 1-2.2 mm. long, the nerves obscure; callus
minutely bearded; awns once-geniculate, 2.8-3.2 mm. long; the basal segments brown,
twisted, the tip exserted from the glumes; anthers 3, 0.3-0.6 mm. long. Chromosome
number n = 14 from Costa Rican specimens.

FIG. 8. Aira caryophyllea. Plant, spikelet, and florets.
40

BURGER: FLORA COSTARICENSIS 41

This delicate little annual grass has been collected from pastures
and the devastated area on Irazu, and also on Turrialba, from 3,000-
3,400 m. elevation. June to August. This species is native to Eurasia
and Africa. It occurs as an introduction in eastern and western United
States, but has not previously been recorded from Mexico or Central
America. Probably introduced in seed mixtures.

European authors differ widely in their treatment of this species.
Some separate a diploid race (n = 7) as true A. caryophyllea and
regard the tetraploids as a separate species. Bocher & Larsen include
both forms as A. caryophyllea (in Kongel. Danske Vidensk.-Selsk.
Biol. Skr. 10, 2:4. 1958).

ANDROPOGON Linnaeus

REFERENCES: S. T. Blake, Taxonomic and nomenclatural studies in
the Gramineae, No. 1, Proc. Roy. Soc. Queensland 80:55-84. 1969. W.
D. Clayton, Studies in the Gramineae XXXI. The awned genera of
Andropogoneae, Kew Bull. 27:457-474. 1972. F. W. Gould, The grass
genus Andropogon in the United States, Brittonia 19:70-76. 1967.

Usually perennial and caespitose grasses; inflorescences often complex, but basically
composed of units of 2-many rames borne on a bracted or bractless peduncle; rames
composed of several to many internodes, these disarticulating at maturity; rachis inter-
nodes and pedicels flattened, not thin in the center; each internode bears a sessile,
well-developed, fertile, usually awned spikelet at its base; pedicel similar, bearing a
reduced, abortive, or obsolete spikelet; internode, pedicel, and spikelet pair shed from
the plant as a unit; terminal segment of the rame composed of a sessile spikelet accom-
panied by two pedicels bearing reduced or abortive spikelets. Sessile spikelet s ovate,
acute, usually with an exserted geniculate awn; first glume flat or concave between 2
laterally winged submarginal keels, its inflexed edges covering the margins of a boat-
shaped, 1-nerved, keeled second glume; glumes subequal, cartilaginous, completely
covering and concealing the inner spikelet parts; lower (sterile) lemma hyaline, nerve-
less, flattened, conforming to the outline of the first glume, lacking a flower or palea;
upper (fertile) lemma hyaline, narrow, tapering into an exserted awn, rarely with apical
teeth; awn, when present, usually geniculate and twisted just above the base; palea
lacking; lodicules oblong, hyaline, vasculated; anthers 1 or 3; style branches 2, separate;
caryopsis linear or narrowly ovoid. Pedicellate spikelets much reduced or abortive,
mostly lacking flowers, sometimes entirely lacking.

The genus Andropogon is variously construed by authors. There is
little agreement as to the generic limits. The following genera included
in this treatment may by some writers be included in Andropogon:
Bothriochloa, Cymbopogon, Diectomis, Euclasta, Hyparrhenia,
Hypogynium, and Schizachyrium. The genus is worldwide in warm
temperate and tropical regions. (Panicoideae: Andropogoneae.)

42 FIELDIANA: BOTANY

KEY TO SPECIES OF Andropogon

la. Spikelets all lacking awns; anthers 3 2

Ib. Sessile spikelets with conspicuous, exserted awns; anther 1 4

2a. One or several of pedicellate spikelets at tips of each rame enlarged, conspicu-
ous, longer than sessile spikelets; inflorescence a large ovoid compound mass;

plants 1-1.5 m. tall A. bicornis

2b. Pedicellate spikelets all much reduced or rudimentary; inflorescences 1-several

per culm, individually long-stalked; plants less than 1 m. tall 3

3a. Leaf blades up to 5 mm. wide, rounded abruptly to a boat-shaped tip; rames 3-5 per

peduncle A. selloanus

3b. Leaf blades 1.5-2.5 mm. wide, tapering to an acuminate tip; rames 2-3 per peduncle

A. leucostachyus
4a. Inflorescence a dense corymbose mass of numerous crowded pedunculate pairs

of rames near apex of culm A. glomeratus

4b. Inflorescence slender and elongated, made up of small groups of axillary pedun-
cles bearing paired rames and arising from sheath axils of upper half of culm

A. virginicw

Andropogon bicornis L., Sp. PL .1046. 1753. Figure 9.

Coarse caespitose perennial, in large, dense clumps; culms erect, up to 2.5 m. tall,
branching abundantly from the middle and upper nodes; internodes glabrous, up to 6
mm. thick, hollow, thick-walled; nodes glabrous; basal leaf sheaths densely overlapping,
keeled; upper sheaths shorter than the internodes, glabrous; ligule a short, stiff mem-
brane, 1.0-1.2 mm. long, minutely ciliolate; leaf blades up to 50 cm. long, 2-6 mm. wide,
mostly glabrous or with a few hairs on the upper surface behind the ligule and occasion-
ally with scattered papillose-based hairs on the basal margins; edges and midrib promi-
nently scabrous. Inflorescence a large feathery ovoid compound mass, made up of
numerous repeatedly branching axillary branches which terminate in slender wiry
peduncles bearing 1-3 slender bladeless sheaths and terminating in a digitate pair (rarely
3) of rames. Rames divergent, 2.5-3.5 cm. long, the rachis and pedicels bearded with
hairs up to 8 mm. long; spikelets paired, the pedicellate member of each pair rudimen-
tary or absent, or in the terminal triad, much enlarged and differing from the sessile
spikelets; rachis internodes 2.5-3.0 mm. long; pedicels 3.4-4.0 mm. long. Sessile spikelets
3.0-3.5 mm. long, ovate, acute; first glume flattened, with 2 lateral keels, nerveless
between the keels; margins inflexed, clasping the edges of a boat-shaped, 1-nerved
second glume 2.3-2.7 mm. long; lower (sterile) lemma 2.0-2.4 mm. long, conforming in
shape to the first glume, hyaline, nerveless, its upper margins ciliate; upper (fertile)
lemma 1.6-2.2 mm. long, hyaline, nerveless; anthers 3, 0.5-0.7 mm. long, purple; cary-
opsis cylindrical, brown, 1.6-2.0 mm. long. One pedicellate spikelet of the terminal triad
and occasionally 1 to several of the lower ones enlarged, conspicuous, 3.7-4.1 mm. long,
somewhat laterally compressed, first glume convex on the back, 5-nerved; second glume
boat-shaped, 3-nerved, 3.5-3.7 mm. long; sterile lemma 3.0-3.5 mm. long; fertile lemma
2.8-3.0 mm. long; flower lacking or staminate, the 3 anthers 0.5-1.0 mm. long. Chromo-
some number n = 30 from Costa Rican specimens.

This species is a common weedy inhabitant of open roadsides and
savannas or brushy areas, on both Pacific and Caribbean slopes, from
low elevations to 1,500 m. The plants are conspicuous because of their

FIG. 9. Andropogon species. A. bicomis: A, portion of a rame showing enlarged
terminal spikelet; B, plant base and compound inflorescence; A. glomeratus: C, portion
of rame with awned spikelets.

44 FIELDIANA: BOTANY

large, plumy inflorescences. Flowering mostly from July to October,
but more or less intact inflorescences may be found at other times of
the year. Southern Mexico to Bolivia and Argentina; West Indies.
Common names: Cola de Venado, Cola de Coyote.

Andropogon glomeratus (Walt.) B.S.P., Prelim. Cat. N.Y. 67.
1888. Cinna glomerata Walt., Fl. Carol. 59. 1788. Andropogon mr-
ginicus L., var. abbreviatus (Hack.) Fern. & Grisc., Rhodora 37:142.
1935. Figure 9.

Densely caespitose perennial; culms erect, 60-150 cm. tall, branching freely from the
middle and upper nodes; internodes up to 6 mm. thick, solid, pithy, glabrous; nodes
glabrous; basal sheaths strongly keeled, closely overlapping; much of the foliage basal;
margins of the sheaths appressed-hirsute, the back usually glabrous; ligule a stiff ciliolate
membrane, 0.8-1.5 mm. long; leaf blades up to 60 cm. long, 4-7 mm. wide, the tip acute,
boat-shaped; midrib keeled beneath, scabrous; margins sometimes with a few long hairs
near the base. Inflorescence a large ovoid feathery mass, the numerous upper branches
repeatedly branching, terminating in bracted peduncles, each bearing a pair (rarely 3) of
divergent rames, each 2-3 cm. long; rachis internodes and pedicels strongly ciliate with
silky hairs 5-8 mm. long; internodes 2.0-3.2 mm. long, the pedicels 3.5-4.2 mm. long.
Sessile spikelets 3.2-3.5 mm. long, ovate 6:1, acute; first glume flat, with 2 marginal
ciliate scabrous keels, the edges inflexed over the margins of the second glume; second
glume 3.0-3.2 mm. long, 1-nerved, boat-shaped, keeled; lower (sterile) lemma hyaline,
2.3-2.7 mm. long, conforming to the shape of the first glume; upper (fertile) lemma
hyaline, 1-nerved, 2.0-2.5 mm. long, narrow, tapering to an awn 10-15 mm. long; base of
the awn weakly twisted and geniculate near the base; anther 1, 0.8-1.3 mm. long,
brownish; lodicules 2, oblong, hyaline, vasculated; caryopsis linear, up to 1.8 mm. long,
brown. Pedicellate spikelets abortive, linear, 1-2 mm. long.

Open roadsides, marshes, pastures, occasional in the Meseta Cen-
tral; San Vito; elevations from 1,100-1,800 m.; beach at Limon. July to
November, rarely later. Southeastern and southern United States;
Yucatan and Central America; West Indies.

This species is superficially similar to A. bicomis, but the plants are
smaller, and the spikelets are awned. It also differs from A. bicomis in
stamen number, the latter having three anthers.

Andropogon leucostachyus H.B.K., Nov. Gen. & Sp. 1:187. 1816.

Caespitose perennial in dense tufts; plants 40-100 cm. tall, culms erect, branching on
the upper half; internodes 0.7-2.0 mm. thick, solid, pithy, glabrous; nodes glabrous;
foliage mostly basal; sheaths keeled, glabrous; ligule membranaceous, 0.7-1.7 mm. long;
leaf blades up to 32 cm. long, 1.5-2.5 mm. wide, keeled beneath, tapering to an acumi-
nate apex; upper surface with a few weak hairs above the ligule. Peduncles slender,
wiry, several exserted from each of the upper 3 or more leaf sheaths, each bearing a
bladeless sheath; each peduncle bears a terminal inflorescence of 2-3 slightly divergent
silky rames, 2-4 cm. long, the tan to purplish spikelets mostly concealed by the white to
beige hairs; rachis internodes flattened, 1.8-2.7 mm. long, the apex obliquely cup-

BURGER: FLORA COSTARICENSIS 45

shaped; hairs up to 9 mm. long, the longest ones near the summit; pedicels similar but
thinner, 2.5-3.5 mm. long. Sessile spikelets 2.7-3.2 mm. long, ovate 5-6:1, acute; callus
bearded with silky hairs 4-5 mm. long; first glume 2.6-3.2 mm. long, 2-keeled; its margi-
nal flanges inflexed and clasping the margins of the second glume; second glume 2.3-2.7
mm. long, boat-shaped, 1-nerved, the keel convex; lower (sterile) lemma hyaline, con-
forming in shape to the first glume, 1.8-2.6 mm. long, its upper margins ciliate, tip
tapering into a slender weak included awn; upper (fertile) lemma hyaline, keeled, 1.5-2.5
mm. long, ciliate on the upper margins; palea absent or a short, nerveless scale; anthers
0.6-0.7 mm. long, yellow; caryopsis 1.8-2.3 mm. long, fusiform, amber; pedicellate
spikelet abortive, 1.1-1.5 mm. long. Chromosome number n = 10 from Costa Rican
specimens.

Dry savannas at elevations up to 740 m.; La Cruz, Nuestro Amo,
Buenos Aires, Paso Real, Boruca, Cabagra, Canas Gordas. April to
December. Southern Mexico to Argentina; West Indies.

Andropogon selloanus (Hack.) Hack., Bull. Herb. Boissier II.
4:266. 1904. Andropogon leucostachyus ssp. selloanus Hack, in DC.,
Monogr. Phan. 6:420. 1889.

Perennial, caespitose in small, dense clumps; culms 40-110 cm. tall, branching from the
middle and upper nodes, erect; internodes to 3.5 mm. thick, solid, pithy, glabrous; nodes
glabrous, slightly shrunken; foliage mostly basal, the upper leaf blades more or less
reduced; sheaths shorter than the internodes, strongly compressed and keeled, gla-
brous; ligule a short-ciliate membrane, 0.5-1.0 mm. long; leaf blades up to 40 cm. long
and 5 mm. wide, ciliate near the base with scattered elongated, weak, papillose-based
hairs; blade tip concave, boat-shaped, blunt. Peduncles several from each of the upper
2-3 sheaths, slender, bearing bladeless sheaths. Individual inflorescences of 3-5 rames
borne subdigitately at the bearded apex of the peduncle; rames forming a fan-shaped
group, ascending, 3-6 cm. long; rames very silky, whitish or beige; rachis internodes
2.0-2.8 mm. long, flattened, the apex obliquely cup-shaped, the edges bearded, the hairs
up to 10 mm. long, the longest ones near the summit of the internode; pedicels similar
but thinner, 3.5-3.8 mm. long. Sessile spikelets 3.2-3.5 mm. long, bearded on the callus
with hairs up to 6 mm. long; spikelet acute, ovate ca. 5:1, the glumes glabrous; first
glume concave between the 2 marginal keels, slightly winged below the bifid tip, its
marginal flanges clasping the edges of the second glume; second glume equal to the first,
boat-shaped, 1-nerved, the keel convex; lower (sterile) lemma 2.0-2.5 mm. long, flat-
tened, conforming to the shape of the first glume, hyaline, nerveless, empty; upper
(fertile) lemma hyaline, keeled, conforming to the second glume, narrowly triangular,
nerveless, 1.5-2.0 mm. long, tapering to an acuminate apex or a weak short awn, the
upper margins ciliate; palea absent or a small nerveless ciliate scale; anthers ca. 0.6 mm.
long, white; stigmas emerging laterally from the glumes; caryopsis linear, ca. 1.7 mm.
long. Pedicellate spikelet rudimentary, 0.6-1.2 mm. long, inconspicuous.

This species is apparently rare in Costa Rica. Our only specimen is
the following: Guanacaste, 4 km. S of LaCruz along the CIA, 230 m.,
rocky roadside in open savanna, 27 June 1968, Pohl & Davidse 10590B.
Southern Mexico, Guatemala, Belize, Honduras, Costa Rica, and
Panama to Argentina; West Indies.

46 FIELDIANA: BOTANY

Andropogon virginicus L., Sp. PL 1046. 1753.

Caespitose perennial in dense tufts; plants 50-100 cm. tall; culms erect, branching
freely from the middle and upper nodes; internodes compressed, to 4 mm. thick, hollow
but partially pithy, glabrous; basal sheaths closely overlapping, strongly keeled, hirsute
on the margins; foliage mostly basal; ligule a ciliolate membrane, 0.5-0.7 mm. long; leaf
blades up to 35 cm. long, the basal ones longest, 2-5 mm. wide, hirsute near the base and
on lower margins, strongly keeled beneath; branches several from each of the middle and
upper nodes, slender and wiry, erect or ascending, each bearing several peduncles that
arise in the axils of bladeless spathes; peduncles very short, less than 1 cm. long, each
bearing at its apex 2-4 digitate, diverging rames 2-3 cm. long; subtending spathes mostly
as long as the rames; rachis internodes and pedicels ciliate with abundant silky hairs,
these up to 8 mm. long; rachis internodes 1.5-3 mm. long; pedicels 3.1-5 mm. long.
Sessile spikelets narrowly ovate 4-5:1, acute, 3.8-4.1 mm. long; first glume flattened, the
2 lateral keels scabrous-ciliate near the apex, the margins inflexed and covering the
edges of the second glume. Second glume 3.5-3.6 mm. long, boat-shaped, keeled, 1-
nerved; lower (sterile) lemma hyaline, 3.0-3.5 mm. long, conforming in shape to the first
glume; upper (fertile) lemma hyaline, narrow, 2.5-3.0 mm. long, ciliate; awn 11-17 mm.
long, twisted near the base; anther 1, 0.8 mm. long, purple; caryopsis ovate 4-5:1, 1.9-2.4
mm. long, brown. Pedicellate spikelets rudimentary or absent.

This is a common, highly variable species in the eastern and mid-
western United States, extending southward to Panama and the West
Indies. It is rare in Costa Rica, being known only by the following
specimen: San Jose, Guadalupe, Hitchcock 8483, 22-24 October 1911.

Andropogon virginicus is a member of an intricate complex of
species or subspecific populations that intergrade freely. The common
member of this group in Central America is A. glomeratus, which
differs in its much denser and more compact inflorescence.

ANTHEPHORA Schreber

REFERENCE: J. P. Reeder, The systematic position of the grass
genus Anthephora, Trans. Amer. Microscop. Soc. 79:211-218. 1960.

Caespitose annual grasses; inflorescence a cylindrical spike of fascicled spikelets; fasci-
cles overlapping, attached singly at the nodes of a tortuous rachis and readily detachable
from it; fascicle with a short, thick basal stipe which bears 4 thick, rigid, many-nerved
ovate bracts, these enclosing 2-4 spikelets, 1 or 2 of them sterile or reduced to small
rudiments; first glume absent, second glume acicular, awned, 1-nerved; sterile lemma,
fertile lemma and its palea subequal, as long as the spikelet; sterile lemma 7-nerved;
fertile lemma faintly 3-nerved; caryopsis plump, elliptical, with a large embryo.

Some authors interpret the bracts of the fascicle as first glumes of
the spikelets. (Panicoideae: Paniceae.)

Anthephora hermaphrodita (L.) 0. Kuntze, Rev. Gen. PI. 2:759.
1891. Tripsacum hermaphroditum L., Syst. Nat. ed. 10. 2:1261. 1759.
Figure 10.

FIG. 10. Anthephora hermaphrodite. A, inflorescence; B, detached fascicle; C,
spikelet inside of external bract; D, caryopsis.

48 FIELDIANA: BOTANY

Caespitose annual; culms erect or sometimes decumbent and rooting at the lower
nodes, branching from the base; culms glabrous, hollow, the nodes not prominent;
prophylla up to 17 mm. long; leaves numerous, the sheaths mostly overlapping; sheaths
and blades papillose-hispid to nearly glabrous; ligule a brownish membrane, 1.5-2.5 mm.
long; blades flat, 4-17 cm. long, 2-8 mm. wide; peduncle included or exserted up to 10
cm.; inflorescence solitary, terminal, slender, cylindrical, 4-12 cm. long, 5-8 mm. in
diameter, bearing up to 60 fascicles; fascicles 5-7 mm. long, the bracts ovate, acuminate,
flat and somewhat recurved near the tips; fertile spikelets 3.5-4.5 mm. long, ovate,
acute; first glume absent; second glume acicular, awn-tipped, 1.7-4.2 mm. long; sterile
lemma 3.6-4.5 mm. long, 7-nerved, scabrid between the nerves; fertile lemma 3.7-4.0
mm. long, glabrous, faintly 3-nerved, its thin margins overlapping the edges of the
palea; caryopsis plump, elliptical, ca. 2 mm. long. Chromosome number n = 9 from Costa
Rican material.

Sea beaches and lowland pastures and disturbed areas, especially
common along the Pacific Coast. June to December, probably year-
long. Mexico to Peru and Brazil; Caribbean Islands.

ANTHOXANTHUM Linnaeus

Caespitose grasses; inflorescence a dense, spikelike terminal panicle; spikelets later-
ally compressed; glumes unequal, the first 1-nerved, much shorter than the 3-nerved
second, which exceeds the florets and envelopes them; disarticulation above the glumes;
florets 3, falling as a group; lower 2 florets sterile, lacking paleas; lemmas 5-nerved,
obtuse and bifid at the tip; first floret with a straight awn from the back above the
middle; second floret with a longer twisted geniculate awn from near the base; third
(fertile) floret awnless, blunt, the lemma 1-nerved, slightly bifid; palea 1-nerved, longer
than the lemma; anthers 2; flower perfect. Plants with odor of coumarin. (Pooideae:
Phalarideae.)

Anthoxanthum odoratum L., Sp. PL 28. 1753. Figure 11.

Slender perennial, forming small tufts; culms erect or spreading, 30-60 cm. long, ca. 1
mm. thick, hollow, glabrous; nodes dark, somewhat contracted, glabrous; leaves few;
sheaths shorter than the intemodes, glabrous or with weak retrorse hairs, ciliate at the
throat; blades 5-20 cm. long, 2-7 mm. wide, glabrous or with scattered weak, soft hairs,
conspicuously auriculate, the dewlap often purplish. Peduncle slender, smooth, 10-35
cm. long; panicle solitary, terminal, dense, 4-8 cm. long, cylindrical, the rachis covered
by the imbricated spikelets; branches very short, the spikelets subsessile; spikelets
lanceolate in outline, 6.5-9 mm. long; glumes membranaceous, glabrous or with scattered
weak hairs, the first ovate, acute, 3.5-4 mm. long, 1-nerved, the second ovate, acumi-
nate, 3-nerved, 6.5-8.5 mm. long; sterile florets subequal, 2.5-3.2 mm. long, the lemmas
oblong, dilated near the tip, brownish and appressed-hirsute on the lower parts, whitish,
glabrous, translucent near the tip; fertile floret 2.0-2.5 mm. long, the lemma glabrous,
broadly ovate; flower protogynous, the stigmas and anthers extruding apically; lodicules
absent or not functioning; anthers pink or purplish, 4-5 mm. long. Chromosome number
n = 10 from Costa Rican material.

Common along roads and in moist pastures; upper elevations of

FIG. 11. Anthoxanthum odoratum. A, plant and inflorescence; B, awned sterile floret;
C, awnless fertile floret; D, spikelet.

50 FIELDIANA: BOTANY

Poas, Barba, Irazu, Turrialba; blooming from June to November, pos-
sibly yearlong. This Eurasian grass was introduced into North
America to give a sweet odor to hay. It occurs from Greenland and
British Columbia southward through the moister parts of the United
States. In Costa Rica, its occurrence in dairy pastures suggests that it
was introduced as a component of early seed importations.

This species is generally regarded as an undesirable weed, since it
contains the bitter toxic substance coumarin, which is also responsible
for the sweet, vanilla-like odor.

ARISTIDA Linnaeus

REFERENCES: J. Th. Henrard, A critical revision of the genus Aris-
tida, Meded. Rijks-Herb. 54:VIII + 747. 1926, 1927, 1928, 1933; A
monograph of the genus Aristida, Meded. Rijks-Herb. 58:1-325 + 159
plates + XII. 1929, 1932. A. S. Hitchcock, The North American
species of Aristida, Contr. U.S. Natl. Herb. 22:7:517-586. 1924.

Annual or perennial, nearly always caespitose grasses of low to moderate stature,
often of xeromorphic aspect; culms unbranched or less commonly branched; internodes
slender, solid or thick-walled; sheaths usually somewhat keeled; ligule a minute ciliolate
rim; blades flat or usually folded or involute. Inflorescence a terminal panicle, open or
congested. Spikelets 1-flowered, disarticulating above the glumes; glumes keeled, sub-
equal or unequal, usually 1-nerved, at least the first scabrous on the keel, the apices
often bifid and with a short straight awn-tip; floret about as long as the glumes, or the
column exceeding them; lemma rigid, cylindrical, its margins overlapping; callus oblique,
sharp-pointed, often prominent, bearded with ascending hairs; apex of the lemma often
prolonged into a straight or twisted beak or column, this often scabrous; awns 3, or by
abortion of the lateral ones, single; central awn usually longer than the lateral ones,
sometimes bent or curved; lateral awns similar to the central one or much shorter in
some species; all awns in our species upwardly scabrous; palea small, completely con-
cealed by the lemma, or not evident; lodicules 2 or 3; anthers 3, or by abortion, 1;
caryopsis linear-cylindric.

Aristida ;s a large genus of grasses distributed in temperate and
tropical climates throughout the world. They are most abundant in
grassland, savanna, and desert climates. Most of the species are low in
the plant successional stages, and become very abundant upon distur-
bance or overgrazing of grasslands. They have little forage value, and
are disliked because of their offensive florets. The combination of a
sharp, bearded callus, rigid lemma, and upwardly scabrous awns en-
ables the florets to penetrate clothing, fur, or hair, or to irritate eyes,
nostrils, and mouth. Henrard indicates that the genus contains about
320 species. In spikelet structure, the genus resembles Stipa, but is
not regarded as being closely related. Species such as A. temipes and

BURGER: FLORA COSTARICENSIS 51

A. jorullensis, with reduced lateral awns, may be confused with
species of Muhlenbergia. (Arundinoideae: Aristideae.)

KEY TO SPECIES OF Aristida

la. Central awn well-developed, lateral awns rudimentary (up to 3 mm. long), or

absent 2

Ib. All 3 awns well-developed, laterals at least half as long as central awn 3

2a. Lateral awns present but short; plants lacking scattered long weak hairs; pani-
cles large and very open, up to 50 cm. long; spikelets borne near the tips of

branches A. ternipes

2b. Lateral awns absent; foliage and inflorescences bearing elongate weak hairs;

panicle slender, up to 20 cm. long A. jorullensis

3a. Panicles open, elliptical or pyramidal, rachis plainly exposed throughout the

length 4

3b. Panicles narrow, usually congested, axis more or less concealed by the branches and

spikelets 5

4a. Lemmas less than 3 mm. long; delicate low annual, usually less than 35 cm. tall,

lacking curled basal leaves A. capillacea

4b. Lemmas 10-12 mm. long; perennial, up to 1 m. tall; basal leaf blades persistent,

conspicuous, curly A. laxa

5a. All 3 awns loosely contorted above the base into loose ascending spiral; basal leaf

blades conspicuous, persistent, curly A. recurvata

5b. Awns not spirally contorted, central awn sometimes strongly recurved; plants lack-
ing curly basal foliage 6

6a. Lemma 8-9 mm. long, the upper 2.0-2.5 mm. twisted, scabrous; first glume

scabrous only on the keel; foliage bearing elongated weak hairs A. orizabensis

6b. Lemma less than 5.5 mm. long, the upper portion straight, not twisted; first

glume scabrous on the keel and surface; foliage lacking elongated weak hairs

A. tincta

Aristida capillacea Lam., Tabl. Encycl. 1:156. 1791. Figure 12.

Delicate tufted annual, in small dense clumps; plants 5-37 cm. tall; culms very slender,
ca. 0.5 mm. thick, the internodes angular, reddish-speckled, glabrous, solid, branching
from the base and usually from a middle node; leaves ca. 4 per culm, 2 from the base and
2 from 2 adjacent middle nodes that are separated by a very short internode; sheaths
glabrous; ligule a minute ciliolate rim, ca. 0.2 mm. long; leaf blades 0.5-0.7 mm. wide,
folded; lower surface glabrous; upper surface ridged, scabrous, bearing scattered
elongate weak hairs that emerge between the folded edges of the blades. Peduncle
elongated, making up, with the panicle, ca. two-thirds of the height of the plant; inflores-
cences terminal, often a second axillary one borne from a middle node of the culm;
panicle open, delicate, ovoid 3:1, 3-10 cm. long; branches usually paired, up to 3 cm. long,
bearing spikelets on their outer half; rachis and branches angular, scabrous; pedicels
slender, flexuous, longer than the spikelets. Spikelets V-shaped, the glumes spreading;
glumes subulate, scabrous on the keel and with scattered scabrous hairs on the surfaces,
often purplish; first glume 2.2-3.0 mm. long, 1-nerved, scabrous on the keel, tapering to
an awn tip; second glume similar, 2.5-3.5 mm. long, faintly 3-nerved; lemma linear-
cylindric, 1.8-2.2 mm. long, including the blunt, bearded callus, scabrous near the apex;

FIG. 12. Aristida capillacea. A, plant with panicles; B, group of spikelets; C, single
floret.

BURGER: FLORA COSTARICENSIS 53

column twisted, 1.5-2.2 mm. long; awns 3, slightly contorted, the central one 4.5-7.5 mm.
long, the lateral ones slightly shorter; palea not seen; anthers 3, purple, 0.3 mm. long;
caryopsis linear-cylindric, 1.4 mm. long, amber, translucent. Chromosome number n =
11 from a Costa Rican specimen.

The delicate little plants of this species occur on dry, open sites,
mostly at low elevations and never over 1,000 m. They are especially
common on volcanic tuff savannas in Guanacaste and have also been
collected in the General Valley at Boruca, Buenos Aires, and Paso
Real; Hacienda Argentina; San Ramon. December to February.
Southern Mexico to northern South America, Brazil and Bolivia.

Aristida jorullensis Kunth, Rev. Gram. 1:62. 1829. Figure 13.

Caespitose annual, in dense, small tufts; culms 10-60 cm. tall; branching abundant
from 1-3 culm nodes; inter-nodes very slender, solid, glabrous; nodes glabrous; leaf
sheaths glabrous; ligule a minute ciliate rim, 0.1-0.2 mm. long; leaf blades 4-20 cm. long,
1.0-1.5 mm. wide, folded or involute; upper surface uniformly finely ridged, scaberulous,
with scattered elongated flexuous hairs that gyrate when wetted. Inflorescences termi-
nal on the main culm or on leafy branches; peduncle slender, weak, up to 15 cm. long;
panicle slender, 6-20 cm. long; rachis exposed between the isolated solitary branches;
branches 1-4 cm. long, bearing appressed spikelets to their bases; rachis, branches, and
glumes bearing elongated weak flexuous hairs. Spikelets V-shaped, the glumes diverg-
ing, subequal; first glume subulate, 1-3-nerved, scabrous on the keel, 4.5-9.0 (rarely 19)
mm. long; second glume similar, 5.0-8.5 (rarely 13) mm. long; floret 4-7 cm. long, without
clear distinction of lemma and awn; callus ca. 0.5 mm. long, bearded with hairs ca. 1 mm.
long; lemma somewhat laterally compressed, scabrous above in lines, linear, tapering
gradually into a flattened scabrous beak and flexuous awn; lateral awns absent; palea
1.0-1.5 mm. long; anthers 3, 1.1-1.7 mm. long, purple. Chromosome numbern = 11 from
a Costa Rican specimen.

This species occurs on dry Curatella-Byrsonima savannas on vol-
canic tuff in northern Guanacaste, from sea level to 200 m. elevation,
and in Crescentia savannas. It has also been collected at Turricares
and Rodeo de Pacaca. Blooming mostly from September to January,
occasionally in June and July. Pacific Coastal regions, from Central
Mexico to Panama.

This species is somewhat anomalous in the genus Aristida because of
its lack of lateral awns. The general structure of the spikelets, how-
ever, indicates that it is closely related to A. temipes, in which the
lateral awns are very short.

Aristida laxa Cavanilles, Icon, et Descr. PI. 5:44. 1799. A. spadicea
H.B.K., Nov. Gen. & Sp. PL 1:123. 1816.

Caespitose perennial in small dense tufts; plants up to 1 m. tall; culms unbranched;
internodes 1.0-1.5 mm. thick, glabrous, solid; nodes glabrous, not prominent; sheaths

FIG. 13. Aristida species. A. temipes: A, panicle; B, single floret; A. jorullensis: C,
spikelet and single floret; D, portion of a panicle.

BURGER: FLORA COSTARICENSIS 55

glabrous, slightly keeled; ligule ca. 0.5 mm. long, a short ciliolate crown; leaf blades
15-30 cm. long, up to 2.5 mm. wide, flat near the base, involute above; lower surface
glabrous; upper surface ridged, scaberulous, with scattered weak thin hairs near the
base and throat; basal blades becoming twisted with age. Peduncle elongated, slender;
inflorescence an open, solitary, terminal, pyramidal panicle; rachis and branches angu-
lar, scaberulous; branches ascending, straight, solitary but branched into 2 just above
the base, up to 8 cm. long; spikelets borne on the outer half of the branch, appressed,
short-pedicellate. Glumes subequal, the first 9.5-11.8 mm. long, subulate 6:1, scabrous
on the keel and the surfaces; second glume similar but glabrous, 10-12 mm. long; lemma
linear-cylindrical, 10-12 mm. long; callus short, 0.5 mm. long, bearded with hairs up to
1.5 mm. long; body of lemma often mottled with dark coloration, glabrous below, scabr-
ous above, passing into a scabrous, twisted beak or column, 5-9 mm. long; central awn
strongly curved at the base, straight above, 24-30 mm. long, the lateral awns shorter,
somewhat spreading; anthers 3, ca. 1.6 mm. long, dark.

Known from Costa Rica only by the following specimen: Guanacaste,
Liberia, hilly Curatella-Byrsonima savanna on volcanic tuff, 14 Jan-
uary 1969, P. & D. 11653. Mexico to Ecuador.

Aristida orizabensis Fourn., Mex. PL 2:78. 1881. A. pseudo-
spadicea Hubb., in Proc. Amer. Acad. Arts 49:500. 1913. A. orizaben-
sis, \ar.pseudospadicea (Hubb.) Henrard, Meded. Rijks-Herb. 54:473.
1928. A. arizonica, sensu Hitchc., Contr. U.S. Natl. Herb. 22:7: 568.
1924, non Vasey.

Caespitose perennial in dense tufts; plants erect; culms unbranched or sparingly
branched, 15-85 cm. tall, ca. 1 mm. thick, hollow, glabrous; sheaths usually longer than
the internodes, glabrous; ligule a minute ciliolate rim, 0.2-0.3 mm. long; leaf blades
usually 15-30 cm. long, 1.5-2.0 mm. wide, glabrous beneath, flat near the base and folded
or involute above; upper surface with flat, thickened marginal bands of sclerenchyma,
the central parts finely ridged, scaberulous; throat and basal parts of upper leaf surface
with scattered elongated weak hairs that gyrate when wetted; leaf tip tapering to a
long attenuate point. Inflorescence a solitary terminal panicle, 8-17 cm. long, ca. 2 cm.
wide, narrow, interrupted, the solitary branches ascending, branched immediately
above the base and spikelet-bearing to the base, angular and scabrous. Spikelets ap-
pressed to the branches, V-shaped, the glumes spreading; first glume 6.5-8.0 mm. long,
including the short awn tip, triangular 6:1, scabrous on the keel; second glume similar,
slightly longer, 7.0-8.0 mm. long, not scabrous; lemma linear-cylindric, dark mottled,
7.8-9.0 mm. long, including the bearded callus 0.5-1.0 mm. long and slightly twisted,
scabrous column 2.0-2.5 mm. long; awns divergent, the central one longer than the
lateral ones and more curved at the base, 10-25 mm. long, the lateral ones slightly
shorter; anthers 3, purple or yellow, 1.7-1.9 mm. long. Chromosome numbern = 22 from
a Costa Rican specimen.

Dry savannas, northern Guanacaste, at elevations up to 400 m.;
Boruca. Blooming June to December. Principal season of bloom ap-
pears to be from June to August. Southern Mexico to Panama.

The plants are quite variable. Early season collections are generally
shorter, whereas those collected in the dry season are tall.

56 FIELDIANA: BOTANY

Aristida recurvata H.B.K., Nov. Gen. & Sp. 1:123. 1816.

Tufted perennial, in dense clumps; culms usually 50-70 cm. tall, erect, unbranched;
internodes ca. 1 mm. thick, hollow, glabrous; basal foliage abundant and persistent, the
blades flat, 2-3 mm. wide, up to 30 cm. long, thick, with broad, flat marginal bands of
sclerenchyma; middle of upper suface finely ridged and scaberulous, bearing scattered
elongate weak hairs; blades becoming spirally curled; upper blades involute, ca. 1 mm.
wide; sheaths longer than the internodes, glabrous; ligule a minute ciliolate rim, less
than 0.2 mm. long. Peduncle slender, glabrous, 10-23 cm. long; inflorescence a solitary
terminal panicle, 5-30 cm. long, narrowly cylindrical, less than 2 cm. wide, dense;
branches numerous, ascending, overlapping, mostly 1-3 cm. long, many-flowered;
spikelets crowded on the branches, their pedicels erect, 1-3 mm. long. Spikelets 8.5-12.5
mm. long, excluding the awns, slender; first glume linear, tapering to a short awn,
1-nerved, 8.5-12.5 mm. long, the keel scabrous; second glume similar but slightly
shorter, 8.0-10.5 mm. long, 1-nerved, not scabrous; floret linear, the short callus
bearded; lemma glabrous below but scabrous in lines on the upper portion, 3.5-4.0 mm.
long, tapering into a scabrous, twisted beak ca. 2 mm. long; awns loosely spirally con-
torted on the lower part, 12-16 mm. long, the central awn slightly longer than the 2
lateral awns; anthers 3, 1.4 mm. long, orange, connivent around the style branches.

Uncommon or overlooked; dry Curatella-Byrsonima savannas on
volcanic tuff, 200 m. elevation; Hacienda Las Animas; Liberia. De-
cember and January. Belize, Costa Rica, Panama, Venezuela to Brazil.

Aristida ternipes Cavanilles, Icon, et Descr. PI. 5:46. 1799. Figure
13.

Perennial, caespitose in large tufts, 80-150 cm. tall, the culms ascending to erect,
unbranched, 1.5-4.0 mm. thick, glabrous, solid; nodes not prominent, glabrous; sheaths
mostly overlapping, glabrous; ligule a stiff ciliolate rim, ca. 0.2 mm. long; leaf blades flat
near the base and involute above, passing into an elongated attenuate scabrous tip;
length up to 50 cm.; width 3-5 mm.; upper surface with appressed hispid hairs near the
base; surface marked with alternating wide flat white bands of sclerenchyma and sets of
several very narrow green scaberulous ridges. Inflorescence a solitary terminal open
panicle, making up, with the exserted peduncle, half or more of the total height of the
plant; length up to 50 cm.; shape open pyramidal; branches solitary but branched im-
mediately above the base, appearing binate or ternate; rachis angular and scabrous
above; branches slender, wiry, scabrous, bearing short-pedicellate spikelets only on the
outer half and appressed to the branchlets. Spikelets linear, the glumes subulate, not
strongly diverging; first glume 6.5-11.5 mm. long, faintly 3-nerved, tapering to a short
awn, scabrous on the keel; second glume similar, 8-12 mm. long; lemma subulate, cylin-
drical, glabrous, 15-22.5 mm. long to the point of insertion of the awns; callus 0.5-1.0
mm. long, bearded with hairs 2-3 mm. long; central awn stiff, arched, 10-15 mm. long;
lateral awns erect, obsolete or up to 3 mm. long; palea stiff, up to 1.3 mm. long; anthers
3, ca. 2.7 mm. long, tan; caryopsis linear-cylindric, 7.0-8.5 mm. long, amber.

Dry savannas, northern Guanacaste, Nicoya Peninsula; Atenas; Rio
Catarata; sea level to 600 m. elevation. Blooming principally from late
October to December. Rare bloom may occur on old culms at the

BURGER: FLORA COSTARICENSIS 57

beginning of the rainy season. Southwestern United States to Colom-
bia and Venezuela; Caribbean Islands.

This species is not readily recognized as belonging to Aristida be-
cause the minute lateral awns can be overlooked. Aristida jorullensis
has similar spikelets, but is much smaller.

Aristida tincta Trin. & Rupr., Gramina Agrostidea III. Mem. Acad.
Imp. Sci. Saint-Petersbourg, Ser. 6, Sci. Math., (Seconde Pt. Sci. Nat.
5:111. 1849.) A. breviglumis Mez, Repert. Sp. Nov. (Fedde) 17:152.
1921.

Perennial; densely caespitose in small hard tufts; plants erect, 25-85 cm. tall; culms
unbranched, 0.5-1.3 mm. thick, hollow but thick-walled, glabrous; sheaths longer than
the internodes, glabrous; ligule a minute rim, ca. 0.2 mm. long; auricles sometimes with
a few slender hairs; leaf blades stiff, ascending, flat or folded, up to 25 cm. long and 2.5
mm. wide, glabrous beneath, ridged and scaberulous above, the margins with thick
bands of sclerenchyma. Inflorescences solitary, terminal; peduncle exserted up to 20
cm.; panicle narrowly cylindrical, 10-18 cm. long, rather dense; branches solitary, erect,
1-4 cm. long, densely flowered to their bases. Glumes subequal, the first scabrous on the
keel and surface, 4.5-6.7 mm. long, subulate; second glume similar but glabrous, 4.5-5.8
mm. long; lemma 4.2-5.3 mm. long, including the very short, nearly glabrous callus,
linear-cylindric, without a twisted column, coarsely scabrous toward the apex; central
awn recurved, ca. 15 mm. long, the lateral awns ascending, 8-11 mm. long; anthers 3,
1.2 mm. long.

Aristida tincta occurs on the savannas of Buenos Aires, elevation
250 m. It was collected by Tonduz in 1891 and 1892. The latter (Tonduz
4879) is the type number of A. breviglumis Mez. Collections made in
1943 by Jorge Leon and in 1966 by Alfonso Jimenez are from the same
area. Blooming in February and March. This species is primarily South
American, ranging from Brazil and the Guyanas to Venezuela,
Panama, and Costa Rica.

The name of this species was published in November 1849, although
the title page indicates that the work was exhibited in a meeting in
June 1842. The title, usually misstated, is Gramina Agrostidea, III.,
Callus obconicus (Stipacea).

ARTHRAXON Beauvois

Delicate creeping annual; inflorescences numerous, borne on slender terminal and
axillary peduncles, fan-shaped, each composed of 2-several slender digitate spikes;
spikelets sessile, solitary at each node of a slender disarticulating rachis, falling accom-
panied by the rachis internode, sometimes with a minute abortive pedicel also attached
at the base of the spikelet; spikelets laterally compressed; glumes subequal, completely
concealing the inner bracts of the spikelet; first glume 5-nerved, membranaceous, folded

58 FIELDIANA: BOTANY

asymmetrically, keeled; second glume 3-nerved, keeled; sterile lemma a minute nerve-
less scale; fertile lemma narrow, thin and hyaline, bearing a twisted brown awn near
its base, the awn exserted from the tip of the spikelet; palea lacking. (Panicoideae:
Andropogoneae.)

Arthraxon quartinianus (A. Rich.) Nash, N. Amer. Fl. 17:2:99.
1912. Alectoridia quartiniana A. Rich., Tent. Fl. Abyss. 2:448. 1852.
Figure 14.

Culms sprawling, rooting at the lower nodes, 10-75 cm. long; branching profuse, the
plants making spreading patches; prophylla brown, membranaceous, 10-20 mm. long;
culms slender, hollow, glabrous; nodes bearded with spreading pubescence; sheaths
much shorter than the internodes, ciliate along the margin, sometimes sparsely hirsute
on the back; ligule a ciliate membrane, 1.0-1.5 mm. long; blades lanceolate, cordate-
based, 2-6 cm. long, 3-11 mm. wide, ciliate on the margins, more or less papillose-hirsute
on both surfaces; peduncles thin, flexuous, up to 10 cm. long; inflorescences 1.5-5 cm.
long, fan-shaped, purplish, the rachis internodes silky-ciliate; spikelets sessile, oblong-
lanceolate, 3.0-3.5 mm. long, usually purplish, scabrous on the nerves near the apex;
awn geniculate, exserted 3-5 mm; anthers purple, 0.5-0.6 mm. long. Chromosome
number n = 18 from Costa Rican material.

Occasional along roads and in moist seepy open areas, mostly in or
near the Meseta Central. In Costa Rica, this species appears to flower
from October to December. In Honduras, however, we have collected
it in June and July. Southern Mexico, Guatemala, Honduras, Central
Costa Rica. Introduced from the Old World.

ARTHROSTYLIDIUM Ruprecht

REFERENCE: F. A. McClure, Genera of bamboos native to the New
World, Smithsonian Contr. Bot. 9:15-21. 1973.

Plants caespitose; culms and branches not thorny; culms cylindrical, hollow, erect or
clambering and drooping; midculm nodes with a single branch bud, covered with a pair of
flattened bracts; branch subtended by a bulge on the main culm below the branch
attachment; branches few-numerous in a fan-shaped cluster from the midculm and upper
nodes; one branch (the primary one) usually larger than the others; leaf blades lacking
pronounced commissural veins. Inflorescences determinate racemes, lacking bracts.
Spikelets sessile or nearly so; glumes 1 or 2, the third bract a sterile lemma; perfect-
flowered florets several, the rachilla terminating in a sterile reduced floret; lemma and
palea gaping; lodicules 3, one smaller than the other two; anthers 3; stigmas 2. (Bam-
busoideae: Arthrostylideae.)

KEY TO SPECIES OF Arthrostylidium

la. Erect or pendent plants, culms up to 2 cm. thick and 10-15 m. long; sheaths and
internodes strongly hispid with appressed hairs A. pubescens

Ib. Plants sprawling or trailing; culms 3 mm. or less thick, up to 3 m. long; culms and
sheaths not hispid , A. venezuelae

Arthrostylidium pubescens Ruprecht, Bambuseae Monogr. Ex-

FIG. 14. Arthraxon qiMrtinianns. A, portion of a spike, the spikelets accompanied by
rudimentary pedicels; B, inflorescence.

60 FIELDIANA: BOTANY

ponit 29. 1839. Arundinaria pubescens (Rupr.) Hack., Oesterr. Bot.
Z. 53:69. 1903. Figure 15.

Caespitose bamboos, the culms 10-50 per clump, 10-15 m. long, at first erect, later
arching and leaning, the upper ends long trailing and forming curtains of foliage; inter-
nodes cylindrical, hollow, up to 2 cm. in diameter, green, densely hispid-scabrous with
appressed glassy papillose-based hairs, their lumens filled with blackish material;
sheaths tight, appressed-hispid as the internodes; blades of midculm sheaths erect, as
wide as the sheath apex, up to 23 cm. long, appressed-hispid. Hairs of culm internodes
and sheaths irritating, readily penetrating human skin; ligules of culm sheaths ca. 2 mm.
long, thick and stiff, erose, bearing stiff brown branching trichomes up to 5 mm. long on
their outer surface. Foliage-bearing branches numerous, up to ca. 40 per node, one
longer and thicker than the others; internodes and sheaths of branchlets mostly glab-
rous, the sheath margins ciliolate; auricles densely fringed with stiff erect branching
brown bristles up to 9 mm. long; pseudopetioles flattened, 2-3 mm. long; leaf blades
ovate 7-10:1, acute or acuminate, drooping, slightly glaucous, glabrous except for a few
fine hairs on the lower surface near the base; margins scabrous.

Forested slopes at elevations below 1,200 m., rare. We have col-
lected this species twice in Costa Rica, these collections apparently
being the first North American records. Although both colonies were
vegetative, the specimens are a good match for South American mate-
rial so named by McClure in the U.S. National Herbarium. The colony
along Hwy. 232 between Bajo de Pacuare and Grano de Oro occupies
an extensive area on a south-facing hillside below the road. The culms
clamber into trees and their upper portions form dense drooping cur-
tains of foliage. Our collections are: Prov. Cartago, 7 km. by road E of
Rio Pacuare, elevation 900 m., 6 June 1976, Pohl & Pinette 13183;
Moravia de Chirripo, 1,100-1,200 m., 9 August 1968, Pohl & Dwoidse
10875.

Arthrostylidium venezuelae (Steud.) McClure, J. Wash. Acad. Sci.
32:172. 1942. Chusquea venezuelae Steud., Syn. PI. Glum. 1:337. 1854.
Arundinaria standleyi Hitchc., Proc. Biol. Soc. Wash. 40:79. 1927.

Slender weak bamboo, the culms 1-3 mm. thick, the lower internodes solid, the upper
hollow, glabrous or retrorsely appressed-pubescent, scaberulous toward the apex;
branches few per node; nodes glabrous or sparsely retrorse-pubescent; sheaths mostly
glabrous, ciliolate on the overlapping margin toward the apex; sheath auricles truncate,
bearing numerous flexuous brown bristles, up to 9 mm. long; ligule a minute ciliolate rim
ca. 0.2 mm. long; pseudopetioles flattened, puberulent above, 1.0-3.5 mm. long; leaf
blades flat, dark green, ovate 5-8:1, acuminate, 5-14 cm. long, 10-15 mm. wide, glabrous
above, bearing scattered weak hairs beneath. Inflorescence of short racemes borne on
leafy branches, 5-8 cm. long; rachis strongly flexuous; internodes 1.0-1.5 cm. long;
spikelets subsessile, diverging strongly from the rachis. Spikelets 1-2 cm. long, very
narrow; florets 4-8; first glume 3-4 mm. long, 5-nerved; second glume 4-5 mm. long,
7-nerved; lemmas appressed-pilose, 9-nerved, 6.0-7.5 mm. long, tapering to an obtuse,
awnless apex; palea subequal, ciliolate on the keels near the tip; rachilla internodes at
least three-fourths as long as the lemma, flat below, tapering to a strongly thickened

FIG. 15. Arthrostylidium pubescens. A, culm sheath with erect blade; B, foliage-
bearing branch; C, a floret; D, a branch with spikelets; E, foliage-bearing branches
arising from a bulge above the node.

62 FIELDIANA: BOTANY

cupulate apex, glabrous except for minute cilia at the apex; anthers 3, yellow, 3.2-3.5
mm. long.

This species was originally collected in Costa Rica from the vicinity
of El Muneco. The only flowering specimens are the type of Arun-
dinaria standleyi, Standley & Torres 51060 and another specimen
from the same area, Standley & Torres 50897. One recent collection
(Pohl & Damdse 11787) from this area is vegetative. It occurred in
dense moist forests south of El Muneco. Our most recent collection
(Pohl & Pinette 13303) occurred in wet forests 3.6 km. by road NE of
the Tapanti Bridge. The species here occurred as a large colony, the
plants vinelike and ascending into trees to ca. 8 m., forming dense
curtains of foliage. The slender culms arose from dense, knotty
crowns. Lower portions of the culms were solid, but upper internodes
had a small lumen.

ARUNDINELLA Raddi

REFERENCES: H. J. Conert, Beitrdge zur Monographic der Arun-
dinelleae, Bot. Jahrb. 77:226-354. 1957. C. E. Hubbard, The genera of
the Tribe Arundinelleae, Bull. Misc. Inform. 317-322. 1936.

Perennial, mostly caespitose grasses; inflorescence a terminal panicle; spikelets usu-
ally paired, on pedicels of differing lengths; spikelets laterally compressed, 2-flowered,
usually V-shaped and wide open; glumes unequal, narrow, acute or acuminate, the first
3-nerved, slightly shorter than the first floret, the second 3-5-nerved, much longer than
the florets; disarticulation at the base of the second floret; lower floret sterile or stami-
nate, its lemma acute, awnless, membranaceous, 3- or weakly 5-nerved; second floret
much shorter than the first, perfect-flowered, its lemma acuminate, long-awned from the
tip or between 2 minute teeth, weakly nerved, the margins inrolled over the margins of
the palea, the callus bearded, awn geniculate, exserted; rachilla not prolonged beyond
the floret. (Panicoideae: Arundinelleae.)

KEY TO SPECIES OF Arundinella

la. Awn 4-6 mm. long, the lower segment tightly twisted A. confinis

Ib. Awn 8-13 mm. long, the lower segment straight or only loosely twisted 2

2a. Leaf blades 3-6 mm. wide; culms 1.5-2.0 mm. thick, usually less than 1 m. long

A. berteroniana

2b. Leaf blades 8-25 mm. wide; culms 3-7 mm. thick, 1-4 m. long . . A. deppeana

Arundinella berteroniana (Schult.) Hitchc. & Chase, Contr. U.S.
Natl. Herb. 18:290. 1917. Trichochloa berteroniana Schult., Mant.
2:209. 1824.

Perennial, in small, dense clumps, tightly clinging to rocks or timbers; culms 75-115
cm. long, erect to arching, rarely becoming decumbent and rooting from the lower
nodes, usually unbranched, 1.5-2 mm. thick, hollow, glabrous; nodes appressed-pubes-
cent; sheaths mostly overlapping, more or less appressed papillose-hispid; ligule 0.5 mm.
long, a thickish membrane; blades up to 25-35 cm. long, 3-6 mm. wide, flat, more or less

BURGER: FLORA COSTARICENSIS 63

papillose-hispid above and beneath; auricular hairs prominent; midrib prominent; mar-
gins with a thick stramineous band, scabrous. Panicle solitary, terminal, slender, 20-40
cm. long, 4-6 x longer than wide; branches slender, virgate, mostly simple, 10-15 cm.
long. Spikelets mostly paired, V-shaped, the glumes recurved, conspicuously nerved;
first glume lanceolate 3.2-4.5 mm. long, 3-nerved, the nerves scabrous; second glume
lanceolate, tapering to a narrow but often truncate apex, smooth, 4.2-5.5 mm. long;
lower floret sterile, the lemma lanceolate, acute, usually 3-nerved or rarely weakly 4- or
5-nerved near the apex, glabrous, palea 1.5-2 mm. long; upper floret disarticulating
above the first floret, perfect-flowered; lemma 1.5-1.8 mm. long, narrowly lanceolate,
faintly 3-nerved, scabrid, brownish when mature, the margins inrolled over the edges of
the palea; palea 1.3-1.5 mm. long; awn once geniculate, the lower segment not strongly
twisted; anthers 3, purple, 0.6-0.7 mm. long. Chromosome number n = 10 from Costa
Rican material.

Conert states that this species is rhizomatous. While rooting culms
are found, these were usually knocked down by flowing water, and are
not true rhizomes. The plants occur along streams, usually anchoring
very tightly on rocks or dead logs. This species occurs occasionally
along rocky streams on both the Caribbean and Pacific slopes, at eleva-
tions from 60-1,400 m. Blooming is apparently yearlong. Mexico to
Brazil; West Indies.

Arundinella confinis (Schult.) Hitchc. & Chase, Contr. U.S. Natl.
Herb. 18:290. 1917. Piptatherum confine Schult., Mant. 2:184. 1824.
Figure 16.

Stout caespitose perennial; culms 95-185 cm. tall, erect, unbranched; culm 4-5 mm.
thick, hollow, glabrous; nodes appressed pubescent; leaf sheaths mostly overlapping,
glabrous near the base, hispid near the apex; ligule a minute thickish membrane, 0.2-0.3
mm. long; leaf blades 20-25 cm. long, 9-16 mm. wide, more or less papillose-hispid above,
especially just above the ligule, or on both sides. Peduncle hollow, glabrous, 2-4 mm.
thick, exserted 20-45 cm.; panicle solitary, terminal, cylindrical, dense, about 25 cm.
long, 4-6 x longer than wide; branches densely whorled; floriferous to the base.
Spikelets usually paired, rather densely arranged on the branches, laterally compressed,
3.7-4.2 mm. long; first glume 2.2-2.9 mm. long, lanceolate, 3-nerved, the nerves ridged,
scabrous; second glume 3.7-4.2 mm. long, 3-5-nerved, lanceolate, tapering to a slender
truncate apex; lower floret sterile, its lemma 2.1-1.5 mm. long, glabrous, narrowly
ovate, acute, 3-nerved, the nerves faint, palea 1.8-2. mm. long; fertile floret lanceolate,
1.5-2. mm. long, bearded on the callus; awn 4-6 mm. long, geniculate, the lower segment
brown, tightly twisted when mature; palea 1.3-1.6 mm. long; anthers 3, 0.8-0.9 mm.
long, purple.

Rare; savannas near El Paraiso, Boruca, and Canas Gordas at eleva-
tions from 400-1,200 m. November to December. Mexico to Panama;
West Indies.

Arundinella deppeana Nees, Bonplandia 3:84. 1855. Figure 16.

Perennial from knotty crowns, with many basal innovations; culms 1-4 m. tall, erect to
arching or scrambling through brush, unbranched, 3-7 mm. thick, hollow, thick-walled,

FIG. 16. Arundinella species. A. deppeana: A, panicle; B, spikelets and fertile floret;
A. confinis: C, spikelets; D, fertile florets.

BURGER: FLORA COSTARICENSIS 65

glabrous; nodes appressed-pubescent; sheaths overlapping, ciliate on the margin,
appressed-papillose hispid, especially near the apex; ligule a minute ciliate membrane,
0.2-0.3 mm. long; larger blades 25-50 cm. long, 8-25 mm. wide, more or less appressed-
hispid on both sides, strongly so on the upper surface just above the ligule. Peduncle
glabrous, 4-30 cm. long; panicle solitary, terminal, loosely cylindrical, 20-60 cm. long.
4-5 x longer than wide. Spikelets usually paired and unequally pedicellate, often
purplish, laterally compressed, 3.8-4.8 mm. long; first glume 2.8-3.2 mm. long, 3-nerved,
lance-attenuate; second glume 3.8-4.8 mm. long, 5-nerved, lance-attenuate; lower floret
2.3-2.5 mm. long, sterile; lemma lanceolate, acute, 3-nerved, glabrous, acute; the palea
1.5 mm. long; second floret disarticulating above the first floret, perfect-flowered; lemma
ca. 1.5 mm. long, lanceolate, faintly 3-nerved, bearded at the base; tapering to a min-
utely bifid apex; awn flat, only slightly twisted, geniculate, 10-13 mm. long; palea 1-1.3
mm. long; anthers 3, 0.7-1 mm. long, purple; mature fertile lemma scabrid, brownish, its
margins inrolled over the edges of the palea. Chromosome number n = 10 from Costa
Rican plants.

Occasional, savannas, forest margins, brush, road embankments;
Pacific slope, 300-1,700 m. elevation, from northern Guanacaste to
Panama. Blooming yearlong. Mexico to Brazil; West Indies.

Common name: Cola de venado. The panicles are sometimes sold for
ornament.

ARUNDO Linnaeus

Giant perennial reeds, the culms arising from thick scaly rhizomes and forming large
colonies; inflorescence a large plumy terminal panicle. Spikelets laterally compressed,
plumose, V-shaped; glumes about equal, 3-5-nerved, nearly as long as the entire
spikelet; florets 4-5, their tips all about at the same level; rachilla disarticulating above
the glumes and between the florets; lemmas with 3 principal vascular bundles and 2-4
weak secondary ones, densely long-hairy on the lower portions of the back, minutely
awned between 2 hyaline teeth; tip of the glabrous rachilla bearing a reduced abortive
floret.

Species three, in Formosa, Asia, and the Mediterranean lands; one
species naturalized in warm temperate and tropical parts of the
Americas. The genus is related to Cortaderia and Gynerium, and, like
them, has plumy spikelets. (Arundinoideae: Arundineae.)

Arundo donax L., Sp. PL 81. 1753. Figure 17.

Culms arising from thick, scaly rhizomes; plants up to 8 m. tall, culms erect or arching,
simple or extravaginally branched above; nodes glabrous, mostly concealed; internodes
hollow, up to 4 cm. thick; foliage distributed rather uniformly along the culm except in
old stems, strongly distichous; sheaths longer than the internodes and strongly overlap-
ping, glabrous; leaf blades up to 1 m. or more long, up to 6 cm. wide, glabrous, the
margins scabrous; leaf bases broader than the sheaths, with prominent triangular
brownish flanges ciliate on the margins; ligule a thin whitish or brownish minutely ciliate
membrane, 1.0-1.5 mm. long. Inflorescence borne on a cylindrical glabrous hollow
peduncle up to 1.5 cm. thick; panicle up to 60 cm. long, ovoid, dense, the branches

FIG. 17. Arundo donax. A, culm internode and leaf; B, branch of panicle with
spikelets; C, single spikelet; D, one floret.

BURGER: FLORA COSTARICENSIS 67

ascending. Spikelets densely clustered along secondary or tertiary branches, 10-14 mm.
long; glumes hyaline, brownish or purplish, 11-13 mm. long, acuminate; florets 4-5, the
upper ones progressively shorter than the lower, so that the tips are about at the same
level; lemmas 8-12 mm. long, lance-ovate, tapering into a short straight awn which arises
between 2 delicate lateral teeth; nerves 3-7, usually 3 major ones anastomosing with the
midrib; lower portions of the back of the lemma heavily bearded with long, silky whitish
hairs, up to 8 mm. long; palea up to 5 mm. long, about half as long as its lemma, whitish,
membranaceous, scabrid on the keels and pubescent near the base between them, hya-
line, truncate; callus short, rounded, short-hairy at its upper end; rachilla glabrous;
flower with 2 truncate lodicules; stamens 3, the anthers 2.5-3.0 mm. long, yellow; pistil
with 2 apical elongated style branches, terminating in plumose cylindrical brownish
stigmas.

Cultivated in the Meseta Central for ornament, and escaping to
roadsides and river banks; practically never blooming under Costa
Rican conditions.

Most of the cultivated plants of this species in Costa Rica are the
form with leaves longitudinally yellow-striped. This has been called
var. versicolor (Mill.) Stokes. Our only flowering specimens of this
species are of the striped form, and were growing in San Jose. It seems
probable that the plants will bloom under Costa Rican conditions only
where supplied with artificial illumination to extend the day length.
Some escaped stands are of the wild type with green leaf blades.
Common name: carrizo.

AULONEMIA Goudot

REFERENCE: F. A. McClure, Genera of bamboos native to the New
World, Smithsonian Contr. Bot. 9. Aulonemia, pp. 53-61. 1973.

Caespitose bamboos of small stature, forming small clumps; culms succulent, arising
from scaly short, thick (pachymorph) rhizomes; culms leafy above the middle, erect or
scrambling in vegetation; midculm branches mostly solitary and about as large as the
main culm and strongly divergent from it, the subtending leaf sheath gaping; sheaths
often bearing conspicuous oral setae; leaf blades broad, lanceolate or ovate; inflorescence
an open panicle. Spikelets few- to many-flowered, the uppermost floret reduced and
sterile; disarticulation above the glumes; first glume small, acute, 3-nerved; second
glume obtuse, 7-nerved; lowermost floret sometimes sterile; lemmas 7-9-nerved, mucro-
nate or awned; paleas 2-keeled; lodicules 3, unequal; stamens 3; stigmas 2.

Aulonemia is a tropical American genus of 24 species. The largest
number of species occurs in Brazil, with others from Guyana to
Ecuador. Three species occur in Central America and Mexico. (Bam-
busoideae: Arthrostylidieae.)

KEY TO SPECIES OF Aulonemia

la. Leaf blades broadly ovate, 2.7-3.5 x longer than wide; auricular bristles numerous,
up to 30 mm. long A. patriae

68 FIELDIANA: BOTANY

Ib. Leaf blades narrowly ovate, 4.7-6.0 x longer than wide; auricular bristles absent

A. viscosa

Aulonemia patriae Pohl, sp. nov.

Gramen altum, sublignosum, perenne, monocarpicum, ab A. laxa (Maekawa) McClure
spiculis muticis, gluma inferiore longiore (5-7 mm. vs. 2 mm.), lemmate primo fertili,
palea lemmatum fertilium lemmatibus aequante, et ab A. viscosa (Hitchc.) McClure
spiculis longioribus (2.5-4.0 cm. vs. 1.5-2.5 cm.), gluma prima longiore (5-7 mm. vs. 2-5
mm.), laminis foliorum latioribus, orificio vaginarum setiferarum recedit.

Perennial, in small clumps of up to 10 culms; culms erect below, to 5 m. long, the lower
internodes up to 1 m. long, less than 1 cm. thick, naked or with reduced leaf blades;
culms branching from the middle and upper nodes; branches one per node, diverging
from the main stem at angles of 30-45 deg. , pushing the leaf sheath away from the main
stem; upper stem portions scrambling through brush; internodes glabrous, hollow, soft
and succulent, easily crushed, strongly viscid just below the nodes; a short, thick obconi-
cal internode, ca. 5-6 mm. long present just above the insertion of each leaf sheath, the
prophyllum and branch attached at the summit; leaf sheaths glabrous, often purple-
spotted, viscid at the apex; pseudopetioles flattened, viscid, 5-6 mm. long; sheath apex
truncate, bearing numerous flattened flexuous bristles up to 30 mm. long; external ligule
a short, stiff membrane; internal ligule a stiff ciliolate membrane 1.2-2 mm. long; leaf
blades spreading or drooping, flat, glabrous except for the scabrous margins; tip rather
abruptly acuminate; blades 20-26 cm. long, 4-8 cm. wide, ovate 2.7-3.5:1, the base
rounded and asymmetric; undersurface glaucous; prophylla ca. 5 cm. long, with 2 strong
keels, many-nerved, the smaller nerves occurring both between the keels and on the
marginal flanges. Peduncles terminal, exserted to 25 cm.; panicles ca. 40 cm. long;
branches ascending, solitary, to 34 cm. long, their branches strongly divaricate, solitary;
pedicels solitary, stiff, divaricate, 20-40 mm. long; spikelets relatively few. Spikelets
2.5-4.0 cm. long, 3-5 mm. wide, linear; first glume ovate 3:1, 5-7 mm. long, 7-nerved;
second glume 7 mm. long, ovate 3:2, 11-nerved; florets ca. 5; disarticulation above the
glumes and between the florets; lemmas 13-17 mm. long, awnless, 9-11-nerved, ovate
3:1, acute, scaberulous on the back; palea as long as the lemma, strongly 2-keeled, the
keels ciliolate; lateral flanges broad, enveloping the flower; tip bidentate; rachilla inter-
nodes 6-8.5 mm. long; lodicules 3, brown or purple, obovate, the upper two-thirds of the
margins ciliolate; anthers ca. 9 mm. long; styles separate; caryopsis cylindric, 8-10 mm.
long, crowned with the persistent style bases; terminal floret rudimentary, cylindric, ca.
9 mm. long.

Aulonemia patriae is similar to A. viscosa of the Talamanca Range
and A. laxa of Mexico. With the recent discovery of fruiting material
of all three species, it has been possible to differentiate them. Their
principal differential characters are given below.

A. laxa
A. patriae
A. viscosa

Auricular
bristles

Palea/
lemma
length
0.3-0.7
equal
equal

Awn
length
(mm.)
7-10
0
0

Spikelet
length
(cm.)
5.5-7.0
2.5-4.0
1.5-2.5

First glume

Sterile
lemmas
1
0
0

L (mm.)
2
5-7
2-5

Nerves
1
7
3-5

BURGER: FLORA COSTARICENSIS 69

This species occurs in a scattered stand on steep, wet canyon walls of
the pass at Alto del Roble, just south of the new bridge over the Rio
Patria (Rio Las Vueltas). The colony consists of possibly several
hundred individuals, most of them very inaccessible on the steep walls,
with a few other plants growing on steep embankments north of the
Rio Patria. I have observed the colony repeatedly since 1968, and saw
no signs of flowering until 1978. The stems are very soft and succulent
for a bamboo, and the nodes, upper portions of the sheaths,
pseudopetioles, and bases of the leaf blades are prominently viscid.
Flowering occurred prior to June, 1978, when the colony was revis-
ited. At this time, the entire colony had flowered, and the plants were
moribund. Most of the spikelets had disarticulated, and many of the
stems were disarticulating at the nodes. This species presumably has
been more widespread in the past, since it also occurs on the Cordillera
de Talamanca. Because the appearance of the vegetative and flowering
plants is so radically different, I am designating specimens of both
phases from the type locality as syntypes.

SYNTYPES: Costa Rica: Prov. Heredia: Alto del Roble, N of
Heredia, in the pass, just S of the new bridge; elev. 2,000 m., entire
colony, on both vertical walls of canyon E of road, fruiting and dead or
dying; old culms disarticulating. Pohl & Gabel 13577. 12 June 1978
(fruiting); Same locality and colony: Pohl 12798. 8 April 1972 (vegeta-
tive). Syntypes in ISC.

Other collections: Costa Rica: Prov. Heredia: Alto del Roble. Pohl &
Davidse 11781, 30 March 1969; Prov. Cartago: Madre Selva, km. 67,
along CIA; elevation 2,500 m. Pohl & Davidse 10751. 25 July 1968.

Aulonemia viscosa (Hitchc.) McClure, Smithsonian Contr. Bot.
9:61. 1973. Arundinaria viscosa Hitchc., Proc. Biol. Soc. Wash. 40:79.
1927. Figure 18.

Caespitose perennial bamboo, the culms solitary or in small clumps from pachymorph
rhizomes, 4-5 m. tall, 5-15 mm. thick, hollow, glabrous, erect or scrambling, forking, the
solitary branch at each middle node nearly as thick as the main culm and strongly
divaricate from it; surface of culms strongly purple spotted or solid purple; nodes con-
spicuous, very viscid in living plants; sheaths shorter than the internodes, glabrous,
striate, conspicuously purple spotted; apex of sheath with an erect rounded auricle on
one side; internal ligule a firm membrane, 1.0-2.5 mm. long; external ligule (exterior to
the insertion of the pseudopetiole) 0.5-1.0 mm. long, thick; pseudopetiole 5-7 mm. long,
viscid; leaf blades few, flat, ovate 4.7-6:1, acuminate, 21-26 cm. long, 4-5 cm. wide, the
bases rounded and oblique; glabrous and dark green above, scaberulous and glaucous
beneath. Peduncle purple splotched, viscid, as also the rachis and branches of the pani-
cle; inflorescence apparently terminal, an open pyramidal panicle, 15-25 cm. long;
branches solitary, naked at the base; spikelets solitary, on elongated stiff flexuous

JEM

FIG. 18. Aulonemia viscosa. A, panicle; B, spikelet with sterile terminal floret; C,
culm internode with a single leaf.

BURGER: FLORA COSTARICENSIS 71

pedicels. Spikelets laterally compressed, linear, 1.5-2.5 cm. long, disarticulating above
the glumes and between the 3-6 florets; glumes 2, the first 3-5 mm. long, lanceolate,
acute, 3-nerved; second glume 7-9 mm. long, narrowly ovate, blunt-tipped, 7-nerved;
lemmas narrowly ovate, blunt-tipped, 13-14 mm. long, 7-nerved, internally purple
spotted; palea equal to the lemma, scabrous on the keels; caryopsis ovoid 4:1, tapering to
an acuminate apex, dark brown.

Cerros de Velirla near Copey (TYPE: Tonduz 11729); between Divi-
sion and Lagunilla; Chirripo Grande. Rare, moist forests between
1,800-3,000 m. elevation. Recent specimens have all been vegetative,
and no blooming material has been collected since 1898. Known also
from Venezuela.

AVENA Linnaeus

Caespitose annual grasses; inflorescence a solitary terminal panicle. Spikelets usually
large, laterally compressed; glumes about as long as the entire spikelet, equal, many-
nerved, papery; florets several; disarticulation above the glumes and usually between
the several florets; lemmas rounded on the back, firm, 5-9-nerved; apex 2-toothed; awn
usually present, originating on the back of the lemma above the middle. (Pooideae:
Aveneae.)

Avena sativa L., Sp. PI. 79. 1753. Figure 19.

Caespitose annual in small clumps; culms ca. 1 m. tall. Inflorescence an open pyramidal
terminal panicle. Spikelets large, drooping, usually 3.5-4.5 cm. long; glumes equal,
spreading at maturity, conspicuously nerved; florets usually 2-3, the upper ones shorter
than the lowermost and the terminal one often abortive; callus sometimes short-bearded;
back of the lemma glabrous; awn well developed and geniculate or reduced to a short
rudiment in some strains; cultivated strains disarticulate tardily by a straight line of
fracture at the base of each lemma.

Oats is grown as a grain crop in the temperate zone and the grain is
frequently used for human food in the tropics as a breakfast cereal or in
drinks. It is rarely cultivated at middle elevations on the volcanoes of
the Meseta Central as a forage crop for dairy cattle, sometimes mixed
with Lolium. Common names: avena, "oats."

AXONOPUS Beauvois

REFERENCES: G. A. Black, Grasses of the genus Axonopus (a
taxonomic treatment), L. B. Smith, ed. Advancing Frontiers of Plant
Sciences 5:vi + 186. 1963. M. C. M. Hickenbick, J. F. M. Vails, F. M.
Salzano, & M. I. B. de Moraes Fernandes, Cytogenetic and evolution-
ary relationships in the genus Axonopus (Gramineae), Cytologia
40:185-204. 1975.

Perennial or annual Caespitose or rhizomatous, often stoloniferous grasses of low to
moderate stature. Peduncles 1-several from upper or terminal nodes; inflorescence of

FIG. 19. Avena saliva. A, panicle; B, spikelet; C, group of florets.

BURGER: FLORA COSTARICENSIS 73

several-many digitate or paniculate slender racemes, the spikelets borne in two rows
along the lower sides of a slender triquetrous or flattened rachis; pedicels very short;
spikelets appressed to the rachis, each overlapping sequentially with the spikelets next
above and below it. Spikelets placed with the second glume and back of the fertile lemma
away from the rachis; first glume absent (except occasionally in A. poiophyllus); second
glume and lower (sterile) lemma subequal, 2-5-nerved, concealing the upper (fertile)
floret, slightly or considerably longer than the fertile floret; fertile lemma dorsally com-
pressed, stiff, cartilaginous, usually faintly striate, glabrous or with a few short spicules
at its tip, its margins slightly inturned over the equal palea of similar form and texture;
lodicules 2, truncate; anthers usually 3; styles 2, separate, naked at the base; caryopsis
flattened, elliptical.

Axonopus is a large genus of over 100 described species, confined to
warm climates of the western hemisphere and introduced elsewhere.
The plants could be confused with some species of Paspalum or
Digitaria on casual examination. They differ from Paspalum and
Digitaria in the placement of the spikelets with the fertile lemma away
from the rachis, and from Digitaria in the presence of solitary spike-
lets at each node of the rachis. A relatively small number of the species
have importance as forage grasses. In Costa Rica, A. scoparius
(Zacate imperial), A. compressus (Zacate amargo), and A. affinis are
all components of pastures. (Panicoideae: Paniceae.)

KEY TO SPECIES OF Axonopus

la. Rachis of racemes beset with numerous elongated, stiff, golden hairs that surround

spikelets 2

Ib. Rachis of racemes scabrous or rarely sparsely hairy, lacking conspicuous golden

hairs 3

2a. Rachis ca. 0.5 mm. wide, spikelets not sunken into pockets; rachis bearing

spikelets to the tip A. aureus

2b. Rachis 1.0-1.5 mm. wide, spikelets sunken into pockets between the midrib and
margin; rachis extended beyond the ultimate spikelet as a flattened naked point
2-3 mm. long, sometimes with a solitary abortive spikelet at its tip

A, chrysoblepharis

3a. Spikelets 1.2-1.6 mm. long; weak caespitose annual; culms 20-40 cm. tall

A. capillaris
3b. Spikelets 1.8-3.5 mm. long; perennials with hard bases, often rhizomatous or

stoloniferous 4

4a. Inflorescence of very numerous racemes (up to 100), racemose along rachis, up

to 50 cm. long; internodes of culms up to 7 mm. thick A. scoparius

4b. Inflorescence of 2-8 racemes borne on short common rachis; internodes of culms

3 mm. or less thick 5

5a. Spikelets 1.8-2.2 mm. long A. purpusii

5b. Spikelets 2.3-3.5 mm. long 6

6a. Second glume exceeding fertile floret by 0.2 mm. or less; nerves of bracts
obscured by dense bands of silky pubescence 7

74 FIELDIANA: BOTANY

6b. Second glume exceeding fertile floret by 0.2-1.2 mm.; nerves of bracts not

obscured by pubescence 8

7a. Culm internodes 1-3, not entirely covered by leaf sheaths; spikelets 2.9-3.1 mm.
long; bracts 2-nerved; anthers 1.5-1.8 mm. long; coastal savannas, Guanacaste

A. poiophyllus

7b. Culm internodes numerous, short, culms clothed by overlapping sheaths nearly to
peduncle; spikelets 3.0-3.5 mm. long, bracts 4-5-nerved; anthers 2.2 mm. long;

Volcan Rincon de la Vieja A. volcanicus

8a. Fertile floret 1.0-1.2 mm. shorter than the spikelet; second glume 3-nerved,
lateral nerves projecting as short points, apex of the glume trifid; spikelets

3.0-3.6 mm. long A. centralis

8b. Fertile floret 0.3-0.7 mm. shorter than spikelet; second glume 2- or 4-nerved,

lateral nerves not projecting; spikelets usually 2.4-2.7 mm. long 9

9a. Leaf blades linear with very blunt, rounded tips; fertile floret up to 0.4 mm. shorter

than second glume; middle elevations, mostly in the Meseta Central . . A. affinis

9b. Leaf blades narrowly ovate, tapering from middle to an acute tip; fertile floret

0.3-0.6 mm. shorter than second glume; widespread at lower and middle elevations

A. compressus

Axonopus affinis Chase, J. Wash. Acad. Sci. 28:180. 1938.

Perennial, caespitose or with stolons; culms unbranched, 20-60 cm. tall; internodes up
to 2 mm. thick, pithy, glabrous; nodes glabrous or slightly bearded; sheaths compressed,
glabrous except for the ciliate overlapping margin, the inner margin thin and fragile;
ligule a ciliolate membrane, in total 0.3-0.5 mm. long; leaf blades linear, flat or folded,
4-15 cm. long, 3-5 mm. wide, papillose-ciliate near the base, otherwise glabrous, the
apex obtuse. Peduncles 1-2 from the terminal sheath, exserted up to 16 cm.; inflores-
cence 5-11 cm. long, of 2-7 divergent racemes on a short common rachis; individual
racemes slender, 3.5-5.0 cm. long; rachis triquetrous, ca. 0.5 mm. wide, scabrous on the
angles; spikelets subsessile, the pedicels less than 0.2 mm. long; spikelets overlapping
sequentially one-third to one-half of their length. Spikelets 2.3-2.8 mm. long, elliptic-
obovate, 2.4-2.7:1, acute, slightly pubescent on the margins of the glume and sterile
lemma and at the apex; second glume and lower (sterile) lemma equal, exceeding the
floret by 0.2-0.4 mm.; nerves 2, submarginal, the midnerve lacking; fertile floret
stramineous; lodicules 2, truncate; anthers 3, purple, ca. 1.5 mm. long; styles 2, sepa-
rate, naked at the base; stigmas 2, purple.

Pastures and open areas, mostly 1,700-2,200 m. elevation; Vara
Blanca, Volcan Barba, San Ramon, Tarbaca. June to December. Wide-
spread, southeastern United States to Argentina; introduced
elsewhere.

This species, along with A. compressus, comprises an intricate and
difficult taxonomic group, as yet poorly understood. My treatment
should be regarded as tentative. I have named as A. affinis our speci-
mens that have a chromosome number of n = 50 and which possess
linear rather than narrowly ovate leaf blades. All have outer bracts
that only slightly exceed the fertile lemma. Presence or absence of

BURGER: FLORA COSTARICENSIS 75

stolons, often used as a character in Axonopus, is unreliable, as plants
in dense turf, like those in pastures, frequently lack stolons.

Axonopus aureus Beauv., Ess. Nouv. Agrost. 12. 1812. A. chry sites
(Steud.) Kuhlm., Comm. Linh. Telegr. Estrat. Mato Grosso Amazonas
67, Annexo 5, Bot. pt. 11:88. 1922. Panicum chrysites Steud., Syn. PI.
Glum. 1:38. 1854. Figure 20.

Caespitose perennial in clumps from knotty crowns; plants 40-90 cm. tall, branching
from the lower nodes, much of the foliage borne toward the base; internodes 1.0-1.5 mm.
thick, hollow, glabrous, rarely with a few short golden bristles near the apex; nodes
glabrous, dark, not prominent; lower sheaths overlapping, the upper shorter than the
internodes, keeled, glabrous or papillose-hispid, the margins usually ciliolate; ligule a
dense ciliolate fringe, usually less than 0.5 mm. long; leaf blades 8-15 cm. long, 4-7 mm.
wide, glabrous or the margins and sometimes the surfaces papillose-hispid, a dense tuft
of long hispid hairs occasionally just behind the ligule. Peduncles solitary, exserted 2-15
cm., terminal on erect leafy branches. Panicle vase-shaped, up to 9 cm. long, made up of
2-9 slender ascending racemes borne on a short central axis; racemes 4-9 cm. long; rachis
triquetrous, ca. 0.5 mm. wide, strongly papillose-ciliate with stout golden hairs 2-3 mm.
long; tufts of similar hairs borne on a transverse ridge just below the insertion of each
spikelet; pedicels less than 0.2 mm. long; spikelets subsessile in shallow excavations of
the rachis, in 2 alternating rows on the 2 lower sides, each overlapping the next above by
about one-third of its length. Spikelets elliptic-obovate 2:1, biconvex, glabrous, 1.2-1.5
mm. long; second glume and lower (sterile) lemma equal, as long as the spikelet, gla-
brous, usually purple, faintly 2-3-nerved; upper (fertile) lemma elliptical, cartilaginous,
1.2-1.3 mm. long, chestnut-colored, the palea similar, bulging; lodicules 2, truncate;
anthers 3, purple, 0.8-0.9 mm. long; styles 2, separate; lodicules 2. Chromosome number
n = 10 from a Costa Rican specimen.

Dry Curatella-Byrsonima savannas, and other open areas, espe-
cially on volcanic tuff, 200-1,100 m. elevation; occasional in Guanacaste,
western Meseta Central (Hda. Argentina, Nuestro Amo, Rodeo de
Pacaca, Paraiso); Buenos Aires, Boruca, Canas Gordas. October to
January. Mexico to Panama; northern South America to Brazil and
Bolivia; West Indies.

Black has applied the name A. chrysites to this species, deeming the
name A. aureus dubious. However, Chase (Proc. Biol. Soc. Wash.
24:135. 1911) discussed the application of the name A. aureus and fixed
it in the sense used here.

Axonopus capillaris (Lam.) Chase, Proc. Biol. Soc. Wash. 24:133.
1911. Paspalum capillare Lam., Tabl. Encycl. 1:176. 1791. Figure 23.

Plants annual, caespitose, rather delicate; culms mostly 20-40 cm. long, often genicu-
late at the base and sprawling, branching freely from the base and lower nodes; inter-
nodes slender, 0.7 mm. or less thick, hollow, glabrous; nodes glabrous or minutely
bearded; leaf sheaths shorter than the internodes, glabrous except for the short-ciliate
overlapping margin; ligule a densely ciliolate membrane, 0.3-0.5 mm. long; leaf blades

FIG. 20. Axonopus species. A. aureus: A, culm and inflorescence; B, C, rachis and
spikelets; A. chrysoblepharis: D, E, tip of rachis and spikelets.

BURGER: FLORA COSTARICENSIS 77

flat, tapering from a broad base, 1.5-7.0 cm. long, 3-7 mm. wide, the length 5-12 x the
width, glabrous except for a few marginal cilia near the base. Peduncles slender,
arcuate, 1-3 from the terminal sheath and sometimes others from the upper leaf axils,
exserted up to 15 cm.; inflorescence of 2 conjugate divergent racemes 2.0-3.5 cm. long
borne at the apex of the peduncle, often a third borne a short distance below; racemes
very slender, the triquetrous rachis less than 0.5 mm. wide, scabrous on the angles,
undulate; spikelets borne in 2 rows on the lower 2 sides of the rachis, each one barely
overlapping the base of the next above in sequence. Spikelets obovate 2.3-2.5:1, min-
utely puberulent, 1.2-1.6 mm. long, stramineous or purplish; second glume as long as the
spikelet, 4-nerved, lacking a midrib; sterile lemma similar, 2-nerved; upper (fertile)
lemma about as long as the spikelet, faintly striate, its palea similar; anthers 3, purple,
0.4 mm. long; styles 2, separate; stigmas purple; caryopsis amber, elliptical 2:1, 1.1 mm.
long. Chromosome number n = 10, 20 from Costa Rican specimens.

Somewhat weedy; beaches, roadsides, pastures. Playas del Coco,
San Ramon area, Turrucares, Alajuela, San Jose. September to
January. Honduras and El Salvador, Costa Rica and Panama to north-
ern South America, southward to Peru, Brazil, and Paraguay; Lesser
Antilles.

Black (1963) states that some specimens have pilose foliage, but ours
are nearly glabrous.

Axonopus centralis Chase, J. Wash. Acad. Sci. 17:143. 1927. Figure
24.

Caespitose perennial; culms 35-80 cm. tall, erect or spreading, unbranched; internodes
1.5-3.0 mm. thick, pithy, glabrous; nodes glabrous or minutely woolly; leaf sheaths
keeled, longer than the internodes, the overlapping margin ciliate, the other margin
very thin and fragile; collar more or less pubescent; ligule a minute ciliolate rim, 0.2-0.3
mm. long; leaf blades rather thin, flat, 8-50 cm. long, 8-13 mm. wide, papillose-ciliate at
the base and with occasional appressed hairs on the upper surface. Peduncles 1-2 from
the uppermost sheath, slender and arcuate, exserted up to 27 cm., slightly woolly at the
apex; inflorescence usually of 2-3 ascending racemes borne on a common rachis up to 6
cm. long; racemes slender, 7-13 cm. long; rachis triquetrous, the spikelet-bearing sides
ca. 0.7 mm. wide, the third side narrower; spikelets overlapping sequentially about
one-third. Spikelets 3.4-3.6 mm. long, very flat, ovate 3.1-3.5:1, the apex rather blunt;
second glume trifid at the tip, the 2 lateral nerves exserted as short points; lateral nerves
submarginal, flanked on both sides by a silky band; midnerve usually present but faint;
lower (sterile) lemma similar to the glume but slightly shorter, the apex acute; upper
(fertile) floret much shorter than the outer bracts, 1.9-2.1 mm. long, elliptical 2.1:1,
glabrous, stramineous; palea similar to the lemma; anthers 3, brownish and shriveled,
ca. 0.6 mm. long; caryopsis elliptical, 2.0-2.5:1, tan, 1.4-1.6 mm. long.

In light shade, northwestern Guanacaste, Hda. Las Animas, Hda.
Palo Verde, Finca la Pacifica, Playa Tamarindo; elevations from sea
level to 200 m. June to December. Southwestern Mexico to Panama;
Ecuador to Venezuela.

In several of the specimens examined, the anthers were trapped

78 FIELDIANA: BOTANY

within the fertile floret at the apex of a well-developed caryopsis. They
were shriveled and contained shrunken or empty pollen grains. It is
probable that this species is apomictic or cleistogamous.

Axonopus chrysoblepharis (Lag.) Chase, Proc. Biol. Soc. Wash.
24:134. 1911. Cabrera chrysoblepharis Lag., Gen. & Sp. Nov. 5. 1816.
Figure 20.

Duration indefinite, possibly annual; caespitose; plants 70-100 cm. tall, erect; culms
branching freely from lower and middle nodes; internodes 1-2 mm. thick, hollow, gla-
brous, golden colored; nodes glabrous or bearded with short golden hairs; leaf sheaths
nearly glabrous to pilose or pustulose-hispid; ligule a ciliolate membrane, 0.3-1.2 mm.
long; leaf blades flat, 5-30 cm. long, up to 15 mm. wide, marginally pustulose-hispid, the
surfaces more or less pilose and sometimes papillose-hispid as well. Peduncles terminal
on the main culm or leafy erect branches, exserted 7-26 cm.; inflorescence a vase-shaped
group of 4-10 slender ascending racemes borne on a short common rachis 1-2 cm. long.
Rachis of individual spikes triquetrous, the back side 1-1.5 mm. wide, with a conspicuous
flattened midrib and thickened margins that are densely pustulose hispid-ciliate with
conspicuous golden hairs 2-3 mm. long; midrib produced between the spikelets as a
thickened corky ridge, also bearing pustulose hairs; tip of rachis prolonged beyond the
spikelets as a naked flattened point 2-3 mm. long, sometimes bearing a solitary abortive
spikelet on its tip; spikelets sunken into cavities between the midrib and margins of the
rachis, each spikelet overlapping the next in sequence by about one-half. Spikelets
1.4-1.6 mm. long, ovate 2.1-2.7:1; second glume and sterile lemma similar, with 2 sub-
marginal nerves, equal in length and barely exceeding the fertile floret; texture of bracts
very thin, revealing the brown color of the fertile floret; fertile lemma brown, 1.3-1.5
mm. long; anthers 3, purple, 0.5-0.6 mm. long; styles 2, separate; stigma purple.
Chromosome number n = 10 or 10 + 2b from Costa Rican and Venezuelan specimens.

Rare; dry savannas. We have seen Pittier & Tonduz specimens col-
lected before 1900 from Boruca, Mano de Tigre, and Canas Gordas.
Our sole recent specimen was from the Boruca savannas. November to
February. Guatemala to Panama and northern South America, to
Peru, Bolivia, Brazil, and Paraguay; Trinidad.

Axonopus compressus (Swartz) Beauv., Ess. Nouv. Agrost. 154.
1812. Milium compressum Swartz, Prodr. Veg. Ind. Occ. 24. 1788.
Figure 21.

Perennial; stoloniferous or caespitose (especially when crowded in turf), usually
branching from the base or from rooted stolons; culms 1-3 mm. thick; internodes gla-
brous, hollow; nodes glabrous or appressed bearded; sheaths keeled, usually glabrous but
the overlapping margin ciliate, the collar often with a pubescent line; ligule a short
ciliolate membrane, in total 0.2-0.5 mm. long; leaf blades flat, thin or firm, 8-26 cm. long,
7-13 mm. wide, narrowly ovate, tapering from below the middle to an acute apex,
papillose-ciliate on the lower margins and sometimes with scattered weak appressed
hairs on the upper surface. Peduncles 1-2 from the uppermost sheath, exserted up to 17
cm.; inflorescence of 2-6 divergent slender racemes borne on a short common rachis;
pedicels very short, usually less than 0.2 mm. long. Spikelets overlapping sequentially
one-fourth to one-third of their length, 2.4-2.7 mm. long, ovate, acute, the second glume

FIG. 21. Axonopus compressus. Plant with inflorescences, spikelet, and fertile floret.

80 FIELDIANA: BOTANY

and lower (sterile) lemma 0.3-0.7 mm. longer than the upper (fertile) floret; both bracts
with 2 submarginal nerves and more or less pilosity along both sides of the nerves; fertile
lemma stramineous, its palea similar; lodicules 2, truncate; anthers 3, purple; caryopsis
tan or white, elliptical, 1.0-1.6 mm. long, flattened.

Widespread and common in pastures and open areas, open shade,
usually in moist sites; sea level to 1,400 m. Probably blooming year-
long. Widespread in warmer parts of the World.

Axonopus compressus is complex and highly variable, with many
morphological races and several chromosomal levels. It is unlikely that
this and related species can be properly understood without extensive
cytological, genetic, and cultural studies. My treatment should be re-
garded as tentative. Among our specimens that have known chromo-
some numbers, I have been able to recognize roughly several groups
based upon chromosome numbers and morphology; however, many
cytologically unknown specimens can only be placed very approxi-
mately with one or another of these groups. Descriptions of the princi-
pal differences among these cytotypes are given below.

n = 40. Plants 45-135 cm. tall; leaf blades 12-22 x longer than wide;
spikelets ovate 2.7-2.8:1; anthers 1.0-1.3 mm. long. Known Costa
Rican specimens are from elevations above 1,300 m. in the Meseta
Central.

n = 20. Plants 20-60 cm. tall; leaf blades mostly 8-11 x longer than
wide, thin; spikelets ovate, 2.8-3.3:1; anthers 0.5-0.7 mm. long, brown
to purplish. Widespread, sea level to 1,100 m. elevation.

n = 30. One specimen so determined from the Siquirres area (Pohl
& Davidse 11463) has heavily bearded nodes and leaf blades promi-
nently ciliate for their full length; second glume 4-nerved.

Axonopus poiophyllus Chase, Proc. Biol. Soc. Wash. 24:133. 1911.
A. blakei Hitchc., Proc. Biol. Soc. Wash. 40:85. 1927. A. rhizomatosus
Swallen, J. Wash. Acad. Sci. 23:458. 1933. Figure 22.

Perennial, caespitose or with short, knotty rhizomes; culms 25-100 cm. tall, erect,
unbranched; foliage mostly basal, the lower sheaths overlapping; culm internodes 1-3, up
to 3 mm. thick, hollow; nodes appressed-bearded; leaf sheaths keeled, more or less
papillose-hirsute above the nodes and at the apex; overlapping margins ciliate; ligule a
minute ciliate fringe, 0.3-0.5 mm. long; leaf blades flat or folded, 13-33 cm. long, up to 5
mm. wide, the uppermost one much reduced. Peduncles solitary or 2 from the upper-
most sheath, exserted 6-25 cm.; inflorescence of 3-7 ascending racemes borne on a
common axis up to 4 cm. long; racemes up to 11 cm. long, the slender triquetrous
undulate rachis ca. 0.5 mm. wide, scabrous and with a few scattered elongate hairs;
spikelets borne on short pedicels less than 0.5 mm. long; spikelets overlapping sequen-
tially about one-third, 2.5-2.8 (-3.1) mm. long, ovate 2.9-3.1:1; first glume absent or if

JF/I

FIG. 22. Axonopus species. A. purpusii: A, inflorescence; B, base of plant; C, portion
of raceme with spikelets; A. poiophylltis: D, inflorescence; E, portion of raceme with
spikelets.

82 FIELDIANA: BOTANY

present, narrowly triangular, up to 2.5 mm. long, 1-5-nerved; second glume and lower
(sterile) lemma equal, as long as the spikelet, 2-nerved, silky near the margins and at the
base; upper (fertile) lemma slightly shorter than the outer bracts, ovate 2.7-2.8:1, faintly
striate, ciliate at the tip; anthers 3, purple, 1.5-1.8 mm. long; styles 2, separate; stigmas
purple. Chromosome number n = 30 from Costa Rican and Honduran specimens.

Dry Curatella-Byrsonima savannas on volcanic tuff, mostly at ele-
vations under 200 m.; northern Guanacaste south to Bagaces. June to
July; January. Southern Mexico to Honduras; Colombia; Cuba.

We have previously confused this species with the endemic A. vol-
canicus from Rincon de la Vieja. In addition to the differences stated
in the key, they differ in chromosome number. Spikelets in the genus
Axonopus lack a first glume, and the occurrence of this structure in
some of our specimens of A. poiophyllus is apparently unique.

Axonopus purpusii (Mez) Chase, J. Wash. Acad. Sci. 17:144. 1927.
Paspalum purpusii Mez, Bot. Jahrb. 56, Beibl. 125:10. 1921.
Axonopus anomalus Swallen, Contr. U.S. Natl. Herb. 29:268. 1949.
Figure 22.

Densely caespitose perennial; culms 50-80 cm. tall, erect, simple; internodes 1-2, elon-
gated, less than 1 mm. thick, glabrous; nodes dark, not enlarged, glabrous or rarely
sparsely appressed-bearded; foliage mostly basal, the culms rather naked; sheaths
keeled, much shorter than the internodes, glabrous to densely pilose, the overlapping
margin ciliate; ligule a densely ciliate rim, in total 0.3-0.6 mm. long; collar usually pilose;
blades 15-25 cm. long, 2-4 mm. wide, more or less papillose-pilose, the tip abruptly
rounded; uppermost blade usually much reduced; basal foliage frequently burned off in
herbarium specimens. Peduncles 1-2, exserted 12-17 cm. from the apical sheath, very
slender; inflorescence 8-11 cm. long, vase-shaped, of 3-6 slender ascending racemes
borne on a short common rachis 1-3 cm. long; racemes 4-8 cm. long, woolly at the base;
rachis slender, 0.3-0.5 mm. wide, undulate, scabrous on the angles and with scattered
long hairs at the nodes; spikelets subsessile, the pedicels 0.3 mm. or less long. Spikelets
overlapping sequentially for one-third to one-half their length, 1.8-2.2 mm. long,
oblong-ovate 2.5-3.3:1; second glume and lower (sterile) lemma similar, as long as the
spikelet, 2-nerved submarginally, the nerves mostly concealed by dense silky appressed
hairs that extend to 0.3 mm. beyond the acute tip of the bracts; upper (fertile) lemma
ovate ca. 2.4:1, stramineous, faintly striate, with a few minute spicules at its tip; palea
similar; lodicules 2, truncate; anthers 3, purple, 1.2 mm. long; styles 2, separate; stigmas
light-colored. Chromosome number n = 10 from a Costa Rican specimen.

Dry savannas, especially with Curatella and Byrsonima; northern
Guanacaste, between Liberia and La Cruz; savannas of Buenos Aires;
elevations 75-380 m. March to August. Southern Mexico to Panama;
northern South America to Bolivia, Brazil, Paraguay, and Argentina.

Axonopus scoparius (Fliigge) Kuhlm., Comm. Linh. Telegr. Es-
trat. Mato Grosso Amazonas, Publ. 67, Annexe 5, Bot. 11:45. 1922.
Paspalum scoparium Fliigge, Gram. Monogr. 124. 1810. Figure 23.

FIG. 23. Axonopus species. A. scoparius: A, inflorescence; B, spikelets, both sides; A.
capillaris: C, blooming plant; D, spikelets, both sides.

•84 FIELDIANA: BOTANY

Tall, vigorous perennial from a matted crown; culms erect, to 1.5 m. tall; plants
sometimes producing lengthy coarse stolons when pendent on steep slopes; culms occa-
sionally branched; internodes up to 7 mm. thick, solid, pithy, glabrous; lower leaf
sheaths closely overlapping, strongly keeled, glabrous; ligule a thick membrane, bearing
short cilia, in total 1.0-2.7 mm. long; dewlap conspicuous, yellowish; collar bearing a line
of short, stiff hairs; leaf blades flat, 15-50 cm. long, 0.5-3.0 cm. wide, tapering to an acute
apex; lower surface glabrous; upper surface papillose-hirsute. Peduncle included or ex-
serted up to 30 cm.; inflorescence a terminal panicle made up of numerous simple or
rarely branched spreading or ascending racemes; panicle open, dome-shaped, often
purplish, usually 15-30 cm. long and nearly as wide; individual racemes to 12 cm. long;
rachis of racemes slender, triquetrous, strongly scabrous on the angles and sometimes
with a few longer hairs; pedicels stiff, appressed, scabrous, less than 1 mm. long; spike-
lets borne in 2 rows appressed to the lower sides of the rachis; successive spikelets
overlapping by about one-third. Spikelets 2.7-2.9 mm. long, ovate 2.5-3.3:1, acute or
rather blunt, usually purple; second glume and lower (sterile) lemma equal, as long as
the spikelet, covering and concealing the upper (fertile) floret, both sparsely appressed
pubescent between the nerves; upper (fertile) floret 2.2-2.4 mm. long, oblong, rather
blunt; lemma cartilaginous, stramineous, its apex bearing a few minute spicules, the
margins slightly inrolled over the edges of a similar palea; lodicules 2, truncate; anthers
3, purple, 1.5-1.7 mm. long; styles 2, stigmas purple. Chromosome numbern = 10 from
Costa Rican specimens.

This species is widely cultivated in moister parts of the Meseta
Central and on the volcanoes of the Cordillera Central, at elevations up
to 2,500 m. It appears to persist after cultivation or to spread freely to
field margins and road embankments. Black reports A. scoparius from
Mexico to Peru, without indicating whether part of this range is due to
spread in cultivation.

None of our specimens has mature seed, and caryopses are appar-
ently rarely produced. In cultivation, the plants are reproduced by
cuttings or by placing culms in furrows as is done with sugar cane.

The species is widely cut as green feed for dairy cattle and produces
tremendous yields of forage under optimum conditions. Common
name: Zacate Imperial. We have seen a strain with purple leaves
cultivated near Pacayas.

Axonopus volcanicus Pohl, sp. nov. Figure 24.

Axonopus poiophyllo Chase similis, sed ab eo folii numerosis (6-11), vaginis imbricatis,
spiculis longioribus (3.0-3.5 mm.), nervis glumae secundae et lemmatis sterilis 4-5, num-
ero chromosomico n = 19 recedens.

Densely caespitose perennial, forming thick sods; culms erect, 30-80 cm. tall, branch-
ing freely from the base and lower nodes; internodes compressed, to 3 mm. thick, hollow
with a small lumen or solid and pithy, glabrous; leaf sheaths keeled, closely overlapping
and clothing most of the culm; collar, keel, and margins silky ciliate, especially near the
apex; ligule a minute membrane, densely ciliate with silky white hairs, in total 0.7-0.9
mm. long; leaf blades 6-11 per culm, 9-20 cm. long, 4-7 mm. wide, long-pubescent on the

FIG. 24. Axonopus species. A. volcanicus: A, inflorescence; B, spikelets, both sides;
C, culm invested with leaves; A. centralis: D, inflorescence; E, spikelets, both sides.

86 FIELDIANA: BOTANY

upper surface above the ligule; margins papillose-ciliate with long coarse hairs to 4 mm.
long; midrib sometimes pubescent above; margins scaberulous; midrib prominent be-
neath; tip of blade blunt, boat-shaped. Peduncles exserted 6-15 cm.; inflorescences 1-2
from the terminal sheath; composed of 3-8 ascending racemes borne on a common rachis
1-3 cm. long; inflorescence 6-14 cm. long, the individual racemes 6-13 cm. long, minutely
bearded at the base, spikelet-bearing nearly to the base; rachis triquetrous, ca. 0.5 mm.
wide, scabrous on the angles and with a few scattered elongated papillose-based hairs;
pedicels 0.3-0.5 mm. long. Spikelets overlapping sequentially about one-third their
length, 3-3.5 mm. long, ovate 2.8-3.1:1, silky on the margins of the bracts and at the
base, often purplish; second glume and lower (sterile) lemma equal, as long as the
spikelet and slightly exceeding the tip of the fertile lemma, 4-5-nerved, the nerves
usually submarginal, a weak midrib present or absent; upper (fertile) lemma 2.5-3.1 mm.
long, elliptic, stramineous, faintly striate, with a tuft of short cilia at the tip; palea
similar; lodicules 2, truncate, fleshy; anthers 3, purple, 2.2 mm. long; styles 2, separate;
stigmas purple. Immature caryopses seen.

A large, dense stand of this species occurs above timberline on the
west face of Rincon de la Vieja, at a locality on Hacienda Guachipelin
known as Los Copelares. It also occurs around a fumarole called Las
Hornillas. In both cases, chromosome counts indicate n = 19. We have
previously considered that these plants were conspecific with A.
poiophyllus Chase, which, according to our counts, has 30 pairs of
chromosomes. Both populations, however, differ from that species in
having longer, more densely silky spikelets with 4-5 nerves on the
bracts, typical A. poiophyllus having 2-nerved bracts. More strik-
ingly, the montane A. volcanicus has a much larger number of foliage
leaves per culm, their sheaths densely clothing the stems nearly to the
inflorescence. Axonopus poiophyllus typically has 1-3 culm blades and
more or less exposed internodes. None of our specimens has spikelets
with first glumes, while the common lowland A. poiophyllus in the
region frequently has them. The peculiar aneuploid chromosome
number of A. volcanicus suggests that it is a recent derivitive that is
successful in the rather extreme habitats of Rincon de la Vieja.

SPECIMENS SEEN: HOLOTYPE: Costa Rica; Prov. Guanacaste,
La Hornillas, Volcan Rincon de la Vieja, Hda. Guachipelin, elevation
750 m., 17 January 1969, n = 19, Pohl & Davidse 11667, ISC 277812.
OTHER SPECIMENS: Prov. Guanacaste, Los Copelares, Volcan
Rincon de la Vieja, Hda. Guachipelin, above timberline on W side of
volcano, elevation 1,400 m., 30 July 1971, n = 19, Pohl 12662. Another
sheet from the same locality: Burger & Pohl 7763.

BAMBUSA Schreber

Caespitose bamboos of medium to tall stature; culms hollow or sometimes nearly
solid; culm sheaths early deciduous; branches unarmed or with stout straight or hooked

BURGER: FLORA COSTARICENSIS 87

branch thorns; branches 1-several per node, one usually larger than the others; foliage
blades without conspicuous commissural veins. Inflorescence spicate, of sessile, clus-
tered pseudospikelets, these with basal prophylla and bracts, the lower glumelike, en-
closing branch buds and short paleas or true spikelets; pseudospikelets continued with-
out interval into several-flowered spikelets, their lemmas many-nerved, the paleas about
as long as the lemma; lodicules 3, flat, vasculated, ciliate; anthers 3 or 6; style 1, stigmas
2 or 3.

As treated by McClure (1973), thorny American bamboos previously
considered as constituting the genus Guadua Kunth, are here included
as subgenus Guadua (Kunth) McClure. Subgenus Bambusa consists of
Asiatic bamboos, either thorny or not, many of which are cultivated in
the American tropics. In addition to the species treated here, others
may be found in cultivation. (Bambusoideae: Bambuseae.)

KEY TO SPECIES OF Bambusa

la. Culm branches with straight or hooked thorns; internodes not striped 2

Ib. Culm branches lacking thorns; culms usually longitudinally striped with green and

yellow B. vulgaris

2a. Culms up to 3 cm. thick, 5 m. tall; pseudopetioles less than 1 mm. long, leaf
blades 10 mm. or less wide; native, dry savannas, northern Guanacaste

B. paniculate,

2b. Culms up to 15 cm. thick, 30 m. tall; pseudopetioles 2-5 mm. long, leaf blades
10-18 mm. wide; cultivated Asiatic species B. arundinacea

Bambusa arundinacea Willd., Sp. PL 245, 1799, sensu Gamble,
Ann. Roy. Bot. Card. Calcutta 7:51, pi. 48. 1896. Figure 25.

Giant caespitose bamboos in large dense clumps; culms up to 30 m. tall and 10-15 cm.
thick, nearly erect; internodes cylindrical, green, densely glaucous when young with
siliceous powder, lower nodes ciliate with brown hairs; culm sheaths deciduous, coriace-
ous, glabrous outside, sheath blades as wide as the sheath apex, broadly triangular,
erect, the abaxial surface glabrous, the adaxial surface densely hispid with blackish
hairs; ligule a short thick ciliolate membrane, 1-2 mm. long; lower nodes of the culms
producing numerous weak spreading thorny branches; foliage-bearing branchlets 1-3 per
node, solid, frequently with 1-several straight or hooked thorn-branches arising at their
bases; sheaths on foliage-bearing branchlets overlapping, glabrous except for the cilio-
late margin; auricles ciliate with light-colored bristles up to 6 mm. long; external ligule
prominent, coriaceous; pseudopetioles 2-5 mm. long; margins of blades white-banded;
surfaces glabrous, slightly glaucous, 7-18 cm. long, 10-18 mm. wide, leaves crowded
towards the tips of the branchlets, the sheaths overlapping. Inflorescences large,
covering at least the terminal 5 m. of the culms; pseudospikelets subsessile, 1.5-2.0 cm.
long, their bases enclosed by prophylls, clustered at the nodes of slender naked branch-
lets up to 50 cm. long, usually 2-5 per node of the slender rachis, with several short
prophylla at the base, branching into true spikelets that are continuous with the basal
bracts and prophylls; prophylla 4-5 mm. long, ciliate on the keels, no definite "glumes"
above the basal bracts; true spikelets disarticulating above the basal bracts and between
florets; lemmas broad, ca. 15-nerved, rounded on the back, mucronate, 8-9 mm. long, the
margins short-ciliate, enwrapping the rachilla at the base; palea conspicuously ciliate on

FIG. 25. Bambusa arundinacea. A, pseudospikelet; B, portion of inflorescence; C,
twig node with branch thorns; D, base of seedling.

BURGER: FLORA COSTARICENSIS 89

the keels, as long as the lemma or slightly longer; rachilla internodes short, flattened;
florets 5-7, the uppermost reduced; lodicules 3, flattened, vasculated, broadly spatulate,
long-ciliate at the tip; anthers 6, yellow, 4-5 mm. long; style 1; stigmas 3, plumose;
caryopsis plump, ovate-fusiforme, acute, tan, 7.0-7.5 mm. long, 2.5 mm. wide; embryo
1.5 mm. long; style base persistent; adaxial groove conspicuous, running the full length
of the caryopsis.

The above inflorescence and spikelet description was taken from a
specimen collected by Mayra Montiel de B., 13 May 1974. I have vis-
ited the same colony on the estate of Dr. Antonio Pena Chavarria in
Rio Segundo. The clump was dense, 10-12 m. in diameter and the
erect to arching culms reached 20-30 m. in height. Individual culms
were 10-12 cm. thick. The internodes of young culms were densely
whitened with siliceous powder (tabasheer). This clump began to
bloom in 1974 and the specimen collected by Sra. Montiel de B. in May
had intact inflorescences. When I saw it in December 1974, most of the
clump was still vegetative, but many culms were dead and the
spikelets had shattered. The gardener stated that the clump was at
least 25 years old and that this was the first flowering. The plants
produced prodigious quantities of fallen spikelets. Many of the florets
were sterile and empty. An analysis of florets collected under this
clump, performed by the Iowa State Seed Laboratory, indicated that
nearly 20 per cent of the material contained caryopses. Enough
caryopses were produced that the seedlings constituted a weed prob-
lem in the flower beds near the clump. Seedlings 25-30 cm. tall were
already present and were producing short rhizomes or tillers.

This species, of Asiatic origin, is occasionally cultivated in Central
America, but is disliked because of the thorns. A large clump occurs in
the bamboo grove of the CATIE of Turrialba. Blooming during the
1974-1975 period is known from Panama and other parts of Central
America.

Bambusa paniculata (Munro) Hack., Oesterr. Bot. Z. 53:195. 1903.
Guadua paniculata Munro, Monogr. Bamb. 85. 1868. Figure 26.

Long-lived perennial bamboo; blooming rare; plants caespitose in dense clumps of
10-20 culms; culms 5-10 m. tall, erect below, the upper portions stiffly arching, branching
freely from the middle and upper nodes, the branches spreading horizontally; culms up
to 2.5 cm. thick, very thick-walled or solid, green when immature, yellow at anthesis;
internodes cylindrical, grooved on the side toward the bud or branch; nodes with a
prominent sheath girdle and swollen supranodal ridge; apex of internodes appressed-
velvety; one principal branch per node, accompanied by 1-2 smaller ones and stout
straight thorn branches up to 2 cm. long. Primary branches from culms spreading, their
naked internodes hollow, bearing secondary leaf-bearing branches in clusters of 6-10,
their internodes retrorsely puberulent; sheaths ciliolate on the overlapping margins;
auricles truncate, bearing numerous brownish flexuous bristles up to 7 mm. long;

FIG. 26. Bambusa paniculate. A, spikelet-bearing branches with nodal thorns; B,
pseudospikelet; C, thick-walled culm with a major branch.

BURGER: FLORA COSTARICENSIS 91

pseudopetioles less than 1 mm. long, hispidulous with erect hairs on the lower surface,
these hairs continued onto the midrib of the blade; blades flat, ovate 10-17:1, acuminate,
3-14 cm. long, 4-10 mm. wide. Inflorescences solitary at the tips of minor, leaf-bearing
branchlets, each consisting of 1 or 2 pseudospikelets, the base sometimes included in the
ultimate leaf sheath; pseudospikelets 2-3.5 cm. long, the basal 1 or 2 bracts glumelike,
shorter than the florets, with a reduced axillary prophyllum and a bud or axillary
spikelet; remainder of the pseudospikelet consisting of up to 12 normal florets; rachilla
disarticulating between florets; lemmas 6-7 mm. long, usually 11-nerved, broadly ovate,
mucronate; palea at least three-fourths as long as its lemma, broadly winged, multi-
nerved, ciliate on the keels; lodicules 3, flat, ovate, vasculated, ciliolate at the tip;
anthers 3, ca. 4 mm. long, yellow; ovary swollen and hardened, style 1, stigmas 3;
caryopsis tan, obovate, 3:1, 4.0-4.5 mm. long, the embryo ca. one-fourth as long, the
style base persistent.

This species is common on low elevation savannas in Guanacaste.
Since the lower parts of the culms are often solid, it may be mis-
identified as a species ofChitsqiiea, but can usually be differentiated by
the thorns. The smaller lateral branches of the culms seem to be regu-
larly hollow. We have collections from N of Bagaces, 10 km. S of La
Cruz, and Hacienda Murcielago. The only flowering colony seen was on
the road to Hacienda los Inocentes, 3 km. E of the CIA. At this site,
and also further east on the same road, a large colony was in flowering
or fruiting condition in 1976. The plants were all dying. An im-
mediately adjacent colony, with slightly different foliage, was com-
pletely vegetative. Fruiting specimens from this colony are Pohl &
Pinette 12329 (ISC, US, F, CR).

Bambusa vulgaris Schrad. ex Wendl., Coll. PI. 2:26, p. 47. 1810.
Figure 27.

Clumps large, open, the culms erect to arching, 10-15 m. long; internodes cylindrical,
up to 10 cm. thick, rather thin-walled, yellow or striped with yellow and green; nodes not
prominent, usually brown-ciliate; sheaths of main culms 15-25 cm. long, 18-23 cm. wide,
appressed-hispid above with brown hairs; sheath blades triangular, acute, 5-15 cm. long,
up to 10 cm. wide, appressed pubescent on both inner and outer surfaces; auricles
rounded, bristly-ciliate; ligule 5-8 mm. long; sheaths of foliage leaves pubescent, their
rounded auricles bearing a few bristles; ligule short, ciliolate; leaf blades flat, 15-25 cm.
long, 18-43 mm. wide, their surfaces usually glabrous when mature; edges and marginal
nerves scabrous; pseudopetiole ca. 5 mm. long. Inflorescence large, leafy, compound, the
spikelike branches with fascicled clusters of pseudospikelets at the nodes; pseudo-
spikelets ca. 2 cm. long, subtended by short ciliate prophylls and basal bracts (glumes?)
that subtend lateral spikelets, the rachilla continuing into a true spikelet, without evi-
dent glumes; florets 6-10, some of them sterile; lemmas many-nerved, ca. 10 mm. long,
broadly ovate, acute, the upper margins ciliate; palea about as long as the lemma,
narrowly oblong, pectinate-ciliate, the hairs longest near the tip; rachilla segments
clavate; lodicules 3, oblong, long-ciliate toward the tip; anthers 6, ca. 5 mm. long; style
elongate, ciliate to the base; stigmas 2-3. The margins of the lemmas are somewhat
inrolled, so that the spikelet appears to have a deep groove along the center. The above

FIG. 27. Bambusa vulgaris. A, pseudospikelet containing several spikelets; B,
foliage-bearing vegetative branchlet; C, portion of inflorescence with pseudospikelets.

BURGER: FLORA COSTARICENSIS 93

description was compiled from that of Gamble and limited spikelet material available to
me.

This species is frequently cultivated in Central America for orna-
ment and construction materials. We have seen no blooming Central
American specimens in the field or herbarium, and literature records
indicate that blooming is very rare. Nearly all clumps that I have seen
have yellow and green striped internodes. This form has variously
been designated as var. striata Gamble or as horticultural form vittata
A. & C. Riv. The native home of this Old World species is uncertain,
but it is widely cultivated in both hemispheres.

BOTHRIOCHLOA 0. Kuntze

REFERENCES: S. T. Blake, Taxonomic and nomenclatural studies in
the Gramineae, No. 1, Proc. Roy. Soc. Queensland 80:55-84. 1969. F.
Gould, New North American Andropogons of subgenus Amphilophis
and a key to those species occurring in the United States, Madrono
14:18-29. 1957.

Caespitose or stoloniferous grasses; inflorescence of several rames borne on a central
rachis; rames consisting of several to many spikelet pairs borne on a slender rachis that
disarticulates at the apex of each internode, spikelet pairs falling as units with the
attached rachis internode. One spikelet of each pair sessile, awned, perfect-flowered and
one pedicellate, awnless, staminate or sterile; some basal pairs of spikelets alike and
awnless, staminate or sterile; rachis internodes and pedicels with thickened margins and
a very thin, translucent line down the middle. Spikelets dorsally compressed, the sessile
ones with a flattened, many-nerved first glume whose edges are inrolled over the mar-
gins of the second and slightly keeled on the upper half; second glume slightly longer
than the first, acuminate, 3-nerved, convex on the back; glumes completely enclosing
and concealing the floret. Awned spikelets: florets 2, the lower represented by a thin,
nearly nerveless translucent scale, the second reduced to the flattened base of the awn;
lodicules 2, truncate; awn twisted and geniculate. Pedicellate spikelets: dorsally flat-
tened, biconvex, similar to the sessile spikelets but awnless; a single lemma present; no
flower present.

Bothriochloa is primarily a genus of the Old World tropics, with a
few species native in warmer parts of the Americas. It is similar to
Andropogon, from which it differs in the thin line down the middle of
the rachis joints and pedicels, and in the fertile lemma, which is re-
duced to an awn, lacking a membranaceous body. (Panicoideae: An-
dropogoneae.)

Bothriochloa pertusa (L.) Camus, Ann. Soc. Linn. Lyon n. ser.
76:164. 1931. Holcus perticsus L., Mant. PL 2:301. 1771. Andropogon
pertusus (L.) Willd., Sp. PL 922. 1806. Figure 28.

FIG. 28. Bothriochloa pertusa. A, inflorescence and culm; B, portion of a rame, the
sessile spikelets with pits in the first glumes.

BURGER: FLORA COSTARICENSIS 95

Plants sprawling, weak-stemmed, rooting at the lower nodes; duration indefinite;
culms 30-100 cm. long, freely branching, glabrous except upwardly bearded at the
nodes, hollow; sheaths keeled, more or less hirsute; ligule a ciliate membrane, 0.7-1.2
mm. long; leaf blades 3-4 mm. wide, with scattered elongate papillose-based hairs on the
margins and above the ligule. Peduncle exserted up to 12 cm. from the nearly glabrous,
bladeless, upper sheath, glabrous, slightly bearded at the apex; inflorescences terminal
on the main culms and on leafy branches, 3-5 cm. long, fan-shaped, often purplish.
Rames several, racemosely arranged along a short rachis, ascending. Sessile spikelets
awned, 3.2-4.0 mm. long, lanceolate; first glume ca. 9-nerved, tapering to a narrow
truncate apex, with a prominent circular pit near the middle; second glume slightly
longer, tapering to an acuminate apex, its margins somewhat ciliate above; lower lemma
oblong, 2.5-2.7 mm. long; upper lemma reduced to the awn, which has a flattened whitish
base; anthers 3, yellow, 1.0-1.8 mm. long. Chromosome numbern = 20 from this speci-
men.

Weed; dock area, Quepos. January.

Introduced from the Old World; southern United States and Mexico;
West Indies.

BOUTELOUA Lagasca

REFERENCES: F. W. Gould, Taxonomy of the Bouteloua repens com-
plex, Brittonia 21:261-274. 1969. F. W. Gould & Z. J. Kapadia, Biosys-
tematic studies in the Bouteloua curtipendula complex, Brittonia
16:182-207. 1964. David Griffiths, The grama grasses: Bouteloua and
related genera, Contr. U.S. Natl. Herb. 14:343-428 + XI. 1912.

Annual or perennial caespitose or rhizomatous grasses; inflorescence a raceme of
1-many unilateral spikes; spikelets usually 3-many per spike, borne in 2 rows on the
lower side of the rachis, usually densely crowded; disarticulation above the glumes or (in
all our species) at the base of the individual spikes, which fall as units; glumes 1-nerved,
unequal, shorter than the florets; spikelets with one fertile floret at the base and one or
two variously modified or ornamented sterile florets above it; lemma 3-nerved, the
nerves often excurrent as awns.

Bouteloua is an American genus of about 40 species, native to warm
or arid portions of North, Central, and South America. In the Central
American flora, its closest relatives are Pentarraphis, Aegopogon,
Chloris, Eustachys, and Gymnopogon. (Chloridoideae: Chlorideae.)

KEY TO SPECIES OF Bouteloua

la. Spikes 20 or more per inflorescence, drooping 2

Ib. Spikes 10 or fewer per inflorescence, usually ascending or erect 3

2a. Spikelets 2-4 per spike; anthers ca. 1.5 mm. long; weak prostrate annual

B. disticha

2b. Spikelets 8-11 per spike; anthers ca. 3 mm. long; tall erect perennial B. media
3a. Rachis and glumes heavily bearded; awns short and inconspicuous

B. chondrosioides

96 FIELDIANA: BOTANY

3b. Rachis and glumes glabrous or short ciliate; awns usually conspicuous 4

4a. Spikes slender, successive spikelets separated by about half their length;
rudimentary floret sterile, reduced to 3 stiff awns attached to a small rigid

cylindrical lemma body B. americana

4b. Spikes not slender, the spikelets crowded; rudimentary floret with a well de-
veloped flat lemma 5

5a. Awns of rudimentary floret 12-17 mm. long; spikelets 3-4 per spike, crowded near

the base of the rachis; plants annual B. alamosana

5b. Awns of rudimentary floret 2-10 mm. long; spikelets 4-8 per spike, distributed along
the lower half of the rachis; plants perennial B. repens

Bouteloua alamosana Vasey, Contr. U.S. Natl. Herb. 1:115. 1891.
Figure 29.

Weak, sprawling annual; culms 20-80 cm. long, branching freely from the base and the
lower culm nodes, ca. 1 mm. thick, solid and pithy, glabrous; sheaths shorter than the
internodes, glabrous to papillose-hirsute; ligule a minute membranous rim, ciliolate,
0.2-0.3 mm. long; blades 3-7 cm. long, 1.5-3.0 mm. wide, more or less papillose-hirsute on
both surfaces, especially near the base; peduncle 3-25 cm. long; inflorescences terminal
and axillary; inflorescence a unilateral raceme of 4-9 ascending or spreading unilateral
spikes; rachis of spikes strongly hispid-bearded, flat, ca. 10 mm. long, prolonged as a
thickish stipe ca. 1 mm. long below the spikelets. Spikelets usually 3-4, crowded near the
base of the rachis, ca. 8 mm. long (excluding the awns), often purplish; glumes subequal,
5-7 mm. long, 1-nerved, linear to lanceolate, strongly short-hispid on the keels; lower
floret 6.0-6.5 mm. long; lemma glabrous, lanceolate, the 3 nerves extending as short
awns from the upper quarter of the body; palea 7-8 mm. long, longer than the lemma,
firm, oblong, bidentate, pubescent between the keels, the margins broad, overlapping
near the apex; anthers 1.1-1.3 mm. long; second floret staminate; lemma 5.5-6.0 mm.
long, wider than the first lemma; awns subequal, 12-17 mm. long, flat, rigid, scabrous,
the lateral ones arising about the middle of the lemma, the middle one between 2 apical
teeth; palea ca. 5.5 mm., bidentate. Chromosome number n = 30 from a Honduran
specimen.

This species has been found only near Liberia, along the Carretera
Interamericana, at Puntarenas, and on the bluffs at Playas del Coco.
Blooming in November and December; elevations from sea level to 100
m. Mexico to northern Guanacaste, along the Pacific slope.

Bouteloua americana (L.) Scribn., Proc. Acad. Nat. Sci. Philadel-
phia 43:306. 1891. Aristida americana L., Syst. Nat. ed. 10; 2:879.
1759. Figure 30.

Duration indefinite; culms prostrate to ascending, usually 25-50 (100) cm. long, freely
branching; prophyllum 25-35 mm. long, bidentate at tip; culms 1.0-1.5 mm. thick, solid,
pithy, glabrous; leaves numerous, the sheaths shorter than the internodes, glabrous;
ligule 0.5-0.8 mm. long, a strongly ciliate membrane; leaf blades 4-11 cm. long, 2-4 mm.
wide, pustulose-ciliate on the margins near the base and sometimes on the upper sur-
face. Peduncle usually 3-5 cm. long; inflorescence 6-12 cm. long, of 5-9 slender, ascending
unilateral spikes borne racemosely along a slender rachis, naked at the base for 1-2 mm.,
the rachis 2-4 cm. long, triquetrous, the 5-10 spikelets somewhat remote, appressed,

FIG 29. Bouteloua species. B. repens: A, inflorescence; B, single spike, seen from
beneath; B. alamosana: C, single spike.

FIG. 30. Bouteloua species. A, B. media; B, B. chondrosioides, C, B. americana.

BURGER: FLORA COSTARICENSIS 99

distant by one-half to three-fourths of their length, 5.5-8.0 mm. long, excluding the awn
of the rudiment; disarticulation at the base of the individual spike, or sometimes above
the glumes, the 2 florets falling together; glumes subequal, 3.5-4.5 mm. long, 1-nerved,
narrowly ovate, acute; florets 2, the lower lemma with an oblique bearded callus, other-
wise glabrous, lanceolate, 3-nerved, the nerves excurrent as short awns, the central one
ca. 2 mm. long; lemma and palea firm, shining, purplish; palea bidentate at the tip;
rachilla segment slender; rudimentary floret reduced to 3 stiff flat scabrid awns jointed
onto a very short firm cylindrical lemma body; palea ca. 1.0-1.5 mm. long; rachilla
prolonged beyond the palea as a minute bristle. Chromosome number n = 20 from Costa
Rican specimens.

This species has been collected in Costa Rica only in the vicinity of
Puntarenas, from sea level to 125 m. elevation. It grows along the
Carretera Interamericana south of the Puntarenas junction. October.
Bahamas and Caribbean Islands; Guatemala to Panama, Venezuela,
and Brazil.

Bouteloua chondrosioides (H.B.K.) Benth. ex S. Wats., Proc.
Amer. Acad. Sci. 18:179. 1883. Dinebra chondrosioides H.B.K., Nov.
Gen. & Sp. 1:173. 1816. Figure 30.

Erect caespitose perennial; culm 10-50 cm. tall, ca. 1 mm. thick, ridged, glabrous,
solid, pithy, arising from a knotty crown; nodes glabrous; foliage mostly aggregated on
the lower half of the culm; sheaths shorter than the internodes, glabrous, glaucous,
ridged, 1-10 cm. long, the upper ones much reduced, 1.5-3.0 mm. wide, somewhat
pustulose-hispid, especially on the margins; peduncle exserted 2-7 cm.; inflorescence 3-7
cm. long, a raceme of 3-8 ascending or appressed thick, rhombic spikes; individual spikes
8-10 mm. long, purplish, heavily bearded at the base and along the rachis; spikelets 9-11
per spike, densely crowded; rachis usually extended as a naked point up to 5 mm. beyond
the spikelets. Spikelets 7.0-7.5 mm. long; first glume acicular, 2.5-4.5 mm. long, hispid
along the midrib; second glume 4.5-6.5 mm. long, narrowly lanceolate, with a very
broad, flat midrib which is heavily hispid; lower lemma 4.7-6.2 mm. long, narrowly
ovate, hispid on the upper half, especially along the nerves; awns 3, short, at the tip of
the lemma; palea longer than the lemma, 5.0-7.2 mm. long, somewhat hispid on the
upper half; anthers yellow, 2.8-3.5 mm. long; second floret rudimentary, composed of 3
awns 2-7 mm. long, the central one sometimes with a membranaceous margin. Chromo-
some numbers n = 10, 20.

Western Texas and southern Arizona to Guanacaste. Reported from
the Nicoya Peninsula by Hitchcock.

Bouteloua disticha (H.B.K.) Benth., J. Linn. Soc. Bot. 19:105.
1881. Polydon distichum H.B.K., Nov. Gen. & Sp. 1:175. 1816.
Bouteloua pilosa (Hook, f.) Benth. ex S. Wats., Proc. Amer. Acad.
Sci. 18:179. 1883.

Annual; plants decumbent to prostrate, the culms rooting at the lower nodes; branch-
ing abundant; prophyllum 15-35 mm. long, the keels ciliolate; culms glabrous, ca. 1 mm.
thick, solid, pithy; sheaths much shorter than the elongated internodes, glabrous to
papillose-hirsute; dewlap prominent; auricular hairs sometimes present; ligule a ciliolate

100 FIELDIANA: BOTANY

membrane, 0.2-0.5 mm. long; leaf blades 6-13 cm. long, 2-5 mm. wide, glabrous to
papillose-hirsute on both surfaces and the margins; peduncle slender, glabrous, exserted
4-22 cm.; inflorescence solitary, terminal, unilateral, 8-15 cm. long, bearing 30-50 pen-
dant spikes on minute branchlets; individual spikes unilateral, the 2-4 spikelets borne on
the underside of the stiff flattened rachis near its base, occasionally 1 or 2 of them
reduced or sterile; rachis of spikes 4.0-5.5 mm. long, often bidentate at the tip. Spikelets
narrow, 5.5-7.5 mm. long, excluding the awn of the rudiment; first glume acicular,
1-nerved, 3.8-5.5 mm. long; second glume lanceolate, 1-nerved, 5.5-7.0 mm. long; lemma
of lower floret glabrous, lanceolate, 5-7 mm. long, the apex trifid, with 3 short awns;
palea bifid, 5-6 mm. long, glabrous; anthers ca. 1.5 mm. long, orange, second floret
sterile, with a very short palea, the lemma from very small to larger than the fertile
floret, deeply 3-lobed, the lateral nerves extending into awns 4-8 mm. long, the midrib
extending into an awn 7-10 mm. long, arising between 2 hyaline teeth; rachilla not
prolonged beyond the second floret. Chromosome number n = 20 from Costa Rican
specimens.

Roadsides and weedy open areas, sea level to 1,200 m. elevation;
Pacific slope, from northern Guanacaste to Atenas. October to Feb-
ruary. Southern Mexico to Ecuador, Peru, and the Galapagos Islands.

Bouteloua media (Fourn.) Gould & Kapadia, Brittonia 16:196. 1964.
Atheropogon medius Fourn., Mex. PI. 2:139. 1881. Figure 30.

Tall, leafy perennial, in dense clumps; culms erect, 70-200 cm. tall, usually unbranched
or sometimes with an axillary inflorescence below the terminal one; culms solid, pithy,
scabrid or papillose-hirsute; sheaths mostly overlapping, scabrous, sometimes
papillose-hirsute; ligule membranaceous, ciliolate, 0.5-0.7 mm. long; leaf blades up to 30
cm. or more long, 4-6 mm. wide, scabrous, also papillose-hirsute on auricles, upper
surface above the base, and margins; peduncle scabrous, ridged; terminal inflorescence a
slender raceme 20-25 cm. long, of up to 40 drooping unilateral spikes borne on slender,
lax, scabrous branchlets 2-3 mm. long; individual spikes 1-2 cm. long, tending to be
approximate in pairs. Spikelets usually 8-11 per spike, often some of the basal ones
abortive, sessile in 2 rows on the lower side of the flat scabrous rachis; rachis 8-10 mm.
long, sometimes extended beyond the spikelets as a naked point. Spikelets 5-6 mm. long,
excluding the awns; first glume 4.0-4.5 mm. long, linear, awn-tipped, second glume
4.8-5.3 mm. long, lanceolate, acute; lemma of lower floret 5.0-5.5 mm. long, lanceolate,
scabrid in lines, the nerves extended into 3 short awns near the tip; palea 5.2-5.5 mm.
long; anthers 2.8-3.5 mm. long, yellow to orange; rudimentary florets 1 or 2, the first
with a lemma ca. 3 mm. long, bifid to the base, the lateral awns 4-5 mm. long, the central
one 5-9 mm. long, palea absent; second rudimentary floret, when present, much smaller.
Our single chromosome count of this species was aneuploid, with 2n = 27. The only
previous count was diploid, 2n = 20.

Upper grassy slopes of bluffs, south end of Play as del Coco,
Guanacaste; elevation ca. 100 m. July to December. This is the south-
ern limit of the range of this species, which extends southward from
southern Mexico.

Bouteloua repens (H.B.K.) Scribn. & Merr., Bull. U.S.D.A. Div.
Agrost. 24:26. 1901. Dinebra repens H.B.K., Nov. Gen. & Sp. 1:172.

BURGER: FLORA COSTARICENSIS 101

1816. B(wtelouafiliformis (Fourn.) Griffiths, Contr. U.S. Natl. Herb.
14:413. 1912. B. pubescens Pilger, Verb. Bot. Vereins Prov. Branden-
burg 51:193. 1909. B. heterostega (Trin.) Griffiths, Contr. U.S. Natl.
Herb. 14:414. 1912. Figure 29.

Perennial; culms 15-65 cm. long, glabrous, solid, pithy, prostrate to ascending, the
lower nodes sometimes rooting; sheaths glabrous to softly pubescent; auricular hairs
present; ligule a minute ciliolate rim, 0.2-0.3 mm. long; blades 5-20 cm. long, 1-4 mm.
wide, papillose-ciliate along the margins near the base, sometimes puberulent or pubes-
cent on one or both surfaces; peduncle stiff, 4-10 cm. long; inflorescence 4-14 cm. long, a
unilateral raceme of usually 7-9 unilateral spikes, these deciduous as wholes; individual
spikes with a minute ciliate stipe at the base, bearing usually 4-8 spikelets crowded in 2
rows on the basal 6-10 mm. of the rachis, which extends above the spikelets as a naked
stipe 4-6 mm. long. First glume 4-6 mm. long, 1-nerved, ovate, scabrous on the keel;
second glume similar, 4-9 mm. long; lemma of lower floret 5.0-7.5 mm. long, lanceolate,
glabrous; lateral nerves excurrent as short awns ca. 1 mm. long near the tip, the central
awn slightly longer; palea 6-8 mm. long, glabrous or cottony between the keels; anthers
3.5-5.5 mm. long, yellow or orange, second floret usually staminate, its lemma 5.5-7.0
mm. long, ovate, 3-awned, the lateral nerves excurrent as awns about halfway up the
lemma, the midnerve awned between 2 teeth; awns about equal, 2-10 mm. long; anthers
usually present, smaller than those of the lower floret; palea 4-7 mm. long, glabrous or
cottony between the keels; rachilla prolonged beyond the second floret as a short bristle.
Chromosome numbers n = 10, 20, 30, 21, 22, ca. 45, 46.

Savannas, roadsides, often on volcanic ash; from sea level to 100 m.
Guanacaste, S to the area of Puntarenas. July to December. Southern
Arizona and Texas to Venezuela and Colombia; Caribbean Islands.

BRACHIARIA Grisebach

REFERENCE: S. T. Blake, New criteria for distinguishing genera
allied to Panicum (Gramineae), Proc. Roy. Soc. Queensland 70:15-19.
1958.

Plants annual or perennial, the culms often decumbent and rooting. Inflorescence a
panicle of several-many slender racemes borne racemosely along a central rachis;
racemes rarely secondarily branched and bearing short fascicles of spikelets; spikelets
usually solitary or paired, short-pedicellate along the rachis, their first glumes turned
toward the midrib of the rachis. Spikelets disarticulating below the glumes, dorsally
compressed, ovate-obovate, plano-convex or biconvex; first glume short, 1-many-
nerved; second glume and lower (sterile) lemma subequal, as long as the spikelet, 5-9-
nerved; lower lemma with a well-developed palea and usually a staminate flower; upper
(fertile) floret shorter than the second glume and sterile lemma, cartilaginous or rigid,
rugulose or striate, the lemma elliptical or obovate, its margins incurved over the keels
of the equal palea of similar texture; palea sometimes convex; lodicules 2, truncate;
stamens 3; style branches separate; caryopsis elliptical, dorsally flattened, with a large
embryo.

Brachiaria is a large genus of grasses of warm climates in both the
eastern and western hemispheres, most numerous in Africa. It is most

102 FIELDIANA: BOTANY

closely related to Eriochloa, Setaria, Paspalidium, and Urochloa. It
is distinguished mostly by the simple panicle branches with the
spikelets usually in orderly rows along them, the first glumes turned
toward the midrib. Blake has indicated that the presence of a promi-
nent "rupture line" at the base of the fertile lemma distinguishes this
genus from Panicum, although this feature occurs throughout the
Paniceae. (Panicoideae: Paniceae.)

KEY TO SPECIES OF Brachiaria

la. Spikelets 4.5 mm. or more long 2

Ib. Spikelets 4.0 mm. or less long 3

2a. Rachis of racemes prominently papillose-ciliate; spikelets hairy near the tip

B. brizantha

2b. Rachis of racemes not ciliate; spikelets glabrous B. plantaginea

3a. Spikelets pubescent with papillose-based hairs B. mollis

3b. Spikelets glabrous 4

4a. Spikelets 3 mm. or less long, dull yellow, brown, or deep purple; racemes

numerous B. fasciculate

4b. Spikelets over 3.2 mm. long, green or marked with purple; racemes few to

many 5

5a. First glume 9-nerved; nodes glabrous or nearly so; racemes 3-4 B. distachya

5b. First glume 1-nerved; nodes conspicuously retrorsely hirsute; racemes
numerous B. mutica

Brachiaria brizantha (Hochst.) Stapf, Fl. Trop. Africa 9:531. 1919.
Panicum brizanthum Hochst. ex Rich., Tent. Fl. Abyss. 2:363. 1851.

Erect perennial, to 2 m. tall; culms branching occasionally from the middle nodes,
internodes up to 3 mm. thick, hollow, thick-walled, smooth and glabrous or somewhat
hairy; sheaths about equal to the internodes, glabrous; ligule a short, stiffly ciliate
membrane, in total 1.2-2.0 mm. long; leaf blades 15-35 cm. long, 7-18 mm. wide, glabrous
or pubescent, the margins scabrous, with thick, whitish sclerenchyma bands. Inflores-
cence of 2-many remote arching racemes, these one-sided, 6-12 cm. long, slender, the
spikelets apparently 1-rowed; rachis flat, less than 1 mm. wide, papillose-ciliate on the
edges. Spikelets 5.0-5.8 mm. long, obovate 2.5:1, with a short basal stipe ca. 0.5 mm.
long, a similar internode between the first and second glumes; first glume broadly deltoid
with overlapping edges, 7-9-nerved; second glume and lower (sterile) lemma equal,
about as long as the spikelet; second glume 5-7-nerved; lower lemma 5-nerved, with a
large palea and sometimes 3 stamens; both second glume and lower lemma sparsely
papillose-hirsute near the tip and sometimes purple-marked; upper floret 4.3-4.6 mm.
long, rigid, finely striate or minutely rugulose; palea equal to the lemma; lodicules 2,
truncate; anthers 3, 2.7 mm. long, brown; styles separate; stigmas purple.

Cultivated in the grass garden at the CATIE at Turrialba and at
Guapiles; possibly in commercial production. Native to tropical Africa.

Brachiaria distachya (L.) Stapf, Fl. Trop. Africa 565. 1919.
Panicum distachyon L., Mant. Alt. 183. 1771. Panicum subquad-

BURGER: FLORA COSTARICENSIS 103

riparum Trin., Gram. Pan. 145. 1826; Brachiaria subqitadripara
(Trin.) Hitchc., Lingnan Sci. J. 7:214. 1931. Figure 32.

Duration indefinite; plants sprawling, the culm bases long decumbent and rooting at
the nodes, the erect portions 20-30 cm. long; branching abundant, older culms bearing
fascicles of branches; culms solid, glabrous, or with scattered papillose-hispid hairs;
nodes glabrous or bearded below the sheath margin; sheaths keeled, glabrous or with
scattered hispid hairs, the overlapping margin densely papillose-ciliate; ligule a short
membrane, long-ciliate, in total 0.5-1.3 mm. long; leaf blades flat, 3-9 cm. long, 4-8 mm.
wide, the edges thickened, scabrous, glabrous or with scattered papillose-hispid hairs on
the basal margins and on the surfaces. Peduncle included or exserted up to 15 cm.;
inflorescences numerous, terminal or axillary, 4-8 cm. long, composed of usually 3 short,
ascending, racemosely arranged, one-sided racemes, each 1.5-3.5 cm. long. Spikelets
borne in 2 rows on the lower side of a winged, triquetrous rachis ca. 1 mm. wide; pedicels
0.5-0.7 mm. long, angular. Spikelets glabrous, 3.5-3.8 mm. long, ovate to obovate, first
glume 1.6-1.8 mm. long, 9-nerved, transversely depressed ovate, blunt, enwrapping the
base of the spikelet, the margins meeting; second glume and lower (sterile) lemma equal,
as long as the spikelet; second glume 7-nerved; sterile lemma 5-nerved, inclosing an
oblong palea 2.7-2.8 mm. long; upper (fertile) lemma rigid, elliptic-obovate 2:1, 2.7-2.8
mm. long, rugulose, with an areole near the base; margins thick, barely covering the
keels of the palea of similar texture and length; anthers 1.3 mm. long; stigmas purple;
caryopsis elliptical 2:1, 2.0-2.1 mm. long, whitish; embryo large. Chromosome number
n = 36.

Elsewhere in America, it is known only from Veracruz and Pro-
greso, Mexico. Pacific Islands and southeastern Asia; tropical Africa.
Known in Costa Rica only by the following specimen: Puntarenas,
Esterillos Este, sandy field behind beach, P. & D. 11687, 28 January
1969.

Brachiaria fasciculata (Sw.) Parodi, Darwiniana 15:96. 1969.
Panicum fasciculatum Swartz, Prodr. Veg. Ind. Occ. 22. 1788.

Annual; plants tufted, erect, or the lower nodes of the culms decumbent and rooting;
culms 10-100 cm. long, branching from the lower and middle nodes; prophylla prominent,
up to 5.5 cm. long; internodes up to 2 mm. thick, hollow, thick-walled, more or less
papillose-hispid, especially toward the apex; sheaths about as long as the internodes,
keeled near the apex, more or less papillose-hispid, the overlapping margin strongly
papillose-ciliate; ligule a short membrane, densely ciliate, in total 0.3-2.3 mm. long; leaf
blades flat, rounded to the base, 4-30 cm. long, 7-18 mm. wide, more or less papillose-
pilose or hispid on both surfaces. Inflorescences terminal on the culm or on leafy
branches; peduncle exserted up to 15 cm.; panicles 3.5-15 cm. long, ovoid, 1-9 cm. wide,
composed of numerous ascending simple branches racemosely arranged along a grooved
central rachis, 1-several per node; spikelets solitary, short-pedicellate in 2 rows along
the lower sides of the branches, or more commonly in small clusters of 2-5 borne along
the lower sides of the primary branches; rachis and branches angular, scabrous, some-
times papillose-pilose. Spikelets turgid, biconvex, obovate 5:3, bluntly mucronate, dull
yellow or deep purple, 2.3-3.0 mm. long; first glume transversely ovate, acute, its edges
overlapping; nerves 3-5; second glume and lower (sterile) lemma equal, as long as the

104 FIELDIANA: BOTANY

spikelet; second glume 9-nerved, often with small cross-veins near the apex; lower
lemma similar, 7-nerved; upper (fertile) floret 1.9-2.5 mm. long, elliptical-obovate, acute
4:3; lemma rigid, strongly rugose, with a conspicuous basal areole; margins thick, clasp-
ing the keels of the similar convex palea of equal length. Chromosome number n = 9
from Costa Rican specimens.

Open disturbed areas, pastures, roadsides, river banks; low eleva-
tions on the Pacific slope; common in Guanacaste, usually below 600 m.
elevation; western parts of the Meseta Central; Turrialba; Limon area;
Guapiles. Blooming June to February. Extreme southern United
States to Brazil and Ecuador; West Indies.

This species has been included in the genus Panicum in most Ameri-
can publications. Recent authors have assigned it to Brachiaria, al-
though the placement of the spikelets is not as regular as in other
species. The current placement is based principally on the rugose
character of the fertile lemma and the presence of an areole (germina-
tion lid) at its base, along with the rather simple panicle branches.

Brachiaria mollis (Sw.) Parodi, Darwiniana 15:100. 1969. Panicum
molle Swartz, Prodr. Veg. Ind. Occ. 22. 1788.

Annual; plants erect to sprawling, the bases sometimes long decumbent and rooting at
the nodes; branching from the lower and middle nodes; prophylla up to 2.5 cm. long; culm
internodes up to 2.5 mm. thick, hollow, thick-walled, more or less papillose-pilose or
puberulent; nodes bearded; leaf sheaths about as long as the internodes, papillose-pilose
or puberulent; ligule a ciliate membrane, 0.5-1.0 mm. long; leaf blades broad-based, 6-14
cm. long, 5-15 mm. wide, flat, papillose-pilose, or velvety. Peduncle included or exserted
up to 13 cm; inflorescences terminal on leafy branches, numerous, 3-7 cm. long, 1-3 cm.
wide, consisting of up to 8 short, ascending, 1-sided racemes, each 1-3 cm. long; rachis
and branches puberulent or pilose, the short pedicels sometimes bearing glassy hispid
hairs; spikelets solitary or paired along the lower sides of the rachis, the first glumes
turned toward the center of the rachis. Spikelets 3.4-4.0 mm. long, villous, obovate 2:1,
apiculate, biconvex; first glume 2.0-2.7 mm. long, 5-nerved, ovate, acute; second glume
and lower (sterile) lemma equal, as long as the spikelet; second glume 7-nerved; lower
lemma similar, but 5-nerved; its palea 2.7-3.0 mm. long; upper (fertile) floret 2.6-3. 1 mm.
long, rigid, obovate 5:3, rugulose, apiculate, its margins inrolled over the margins of a
similar palea; lodicules 2, fleshy, truncate; anthers 3, tan, 1.0-1.1 mm. long; styles
separate; stigmas purple; caryopsis white, 2 mm. long, elliptical 4:3; embryo three-
fourths as long as the grain. Chromosome number n = 27 from Costa Rican specimens.

Occasional, dry roadsides and savannas, low elevations, northern
Guanacaste; Puntarenas, Atenas. June to November. Mexico and the
West Indies to Argentina.

This species has generally been included in the genus Panicum in
American publications, but has been transferred to Brachiaria be-
cause of the form of the inflorescence and the rugose floret.

BURGER: FLORA COSTARICENSIS 105

Brachiaria mutica (Forsk.) Stapf, Fl. Trop. Africa 9:526. 1919.
Panicum muticum Forsk., Fl. Aegypt.-Arab. 20. 1775. Panicum
purpurascens Raddi, Agrost. Bras. 47. 1823. Figure 31.

Sprawling perennial, the culms becoming long-decumbent and rooting at the lower
nodes, up to 6 m. long, branching from lower and middle nodes; internodes glabrous,
hollow, thick-walled; nodes prominent, retrorsely papillose-hirsute; sheaths longer than
the internodes, more or less papillose-hirsute to nearly glabrous; ligule a very short
membrane, densely white ciliate, in total 1.5-1.8 mm. long; dewlap and collar finely
velvety; blades flat, up to 25 cm. long and 15 mm. wide, mostly glabrous or with a few
hairs near the base; midrib broad and white above near the base; margins thick, purple,
scabrous. Inflorescences terminal on leafy branches, up to 20 cm. long, of several to
many solitary or clustered ascending racemes borne along a central rachis; racemes 1-7
cm. long; spikelets solitary, paired, or in small clusters along the lower sides of the
triquetrous rachis; bases of branches velvety; rachis up to 1 mm. wide, the angles
scabrous and bearing scattered papillose hairs. Spikelets 3.2-3.4 mm. long, ovate 3:2,
acute, often purple, glabrous; first glume 0.8-1.2 mm. long, deltoid, 1-nerved; second
glume and lower lemma equal, about as long as the spikelet; second glume 5-7-nerved;
lower lemma similar, 5-nerved, inclosing a large palea that frequently protrudes be-
tween the lemma and second glume at the tip; stamens 3; upper (fertile) floret 2.1-2.5
mm. long, elliptic-obovate, striate or rugulose; palea similar, flat; lodicules 2, truncate;
anthers 3, 1.3-1.5 mm. long, yellow or purple; style branches separate; stigmas purple.

Cultivated for forage, especially on the Caribbean slope and occur-
ring in the wild, in wet sites or water; elevations up to 1,600 m. This
species has had an involved nomenclatural and migrational history. It
has been known as Panicum purpurascens in American literature, but
is now usually referred to the genus Brachiaria. It is probably of
African ancestry, but has long been resident in the American tropics.
The plants are very similar to those of Eriochloa polystachya in veg-
etative and flowering structure and may grow intermixed with the
latter. Common name: Zacate pard.

Brachiaria plantaginea (Link) Hitchc., Contr. U.S. Natl. Herb.
12:212. 1909. Panicum plantagineum Link, Hort. Berol. 1:206. 1827.
Figure 32.

Duration indefinite; plants sprawling, the culms decumbent and rooting at the lower
nodes, branching freely from the prostrate portions, up to 1 m. long; culms glabrous,
solid or the decumbent parts with a small lumen; nodes glabrous, not prominent; leaf
sheaths about as long as the internodes, keeled, glabrous but papillose-ciliate on the
overlapping edge; ligule a very short membrane, ciliate with a dense row of stiff hairs, in
total 0.5-1.5 mm. long; leaf blades flat, glabrous except for a few long cilia at the base,
4-21 cm. long, 6-13 mm. wide, the margins thickened, scabrous; midrib prominent be-
neath. Inflorescences terminal on leafy ascending branches; peduncle included or ex-
serted up to 8 cm.; inflorescence of 4-5 distant ascending racemes, borne racemosely
along a flattened, grooved rachis; racemes 2-11 cm. long, slender, bearing spikelets
nearly to the puberulent basal pulvinus; rachis of racemes prominently 3-winged, 1.1-1.2

FIG. 31. Brachiaria mutica. Plant, inflorescence, fertile floret, and two views of a
spikelet.

106

FIG. 32. Brachiaria species. B. plantaginea: A, inflorescence; B, C, two views of a
spikelet; D, rugose fertile lemma; B. distachya: E, inflorescence; F, two views of a
spikelet; G, fertile lemma.

107

108 FIELDIANA: BOTANY

mm. wide, the angles scabrous; spikelets borne alternately in 2 rows on opposite sides of
the winged midrib of the rachis, their pedicels up to 1 mm. long; spikelets oriented with
their first glumes toward the midrib. Spikelets 4.7-5.2 mm. long, ovate-obovate, 2.5-3:1,
acute, glabrous; first glume transversely broadly ovate, 5:7, blunt, clasping the base of
the spikelet, the margins in contact with each other, nerves 9-11; second glume and
lower (sterile) lemma equal, as long as the spikelet, concealing the shorter fertile floret;
second glume 7-nerved; lower lemma 5-nerved, concealing a membranaceous palea of
equal length; upper (fertile) lemma 3.2-3.6 mm. long, elliptical 7:4, faintly 5-nerved,
minutely rugulose, rigid, with a horseshoe-shaped areole near the base; middle of lemma
flattened or depressed; palea of equal length, its keels and margins covered by the
inflexed thick margins of the lemma; anthers 3, yellow, 0.7-1.0 mm. long; stigmas purple;
flowers probably cleistogamous; caryopsis flattened, elliptical, whitish, 2.2 mm. long.
Chromosome number n = 18 from a Costa Rican specimen.

Roadsides, cafetales, weedy pastures and savannas, up to 1,500 m.
elevation; Meseta Central, Cartago, Canas area. Blooming yearlong.
Mexico to Brazil and Bolivia.

This species is common around San Jose, and Tonduz noted on a
herbarium specimen that it was once cultivated in an experimental
field in Guadelupe. He gives the common name as arrocillo.

BRACHYPODIUM Beauvois

Caespitose perennial grasses; culms becoming much-branched; inflorescence a slender
terminal raceme of a few erect spikelets borne on a slender axis. Spikelets several-
many-flowered, at first cylindrical, becoming laterally compressed; glumes and lemmas
rounded on the back, not keeled; glumes somewhat unequal, the first slightly shorter
than the second, both with about 7 nerves; disarticulation above the glumes and between
the florets; lemmas 7-nerved, tapering into a short stiff awn; paleas slightly shorter than
the lemmas, their keels pectinate-ciliate.

A small genus of about 15 species, mostly of the temperate and
tropical regions of the eastern hemisphere. Three species have been
credited to Mexico and Central America, but probably all represent
phases of one. The genus is easily confused with Agropyron, but
species of the latter have sessile spikelets and unbranched culms,
whereas Brachypodium plants have the spikelets borne on short erect
pedicels, and the plants become much-branched with age. (Pooideae:
Poeae?)

Brachypodium mexicanum (Roem. & Schult.) Link, Hort. Berol.
1:41. 1827. Festuca mexicana Roem. & Schult., Syst. Veg. 2:732.
1817. Figure 33.

Perennial, caespitose, becoming bushy-branched, the branches decumbent and root-
ing from the lower nodes; culms slender, 10-100 cm. long, thin- walled, hollow, glabrous;
nodes retrorsely silky-bearded; sheaths glabrous, ciliate on the margins, the collar
pubescent; ligule a ciliate membrane, decurrent on the sheath margin, 1.2-4.0 mm. long;

J&J

FIG. 33. Brackypodium mexicanum. A, inflorescence; B, plant base; C, spikelet,
pedicel, and rachis internode.

109

110 FIELDIANA: BOTANY

blades 4-15 cm. long, 2-6 mm. wide, appressed-hirsute above and beneath. Peduncle
smooth or scabrous, up to 13 cm. long; racemes terminal on the main culm or on leafy
branches, linear, 6-11 cm. long, sometimes reduced to 1-2 spikelets, especially when the
plants are much-branched; spikelets erect, appressed to the rachis segments; pedicels
villous, stiff, 1.0-2.5 mm. long. Spikelets 15-30 mm. long, readily disarticulating; first
glume lanceolate, blunt at the tip, stiffish, 7-nerved, 5-10 mm. long; second glume simi-
lar, 6.5-10.5 mm. long; florets 5-12; lemmas 10-13 mm. long, lanceolate, 7-nerved, scabrid
on the back, tapering into a short stiff awn 2-6 mm. long; palea 9-10 mm. long, conspicu-
ously pectinate-ciliate on the keels; anthers 1.5-2.0 mm. long, yellow. Chromosome
number n = 19 from Costa Rican material.

Mountains of central and southern Costa Rica; rare; elevations from
2,000-3,400 m. We have specimens from Irazu, Ascuncion, and Chir-
ripo Grande. Paramos and open pastures. Blooming probably year-
long. Mexico, Guatemala, Costa Rica and northern Panama; Colombia
and Venezuela to Bolivia.

This species is somewhat variable, especially in awn length and leaf
blade size. Part of the leaf variation may be attributed to the stage of
growth and degree of branching of the plants. Fournier, in Mex. PL
2:125, described two new species of Brachy podium, B. subulatum and
B. latifolium. Most of the material cited by Fournier for his new
species and B. mexicanum was collected from the summit of Istepec
by Liebmann. It seems likely that all are variants of one species. Some
of our Costa Rican material is a close match for the type of B. sub-
ulatum Fourn.

BRIZA Linnaeus

Caepitose annual grasses; inflorescence a panicle; spikelets several-flowered; glumes
and lemmas very broad, blunt, placed at right angles to the rachilla; disarticulation
above the glumes and between the florets; glumes faintly 3-nerved, circular, cucullate;
lemmas circular, cordate at the base, faintly 5-7-nerved; palea much shorter and nar-
rower than the lemma. (Pooideae: Poeae.)

Briza minor L., Sp. PL 70. 1753. Figure 34.

Caespitose annual; culms erect, simple, 20-50 cm. tall, branching from the base only;
prophylla prominent at the base of the plant; culms 1-2 mm. thick, hollow, thin-walled,
glabrous; nodes glabrous, dark, shrunken; leaves 2-4; sheaths glabrous, strongly ribbed,
shorter than the internodes, the margins united for a short distance above the node;
ligules membranaceous, the upper ones as much as 8 mm. long, their margins decurrent
on the sheaths; leaf blades 6-13 cm. long, 4-8 mm. wide, glabrous; peduncle 10-15 cm.
long, ridged, scaberulous. Panicle solitary, terminal, broadly pyramidal, 10-15 cm. long,
often nearly as wide; branches solitary or paired, spreading. Spikelets solitary, pendent,
tremulous on flexuous pedicels, deltoid in outline, broadest at the straight base, about as
wide as long, 3.0-4.5 mm. long, mostly about 5-flowered; glumes subequal, 1.5-2.0 mm.
long, faintly 3-nerved, circular but folded into an oblong-cucullate form; lemmas 1.5-2.0
mm. long, circular and cordate at the base, faintly 5-nerved, utriculate at the center, the

FIG. 34. Briza minor. Plant, spikelet, and a single floret.
Ill

112 FIELDIANA: BOTANY

paJea closing off the cavity of the lemma; palea obovate, 1.0-1.5 mm. long, ciliate on the
lateral margins; anthers 3, purplish, 0.7 mm. long. Chromosome number n = 5 from a
Costa Rican specimen.

Occasional; roadsides, cultivated fields, pastures, middle elevations,
from 1,800-2,600 m.; Poas, Barba, Irazu; Cordillera de Talamanca; San
Jose. Blooming from August to March, possibly yearlong. Introduced
from Europe; southern United States and Mexico; Guatemala; Costa
Rica.

This delicate little grass is quite ornamental and is sometimes culti-
vated for the odd, trembling spikelets.

BROMUS Linnaeus

REFERENCE: T. R. Soderstrom & J. H. Beaman. The genus Bromus
(Gramineae) in Mexico and Central America, Pub. Mus. Michigan
State Univ., Biol. Ser. 3(5):465-520. 1968.

Plants annual or perennial, caespitose or rarely rhizomatous; culms unbranched;
sheaths with united edges. Inflorescence a solitary terminal panicle. Spikelets several to
many-flowered, laterally compressed; disarticulation above the glumes and between the
florets; glumes unequal, acute or acuminate, 1-several-nerved, the second longer and
usually wider than the first; lemmas 5-9-nerved, rounded or keeled on the back, usually
awned, the awn arising just below the tip or between 2 apical teeth.

A large and diverse genus, mostly of temperate climates of the
northern hemisphere. The spikelets are similar to those of species of
Festuca, differing in the subapical awns of the lemmas and the usual
presence of lateral teeth. Vegetatively, Bromus can be separated from
Festuca by the united margins of the sheaths. (Pooideae: Poeae.)

KEY TO SPECIES OF Bromus

la. Second glume 5-nerved; spikelets strongly flattened, glumes and lemmas acutely
keeled B. carinatus

Ib. Second glume 3-nerved; spikelets not strongly flattened; lemmas rounded on
back B. exaltatus

Bromus carinatus Hook. & Am., Bot. Beechey Voy. 403. 1840.
Bromus laciniatus Beal, Gr. N. Amer. 2:615. 1896. Figure 35.

Duration indefinite; plants caespitose, 35-120 cm. tall, erect; culms unbranched, 2-3
mm. thick, hollow, mostly glabrous, often retrorsely pilose on and below the nodes;
sheaths mostly longer than the internodes, the lower ones often retrorsely pilose, the
upper glabrous or nearly so; ligule a thin membrane, 1-3 mm. long; blades flat, 8-33 cm.
long, 2-7 mm. wide, glabrous or with scattered weak hairs. Peduncle up to 15 cm. long;
inflorescence a solitary terminal panicle, 15-36 cm. long, open, pyramidal, the lower
branches up to 15 cm. long, naked below, the spikelets borne near the outer ends.
Spikelets strongly laterally compressed, 1.5-3.5 cm. long, the glumes and lemmas

FIG. 35. ZJroratts species. B. exaltatus: A, inflorescence; B, spikelet; B. carinatus: C,
spikelet.

113

114 FIELDIANA: BOTANY

strongly keeled; first glume 5-10 mm. long, 3-nerved, narrowly ovate; second glume 7-11
mm. long, 5-7-nerved, lanceolate-ovate; florets usually 6-8; lemmas 8-15 mm. long,
lanceolate, 7-nerved, glabrous or pubescent on the margins; awn up to 10 mm. long,
arising between inconspicuous teeth; palea slightly shorter than the lemma; anthers 3,
yellow. Some plants which are presumably cleistogamous have small anthers, 0.7-1.0
mm. long, remaining tangled with the stigmas; others have large anthers, 3.5-6.5 mm.
long. Both types have the same chromosome number and are externally similar.
Chromosome number n = 28 from two Costa Rican collections.

Roadsides and pastures, occasional, from 1,700-2,600 m. elevation.
August and September. Western United States to Costa Rica.

Bromus catharticus Vahl has been reported from Costa Rica by
Soderstrom & Beaman (1968). The basis of this report was a specimen
apparently cultivated in the garden of the National Museum in San
Jose, and no evidence exists that the species ever became established
in Costa Rica. This species has recently been passing under the name
B. unioloides H.B.K. Pinto-Escobar has now shown that the proper
name is B. catharticus (Caldasia 11:54:9-16).

Bromus exaltatus Bernh., Linnaea 15:Litt. 90. 1841. Figure 35.

Perennial; plants 45-80 cm. tall; culms erect from decumbent bases; unbranched; old
sheaths remaining as fibrous remnants; culms hollow, ca. 2 mm. thick, unbranched,
glabrous or slightly retrorsely pilose, especially below the nodes; lower sheaths mostly
longer than the internodes and overlapping, densely retrorsely pilose; upper sheaths less
pubescent; ligule a brownish membrane, 1-2 mm. long; leaf blades flat, 10-30 cm. long,
3-7 mm. wide, scabrous on the margins, glabrous beneath, the upper surface with
scattered weak hairs. Peduncle 10-12 cm. long, glabrous; inflorescence a solitary termi-
nal panicle, open and nodding, 10-22 cm. long, rather narrow, the branches 1-3 per node,
few-flowered, rarely up to 11 cm. long; pedicels minutely antrorsely scabrous, short or
longer than the spikelets. Spikelets laterally compressed, 2.5-3.2 cm. long, usually with
5-6 florets, the terminal one reduced and sterile; disarticulation above the glumes and
between florets; first glume linear-lanceolate, acuminate, 1-nerved, 5.0-11.5 mm. long;
second glume broadly lanceolate, acuminate, 3-nerved, 8.5-14.0 mm. long; florets 12-17
mm. long, excluding the 2.5-4.0 mm. long awns; lemmas 5-nerved, lanceolate, rounded
on the back, tapering to the base of the awn, the lateral teeth usually inconspicuous;
margins, base, and lower part of the back more or less appressed pilose; glumes and
lemmas often purplish and with golden margins; palea 8.7-10.5 mm. long, narrowly
elliptical, the keels scabrous, the back sometimes with a few hairs; anthers 3, yellow,
2.2-2.8 mm. long. Chromosome number n = 1 from a Costa Rican specimen.

Rare, paramos above 3,200 m. elevation, near Asuncion; Chirripo
Grande. July to August. Southern Mexico; Guatemala; Costa Rica;
Volcan Chiriqui in Panama.

CALAMAGROSTIS Adanson

Perennial caespitose or rhizomatous grasses; inflorescence a usually narrow or con-
tracted terminal panicle. Spikelets small, 1-flowered, laterally compressed, the subequal

BURGER: FLORA COSTARICENSIS 115

glumes 1- or sometimes 3-nerved, keeled, longer than the floret; disarticulation above
the glumes; floret 1; lemma 5-nerved, awned from the back or between 2 teeth; callus
bearded; palea nearly as long as the lemma; rachilla in our species prolonged behind the
palea as a hairy or naked bristle.

A large genus of grasses of the temperate and arctic regions, spar-
ingly represented at high elevations in the tropics. The endosperm in
some species is pasty, as in Trisetum. (Pooideae: Agrosteae.)

KEY TO SPECIES OF Calamagrostis

la. Rachilla internode behind palea glabrous or with few short hairs not exceeding its

tip; awn inserted near base of lemma C. nuda

Ib. Rachilla internode heavily bearded, with long hairs extending beyond its tip; awn

inserted near or above middle of lemma 2

2a. Culms erect, in dense clumps; leaf blades tightly involute; sheaths auricled;

anthers 3, 2.5-2.8 mm. long C. intermedia.

2b. Culms decumbent at base; leaf blades mostly flat, sheaths not auricled; anthers
2, 1.2-1.4 mm. long C. pittieri

Calamagrostis intermedia (Presl) Steud., Nom. Bot., ed. 2. 1:250.
1840. Deyeuxia intermedia Presl, Rel. Haenk. 1:249. 1830. Figure 36.

Perennial, in dense hard tussocks; plants 45-110 cm. tall, stiffly erect; culms 1.5-3.0
mm. thick, hollow, glabrous; sheaths mostly basal, densely overlapping; culm leaves
about 2; sheaths glabrous, the apex on one side prolonged into a stiff rounded auricle,
1.5-3.5 mm. long, continuous with the ligule; ligule a stiff membrane, 1.0-2.9 mm. long;
leaf blades mostly from the base of the plants, stiff and rigid, tightly involute, 1.0-1.5
mm. thick as rolled, 10-45 cm. long, tapering abruptly to a point, scaberulous beneath.
Peduncle included or exserted up to 20 cm.; inflorescence a solitary terminal panicle,
purple, 12-35 cm. long, loosely cylindrical, tapering to a narrow apex, the ascending
lower branches up to 8 cm. long; panicle somewhat interrupted, the scabrous axis and
branches partially exposed; spikelets appressed along the branches; pedicels slender and
scabrous, shorter or longer than the spikelets. Spikelets laterally compressed, the
glumes subequal, keeled, lanceolate-attenuate, 6-8 mm. long exceeding the floret, the
tips recurved; disarticulation above the glumes; lemma lanceolate, 5.0-6.5 mm. long, the
callus rather short, sparsely bearded with hairs less than 1 mm. long; back scaberulous;
nerves faint; apex tapering into 2 teeth about 1 mm. long; awn inserted on the back
below the middle, geniculate, 7-11 mm. long; palea broad, 4-5 mm. long, the apex
truncate; anthers 3, yellow or purple, 2.5-2.8 mm. long; rachilla 1.5-3.5 mm. long, the
hairs appressed, those at the apex 1.0-1.5 mm. long. Chromosome number n = 28 from a
Costa Rican specimen.

Occasional, Cordillera de Talamanca, mostly on paramos above 3,100
m. elevation; Cerro de la Muerte, Chirripo Grande. Apparently
blooming yearlong. Plants from the highest elevations of Chirripo
Grande are markedly smaller than average. Costa Rica to Argentina.

FIG. 36. Calamagrostis species. C. nuda: A, floret and spikelet; C. intermedia: B,
floret and spikelet; C, inflorescence; C. pittieri: D, floret and spikelet.

116

BURGER: FLORA COSTARICENSIS 117

Calamagrostis nuda (Pilger) Pilger, Bot. Jahrb. Syst. 42:60. 1908.
Deyeuxia nuda Pilger, Bot. Jahrb. Syst. 27:29. 1899. Figure 36.

Perennial; plants erect, in large, dense tufts up to 60 cm. in diameter; culms 45-95 cm.
tall, unbranched, hollow, thin-walled, 1.5-2.0 mm. thick, minutely scaberulous; nodes
purple, up to 2 mm. high, not prominent; culm leaves up to 4, the uppermost one
reduced; sheaths much shorter than the internodes, the lower ones breaking down into
stiff fibers, lower sheaths sometimes with a few scattered weak appressed long hairs,
otherwise glabrous; ligule 3.5-5.0 mm. long, a firm rounded membrane, decurrent on the
sheath margins; blades stiff, strict, mostly involute, up to 5 mm. wide when unrolled, 2
mm. thick when rolled, smooth or scabrid beneath, scabrous-puberulent and deeply
grooved above. Peduncle included or exserted up to 17 cm.; inflorescence a solitary
terminal panicle, densely cylindrical, lobed, purple, 12-15 cm. long, 1.0-1.5 cm. thick, the
spikelets densely overlapping on the short, erect branches, short-pedicellate; pedicels
and branches scabrous. Spikelets laterally compressed, purple or greenish, disar-
ticulating above the glumes, 3.7-4.1 mm. long, the glumes subequal, exceeding the
floret; first glume 1-nerved, the second sometimes weakly 3-nerved, both strongly
keeled, scabrous on the upper half of the keel, ovate, acuminate; lemma ovate, 3.3-3.5
mm. long, the tip erose or 4-toothed; callus hairs scant or lacking, usually less than 0.5
mm. long; back of lemma scabrous; awn inserted near the base of the lemma, rather thick
and scarcely twisted or geniculate, slightly exceeding the lemma and exserted at the tip
of the glumes, 3.3-3.4 mm. long; palea slightly shorter than the lemma, 2.8-3.3 mm. long;
anther 1, yellow or purple, 1.2-1.5 mm. long; rachilla internode 0.7-1.0 mm. long, naked
or with a few short hairs. Chromosome number n = 35 from a Costa Rican specimen.

High paramos, 3,300-3,500 m. elevation; Asuncion, Buena Vista,
Chirripo Grande. January and July. This species was previously
known only from South America.

Calamagrostis pittieri Hack., Oesterr. Bot. Z. 52:108. 1902.
Figure 36.

Perennial; plants 30-100 cm. tall, erect, the bases of the culms often decumbent; culms
unbranched, glabrous or rarely with a few weak hairs below the nodes, 1-3 mm. thick,
hollow; nodes mostly glabrous, yellow or purple; sheaths mostly shorter than the inter-
nodes, retrorsely pilose or the upper ones glabrous; ligules 1.0-3.0 mm. long, mem-
branaceous; leaf blades 10-30 cm. long, 3-6 mm. wide, ridged and pilose above, flat or
folded. Peduncle included or exserted up to 26 cm.; inflorescence solitary, terminal, a
loosely cylindrical panicle, tapering to a narrow apex, the ascending branches densely
clothed with overlapping spikelets. Spikelets often purplish, silky because of the evident
rachilla hairs, overlapping, appressed along the branches; pedicels short, scabrous.
Spikelets laterally compressed, 5-6 mm. long; glumes subequal, lance-attenuate, 5-6
mm. long; scabrous on the keels, often purple-striate, the first 1-nerved, the second
weakly 3-nerved; floret disarticulating above the glumes and shorter than them; lemma
3.8-4.5 mm. long, lanceolate, the callus acute, sparsely bearded with hairs less than 1
mm. long; nerves faint; awn 4.2-5.7 mm. long, geniculate, twisted below, exserted from
the glumes, attached between 2 acuminate apical teeth 1.2-1.7 mm. long; palea 2.8-3.5
mm. long, the apex bidentate; anthers 2, 1.2-1.4 mm. long; caryopsis spindle-shaped, 2.0
mm. long, soft and pasty; rachilla internode 1.3-2.1 mm. long, heavily bearded with
white hairs, those at the apex ca. 2.5 mm. long. Chromosome number n = 14 from a
Costa Rican specimen.

118 FIELDIANA: BOTANY

Paramos of the Cordillera de Talamanca: Buena Vista, Asuncion,
Chirripo Grande; brushy roadsides in Quercus forests; elevations
2,700-3,450 m. July to October. Apparently confined to Costa Rica.

CENCHRUS Linnaeus

REFERENCE: D. G. DeLisle, Taxonomy and distribution of the genus
Cenchrus, Iowa State Univ. J. Sci. 37:259-351. 1963.

Plants annual or perennial, caespitose, the culms solid or hollow, often decumbent and
rooting at lower nodes. Inflorescences terminal on the culms or on leafy branches;
inflorescence unbranched, a dense spike of detachable involucres, borne singly at the
nodes of a flattened, flexuous rachis; each involucre (fascicle or bur) consisting of numer-
ous bristly hairs or flattened retrorsely barbed spines, these more or less connate at the
base and permanently enclosing several sessile spikelets. Spikelets dorsally compressed;
first glume 1-3-nerved, usually about half as long as the spikelet; second glume and lower
lemma subequal, as long as the spikelet; second glume 1-7-nerved; lower lemma her-
baceous, ovate, acuminate, 3-7-nerved, containing a 2-nerved palea about equal in size
and usually a staminate flower with enlarged anthers; upper floret perfect-flowered, the
lemma chartaceous, 5-7-nerved, ovate and acuminate, its margins enveloping the edges
of the palea, not inrolled; palea broad, acuminate, 2-nerved, chartaceous, equal to the
lemma; flower lacking lodicules; anthers 3; caryopsis elliptic or ovoid, plump.

A genus of about 20 species, widespread in temperate and tropical
regions of both eastern and western hemispheres. The plants are found
frequently on disturbed or sandy soils. Cenchrus is closely related to
Pennisetum, differing in the connate spines, but some species have
been shifted from one genus to the other. Setaria, Anthephora, and
the subgenus Paurochaetium of Panicum are also in the same affinity
group. Cenchrus plants are readily recognizable in most cases by the
pungent adhering burs, by which the spikelets are readily dispersed by
man and animals. The spines inflict painful puncture wounds which
readily become infected. (Panicoideae: Paniceae.)

KEY TO SPECIES OF Cenchrus

la. Spines and bristles retrorsely barbed, so that burs readily adhere to objects when
brushed upwardly 2

Ib. Spines antrorsely scabrous, not adhering when brushed upwardly C. pilosus

2a. Spines separate to base of bur, spikelet exposed between them C. myosuroides

2b. Lower half of spines united into flat plates, forming a more or less solid bur

concealing the spikelets 3

3a. Burs with a ring of slender bristles at the base, much finer than flattened inner
spines of bur 4

3b. Burs lacking outer ring of bristles, all spines about the same size C. incertus

4a. Inflorescence very dense, the burs completely hiding rachis; internodes of rachis
between 2 adjacent burs less than 2 mm. long; body of burs (excluding the

BURGER: FLORA COSTARICENSIS 119

spines) less than 4.5 mm. wide, burs stramineous; some outer bristles about as

long as the bur C. brownii

4b. Inflorescence not dense, rachis partly visible between burs; rachis internodes
2-3 mm. long; body of burs 3.5-6.0 mm. wide; burs often purplish; outer bristles
usually less than half as long as bur C. echinatus

Cenchrus brownii Roem. & Schult., Syst. Veg. 2:258. 1817. C.
viridis Spreng., Syst. Veg. 1:301. 1825. Figure 37.

Duration indefinite; culms erect to long-decumbent and rooting at the lower nodes,
25-95 cm. long, glabrous, solid or hollow; sheaths mostly longer than the internodes,
keeled, the margins more or less pilose; ligules 0.6-1.3 mm. long, ciliate; blades flat, 8-30
cm. long, 4-11 mm. wide, the upper surface sometimes pilose. Inflorescences terminal on
leafy branches, 3-12 cm. long, densely cylindrical, 1.0-1.5 cm. wide. Burs globose, 2.0-4.5
mm. wide (5-8 mm. including the bristles), the stipe and lower parts of the spines villous;
some outer bristles as long as the bur; inner spines flattened, often bent and interlocking;
both spines and bristles retrorsely barbed. Spikelets 2-3 per bur, sessile and perma-
nently attached at the base of the bur, dorsally compressed, 4-6 mm. long; first glume
0.5-2.5 mm. long, 1-nerved; second glume 2.2-4.9 mm. long, 3-5-nerved; lower lemma
3.5-5.5 mm. long, its palea equal; upper floret perfect flowered; lemma 3.6-5.4 mm. long,
ovate-acuminate, glabrous; anthers 3, 0.8-2.3 mm. long. Chromosome number n = 17
from a Costa Rican specimen.

Roadsides, pastures, beaches, waste ground; common in
Guanacaste, scattered elsewhere; elevations sea level to 100 m. , rarely
to 600 m. June to October. Florida Keys; Rio Grande Valley; West
Indies; Southern Mexico to northern South America, rarely elsewhere;
introduced in South Africa, the Philippines and tropical Asia.

This species is very closely related to C. echinatus, differing in the
much denser inflorescence, smaller burs, shorter rachis internodes,
and in usually being diploid.

Cenchrus echinatus L., Sp. PI. 1050. 1753. C. insularis Scribn. ex
Millsp., Publ. Field Mus., Bot. Ser. Vol. 11:26. 1900. Figure 37.

Duration indefinite; culms 15-85 cm. long, glabrous, solid or hollow, ascending from
long-decumbent and rooting bases; branching abundant from the decumbent culm bases;
sheaths keeled, mostly overlapping, glabrous to heavily pubescent; ligules 0.7-1.7 mm.
long, ciliate; blades flat, 4-26 cm. long, 3.5-11 mm. wide, glabrous or with scattered long
weak hairs on the upper surface near the base. Inflorescences terminal on leafy
branches, exserted, cylindrical, 2-10 cm. long, up to 2 cm. wide, the burs spaced, the
flexuous rachis often visible between them; rachis internodes 2-3 mm. long. Burs
globose, 5-10 mm. long, 3.5-6.0 mm. wide; outer slender bristles much shorter than the
flat, mostly erect inner spines; color of burs often purplish. Spikelets 2-3 per bur, dor-
sally compressed, sessile within the bur and permanently attached to it, 5.0-7.0 mm.
long; first glume 1.3-3.4 mm. long; second glume 3.8-5.7 mm. long, 3-6-nerved; lower
lemma 4.5-6.4 mm. long, the palea slightly longer, scabrous; upper lemma 4.7-7.0 mm.
long, ovate-acuminate; anthers 0.8-2.4 mm. long. Chromosome number in recent Ameri-
can specimens, n = 34.

FIG. 37. Cenchrus species. C. echinatus: A, bur; C. incertus: B, bur; C. pilosus: C,
bur; C. brownii: D, bur; E, plant and inflorescence.

120

BURGER: FLORA COSTARICENSIS 121

Beach of Caribbean Sea, between Rio Banano and the Limon Air-
port; beach at Tortugero; Cahuita. July to September, probably year-
long. Transcontinental in the southern United States, southward to
southern South America; West Indies. Introduced in the Pacific Is-
lands, China, and Australia.

This species is closely related to C. brownii, differing in the more
open inflorescence, short outer bristles of the burs, and larger bur size,
as well as in the chromosome number.

Cenchrus incertus M. A. Curtis, Boston J. Nat. Hist. 1:135. 1835.
C. pauciflorus Benth., Bot. Voy. Sulph. 56. 1844. Figure 37.

Duration indefinite; plants decumbent to erect, the culms 5-80 cm. long, sometimes
stoloniferous or rhizomatous on shifting sands; branching abundant; culms round, 1-2
mm. thick, glabrous, solid with a pithy center; leaf sheaths keeled, longer or shorter
than the internodes, glabrous to pilose, the upper margins and throat pilose; ligule
ciliate, 0.5-1.5 mm. long; leaf blades flat or folded, 2-18 cm. long, 2-6 mm. wide, glabrous
beneath, loosely pilose above. Inflorescences terminal on leafy branches, 2.0-8.5 cm.
long, 8-20 mm. wide, cylindrical, the rachis flexuous, visible between the burs; inter-
nodes 2.0-5.0 mm. long. Burs (fascicles) stramineous to purplish, the body ovoid to
globose, split on 2 sides, pubescent, 5-10 mm. long, the body 2.5-5.5 mm. wide, the stipe
up to 2 mm. long; spines 8-40, more or less flattened, to 2 mm. wide, retrorsely barbed,
2.0-2.5 mm. long. Spikelets sessile and permanently attached within the bur, 2-4 per
bur, dorsally compressed, 3.5-5.8 mm. long; first glume 1.0-3.3 mm. long, 1-nerved;
second glume 2.8-5.0 mm. long, 5-7-nerved, ovate-acuminate; lower lemma similar,
3.0-5.9 mm. long, 4-7-nerved, the palea 3.5-6.2 mm. long; fertile lemma chartaceous,
3.4-6.0 mm. long, ovate-acuminate, 3-nerved, the broad margins covering the margins of
the palea but not inrolled, glabrous; anthers 3, 0.5-2.0 mm. long. Chromosome number
n = 17 from a Costa Rican specimen.

Sandy beaches near ports, Puntarenas, Boca de Barranca, Puerto
Limon; June and July, but probably blooming yearlong; possibly intro-
duced. Transcontinental in the southern United States, southward to
Panama; West Indies; central South America.

Cenchrus myosuroides H.B.K., Nov. Gen. & Sp. 1:115, t. 35. 1816.

Caespitose perennial, from a hard base; plants 0.5-2.0 m. tall, erect or leaning,
branching from the base or the lower culm nodes; prophylla prominent, up to 6 cm. long;
culms glabrous, round, thick-walled, with a small lumen; nodes dark, glabrous; sheaths
glabrous, longer than the internodes, keeled toward the apex; ligule a short, thick
membrane, crowned with a circle of hairs longer than the membrane, in total 1.5-3.4
mm. long; leaf blades flat, glabrous or slightly pilose, strongly scabrous-margined, 12-38
cm. long, 4-13 mm. wide. Inflorescence a solitary narrowly cylindrical terminal spike of
fascicles, borne on a short glabrous peduncle; length 6.5-23 cm., thickness 0.6-1.5 cm.;
rachis puberulent, the internodes up to 1.7 mm. long. Burs numerous, 3.8-8.1 mm. long,
1.2-3.0 mm. thick, with a short, thick basal stipe; spines numerous, 3-6 mm. long,
retrorsely barbed, 0.2-0.6 mm. thick; spikelets usually 1 per bur, rarely 2-3. Spikelets
ovoid, acute, 3.8-5.6 mm. long; first glume deltoid, acute, 1-nerved, 1.5-3.0 mm. long;

122 FIELDIANA: BOTANY

second glume 3.1-5.0 mm. long, ovate, acute, 3-5-nerved, the margins clasping the
sterile lemma; palea of sterile lemma lacking or present as a tongue-shaped membrane
nearly as long as the lemma; anthers not seen; fertile lemma ovoid, 3-5-nerved, 3.8-5.4
mm. long, acute; palea about equal, grooved; anthers 3, 1.2-2.2 mm. long; caryopsis
elliptical, tan, 1.5-2.6 mm. long.

The only Central American specimen is the following. Costa Rica:
Limon, Uvita, 17 July 1932, Stork 3218, F. Southern Florida; Carib-
bean Islands; southern Texas, Mexico; South America to central
Argentina.

Cenchrus pilosus H.B.K., Nov. Gen. & Sp. 1:116, t. 36. 1816.
Figure 37.

Duration indefinite; plants erect to decumbent, the culm bases rooting; culms 30-70
cm. long, 2-3 mm. thick, round, solid, or hollow, glabrous; branching abundant;
prophylla prominent, up to 30 mm. long; sheaths keeled, longer or shorter than the
internodes, glabrous or scabrous; ligules 0.5-1.6 mm. long, ciliate; blades flat, 6-30 cm.
long, 4-11 mm. wide, glabrous or the upper surface long-pilose near the base. Peduncles
exserted; inflorescence a dense spike of fascicles (burs), terminal on the main culm or on
leafy branches, 2-13 cm. long, up to 2 cm. thick, including the spreading bristles;
spikelets borne in densely overlapping burs on a strongly angled but not zig-zag rachis,
its nodes pilose. Burs numerous, globose, the body 5.0-8.0 mm. long, 3.0-5.5 mm. wide,
but appearing much larger because of the spreading outer bristles, tan or purplish, the
flattened obconical basal stipe and the flattened interlocking inner spines pilose; spines
3.0-6.0 mm. long; outer bristles numerous, many twice as long as the spines, both spines
and bristles antrorsely scabrous, the burs not clinging to objects as in the other species.
Spikelets 2-3 per bur, dorsally compressed, 6.0-7.5 mm. long; first glume 1.0-4.0 mm.
long; second glume caudate-ovate, the broad margins embracing the palea but not in-
rolled; anthers 3, 0.9-1.8 mm. long; caryopsis ovoid, 2.2-3.0 mm. long. Chromosome
number n = 17 from Costa Rican specimens.

Common around Canas and scattered elsewhere in Guanacaste;
Atenas; elevations up to 600 m.; savannas, pastures, roadsides. June to
November. Southern Mexico and Yucatan to Costa Rica; northwestern
South America.

CHAETIUM Nees

REFERENCE: M. B. Montiel, Determination taxonomica de la especie
Chaetium bromoides (Presl) Benth. basada en el estudio anatomico,
Revista Biol. Trop. 20:45-79. 1972.

Caespitose perennial; inflorescence a dense erect panicle; spikelets lanceolate, dorsally
compressed, plano-convex, with a sharp pubescent callus formed of the base of the first
glume, united with the rachilla internode; glumes equal, herbaceous, both longer than
the florets, both bearing long awns; sterile and fertile lemmas equal, chartaceous, ta-
pering into short awns; edges of fertile lemma enclosing the margins of the palea, not

BURGER: FLORA COSTARICENSIS 123

inrolled; palea firm, flat, tapering to an awn-tip, nearly as long as the lemma; disarticula-
tion at the base of the callus, very oblique. (Panicoideae: Paniceae.)

Chaetium bromoides (Presl) Benth. ex Hemsl. , Biol. Centr. Amer.
Bot. 3:503. 1885. Berchtoldia bromoides Presl, Rel. Haenk. 1:324, pi.
43. 1830. Figure 38.

Caespitose perennial, rarely producing stolons; culms erect or spreading, 50-100 cm.
tall, simple or somewhat branched above; prophylla prominent, 5-9 cm. long, pubescent
near the tip; culms 2-3 mm. thick, glabrous and shining, hollow, the cavity small; nodes
upwardly bearded or glabrescent; leaf sheaths keeled, shorter than the internodes,
glabrous except for the upper margins and the collar; ligules prominent, 1.5-2.5 mm.
long, of densely crowded white hairs; blades 10-30 cm. long, 3-7 mm. wide, sparsely
papillose-pilose on both surfaces, rarely puberulent as well; peduncles included or ex-
serted as much as 30 cm.; panicles terminal on the culm or on leafy branches, 10-23 cm.
long, 1-2 cm. wide, the branches erect and appressed; spikelets greenish or purple,
dorsally compressed, plano-convex, 8-10 mm. long (excluding awns); disarticulation
below the glumes, at the base of a slender pilose callus 1.5-2.5 mm. long formed by the
union of the first glume and the lower rachilla joint; disarticulation very oblique; glumes
subequal, lanceolate, the first 7-10 mm. long, the second 6-8 mm., both broad and
concealing the florets, 5-7-nerved, scabrid on the nerves, tapering into erect awns 10-35
mm. long; sterile lemma 6-8 mm. long, smooth and glabrous, narrowly ovate, faintly
3-nerved; fertile floret 6-8 mm. long; lemma smooth, chartaceous, the margins flat,
covering the margins of the palea; lemma with an awn up to 2 mm. long; nerves faint;
anthers 3, purple, 1.5 mm. long. Chromosome number n = 13 from Costa Rican speci-
mens.

Common in the Meseta Central; open or partially shaded areas;
lawns, roadsides, disturbed areas; 1,000-2,000 m. elevation. Blooming
apparently occurs throughout the year. Mexico to Costa Rica.

CHLORIS Swartz

REFERENCE: D. Anderson, Taxonomy of the genus Chloris
(Gramineae), Brigham Young Univ. Sci. Bull, Biol. Ser. 19:2:1-132.
1974.

Annual or perennial caespitose, stoloniferous or rhizomatous grasses; culms solid,
pithy. Inflorescence of 1 or more whorls of 1-sided spikes; spikelets sessile or nearly so,
appressed in 2 rows along the lower sides of a slender triquetrous rachis. Spikelets
laterally compressed, disarticulating above the glumes; glumes narrow, acuminate, 1-
nerved; fertile florets 1-several, the lemma 3-nerved, the lateral nerves marginal; nerves
usually ciliate, especially above; callus bearded; awn inserted just below the bifid apex of
the lemma; palea about equal to the lemma; rachilla prolonged beyond the fertile floret
and bearing 1 to several rudimentary lemmas.

A large genus of grasses of warm climates of both Old and New
Worlds. The genus is related to Eustachys, Bouteloua, and Gymnopo-

J&t

FIG. 38. Ckaetium bromoides. A, inflorescence; B, two views of a spikelet; C, fertile
floret.

124

BURGER: FLORA COSTARICENSIS 125

gon. Some of the species are common tropical weeds, and one, C.
gay ana, is an important forage grass. (Chloridoideae: Chlorideae.)

KEY TO SPECIES OF Chloris

la. Florets 3-5, the lowermost 1 or 2 producing grains, upper ones sterile or rudimen-
tary; cultivated crop C. gayana

Ib. Florets 2, second sterile and rudimentary; wild plants 2

2a. Spikelets 2.5-3.5 mm. long, greenish; fertile lemma 2.5-3.4 mm. long; spikes

somewhat flexuous C. radiata

2b. Spikelets 3.8-4.1 mm. long, purple-tinged; fertile lemma 3.4-4.0 mm. long;
spikes stiff C. aristata

Chloris aristata (Cerv.) Swallen, N. Amer. Fl. 17:8: 596. 1939.
Agrostomia aristata Cerv. Naturaleza 1: 345. 1870. ? Chloris rufes-
cens Lag.?, Varied. Ci. 4:143. 1805. Figure 39.

Duration indefinite; plants forming small circular patches, the culms arising from short
stoloniferous bases; culms unbranched, 15-60 cm. tall, 2 mm. thick, solid, pithy, gla-
brous; nodes dark, contracted; sheaths shorter than the internodes, strongly keeled,
glabrous, glaucous; ligule a short membrane, densely ciliate with a dense row of stiff
white hairs, ca. 1 mm. long; leaf blades flat or folded, blunt-tipped, 1-13 cm. long, 1.5-4.0
mm. wide, the uppermost usually much reduced, scabrous especially on the margins and
on the keeled midrib below, often bearing scattered long weak hairs. Peduncle exserted
4-15 cm., pilose at the apex; inflorescence vase-shaped, of 5-7 spikes, mostly in a single
whorl, or with a solitary spike attached just below the others; spikes 3-8 cm. long;
spikelets appressed in 2 rows along the lower side of the slender triquetrous rachis,
overlapping. Spikelets 3.8-4.1 mm. long, the glumes and lemmas keeled; glumes 1-
nerved, subulate to narrowly lanceolate, acuminate, scabrous on the keel; first glume
2.0-2.2 mm. long, the second 3.2-4.0 mm. long; fertile lemma 3.4-4.0 mm. long, ovate,
acute, the keel bowed out; slightly bifid at the apex, the awn 9-10 mm. long, attached
about one-fourth below the apex; lateral nerves marginal, ciliate on the upper half; callus
short-bearded; palea equal to the lemma or slightly longer, the lower part infolded
around the rachilla segment, the upper half dilated, scabrous-ciliate on the upper mar-
gins; anthers 3, yellow, 0.5-0.8 mm. long; rachilla segment slender, ca. half the length of
the fertile lemma, rudiment 1.7-2.0 mm. long, cylindrical, truncate, consisting of an
empty lemma bearing an awn 2.5-4.0 mm. long; spikelets often purplish. Chromosome
number n = 50.

Occasional; roadsides and open areas, mostly in the Meseta Central;
Palmares. Blooming apparently yearlong. Mexico and Guatemala;
Costa Rica.

This is the species which was called C. orthonoton Doell in Grasses
of Central America. That species, however, is Brazilian and differs in a
number of characters from C. aristata.

Chloris gayana Kunth, Rev. Gram. 1:89. 1829.

Vigorous stoloniferous perennial; plants up to 1.5 m. tall; stolons stout, elongated;
erect branches arising freely from the nodes; prophylla prominent, 2-3 cm. long; culms

FIG. 39. Chloris species. C. aristata: A, inflorescence; B, spikelet; C. radiata: C,
spikelet.

126

BURGER: FLORA COSTARICENSIS 127

glabrous, solid, pithy; nodes glabrous, contracted; sheaths glabrous, somewhat keeled;
ligule a minutely ciliolate membrane, 0.3-0.5 mm. long, a conspicuous tuft of stiff
papillose-based hairs borne just behind it; blades flat, acuminate, 20-45 cm. long, 4-7
mm. wide, glabrous or scabrous, sometimes with scattered long papillose-based hairs on
the upper surface. Inflorescences terminal on the culms, consisting of a single dense
whorl of 6-16 rather thick, somewhat flexuous spikes, each 5-9 cm. long, the spikelets in
2 somewhat overlapping rows on the lower sides of the triquetrous rachis. Spikelets 3-5
mm. long, disarticulating only above the glumes; florets 3-5, the lower 1 or 2 producing
grains, the upper ones staminate or sterile; lower lemma 2.7-3.8 mm. long, ovate, pubes-
cent on the callus and marginal nerves, the hairs longer near the apex; awn 2-4 mm. long,
flexuous, attached just below the apex of the lemma; palea slightly longer than the
lemma; upper lemmas glabrous, successively shorter than the first lemma, the ultimate
one a small obconical empty rudiment; anthers 3, yellow, ca. 2 mm. long.

Native to Africa; cultivated in the grass garden at the IICA at
Turrialba; possibly cultivated for forage elsewhere. "Rhodes grass."

Chloris radiata (L.) Swartz, Prodr. Veg. Ind. Occ. 26. 1788. Agros-
tis radiata L., Syst. Nat. 10. 2:873. 1759. Figure 39.

Duration indefinite; plants spreading by short stout freely branching stolons and
making circular patches; culms erect to spreading, 15-60 cm. long; prophylla prominent,
up to 4 cm. long; culms solid, pithy, glabrous, flattened; foliage glaucous, scabrous,
glabrous or softly hirsute; sheaths strongly flattened and keeled; ligule a minutely cilio-
late membrane, 0.5-0.7 mm. long; leaf blades 6-12 cm. long, 3-5 mm. wide, strongly
keeled, especially near the base, blunt-tipped, scabrous on the margins and midrib,
sometimes on the surface, usually hirsute above, sometimes on both surfaces; dewlap
prominent. Inflorescence solitary, terminal, vase-shaped, of 1-2 closely spaced whorls of
lax spikes, each 3.5-7.0 cm. long; spikes 4-18 per inflorescence; spikelets appressed in 2
rows along the lower sides of the slender triquetrous rachis. Spikelets laterally com-
pressed, 2.5-3.5 mm. long, the glumes and lemmas keeled; first glume linear, 1.5-2.4
mm. long, 1-nerved; second glume similar, 2.2-3.4 mm. long; fertile lemma 2.5-3.4 mm.
long, narrowly ovate, strongly keeled, firm, slightly roughened, the marginal nerves
short-ciliate on the upper half, slightly bifid at the tip, the awn 7-11 mm. long, arising
between the teeth of the lemma; callus short-ciliate; palea equal to the lemma; rachilla
segment slender, half as long as the lemma, bearing a slender rudiment 0.5-1.5 mm.
long, mostly concealed by the fertile lemma; awn of rudiment 2.0-7.5 mm. long; anthers
3, yellow, 0.5 mm. long. Chromosome number n = 20 from Costa Rican material.

Common in open, disturbed areas, cafetales, banana plantations,
cacao groves; sea level to 1,300 m. elevation, on both Caribbean and
Pacific slopes. Blooming apparently yearlong. Mexico to Paraguay;
West Indies.

CHUSQUEA Kunth

REFERENCES: E. G. Camus, Les Bambusees: Monographic, biologic,
culture, principaux usages, Lechevalier. Paris. Text and Plates. 1913.
F. A. McClure, Genera of bamboos native to the New World.

128 FIELDIANA: BOTANY

(Gramineae: Bambusoideae), Smithsonian Contr. Bot. 9:1-148.
Smithsonian. Washington, D.C. 1973. Wm. Munro, A monograph of
the Bambusaceae, including descriptions of all the species, Trans.
Linn. Soc. London 26:1:1-157 + 6 Tab. 1868.

Bamboos of small to moderate stature; rhizomes pachymorphous or occasionally lep-
tomorphous; culms arching, the upper portions often drooping or trailing; branching
from middle and upper nodes; internodes solid, rarely with a small irregular lumen by
disintegration of the central parenchyma; branching usually with a single large primary
branch just above the node, subtended by a fascicle of few-many shorter, foliage-bearing
branchlets; primary branch bud sometimes not developing into a branch and remaining
concealed by the minor branchlets. Inflorescences terminal on the leafy branchlets,
variously open or dense panicles or rarely reduced to a small raceme of few spikelets.
Spikelets narrowly ovate, acute or acuminate, sometimes short-awned; glumes much
shorter than the spikelet, sometimes rudimentary, nerveless or 1-3-nerved; disarticula-
tion above the glumes, the remainder of the spikelet shed as a unit; sterile lemmas 2,
similar, from half as long to nearly as long as the spikelet; fertile lemma ovate, acute or
awn-tipped, rounded or flattened on the back, 5-13-nerved; palea about as long as the
lemma or slightly exceeding it, usually grooved between the keels, 4-8-nerved; lodicules
3, flat, ovate or spatulate, vasculated, usually ciliate on the upper half; anthers 3, large;
ovary beaked or with a short style; stigmas 2.

Chusquea is a large genus of montane bamboos, ranging from
Mexico to southern South America. Vegetatively, the plants are usu-
ally distinguished by the solid culms and the branching pattern of one
large primary branch and numerous small, foliage-bearing branches.
The spikelets are rather uniform in structure and, on the rare occa-
sions when the plants are in bloom, furnish good clues to identity.
Recently, McClure has segregated the genus Swallenochloa for the
high-altitude forms with fewer, more strict branches and an irregular
lumen in the internodes. The distinctions are not sharp, and our
chromosome studies have indicated that both genera have a haploid
chromosome number of n = 20, a somewhat unusual number in the
bamboos. Some species of Bambusa, subgenus Guadua may also have
solid or nearly solid internodes at times. They can usually be dif-
ferentiated by the possession of branch thorns and by their low-
altitude habitats.

Chusquea is an extremely complex genus, and we are not yet able to
name all collections. The treatment offered here is tentative. A few
distinctive, but as yet unnamed, populations are briefly discussed at
the end of this generic treatment. (Bambusoideae: Chusqueae.)

KEY TO SPECIES OF Chusquea

la. Culms of mature plants 1 cm. or less thick 2

Ib. Culms of mature plants usually 2-5 cm. thick 4

BURGER: FLORA COSTARICENSIS 129

2a. Leaf blades 7.5-17 cm. long, 16-23 mm. wide, ovate, 3-5 x longer than wide

C. virgata

2b. Leaf blades 1-9 cm. long, 2-12 mm. wide, ovate, 5.7-7 x longer than wide . 3

3a. Leaf blades on foliage-bearing branchlets 1-2.5 cm. long, 2-4 mm. wide; base of leaf

blades with tuft of woolly hairs on one side of midrib on abaxial surface; internodes

of culms smooth C. coronalis

3b. Leaf blades on foliage-bearing branchlets 5-9 cm. long, 8-14 mm. wide; base of leaf
blades woolly on both sides of midrib on abaxial surface; internodes of culms scab-
rous C. simpliciftora

4a. Leafy branches interspersed with thin, curly, leafless, fibrillar branchlets, up to

10 cm. long C. scabra

4b. Leafy branchlets not interspersed with fibrillar branchlets 5

5a. Lowermost 10-20 nodes of the culms bearing circlets of short, protruding root thorns

up to 10 mm. long C. pittieri

5b. Root thorns absent, lower nodes of culms sometimes with soft, drooping adventiti-
ous roots 6

6a. Ligule 1.5 mm. or less long; leaf blades narrow, 14-51 x longer than wide, not

conspicuously tessellate 7

6b. Ligule 2-10 mm. long; leaf blades 6-14 x longer than wide, strongly tessellate 8

7a. Leaf blades 7-12 mm. wide, 14-32 x longer than wide C. longifolia

7b. Leaf blades 4.5-7 mm. wide, 23-51 x longer than wide C. meyeriana

8a. Leaf blades 10-14 x longer than wide, margins not conspicuously white-banded;
texture thin; base of blade tapering to the pseudopetiole; widespread in the

mountains C. tonduzii

8b. Leaf blades 6-9 x longer than wide, base rounded or subcordate; margins con-
spicuously white-banded; Poas, Irazii, Turrialba . . Swallenochloa vulcanalis

Chusquea coronalis Sods. & Cald., Brittonia 30:158. 1978.
Figure 40.

Caespitose in small clumps of 2-3 culms; rhizomes pachymorphous; culms to 3-5 m. tall;
internodes ca. 1 cm. thick, smooth, cylindrical, solid; sheath girdle retrorsely bearded;
primary branch buds usually developing, the primary branches slender, up to 70 cm.
long; foliage-bearing branchlets on the main culm or on the primary branches numerous,
up to 70 per node of the primary culm or in smaller fascicles on the branches; foliage-
bearing branchlets very slender, simple, 5-11 (-17) cm. long, in blooming specimens with
1-2 leaves; nodes minutely retrorsely bearded; sheath glabrous; ligule minute; blades
flat, 1-2.5 cm. long, 2-4 mm. wide, glabrous except for a minute tuft of hairs on one side
of the midrib on the abaxial surface just above the base. Inflorescences terminal on the
foliage-bearing branchlets; peduncle slender, exserted up to 4 cm.; inflorescence a
raceme or slender simple panicle, 2-4 (6) cm. long, ca. 5 mm. wide, with a few appressed
branches bearing 1-3 spikelets each, most of the spikelets borne racemosely on the
rachis; pedicels ascending or appressed, slender, up to 7 mm. long; spikelets usually 2-10
per panicle, rarely up to 30, appressed to the rachis. Spikelets dorsally compressed,
stramineous or purplish, papery, 5.0-5.5 mm. long; glumes reduced to a minute cupule,
0.2-0.3 mm. long at the tip of the pedicel; disarticulation above the glumes, the remain-
der of the spikelet falling as a unit; first sterile lemma 2.3-2.7 mm. long, ovate ca. 2:1,
blunt, 1-nerved, ciliolate near the tip; second sterile lemma similar, 2.7-3.0 mm. long;

FIG. 40. Chusquea coronalis. A, culm sheath; B, inflorescence; C, spikelet; D, surface
of culm sheaths, square is 0. 1 mm.

130

BURGER: FLORA COSTARICENSIS 131

fertile floret dorsally compressed, the lemma 5.0-5.1 mm. long, ovate, acute, strongly
ridged and grooved, 8-9-nerved, ciliolate near the tip; palea about equal or slightly
longer, 4-nerved, bidentate at the tip, ciliolate on the upper margins, grooved between
the keels; lodicules 3, flat, vasculated, long-ciliate at the tip; anthers 3, yellow, 3.2-3.5
mm. long; style very short; stigmas 2. The description was taken from the specimen
cited below.

Costa Rica: Prov. San Jose, Canyon of Rio Jerico, 2 km. NW of Rio
Conejo, 84° 5' W, 9° 48' N, elevation 1,200 m., 11 June 1976, Pohl &
Pinette 13209, ISC, US, F, CR. The following specimen appears to be
the same species, but is in vegetative condition. Foliage leaves are
larger and more numerous, but have the same pubescence pattern.
Primary culm sheaths are densely splotched with purple and are
strongly hispid with appressed, papillose-based rigid hairs. Some of
the larger branchlets have enlarged foliage leaf blades on the branch
axis, as well as clusters of small branchlets bearing small foliage leaves
at the nodes. Prov. San Jose, Forest valley of Rio Alumbre, near Rio
Conejo, elevation ca. 1,200 m., culms 10-15 m. long, arching and
drooping, solid, forming dense drooping veils of foliage, 6 September
1968, Pohl & Davidse 11054, ISC, US, F, CR.

This species is similar to C. simpliciflora Munro, but differs from it
in the shorter spikelets with much smaller glumes, the blunt sterile
lemmas, strongly ridged and grooved fertile lemma, and the more
numerous spikelets. From C. heydei Hitchc., it differs in its much
shorter spikelets with smaller glumes, in the obtuse one-nerved sterile
lemmas, those of C. heydei being three-nerved, and in its strict, nar-
row panicle with short-pedicellate spikelets.

Chusquea longifolia Swallen, J. Wash. Acad. Sci. 30:210. 1940.

Caespitose bamboo in large, dense clumps; colonial, forming large stands; culms to 10
m. or more long, arching and drooping; internodes up to 3 cm. thick, cylindrical, smooth
or scaberulous, solid; culm sheath (one specimen seen) 12 cm. long; ligule thick, straight
ca. 2 mm. long; blade erect, as wide as the sheath apex, 13 cm. long, 3.5 cm. wide,
acuminate, awn-tipped; foliage-bearing branches numerous in a dense fascicle, up to 60
cm. long, including the inflorescence when present; primary branch bud usually de-
veloping into a branch; leaf sheaths glabrous except for the ciliolate overlapping margin;
external ligule evident; sheath apex with rounded stiff auricles; internal ligule 1.0-1.5
mm. long, membranaceous; leaf blades glabrous or with appressed or velvety pubes-
cence beneath, mostly 14-27 cm. long, 7-12 mm. wide, the length usually 14-32 x the
width. Inflorescence a slender dense panicle, its base usually included in the uppermost
sheath; panicle 8-17 cm. long, 1.0-1.5 cm. wide; branches short, erect, scabrous on the
angles, bearing spikelets to the base. Spikelets stramineous or purplish, borne on short,
erect pedicels. Spikelets 10-15.7 mm. long, including the awn of the fertile lemma,
subcylindric, purple, fading to stramineous, disarticulating above the glumes, the re-
mainder of the spikelet falling as a unit; glumes acute or rounded, usually nerveless; first

132 FIELDIANA: BOTANY

glume 1.0-1.3 mm. long; second glume 1.4-1.8 mm. long, first sterile lemma papery,
ovate 3.2-4.3:1, 7-9-nerved; second sterile lemma nearly as long as the fertile floret,
papery, 8.0-12.7 mm. long, with an awn 1-3 mm. long, ovate 3.2-4.3:1, 7-9-nerved; fertile
lemma smooth, stiff, glabrous, dorsally rounded, 9-14 mm. long, including an awn 1.0-1.5
mm. long, ovate 3:1, 7-nerved or sometimes with an additional marginal pair of weak
nerves; palea equal to the lemma or slightly exceeding it, 6-7-nerved, rounded to the
keels and grooved between them; apex rigidly bidentate; lodicules 3, flat, obovate, acute,
vasculated, long-ciliate at the tip; anthers 3, yellow, 5.1-5.4 mm. long; style short;
stigmas 2; caryopsis oblong, 9 mm. long.

Seedlings of this species were found in abundance growing on leaf
litter in shade on a cliff above the highway 2.5 km. S of the Vara
Blanca-Poas intersection in June 1976. They were all less than 10 cm.
tall and were derived from dead fruiting plants of this species, as could
be determined from the attached spikelet parts. Their leaf blades were
ovate ca. 3:1, and the nodes, sheath margins, auricles, and blade sur-
faces were pubescent. This pubescence is a juvenile feature, not seen
in the parent plants.

The following flowering or fruiting specimens were collected from
Volcan Poas, and the description was largely drawn from them: P & D
11507, Pohl & Lucas 13100, Pohl & Pinette 13217, Tonduz 10747 (cited
by Swallen). The following flowering or fruiting specimens were ob-
tained along the CIA near La Georgina. Their spikelets are slightly
shorter, but are otherwise similar to the Poas material. Leaf blades
are usually narrower and may be pubescent: Pohl & Lucas 13101,
13112. The following flowering specimen came from the Zarcero re-
gion: Prov. Alajuela, Palmira, elevation 6,000 ft., 18 September 1937,
A. Smith A 412. The following vegetative specimen was from
Hacienda Central, Volcan Turrialba. It is similar to the Talamanca
specimens in having pubescent leaf blades: Pohl & Davidse 10867.

Middle to high altitudes, Cordillera Central and Cordillera de
Talamanca, at elevations of 1,700-3,100 m., mostly below the paramo.
According to Swallen, this species ranges from Chiapas, Mexico, to
Chiriqui, Panama. Blooming is known in Costa Rica from the years
1896, 1937, 1968, 1974, and 1976. Our first flowering collection, from
Poas, was from a solitary flowering culm, and no other flowering was
seen at that time. In December 1974, we found a single large clump
flowering, ca. 5 km. below the crater of Poas. The 1976 flowering
involved large stands flowering gregariously in the Vara Blanca area.

Chusquea meyeriana Ruprecht ex Doell, in Martius, Fl. Brasil.
2:203. 1880. Figure 41.

J&4

FIG. 41. Chusquea meyeriana. A, culm node and branch complement; B, inflorescence
and foliage leaves; (', spikelet; D, culm sheath, blade, and ligule.

133

134 FIELDIANA: BOTANY

Caespitose bamboo; culms to 10 m. or more long, arching and drooping; internodes
cylindrical, solid, up to 5 cm. thick, the lower nodes sometimes bearing root-thorns;
sheath girdle prominent; internodes slightly scaberulous, especially toward the apex;
culm sheaths sparsely hispid, especially near the base, the apex with rounded auricles
continuous with a stiff ligule up to 5 mm. long; primary culm branch developing or not;
foliage-bearing branches 30-60 cm. long, including the inflorescence, if present, very
numerous in a dense fascicle; lower internodes of the foliage-bearing branchlets elon-
gated, their sheaths bladeless; leaf blades clustered toward the tips of the branches;
internodes puberulent; sheaths glabrous except for the ciliolate overlapping margin;
external ligule evident; internal ligule a stiff membrane ca. 1.5 mm. long; one sheath
auricle present; leaf blades linear 23-51:1, 14-23 cm. long, 4.5-7.0 mm. wide, sparsely
pubescent, sometimes glaucous beneath. Peduncles well exserted; inflorescence an open
pyramidal panicle, up to 12 cm. long, about as wide; branches solitary, widely spreading,
2-8 cm. long; rachis, branches, and pedicels angular, scabrous on the angles; pulvini of
primary branches evident, puberulent. Spikelets mostly appressed along the primary
panicle branches; pedicels slender, somewhat flexuous, 2-7 mm. long. Spikelets
stramineous, 7.8-9.5 mm. long, narrowly ovate, acute; glumes reduced, nerveless, the
first 0.3-0.8 mm. long, the second 0.5-1.0 mm. long, acute; disarticulation above the
glumes, the remainder of the spikelet falling as a unit; sterile lemmas papery, awn-
tipped, the first 4.0-6.5 mm. long, ovate ca. 2.5:1, 3-nerved; second sterile lemma simi-
lar, 4.8-6.5 mm. long, ovate ca. 3:1, 5-nerved; fertile lemma firmer, 7.2-8.5 mm. long,
with a short awn-tip, ovate 2.4-2.7:1, 7-9-nerved; lodicules 3, flat, vasculated, ovate,
acute, the upper half ciliate with long stiff hairs, the surface toward the tip with short
barbs; the two exterior lodicules much wider than the third; anthers 3, pale yellow,
3.5-5.0 mm. long; style short; stigmas 2; caryopsis not seen.

The above description was compiled from Costa Rican material avail-
able to me. The panicle of Lankester 105 is a reasonably good match
for the illustration given by Camus, Monog. Bamb. pi. 50; however, we
do not have both fruiting and vegetative material taken from the same
stand at the same time. Costa Rican specimens that I have seen are the
following: Prov. Cartago, Cascajal, altitude 5,500 ft., year 1919, C. H.
Lankester 105 (flowering), NE of Cascajal, 1,700 m. elevation, 22 De-
cember 1974, Pohl & Lucas 13089 (vegetative); Prov. Puntarenas,
heavily wooded slopes above Monteverde, elevation 1,500 m., 8 May
1971, R. W. Wilbur 14.254 (flowering), Forest Preserve, Monteverde,
elevation 1,500 m., 20 June 1976, Pohl & Pinette 13248 (vegetative).

Chusquea pittieri Hackel, Oesterr. Bot. Z. 53:153. 1903. Figure 42.

Caespitose bamboo in open clumps of ca. 20 culms; culms arching and drooping, 10-15
m. long, forming delicate curtains of foliage; internodes cylindrical, glabrous, solid, up to
4 cm. thick, green when young, becoming yellow; lower 20 or more culm nodes bearing a
ring of straight projecting root thorns, these up to 10 mm. long; culm sheaths 30-55 cm.
long, tapering from the base to a very narrow apex; surface tawny, purple-blotched, or
solid purple, scabrous-roughened and with scattered coarse, glassy, papillose-based his-
pid hairs; ligule thick, rigid, up to 3.5 mm. long, coarsely hispid at the apex; sheath

FIG. 42. Chusquea pittieri. A, inflorescence; B, culm segment with nodal root thorns;
C, node with branch complement; D, spikelet.

135

136 FIELDIANA: BOTANY

blades early deciduous, ca. 15 cm. long, 7-8 mm. wide (1 specimen seen); sheaths decidu-
ous, but sometimes impaled by the root thorns and remaining on the culm; primary
branches 1-several from each of the upper nodes; foliage-bearing branchlets numerous,
delicate, up to 100 per node, 20-30 cm. long, the base of the fascicle of branchlets
sometimes completely encircling smaller branches; lower leaf blades and sheaths of the
foliage-bearing branchlets deciduous, the branchlet bearing 3-6 blades toward the tip;
sheaths glabrous except for the ciliolate overlapping margin; auricles and external ligule
ciliate with stiff, glassy hairs up to 3 mm. long; ligule a short erose membrane, ca. 0.5
mm. long; pseudopetiole 1 mm. or less long; leaf blades flat, linear 10-20:1, 6-10 cm. long,
4-7 mm. wide, light green, sometimes slightly glaucous; abaxial surface glabrous except
for a dense tuft of short hairs on one side of the midrib at the base (alternating sides on
successive leaf blades); adaxial surface with scattered weak hairs. Inflorescence a nar-
row, rather dense panicle, 4-7 cm. long, up to 2 cm. wide; branches short, ascending,
spikelet-bearing to their bases; spikelets overlapping; pedicels short, mostly less than 2
mm. long, scaberulous. Spikelets dorsally compressed, 11-12.3 mm. long, acute; glumes
much reduced, rounded or barely acute, nerveless, the first ca. 0.5 mm. long, the second
ca. 1.1 mm. long; disarticulation above the glumes, the remainder of the spikelet falling
as a unit; sterile lemmas 2, papery, the first 6.4-7.0 mm. long, ovate 2.3:1, 7-nerved, with
a minute awn-tip; second sterile lemma similar, ca. 7 mm. long, 5-nerved, awn-tipped;
fertile lemma 10.5-12 mm. long, 11-14-nerved; palea slightly longer, 7-8-nerved; apex
bidentate; lodicules 3, flat, strongly vasculated, acute, long-ciliate above the middle;
ovary with a slender terminal appendage and 2 stigmas; caryopses not seen.

Moist canyons of the volcanoes of the Cordillera Central, from
1,500-2,700 m. elevation. The following collections are known from
Costa Rica: Finca San Juan, Volcan Barba, Pohl & Selva 12298; Bajos
de las Nubes, Pohl & Lucas 13088; OK Corral, Pohl & Lucas 13106;
Rio Reventado between Llano Grande and Tierra Blanca, Pohl &
Lucas 13098; Copey, Pohl & Lucas 13140; Santa Maria de Dota; Queb-
radillas; Cuestas de los Arrepentidos between San Marcos and Santa
Maria de Dota, Pittier 2249 TYPE in US.

This species is readily identified vegetatively because of the con-
spicuous root thorns borne on many nodes from the base to the middle
of the culm, and even on some of the primary branches. The type
specimen, collected in 1890, was in the flowering condition. Several
collections by Standley in 1925 also had inflorescences. I have not seen
recent bloom. McClure, in the Flora of Guatemala, indicates that C.
pittieri also occurs in Guatemala and Panama.

Chusquea scabra Sods. & Cald., Brittonia 30:300. 1978.

Caespitose bamboo in large, dense clumps, forming large colonies; culms to 10 m. long,
2-3 cm. thick, arching, scrambling through trees, the upper portions pendent; internodes
green, scabrous-roughened, not hispid, solid; lower nodes sometimes bearing soft roots
up to 5 cm. long; main-culm sheaths scabrous-roughened, more or less purple-spotted;
ligule a straight diagonal line, a thick, ciliolate membrane 0.3-0.5 mm. long with a few
auricular hairs at its ends; culm-sheath blade as wide as the sheath apex, erect, the

BURGER: FLORA COSTARICENSIS 137

adaxial surface scabrous with short, stiff hairs; foliage-bearing branchlets in dense fasci-
cles, ca. 20-30 per node, subtended by conspicuous basal bracts and prophylls; branchlets
subequal, stiff, up to 70 cm. long, including inflorescences when present, bearing 2-3
well-developed leaf blades toward the tip and some reduced ones below; leafy branchlets
interspersed with numerous slender, curly, fibrillar branches up to 10 cm. long, these
bearing reduced bladeless sheaths at their nodes; principal foliage leaf blades flat, 11-15
cm. long, 12-15 mm. wide, ovate 8-10:1, acuminate, scaberulous on both surfaces, espe-
cially toward the tip; margins white-banded, scabrous. Blades are glabrous in the popu-
lations from the Irazu-Turrialba Massiv, but our collection from El Muneco has blades
sparsely hairy beneath. Internodes of foliage-bearing branchlets glabrous; sheaths
glabrous except for the ciliate overlapping margin; sheath auricles erect, rounded at the
apex, up to 3 mm. long, ciliate; external ligule coriaceous, up to 1.5 mm. long;
pseudopetioles 3-4 mm. long, margined. Inflorescences terminal on leafy branchlets;
peduncles usually included in bladeless sheaths; panicles strict, erect, 10-24 cm. long,
less than 1 cm. thick, the branches erect, appressed to the rachis, the lower ones up to 8
cm. long, the upper very short, all bearing overlapping spikelets to their bases; rachis,
branches, and pedicels angular, scabrous; lateral pedicels usually 3-8 mm. long, ap-
pressed. Spikelets numerous, narrowly ovoid, acuminate, awn-tipped, 8.2-10.3 mm.
long; glumes scabrous on the keels, awn-tipped, the first 1-nerved, 2.0-3.2 mm. long, 0.7
mm. wide; second glume 3.2-4.1 mm. long, 1.1 mm. wide, 3-4-nerved, the awn up to 1.2
mm. long; disarticulation above the glumes, the remainder of the spikelet falling as a
unit; first sterile lemma papery, scaberulous, 4.2-5.6 mm. long, including the awn-tip,
ovate 2.0-2.4:1; nerves 5, sometimes with 2 additional weak marginal ones; margins
ciliolate, tapering abruptly to the awn; second sterile lemma similar, 6.2-8.0 mm. long,
5-7-nerved, ovate 2.5-3.1:1, the awn-tip to 1 mm. long; fertile lemma dorsally flattened,
firmer than the sterile lemmas, faintly 7-nerved, 8.0-9.3 mm. long, the palea slightly
shorter, its margins rounded to the scabrous keels; apex bidentate; a deep groove pres-
ent between the keels; lodicules 3, ovate, flat, strongly vasculated, the rounded tip
long-ciliate, the margins shorter-ciliate with 1- and 2-celled microhairs; anthers 3, yel-
low, 4.3-4.5 mm. long; style short, stigmas 2; caryopses not seen. Chromosome number
n = 20 from Pohl & Pinette 13305.

The following collections of this species are known: Prov. Cartago,
Rio Coliblanco, 4 km. NE of Capellades, 1,630 m., 4 June 1976, Pohl &
Pinette 13305 (blooming), Crossing of Rio Aquiares, W of Santa Cruz,
1,570 m., 4 June 1976, Pohl & Pinette 13307 (young bloom), 5 km. NE
of Capellades, 1,650 m., 11 June 1973, Pohl & Selva 12888 (vegeta-
tive), Valley of Rio Sombrero, 2 km. S of El Muneco, 1,300 m., 7 June
1973, Pohl & Selva 12871 (vegetative).

This species is one of the most easily recognized of the Costa Rican
species of Chusquea because of the scabrous internodes and the abun-
dant basal fibrillar branchlets at the leaf-bearing nodes. Moist moun-
tain slopes, 1,200-1,600 m. elevation.

Chusquea simpliciflora Munro, Monogr. Bambusaceae, Trans.
Linn. Soc. London. 26:1:54, Tab. II. 1868.

138 FIELDIANA: BOTANY

Vinelike bamboo; rhizomes leptomorphous; culms very elongated, to 25 m. long; inter-
nodes less than 1 cm. thick, smooth or usually scabrous with hard points, not hispid; culm
sheaths glabrous, purple, tapering to a filiform blade ca. 2 cm. long, its ligule a dense row
of short hairs; foliage-bearing branchlets very slender, 20-40 cm. long, up to 50 per node;
lower internodes elongated, naked; foliage blades 3-5, clustered toward the tip; sheaths
glabrous or puberulent, retrorsely ciliate at the base, ciliolate on the overlapping mar-
gin; auricles more or less ciliate; external ligule evident; internal ligule 0.5-1.0 mm. long,
membranaceous; pseudopetiole 1 mm. or less long; leaf blades thin, 5.5-9 cm. long, 8-14
mm. wide ovate 5.7-7.3:1 flat; abaxial surface with 3 conspicuous, whitened nerves on
each side of the midrib, woolly on both sides of the midrib at the base, the remainder
glabrous or sparsely appressed hairy; adaxial surface glabrous or very sparsely ap-
pressed pubescent, the midrib scabrous. Inflorescence a short raceme of 2-4 spikelets,
terminal on short foliage-bearing lateral branchlets; pedicels 1.0-4.5 mm. long, smooth.
Spikelets 7.7-10.5 mm. long; glumes vestigial, the first ca. 0.2 mm. long, the second
0.3-0.5 mm. long; remainder of spikelet disarticulating above the glumes and falling as a
unit; sterile lemmas 2, similar, faintly 1-3-nerved, glabrous or slightly puberulent at the
base, triangular 5-6:1, the first 4.6-5.0 mm. long, the second 4.9-6.2 mm. long; fertile
lemma 8.0-9.7 mm. long, faintly 5-7-nerved, ca. 3 x longer than wide, acute; palea
similar, slightly longer, faintly 5-nerved, not grooved, bidentate; lodicules 3, ciliate
above the middle, acute; anthers 3; style 1; stigmas 2.

None of our Costa Rican specimens is flowering, and the spikelet
description has been taken largely from Shattuck 71 7, from the Canal
Zone. Munro gives an excellent plate showing flowering material (Tab.
II). The following vegetative specimens are from Costa Rica: Prov.
San Jose, Quizarra, Los Cusingos, elevation 760 m., Pohl & Lucas
13114, same site, Pohl & Pinette 13257, same site, A. Skutch s.n.; 18
km. SW of San Isidro, elevation 800 m., J. P. Smith 3000; 10 km. SW
of San Isidro, elevation 800 m., Pohl & Calderdn 10061; 10 km. SW of
Santiago de Puriscal, elevation 800 m., Pohl & Pinette 13286; Prov.
Alajuela, Rio Zapote, 6 km. S of Upala, elevation 60 m., Pohl &
Pinette 13229; Prov. Puntarenas, 2 km. NW of Guacimo, Goto Brus,
elevation 350 m., Pohl & Pinette 13272.

Plants of this species are scrambling vines that clamber over and
cover small trees and canyon walls. The colony on the Puriscal Road
(13286) is particularly conspicuous, covering the lower parts of a small
canyon.

Ghusquea tonduzii Hackel, Oesterr. Bot. Z. 53:155. 1903. Figure
43.

Caespitose bamboo in large clumps; rhizomes at least in part leptomorphous, possibly
from the burial of culms; culms 5-20 m. long, arching, the upper ends drooping; inter-
nodes 1-3 cm. thick, solid, cylindrical, glabrous or appressed-puberulent; nodes en-
larged, with an evident sheath girdle and supranodal ridge; lower nodes sometimes with
a ring of thin drooping roots; foliage-bearing branches numerous in dense fascicles,
individual branches up to 90 cm. long; primary branch bud apparently not developing,

FIG. 43. Chusquea species. C. tonduzii: A, spikelet; B, inflorescence; C. virgata: C,
inflorescence.

139

140 FIELDIANA: BOTANY

the branches all of equal size; foliage leaves with sheaths glabrous except for the ciliolate
overlapping margin; external ligule evident, cartilaginous; internal ligule stiff, mem-
branaceous, mostly 2-5 (9) mm. long, decurrent on the sheath margins; pseudopetioles
1-3 mm. long; leaf blades flat, 9-19 cm. long, 9-18 mm. wide, ovate 10-14:1, olivaceous or
yellowish green, the upper surface glabrous, the lower appressed-pubescent with fine
hairs or glabrous, tessellate. Inflorescences terminal on foliage-bearing branches;
peduncles included or exserted up to 15 cm.; panicles ovoid 2-5:1, mostly 11-19 cm. long,
3-8 cm. wide, the branches mostly solitary or paired, one long and one short, strongly
spreading at maturity, the longest branch 3-6 cm. long; spikelets and peduncles purple;
peduncles, branches, and pedicels appressed puberulent, the hairs often retrorse;
spikelets clustered along the branches, the pedicels short, 0.5-4.0 mm. long, stiff, ap-
pressed. Spikelets purple, subcylindrical, sometimes arcuate, acute to acuminate, 6-7
mm. long, firm-textured, glabrous except for minute ciliation on the upper margins of
some of the bracts; glumes much reduced, rounded to barely acute at the apex, nerve-
less, the first 0.3-1.0 mm. long, the second similar, 0.3-1.1 mm. long; disarticulation
above the glumes, the remainder of the spikelet falling as a unit; lower 2 lemmas sterile,
lacking paleas, the first 3-4 mm. long, narrowly ovate, acuminate or awn-tipped, 3-
nerved; second sterile lemma similar but longer, 3.8-5.0 mm. long, broader than the
first, acuminate or awn-tipped, 3-, 5-, or 6-nerved; terminal (fertile) floret with a some-
what dorsally flattened lemma, 5.6-6.6 mm. long, acuminate, 5-7-nerved, its lower mar-
gins enveloping the base of the palea; palea as long as the lemma or longer (up to 6.8 mm.
long), broad, enwrapping the flower, rigidly bidentate at the tip, 4-7-nerved; lodicules 3,
flat, vasculated, spatulate, the tip with a few short barbs at the tip; anthers 3, yellow,
2.6-3.8 mm. long; ovary with a short style and 2 plumose stigmas. Caryopses not seen on
our blooming specimens, but we have found seedlings associated with two blooming
colonies, some of them bearing attached spikelet parts. Chromosome number n = 20
from specimens from Poas and Turrialba.

This species is common or abundant on the Cordillera de Talamanca,
large colonies occurring along the CIA at elevations of 2,400-3,140 m.,
below the paramo. Gregarious blooming occurred in some colonies in
this area in 1966, 1967, and 1968. I have not seen recent bloom (1973-
1976) in the same region. Colonies on Volcan Turrialba, east of
Hacienda Central, were in massive bloom in 1966 and 1968. The plants
die after gregarious flowering. Seedlings were found growing on moss
polsters in shade, but not on bare soil or in full sun. Except for their
bladeless lower sheaths and pseudopetiolate leaf blades, they resemble
other sterile grass seedlings and might easily be missed. The type
locality of C. tonduzii is the summit of Volcan Poas, and a large popu-
lation of the species occurs there. Blooming plants were collected there
in 1964, 1967, 1968, and 1972. 1 have not seen recent bloom in the area.
No specimens are recorded from Barba or Irazii, but the species should
be sought there. Chuxquea tonduzii is not known outside of Costa
Rica.

Chusquea virgata Hack. , Oesterr. Bot. Z. 53:156-57. 1903. Figure
43.

BURGER: FLORA COSTARICENSIS 141

Caespitose bamboo in small clumps, the few culms arising from short, pachymorphous
rhizomes; culms solid, weak, less than 1 cm. thick (but bases recorded as up to 2 cm.),
recorded as being up to 6-7 m. long; scrambling into brush and trees, the ends drooping;
internodes cylindrical, glabrous, green or marbled with purple, solid; nodes swollen,
with evident sheath girdle and supranodal ridge; primary culm sheath (one example
seen) 9.5 cm. long, 25 mm. wide, the apex abruptly rounded to the base of an erect
acuminate vestigial blade, ca. 1 cm. long; ligule an erose membrane ca. 1.5 mm. long;
outer surface of sheath strongly and closely ridged, glabrous, purplish; inside surface
tessellate-veined. Primary branch bud subtended by a row of flattened buds of minor
branches; minor branches few, usually ca. 5 per node, up to 50 cm. long, with a few
leaves borne toward their tips; primary branch bud sometimes not developing into a
branch; when a primary branch is present, it is only slightly larger than the minor
branches; sheaths of foliage leaves glabrous; external ligule evident, ca. 0.5 mm. long,
sometimes ciliolate; internal ligule membranous, ca. 1 mm. long; pseudopetioles flat-
tened, 1-3 mm. long; leaf blades ovate 3.2-5.2:1, rather abruptly acuminate, 7.5-17 cm.
long, 16-33 mm. wide, flat, green on both surfaces, glabrous except for a line of short,
stiff tan hairs on each side of the midrib just above the base of the blade. Inflorescence a
slender virgate panicle, its base mostly included in the uppermost sheath, 9-17 cm. long,
1.0-1.5 cm. wide, the slender appressed branches up to 3 cm. long; pedicels slender,
erect, longer than the spikelets, which are set at an angle of ca. 30° to the pedicel.
Spikelets linear, falcate, 8.0-9.7 mm. long; glumes very reduced, semicircular, nerve-
less, their margins overlapping, the first 0.2-0.3 mm. long, the second 0.3-0.5 mm. long;
disarticulation above the glumes, the remainder of the spikelet falling as a unit; lower
two florets sterile, represented by 2 empty sterile lemmas, their tips diverging from the
fertile lemma; first empty lemma 2.8-3.2 mm. long, ca. 2.5 x longer than wide, acute;
second empty lemma 3.4-4.2 mm. long, acuminate; both empty lemmas 1-nerved or
faintly 2-3-nerved; third lemma fertile, linear, subcylindrical, arcuate, acute, its margins
covering the palea; surface glabrous; nerves 7, faint; palea as long as the lemma, broadly
winged, rounded to the keels, 4-nerved, a deep groove between the keels; rachilla not
prolonged behind the palea; lodicules 3, flat, vasculated, broadly spatulate, the tips
densely ciliate with long hairs; anther (only 1 seen) 4.5 mm. long; style 1; stigmas 2, no
caryopses seen.

This species is apparently endemic to Costa Rica. The type, Tonduz
7730, was collected in forests at San Marcos, at an elevation of 1,350 m.
The specimen, collected in 1893, was in bloom. The species is widely
distributed in central Costa Rica, but appears to be rare. Other
blooming specimens were collected from Tarrazu in 1918, La Pena de
Zarcero (1938), Tapesco (1940), Rio Segundo, Barba (1941), Tapesco
(1965), and Frailes (1965). No more recent flowering specimens are
known, but we have recently collected vegetative plants from Rio
Birris near Pacayas. The culms are slender and delicate, and the plants
support themselves by clambering in brush and trees.

OTHER NOTABLE CHUSQUEA POPULATIONS IN COSTA RICA

The abundance and complexity of the Chusquea populations in Costa
Rica make it impossible to identify and classify them all. The popula-

142 FIELDIANA: BOTANY

tions on the following list have been observed, either in vegetative or
blooming condition, but cannot as yet be assigned to definite taxonomic
status. Continued observation may make it possible to resolve their
status, particularly if blooming specimens can be obtained.

1. Tapanti population. Large, coarse bamboos with drooping culms
to 15 m. long; internodes, main-culm sheaths, and sheaths of lateral
branches hispid with irritating hairs. The following vegetative popula-
tions are known: Monteverde, Pohl & Pinette 13246; Alto de Roble,
Pohl & Lucas 12998; Rio Grande de Orosi, near tunnel portal, Pohl &
Selva 12886; Volcan Barba, W. E. Booth 161.

2. Cariblanco population. This striking species grows on the cliff
above the Rio Cariblanco, just east of the highway to Puerto Viejo. It
bloomed in 1968, and most of the colony subsequently died. The plants
are exceptionally large, the solid culms reaching a length of 20 m. , with
long-decumbent bases. Branching is restricted, with usually 2 equal
branches at each node. Sheaths and internodes are scabrous. The
ovate, cordate-based blades are exceptionally large for a species of
Chusquea, 20-37 cm. long and up to 45 mm. wide. The inflorescence is a
slender virgate panicle up to 50 cm. long, less than 2 cm. thick. The
spikelets are more or less typical of those of Chusquea, but the glumes
are better developed. In general appearance, it resembles C. lan-
ceolata Hitchc. of Guatemala, but differs in branching pattern,
inflorescence structure, and details of spikelets and foliage. Lodicules
3, similar to those of other Chusquea species. P. & D. 11023, 11033,
11176, 11267, and Pohl & Pinette 13224 are representative of this
entity.

Because of the unusual branching pattern exhibited by these plants,
Dr. Soderstrom believes that they may represent a new undescribed
genus.

3. Tarrazu population. This species occurs abundantly in and on the
margins of the forest above the new road on the south side of the Rio
Tarrazu, southeast of Frailes, at about 1,600 m. elevation. In January
1975, the plants were seedlings in small clumps, but dead plants were
not observed. By June 1976, the plants were much larger, with culms
up to 1 cm. thick and 3 m. long. The foliage-bearing branchlets were up
to 15 per node, and up to 35 cm. long, bearing 7-8 very slender leaf
blades at the tip. The leaf blades are linear, flat, 14-16 cm. long, the
length ca. 20 times the width, and bear a woolly patch on one side of
the midrib on the abaxial side at the base. The deciduous culm sheaths
are purple, glabrous, and rounded to a rudimentary blade. Pohl &
Lucas 13143 and Pohl & Pinette 13211 are representative.

BURGER: FLORA COSTARICENSIS 143

CINNA Linnaeus

Caespitose perennials; inflorescence a panicle; spikelets laterally compressed, 1-
flowered, disarticulating below the glumes; glumes equal, 3-nerved, longer than the
floret; lemma usually short-awned from just below the tip, faintly nerved; keels of palea
very close together, the minute abortive rachilla segment partially hidden in the groove
between them. (Pooideae: Agrostideae.)

Cinna poaeformis (H.B.K.) Scribn. & Merr., U.S.D.A. Div.
Agrost. Bull. 24:21. 1901. Deyeuxia poaeformis H.B.K. , Nov. Gen. &
Sp. 1:146. 1816. Figure 44.

Tall, succulent perennial, forming dense clumps; culms erect, 90-150 cm. tall, un-
branched, 3-6 mm. thick, hollow, ridged, glabrous; nodes dark colored, contracted;
leaves numerous, the basal ones bladeless; leaf sheaths mostly overlapping, glabrous,
ridged, often purplish; ligules 1.5-15.0 mm. long, the upper ones much longer than the
lower, brownish or purplish, membranaceous, lacerate; leaf blades flat, 5-35 cm. long,
5-15 mm. wide, glabrous. Peduncle up to 20 cm. long, glabrous; panicles solitary, termi-
nal, lax, 15-45 cm. long, often nodding, very open, the long branches naked, spikelet-
bearing only near the tips, borne in verticils; spikelets borne in dense clusters near the
tips of the branches, mostly short-pedicellate, the branches and pedicels scabrous.
Spikelets strongly laterally compressed, the glumes keeled, equal, 3-nerved, 2.5-3.2
mm. long, lanceolate as folded, scabrous on keel, nerves, and sometimes internerves;
floret 1; lemma narrowly ovate, faintly (5?)-nerved, glabrous or scabrid near the tip,
usually awnless or with a short straight awn, up to 0.3 mm. long, attached just below the
tip; palea nearly as long as the lemma, broad, the 2 keels very close together, the minute
rachilla segment held in the groove, ca. 0.3 mm. long; anthers 3, ca. 1 mm. long, tan.
Chromosome number n = 14 from a Costa Rica specimen.

Brushy or forested moist slopes; paramos, 2,800-3,400 m. elevation;
Irazii, Asuncion, Buena Vista, Chirripo. Blooming apparently year-
long. Mexico to Colombia, Venezuela, and Peru.

COELORACHIS Brongniart

REFERENCE: W. D. Clayton, Coelorachis and Rhytachne: A study in
numerical taxonomy, Kew Bull. 24:309-314. 1970.

Caespitose perennial grasses, the stems branched above and bearing terminal and
axillary cylindrical rames, one on each peduncle. Spikelets paired, awnless, one sessile
and one pedicellate, both fitting closely against the rachis; rames disarticulating at
maturity into individual internodes, each with an attached spikelet pair; rachis inter-
nodes thick, cylindrical, hollow, slightly widened upward, truncate; base of internode
with a short rounded projection that fits into the hollow apex of the internode below.
Spikelets dorsally compressed. Sessile spikelets: First glume coriaceous, elliptic-oblong,
flattened, ca. 6-nerved, broadly winged on the upper margins and deeply notched at the
midline; inner surface of the glume bearing 2 narrow flanges that converge toward the
apical notch and clasp the margins of the second glume; second glume shorter and
narrower than the first, narrowly ovate, acute, keeled, 3-nerved; lower (sterile) lemma
nearly as long as the first glume, nerveless, hyaline, ovate; lemma of upper (fertile) floret

FIG. 44. Cinna poaeformis. A, spikelet; B, floret with rachilla; C, panicle.

144

BURGER: FLORA COSTARICENSIS 145

keeled, 3-nerved, stiffish, its palea nearly as long; lodicules 2, truncate; anthers 3; style
branches naked at the base. Pedicellate spikelets: Similar to the sessile ones but smaller;
pedicels thick, dorsally flattened, as long as the rachis joint or longer and fitting closely
against it; first glume similar to that of the sessile spikelet; second glume 3-nerved, more
strongly keeled than that of the sessile spikelet; winged at the tip, sterile lemma, fertile
lemma and its palea well-developed; lodicules 2; anthers 3; stigmas well-developed.

Coelorachis is distributed widely in warmer parts of both eastern
and western hemispheres. The genus is most closely related to
Rhytachne, Rottboellia, and Eremochloa. Our species have usually
been assigned to the genus Manisuris. (Panicoideae: Andropogoneae.)

KEY TO SPECIES OF Coelorachis

la. Axillary inflorescences arising singly from each upper leaf sheath; rames up to 5
mm. thick; rachis internodes at least 3.5 mm. long C. ramosa

Ib. Axillary inflorescences several from each upper leaf sheath; rames less than 2 mm.
thick; rachis internodes less than 3 mm. long C. aurita

Coelorachis aurita (Steud.) A. Camus, Ann. Soc. Linn. Lyon
68:197. 1922. Rottboellia aurita Steud., Syn. PI. Glum. 1:361. 1854.
Manisuris aurita (Steud.) Kuntze, Rev. Gen. PI. 3:356. 1898. Figure
45.

Perennial, caespitose in dense clumps; culms erect, 100-250 cm. tall, branching from
the middle and upper nodes; internodes glabrous, grooved on side toward the branch, 3-7
mm. thick, mostly solid and filled with pith; nodes dark, contracted; prophylla concealed,
3-7 cm. long; foliage clustered toward the base of the culms; sheaths glabrous, the lower
ones overlapping, keeled, the upper shorter than the internodes; lower leaf blades elon-
gated, keeled and mostly folded, up to 5 mm. wide, the upper much shorter; ligule a
ciliolate membrane, 0.6-0.7 mm. long. Peduncles numerous, terminal and axillary, sev-
eral of different lengths arising from one leaf axil, mostly included in bladeless sheaths;
rame solitary on each peduncle, 4-9 cm. long, narrowly cylindrical, 1.5-2.0 mm. thick.
Sessile spikelets: First glume 3.7-4.7 mm. long, oblong, rounded on the back, faintly
pitted in rows between the 5-6 rather faint nerves; the margins winged, especially near
the truncate, 2-lobed apex; second glume keeled, boat-shaped, 3-nerved, scabrid on the
keel, 2.9-3.8 mm. long; lower (sterile) lemma 2.5-3.1 mm. long, ovate, acute, thin and
nerveless; upper (fertile) lemma 2.3-2.8 mm. long, ovate, acute, slightly keeled, nerve-
less; palea 1.9-2.5 mm. long, truncate, nerveless; anthers 3, purple, 0.8-1.5 mm. long.
Rachis internodes and pedicels thick, the internode 2.0-2.7 mm. long, the pedicel similar
but longer, and with a thin triangular wing at the apex on the side away from the sessile
spikelet. Pedicellate spikelets: Similar to the sessile ones, but tending to be slightly
asymmetric, 2.3-4.3 mm. long; first glume 3-5-nerved; second glume 2.4-4.0 mm. long,
1-3-nerved, ovate, acute, keeled; lower lemma 1.8-3.0 mm. long; upper lemma 1.8-2.3
mm. long; palea ca. 1.5 mm. long; flower present in our specimens, with 3 anthers and
ovary with 2 stigmas. Chromosome number n = 9 from a Costa Rican specimen.

This species is known in Costa Rica only from Canas Gordas, where
it was collected by Pittier. We found it also in the same locality, grow-
ing in a marsh in a large sinkhole between Canas Gordas and Agua

FIG. 45. Coelorachis species. C. aurita: A, inflorescence; B, a spikelet pair, two views;
C, culm base; C. ramosa: D, spikelet pair, two views.

146

BURGER: FLORA COSTARICENSIS 147

Buena. July to October. Honduras, Costa Rica and Panama to Bolivia
and Argentina.

Coelorachis ramosa (Fourn.) Nash, N. Amer. Fl. 17:86. 1909.
Apogonia ramosa Fourn., Mex. PL 11:63. 1881. Rottboellia aurita ssp.
stigmosa Hack, in DC., Monogr. Phan. 6:311. 1889. Manisuris ramosa
(Fourn.) Hitchc., Proc. Biol. Soc. Wash. 40:88. 1927.

Densely caespitose perennial; culms 75-125 cm. tall, 1-3 mm. thick, solid, pithy, gla-
brous, erect, branching from the middle and upper nodes; prophylla prominent, up to 10
cm. long; nodes dark, constricted; herbage and stems often purplish; sheaths shorter
than the internodes, keeled, glabrous; ligule a minutely ciliolate membrane, 0.5-1.0 mm.
long; lower blades crowded, up to 60 cm. long and 7 mm. wide; upper blades much
smaller. Inflorescences terminal and axillary from the upper culm nodes, the terminal
one 7-13 cm. long and ca. 5 mm. thick, the axillary ones shorter; rame solitary, cylindri-
cal, the spikelets and rachis internodes fitting closely together; rachis internodes thick,
hollow, striate on the outer surface, 3.5-4.5 mm. long. Sessile spikelet 4.0-5.5 mm. long;
first glume elliptic-oblong, coriaceous, ca. 6-nerved, slightly convex on the back, the
marginal wings broadened toward the apex and deeply notched at the midrib, often
purplish; back of the glume with rows of shallow pits between the nerves; second glume
3.5-4.5 mm. long, keeled, boat-shaped, 3-nerved; lower (sterile) lemma 3.0-4.0 mm. long,
ovate, acute, nerveless; upper (fertile) floret with an ovate, acute, nerveless lemma
3.0-3.5 mm. long; palea 2.5-3.4 mm. long, nerveless; anthers 3, ca. 1.2 mm. long, purple.
Pedicels thick, appressed to the rachis, with a thin triangular wing on the side of the
apex away from the sessile spikelet; pedicellate spikelets similar to the sessile ones but
shorter, 3.5-4.5 mm. long, tending to be more asymmetric than the sessile ones; sterile
lemma and fertile lemma 2.4-2.7 mm. long; palea ca. 2.0 mm. long; anthers 3, 1.1 mm.
long; some spikelets with well-developed stamens and pistil, others sterile and empty.

Mexico to Honduras; Colombia. Not yet found in Costa Rica.

COIX Linnaeus

Tall, caespitose, maize-like plants; duration indefinite in the tropics; culms freely
branching, bearing from the upper leaf axils numerous slender peduncles, each bearing
at its apex a rigid, bony bead that is deciduous at maturity. Spikelets unisexual; pistillate
spikelet solitary, borne within the cavity of the bead, along with two slender, tubular
sterile spikelets. Peduncle passing through the bead and emerging through the apical
ostiole and bearing at its apex several groups of sessile or pedicellate staminate or sterile
spikelets in somewhat irregular groupings. Pistillate spikelet gibbous, with a slender
beak; first glume, second glume, lower (sterile) lemma, fertile lemma and palea present;
stigmas 2, protruding from the mouth of the ostiole at anthesis. Staminate spikelets
herbaceous, with two equal glumes concealing the staminate florets; staminate inflores-
cence deciduous from the bead at maturity; beads deciduous from the apex of the pedun-
cle; caryopsis germinating while confined within the bead.

Coix is a genus of one to several species native to tropical southeast-
ern Asia, but widely cultivated for the beads, and sometimes for forage
or grain. The genus has no close relationship to any native American
genera. (Panicoideae: Andropogoneae.)

148 FIELDIANA: BOTANY

Coix lacryma-jobi L., Sp. PI. 972. 1753. Figure 46.

Duration indefinite; plants 1-3 m. tall, profusely branching above; peduncles flat,
slender, produced in clusters from the axils of the upper leaves; a hard, bony involucre
(modified leaf) borne at the tip of each peduncle. Involucres usually subspherical, 6-8
mm. wide, usually very hard, gray or white, shining. Pistillate spikelet one in each
involucre, broadly ovoid, filling nearly the entire cavity, with a pronounced apical beak;
first and second glumes about equally long, the first enfolding all but the keel of the
second, both fleshy and delicate, almost nerveless; sterile lemma, fertile lemma and its
palea membranaceous, delicate; lodicules none; 1-3 small rudimentary stamens present
near the base of the ovary; stigmas 2, exserted through the ostiole of the bead; 2 sterile
tubular rudimentary spikelets also included in the bead, lying parallel along the keel of
the second glume and just protruding from the ostiole of the bead. Staminate inflores-
cence borne on a flattened slender peduncle arising from the base of the bead and passing
up through the ostiole, parallel to the rudimentary spikelets, and slightly exserted;
staminate inflorescence usually 3-8 cm. long, composed of a varying number of triads of
staminate spikelets, each triad of 1 pedicellate and 2 sessile spikelets; staminate
spikelets soft-textured, with a blunt first glume, 7-12 mm. long, somewhat winged near
the apex, flattened and with 2 lateral flanges which clasp the edges of the boat-shaped,
ovate, acute second glume; florets 2, the upper slightly larger than the lower, both
slightly shorter than the glumes; lemmas many-nerved, narrowly ovate, acute, glabrous;
paleas slightly shorter than the lemmas; anthers 3, yellow, 3-5 mm. long. Chromosome
number n - 10 from Costa Rican specimens.

Blooming yearlong in moist habitats, possibly seasonal elsewhere.
Low and medium altitudes, on both Pacific and Caribbean slopes.

The hard gray or white beads that contain the pistillate spikelets are
frequently used in making necklaces and as rosary beads. Certain
strains of this species, which have soft beads, are sometimes used as a
source of grain under the common name ofTrigo adlay. Common name
of the ordinary strains isLagrimas de San Pedro, or in English, "Job's
tears."

CORTADERIA Stapf

REFERENCES: H. J. Conert, Die Systematik und Anatomic der
Arundineae, pp. 1-208. J. Cramer. Weinheim. 1961. H. E. Conner,
Breeding systems in New Zealand grasses. V. Naturalized species of
Cortaderia, New Zealand J. Bot. 3:17-23. 1965.

Tall, vigorous dioecious perennial grasses, forming large dense clumps. Panicles large,
plumy because of the numerous long silky hairs borne on the lemmas. Spikelets laterally
compressed, wedge-shaped; florets 2-9, all alike or the uppermost much reduced and
sterile; disarticulation above the glumes and near the base of each rachilla segment, the
rachilla forming a stipe or callus below the detached floret; glumes subequal, 1-nerved,
linear-lanceolate, with usually excurrent midrib, pointed or slightly rounded or bifid at
the apex, translucent to light brown or purplish, nearly as long as the entire spikelet;
lemmas green, purplish, or whitish and translucent, little shorter than the spikelet,

FIG. 46. Coix lacryma-jobi. Inflorescence, showing beads and protruding staminate
inflorescences.

149

150 FIELDIANA: BOTANY

3-5-nerved or sometimes 7-nerved at the base, either linear-lanceolate, with a long
narrow tapering apex terminating in an awn, or short and ovate, with a deeply bifid apex
terminating in 2 awned lateral teeth, the awn flat and somewhat twisted, arising from
the cleft between the teeth; backs of the papery lemmas bearing numerous long, silky,
white hairs 3-10 mm. long on the lower third (staminate spikelets less hairy), midnerve
of lemmas always continuous to the tip, the lateral nerves usually extending to the upper
third; palea one- third to one-half as long as undivided lemmas, or reaching as far as the
insertion of the awn in cleft lemmas, 2-nerved, truncate or 2-toothed, hairy or scabrid
between the nerves, sometimes long-hairy on the margins; callus or stipe of the florets
bearded with short silky hairs; lodicules 2, wedge-shaped, flat, ciliate at the tip; pistillate
flowers with 2 terminal styles naked at their bases, their stigmas spreading laterally
from the floret; pistillate flowers with sterile staminodes; staminate flowers with 3 large
anthers and rudimentary ovary.

Measurements quoted are taken from Costa Rican specimens and
may not agree entirely with those given by Conert. The genus is
closely related to Gynerium, Arundo, and Phragmites. Species about
20, in Central and South America and New Zealand. (Arundinoideae:
Arundineae.)

KEY TO SPECIES OF Cortaderia

la. Lemma deeply bifid at the apex, awn arising between conspicuous, awned lateral

teeth 3.0-4.5 mm. long C. haplotricha

Ib. Lemma tapering gradually into awn; lateral teeth of awn minute or absent 2

2a. Panicles silvery white, very plumy, hairs of lemmas 8-10 mm. long; florets 8-9;
pistillate flowers lacking rudimentary stamens; cultivated ornamentals

C. selloana

2b. Panicles brownish or purplish; hairs of the lemmas usually 3-5 mm. long; florets
2-3; pistillate flowers with rudimentary stamens; wild plants of paramos at high
elevations C. bifida

Cortaderia bifida Pilger, Bot. Jahrb. 37:374. 1906. Figure 47.

Tall, stout perennial; culms erect, to 250 cm. tall; clumps large, with very numerous
arching basal blades; basal sheaths often closely overlapping, chartaceous, inflated, cari-
nate, persistent, finally breaking down into curly fibers, glabrous, the margins mem-
branous; ligule a dense row of silky white hairs, 1.5-2.0 mm. long; blades firm, to 1 m.
long, 4-7 mm. wide, glabrous beneath, upper surface above the ligule appressed-hairy or
glabrous, margins silky-ciliate near the base, strongly scabrous toward the tip. Panicles
solitary, terminal, 25-35 cm. long, rather narrow, 6-20 cm. wide, dense to quite loose and
open. Spikelets laterally compressed, wedge-shaped, 10-13 mm. long; first glume 8.0-
11.5 mm. long, narrowly lanceolate; second glume 9.5-11.0 mm. long, narrowly lance-
olate; florets usually 2-3, disarticulating with a bearded rachilla stipe up to 1 mm. long
below the lemma; lemmas ca. 8 mm. long, narrowly ovate, 3-nerved, sometimes with a
very faint additional pair near the base; apical teeth minute or absent; awn 4-8 mm. long;
lower third of lemma bearing white, silky hairs 4-5.5 mm. long, the keels scabrous;
flowers of our specimens functionally pistillate, with sterile abortive anthers. The Costa
Rican specimens have developing caryopses.

Conert (1961) reported only the type specimen of this species from

FIG. 47. Cortaderia species. C. haplotricha: A, spikelet and a single floret; C. sel-
loana: B, spikelet; C. bifida: C, spikelet.

151

152 FIELDIANA: BOTANY

Peru. This specimen was pistillate, and no staminate plants were
known to him. We have never seen staminate plants of C. bifida or C.
haplotricha in Costa Rica, although we have searched for them. Quite
probably, these species are apomictic. Conner (1965) has reported the
occurrence of apomixis in the South American species, C. atacamen-
sis. Conert has identified our specimens, and his determinations have
been followed, although our plants differ in some minor respects from
his descriptions, which are based upon South American material. Such
differences might be expected in apomictic species.

Cortaderia bifida has not previously been reported from Central
America. It is rare to occasional, occurring on the upper cinder slopes
of Irazu and Turrialba and on paramos of the Cerro de la Muerte and
Cerro Chirripo, at elevations from 2,500 to 3,300 m. April to Sep-
tember.

Cortaderia haplotricha (Pilger) Conert, Systematik und Anatomic
der Arundineae 102. 1961. Danthonia haplotricha Pilger, Bot. Jahrb.
25:715. 1898. Figure 47.

Caespitose perennial, forming large tussocks; up to 1 m. tall; culms ca. 5 mm. thick,
hollow, thick-walled; nodes glabrous, not prominent; basal leaves numerous, stiffly erect;
sheaths mostly overlapping, silky-hairy on upper margins, slightly so below the collar,
breaking down into curly fibers when old; blades up to 80 cm. long, 4-5 mm. wide,
glabrous below, scabrous on the margins, upper surface and margins densely silky for
1-2 cm. above the ligule; ligule a dense row of silky hairs, 0.5-1 mm. long; peduncle
included on our specimens; panicle up to 30 cm. long, often purplish; spikelets laterally
compressed, V-shaped; glumes narrowly lanceolate, acuminate, purplish, 1-nerved, 13-
13.5 mm. long; florets 4-5; lemmas 8-10 mm. long, including the bearded basal rachilla
stipe, narrowly ovate, 7-nerved, the apex 2-cleft, the lateral teeth 3-4.5 mm. long,
tapering into short awns; awn inserted between the teeth, flat, twisted, geniculate, 9-12
mm. long; lower third of the lemma bearing numerous long silky hairs 4 mm. long; palea
ca. 4.5 mm. long, ciliate on the lower margins with hairs 2 mm. long; flower pistillate,
with abortive anthers 1.2-1.5 mm. long, yellow; lodicules 0.7 mm. long, flat, spatulate.

This species occurs on the paramos of Asuncion, Buena Vista, and
Chirripo Grande. The plants occur scattered on the paramo, at eleva-
tions of 3,260-3,800 m. Plants have been seen with panicles from July
to December. Cortaderia haplotricha has not been previously re-
corded from Central America, but was previously known from Colom-
bia, where both pistillate and staminate plants have been collected.
Previous publications on Central American grasses have credited C.
nitida (H.B.K.) Pilger to Costa Rica and Panama. Conert does not
indicate this species occurs in Central America.

Cortaderia selloana (Schult.) Aschers. & Graebner, Syn. Mit-

BURGER: FLORA COSTARICENSIS 153

teleurop. Fl. 2:325. 1900. Arundo selloana Schult., Mant. Ill (Add.
1):605. 1827. Figure 47.

Tall, stout perennial, forming large circular clumps; basal leaves prominent, arching
and drooping; culms up to 3 m. tall, nearly leafless on upper portions; sheaths glabrous;
ligule a dense row of white hairs, 1.5-2 mm. long; blades 1-2 m. long, 6-10 mm. wide,
glabrous; midrib protruding below, yellow; blades flat or folded, very scabrous on the
margins; auricular hairs present; peduncle solid, 5-8 mm. thick; inflorescence a rather
dense, very plumy panicle, 70 cm. or more long in well-developed plants, pyramidal, to
25 cm. wide, shining, silvery white; branches in dense clusters. Spikelets densely
crowded, laterally compressed, 15-25 mm. long; glumes 15-25 mm. long, lance-attenuate;
florets 7-9; lemmas ca. 10 mm. long, narrowly lanceolate, 3-nerved, tapering gradually
into an awn ca. 10 mm. long, without evident lateral teeth, the back bearing long hairs
almost to the apex; hairs on lower parts of the back up to 10 mm. long; basal stipe of
floret bearded; palea 4.5-5.5 mm. long, scabrid on the keels; flowers pistillate, without
rudimentary stamens (in Costa Rican cultivated specimens; Conert reports staminate
plants from South America). Chromosome number n = 36 (Conner, 1965).

This striking South American species is sparingly cultivated for or-
nament around San Jose. I have seen it in Curridabat and the city
itself.

CRYPTOCHLOA Swallen

REFERENCE: J. R. Swallen, Cryptochloa, in Woodson and Schery,
Contrib. Fl. Panama VI, Ann. Missouri Bot. Gard. 29:317-322. 1942.

Caespitose perennial grasses; culms unbranched, their lower internodes elongate, the
foliage mostly aggregated near the apex; leaves 2-ranked, the blades lying in one plane,
forming flat terminal sprays; blades borne on short thick pseudopetioles which serve as
pulvini, orienting the blades in a flat plane during the day and folding them face to face at
night. Inflorescences several, few-flowered, arising from the axils of the upper leaves,
the peduncles concealed. Spikelets unisexual, the terminal and upper ones pistillate, the
lower ones usually staminate. Pistillate spikelets: Dorsally compressed, 1-flowered;
glumes equal, 3-5-nerved, longer than the solitary floret; floret borne at the tip of a thick,
hardened rachilla internode and disarticulating with it; glumes finally deciduous; lemma
ovate, acute, dorsally compressed, rigid, faintly 5-nerved, its flat margins incurved and
covering the edges of the palea; palea of similar texture, 2-4-nerved, equal to the lemma
but broader, enwrapping the caryopsis; lodicules 3, flat, vasculated, truncate; style 1;
stigmas 3, exserted at the tip of the lemma. Staminate spikelets: Borne on erect pedicels
on lower parts of the inflorescence, few, dorsally compressed, ovate, acute; glumes
absent; floret 1; lemma 3-5-nerved; palea about equal to the lemma, 2-nerved; lodicules 3,
similar to those of the pistillate spikelets; stamens 3.

A small genus of rain forest grasses of Southern Mexico and Central
America and northern South America. Swallen, in describing the
genus, indicated, by his interpretations of the spikelets, that he con-
sidered it Panicoid; however, the three flat lodicules, which occasion-
ally bear tricellular hairs, and the presence of fusoid cells in the

154 FIELDIANA: BOTANY

leaf cross section indicate that it is Bambusoid. (Bambusoideae:
Olyroideae.)

KEY TO SPECIES OF Cryptochloa

la. Upper leaf blades 12-26 per culm, 2-2.5 cm. long, green; staminate spikelets less
than 3 mm. long C. concinna

Ib. Upper leaf blades usually 5-17 per culm, 5-8 cm. long, purple beneath; staminate
spikelets 5-6 mm. long C. granulifera

Cryptochloa concinna (Hook, f.) Swallen, Ann. Missouri Bot.
Gard. 29:320. 1942. Olyra concinna Hook, f., Curtis Bot. Mag. 3:52, pi.
7469. 1896. Raddia concinna (Hook, f.) Chase, Proc. Biol. Soc. Wash.
21:185. 1908. Figure 48.

Caespitose perennial; plants forming vase-shaped clumps, wider than tall, the culms
20-40 cm. long, arching and spreading from a dense common center, slender and wiry,
hollow or solid, retrorsely puberulent in a line below the opening of the sheath above;
apex of each internode enlarged, the pulvinus contracted, retrorsely puberulent; lower
several internodes much elongated, their leaves with short sheaths and reduced blades;
12-30 leaves crowded on the upper portion of the culm, their sheaths overlapping, the
blades oriented in one plane, forming a flat spray during the day, folded face to face
during the night; sheaths puberulent on the overlapping edge, keeled near the summit;
ligule an erect membrane, truncate, puberulent on the back, 0.2-0.8 mm. long, or the
uppermost one to 1.5 mm.; upper leaf blades 18-25 mm. long, 6-8 mm. wide, ovate
2.5-3:1, abruptly acuminate, flat, glabrous, the margins scabrous; pseudopetiole minute,
the pulvinus united to the base of the leaf blade. Inflorescences several, from the ulti-
mate leaf axils, the peduncles concealed in the sheaths. Spikelets few, racemose, the
terminal ones pistillate, some of the lower ones staminate. Pistillate spikelets: Ovate,
6-7:1, acuminate, 8.4-11.7 mm. long; glumes membranaceous, subequal or the first
slightly longer than the second; compression dorsal; first glume with 3 evident nerves
and 2 faint marginal ones; second glume similar, both deciduous after the maturity of the
spikelet; floret 6.1-6.9 mm. long, borne on a thick, fleshy rachilla internode and decidu-
ous with it; lemma rigid, ivory white when immature, becoming marbled when in fruit,
outline ovate 4:1, acuminate, its margins covering the edges of the similar palea;
lodicules 3, truncate; style 1, stigmas 2, apically exserted; caryopsis ovate 3:1, blunt,
tan, dorsally compressed, the pericarp extremely thin and easily scaling off the seed;
embryo ca. one-sixth as long as the grain. Staminate spikelets: Borne on slender erect
pedicels; few, dorsally compressed, narrowly ovate, acuminate, 2.1-2.6 mm. long;
glumes lacking; floret solitary; lemma 3-nerved; palea 2-nerved; lodicules 3, truncate,
vasculated; anthers 3, 1.2-1.5 mm. long. Rachilla internodes of fruiting florets contain a
liquid, oleaginous material. Chromosome number 2n = 22 from a Costa Rican specimen.

Rare; mostly in dense undisturbed rain forests below 100 m. eleva-
tion. Hamburg Finca; Puerto Viejo; La Selva; Rio Hondo; NE slope of
Volcan Orosi, 400 m. elevation. Our specimens have blooming or
fruiting dates from December, January, April, and August, and it is
possible that the plants bloom yearlong. They are nowhere common,

FIG. 48. Cryptochloa concinna. A, blooming plant; B, two views of pistillate spikelet;
C, staminate spikelet; D, pistillate floret on rachilla internode.

155

156 FIELDIANA: BOTANY

and usually occur in small numbers on slopes. The Rio Hondo collection
was made in an old cacao grove. Nicaragua to Panama and Colombia.

Cryptochloa granulifera Swallen, Ann. Missouri Bot. Gard. 29:321.
1942. Figure 49.

Plants perennial, densely caespitose, 33-55 cm. tall, forming vase-shaped clumps of
numerous ascending and arching culms; lower internodes elongated, the lower 1-3 nodes
bearing bladeless sheaths or short sheaths with reduced blades; culm internodes
roughened or retrorsely hispidulous, purple, thick-walled with a small lumen; nodes
conspicuously enlarged, with a constricted ring at the middle of the enlarged portion,
retrorsely hispidulous; sheaths tight, slightly keeled near the apex, puberulent or
granular roughened, minutely ciliate; collar hispidulous; apex of the sheaths with erect
auricles, the stiff membranaceous ligule 4-6 mm. long, adnate to the sheath margins,
rounded or acute at the apex, puberulent on the back; pseudopetiole thick and fleshy, ca.
1.5 mm. long, puberulent, serving as a pulvinus to orient the blades in one plane parallel
to the length of the stem during the day and to fold them face to face at night; blades flat,
deep green above, purplish beneath, 5-8 cm. long, 14-24 mm. wide, ovate, 3-4:1, abruptly
acute at the tip; usually 5-17 blades crowded near the apex of the culms, the sheaths
overlapping; margins of adjacent blades approaching or overlapping. Inflorescences sev-
eral, axillary from the upper leaf sheaths or terminal, the peduncles not exserted; some
inflorescences bearing only pistillate spikelets, others with 1-several terminal pistillate
spikelets, the lower branches bearing racemosely arranged staminate spikelets, the
rachis and pedicels angular or flattened, scabrous on the angles. Pistillate spikelets:
Erect at the thickened tip of the pedicel, dorsally compressed, ovate 7:1; glumes sub-
equal or the first slightly longer, 10.5-12 mm. long, acuminate, often tapering into an
awn up to 1.5 mm. long; first glume with 3 conspicuous nerves and 2 very faint marginal
ones; second glume 5-nerved, the lateral pairs of nerves close to the margins; glumes
deciduous after the fall of the floret; floret 1, supported on a thick, rigid rachilla 1.2-1.5
mm. long and deciduous along with the rachilla; floret dorsally flattened, ovate 4:1,
tapered to a blunt tip, rigid, shining, ivory white; lemma ovate 2:1 when flat, the margins
incurved over the edges of the palea, flat; nerves 5, faintly visible internally; palea
similar to the lemma, very broadly ovate 2:1, the margins strongly incurved; lodicules 3,
flat, truncate, vasculated; style 1; stigmas 2, exserted apically; caryopsis elliptic ovate
3:1, ca. 5 mm. long, blunt on both ends, dorsally flattened, the pericarp orange; embryo
small, basal, a dark line running the full length of the side opposite the embryo. Stami-
nate spikelets: Borne on 1-several lower branches or lower portions of branches of the
inflorescence, appressed, on pedicels 1-3.5 mm. long; glumes absent; floret 1, dorsally
compressed, triangular 10:1; lemma herbaceous, 4.8-6.0 mm. long, acuminate, 3-nerved,
the lateral nerves near the margin; palea equal to the lemma, with 2 keel nerves and 2
faint marginal nerves; lodicules 3, fleshy, truncate, vasculated; anthers 3, yellow, 2.4-2.6
mm. long, filaments short, fleshy, erect.

This species is known from Costa Rica only from the following
specimens. The plants were abundant in moist forest remnants on
steep slopes. Live plants from Rio Tenorio are now growing vigorously
in the Iowa State University greenhouse and have bloomed.
Guanacaste, Crossing of Rio Tenorio, ca. 3 km. S of Rio Naranjo,
elevation ca. 400 m.,Pohl & Lucas 13061, 18 December 1974; Alajuela,
9 km. by road N of Bijagua, elevation 240 m., 17 June 1976, Pohl &

FIG. 49. Cryptockloa granulifera. A, plant; B, inflorescence with pistillate spikelets
above, staminate spikelets at lower left; C, two views of a pistillate floret on a thickened
rachilla internode.

157

158 FIELDIANA: BOTANY

Pinette 13233. Mexico, Guatemala, and Honduras, northwestern Costa
Rica, Panama.

CYMBOPOGON Sprengel

Caespitose perennial grasses; foliage aromatic (lemon-scented in ours); inflorescence a
dense terminal compound panicle, the branches of the various orders subtended by
bladeless sheaths; ultimate inflorescence unit a pair of rames, exserted laterally from a
bladeless sheath; one rame sessile at the apex of the peduncle, the other short-stalked,
the two equal; rames short, composed of several pairs of spikelets borne on a flattened,
readily disarticulating rachis; one spikelet of each pair sessile, the other pedicellate, both
falling together or the pedicellate one disarticulating; basal pair of spikelets in some
rames equal, awnless, and staminate; other pairs consisting of a sessile, perfect-
flowered, awned spikelet and a pedicellate staminate or sterile spikelet, both usually
similar and of about equal size. Sessile spikelets: Glumes equal, ovate, coriaceous,
covering and concealing the florets; first glume flat, laterally keeled, usually nerveless
between the ciliate keels; upper margins sharply inflexed, covering the edges of the
second glume; second glume boat-shaped, keeled near the apex, 1-3-nerved; lower
lemma membranaceous, nerveless, ciliate, lacking both flower and palea; upper lemma
narrowly triangular, membranaceous, minutely toothed at the apex, tapering toward a
short, straight awn (scarcely exserted in our species); palea minute or lacking; lodicules
2, truncate; stamens 3; styles 2, naked at the base; stigmas exserted laterally. Pedicel-
late spikelets: Similar to the sessile ones, but the first glume somewhat rounded on the
back, 5-9-nerved, of softer texture than that of the sessile spikelet; second glume 1-3-
nerved, boat-shaped; lemma solitary, membranaceous, sterile or with 3 stamens but no
pistil.

Cymbopogon contains about 30 species of grasses of the tropics of
the eastern hemisphere. Several are cultivated for their aromatic con-
stituents. In the structure of the inflorescence, the species are close to
Andropogon and Hyparrhenia. (Panicoideae: Andropogoneae.) Cym-
bopogon citratus, known as Zacate de limdn or Sontol, occurs com-
monly at low elevations in Central America, but practically never
blooms. It can readily be recognized by its lemon odor.

Cymbopogon citratus (DC) Stapf, Kew Bull. 1906:357. Andropogon
citratus DC, Cat. Hort. Monspel. 78. 1813. Figure 50.

Perennial, forming dense vegetative clumps; individual stems very short (5-10 cm.),
ca. 1 cm. thick, solid, stiff and woody, with very short internodes, 3-6 mm. long; foliage
in vegetative forms all basal, leaf sheaths closely overlapping, gaping with age and
forming somewhat flattened fans, surfaces glabrous, heavily glaucous outside and inside
with loose, powdery wax deposits; sheath auricles erect, rounded, longer than the ligule
and adnate to its margins; ligule a stiff, erect membrane, 2.0-2.5 mm. long, minutely
ciliolate, straight; leaf blades at first ascending, finally drooping, up to 70 cm. long and 18
mm. wide, glabrous, light green, broadest at the middle, tapering to a narrow base;
margins thick, white, scabrous; midrib broad, white, protruding on the abaxial surface.
Culms usually absent, the plants essentially nonblooming. Culms up to 2 m. tall, un-

FIG. 50. Cymbopogon citratiis. A, plant base with overlapping sheaths; B, compound
inflorescence of numerous bracted rames.

159

160 FIELDIANA: BOTANY

branched; inflorescence a large terminal panicle of rames, up to 60 cm. long and ca.
one-third as wide, open to rather dense, complexly branched, the branches of each order
subtended by bladeless sheaths. Ultimate inflorescence unit a pair of short, usually
reflexed rames, exserted near the base of a bladeless sheath on a short peduncle; rames
1.0-1.5 cm. long, one of each pair sessile, the other on a very short peduncle; spikelets
paired, one sessile and the other pedicellate, the rame consisting of 1-4 pairs of spikelets
and a terminal triad of one sessile and 2 pedicellate ones; disarticulation at the base of
each rachis internode and pedicel; internodes and pedicels flattened, strongly ciliate on
the margins. Sessile spikelets: 3.2-5.0 mm. long, ovate 3:1, acute; first glume flat on the
back, the margins sharply inflexed and keeled, ciliate above; area between the keels
nerveless or with 2 weak nerves near the bifid tip; second glume boat-shaped, slightly
shorter than the first and clasped by its margins, 1-3-nerved; lower lemma membranace-
ous, ovate, ciliate-margined, 2.8-3.2 mm. long, lacking a flower or palea; upper (fertile)
lemma subulate, 2.0-2.5 mm. long, membranaceous, tapering into a weak awn 1-2 mm.
long, usually straight or slightly twisted near the base; palea minute or lacking; lodicules
2, truncate; stamens 3, the anthers yellow, 1.0-1.5 mm. long; style branches 2, naked
near the base; stigmas purple. Pedicellate spikelets: Similar to the sessile ones but
usually somewhat smaller, awnless; first glume slightly rounded on the back, 2.5-4.4
mm. long, 5-9-nerved; second glume 1-nerved or faintly 3-nerved; spikelets empty or
with the lower lemma developed, sometimes with a staminate flower, the 2-3 anthers
yellow, 2-3 mm. long; no palea, upper lemma, or pistil observed.

This species occurs around houses, but is apparently not cultivated
on a commercial scale in Costa Rica. It is said that the strongly scented
foliage is used for teas. The odor closely mimics that of lemon. Native
to India and widespread in the tropics. Because of the lack of flower-
ing, the plants can be spread only by cultivation. In Guatemala, "lemon
grass" is cultivated on a large scale on the Pacific Coastal Plain for the
production of lemon oil. A few flowering specimens are known from
cultivation. This species bloomed in El Salvador in June 1932. A
blooming specimen from El Zamarano, Honduras, was collected in
November 1948, and another from Turrialba, Costa Rica, in October
1950. We have never observed flowering. Common names: Zacate de
limon, Sontol.

CYNODON L. C. Richard

REFERENCES: W. D. Clayton & J. R. Harlan, The genus Cynodon L.
C. Rich, in tropical Africa, Kew Bull. 24:185-189. 1970. J. R. Harlan, J.
M. J. de Wet, W. W. Huffine, & J. R. Deakin, A guide to the species of
Cynodon (Gramineae), Oklahoma Agric. Exp. Sta. Bull. B-673:l-37.
1970. J. M. J. de Wet & J. R. Harlan, Biosystematics of Cynodon L. C.
Rich. (Gramineae), Taxon 19:565-569. 1970.

Stoloniferous or rhizomatous perennials; inflorescence of 1-several whorls of slender
spikes; spikelets sessile or nearly so in 2 rows along the lower side of the slender rachis.
Spikelets 1-flowered, laterally, compressed and keeled; glumes narrow, 1-nerved, often

BURGER: FLORA COSTARICENSIS 161

arcuate, usually shorter than the floret; lemma boat-shaped, 3-nerved, the lateral nerves
marginal; palea nearly as long as the lemma; rachilla extended behind the palea as a
naked bristle.

This is a small (ca. eight species) but important genus of the warmer
regions of the Old World. Some of the species are extensively variable.
Various species and minor variants, including hybrids, are used as
lawn and pasture grasses. Leaves on stolons are subopposite, because
of alternating long and short internodes of the stems. Cynodon dacty-
lon, "Bermuda grass," is one of the most common pantropical weeds.
(Chloridoideae: Chlorideae.)

KEY TO SPECIES OF Cynodon

la. Plants producing rhizomes as well as stolons; plants usually not more than 20 cm.

tall; mostly wild plants C. dactylon

Ib. Plants producing stolons only; plants up to 60 cm. tall; stolons thick and coarse;

cultivated crop plant C. nlemfuensis

Cynodon dactylon (L.) Pers., Syn. PL 85. 1805. Panicum dactylon
L., Sp. PL 58. 1753. Figure 51.

Perennial, spreading extensively by stolons and rhizomes; culms erect, usually less
than 20 cm. tall; stolons with alternating long and short internodes, causing the leaves to
appear subopposite; culms numerous, arising from the nodes of the stolons, unbranched,
ca. 1 mm. thick, hollow but thick- walled, glabrous; nodes glabrous; prophylla short,
broadly winged, 3-4 mm. long; foliage grayish-green; sheaths mostly glabrous, bearing
long soft hairs on the auricles and collar; leaf blades 1-12 cm. long, 2-4 mm. wide, flat or
folded, the tip blunt, mostly glabrous, but with long soft hairs on the basal margins of the
blade and on the upper surface behind the ligule; ligule membranaceous, ciliolate, 0.2-0.3
mm. long. Peduncle slender, glabrous, exserted; inflorescence solitary, terminal, a
single whorl of usually 4-6 slender spikes, usually 1.5-3 cm. long, rarely longer. Spikelets
overlapping, appressed to the rachis; 2.0-2.5 mm. long; glumes subequal, 1.1-1.7 mm.
long, the first linear, arcuate, appressed to the keel of the lemma, the second straight,
subulate, usually diverging from the floret; lemma boat-shaped, usually slightly silky on
the keel, rarely glabrous; palea about as long as the lemma; rachilla prolonged behind the
palea, about half as long as the floret, bearing a rudiment up to half its own length (rarely
missing); anthers 3, yellow, 1.0-1.4 mm. long. Chromosome number usually n = 18,
sometimes 9.

Common, mostly as a weed or in pastures, from sea level to 1,500 m.
elevation. Blooming yearlong. This is one of the commonest introduced
grasses. It is variously known as "Bermuda grass," "grama," or zacate
Bermuda. Throughout warm climates of the world, apparently
originating in Africa. A number of varieties are listed by de Wet and
Harlan from the Old World.

Cynodon nlemfuensis Vanderyst, Bull. Agric. Congo Beige 13:342.

FIG. 51. Cynodon species. C. dactylon: A, blooming plant; B, spikelet and floret with
rachilla internode; C. nlemfuensis: C, blooming plant; D, spikelet and floret with rachilla
internode.

162

BURGER: FLORA COSTARICENSIS 163

1922. C. dactylon (L.) Pers., var. sarmentosus Parodi, Revista Ar-
gent. Agron. 23:185. 1956. Figure 51.

Coarse stoloniferous perennial, lacking rhizomes; culms erect from the nodes of the
stolons, unbranched, hollow, 2 mm. thick, glabrous, 30-60 cm. tall; stolons 2-3 mm. thick,
with alternating long and short internodes, the leaves appearing to be subopposite;
branching extensive; prophylla prominent, 7-25 mm. long; sheaths glabrous; ligule a
minutely ciliolate membrane, 0.3 mm. long; blades flat, 5-16 cm. long, 2-6 mm. wide,
bearing long soft hairs on the auricles, dewlap, and base of the blade, especially behind
the ligule; sometimes with scattered hairs on the surface, especially beneath; inflores-
cence solitary, terminal, of 1-2 whorls of slender spikes, usually 4-9 spikes per inflores-
cence; racemes 4-10 cm. long; spikelets 2-3 mm. long; glumes subequal, 1.8-2.3 mm. long,
the first arcuate, linear, appressed to the keel of the lemma; second glume narrowly
lanceolate, diverging from the floret; lemma 2.5-2.8 mm. long, boat-shaped, softly
appressed-pubescent on the keel; palea equal to the lemma; rachilla ca. half the length of
the palea, the rudiment minute; anthers 3, yellow, 1.2 mm. long. Chromosome number
n = 9.

This African species has been cultivated in the grass garden of the
IICA at Turrialba, and is now being cultivated extensively in the Orosi
area and in Guanacaste, as well as in other parts of Central America.
The plants are much larger and more vigorous than the common weedy
type of C. dactylon. It may possibly be cultivated under the name of
Estrella africana or "African stargrass" or as C. plectostachyus.

CYNOSURUS Linnaeus

Inflorescence a dense terminal panicle; spikelets paired, of 2 kinds, one of each pair
sterile and one fertile; sterile spikelets conspicuous, fan-shaped, with 2 glumes and a
number of empty sterile lemmas borne on nondisarticulating rachilla; fertile spikelets
similar, mostly hidden by the sterile ones, 2-5-flowered; glumes slender, 1-nerved;
spikelets disarticulating above the glumes and between the florets; lemmas with a visible
midrib and very inconspicuous lateral nerves, short-awned. (Pooideae: Poeae.)

Cynosurus cristatus L., Sp. PL 72. 1753. Figure 52.

Caespitose perennial, leafy at the base; plants 20-80 cm. tall, culms unbranched, with
2-3 nodes, 1.0-1.5 mm. thick, hollow; sheaths much shorter than the slender glabrous
internodes; ligules 1-1.5 mm. long, membranaceous, auriculate, decurrent on the sheath;
blades mostly basal, 4-15 cm. long, 1.5-2.5 mm. wide, glabrous; panicles solitary, termi-
nal, densely cylindrical, 2-8 cm. long, ca. 1 cm. wide, the branches very short and
few-flowered; sterile spikelets fan-shaped, lustrous, mostly borne exterior to the fertile
ones, slightly larger than the fertile spikelets; lemmas empty, 1-nerved, 3-5 mm. long;
fertile spikelets 3-6 mm. long; glumes 3-5 mm. long, 1-nerved, narrowly lanceolate;
lemmas 3-4 mm. long, narrowly ovate, tapering abruptly to a short awn-point, scabrous
on the upper half; paleas 2-keeled, glabrous; anthers 3, yellow, ca. 2 mm. long. Chromo-
some number n = 1.

This species is known from Central America only from the following
specimen: Cartago, pastures on south slope of Volcan Turrialba, eleva-

FIG. 52. Cynosurus cristatus. A, sterile spikelet; B, fertile spikelet; C, inflorescence.

164

BURGER: FLORA COSTARICENSIS 165

tion 2780 m., Pohl & Davidse 10865, 8 August 1968. Cynosurus cris-
tatus is a European species, rather sparingly introduced in northeast-
ern North America and the Pacific Coast states of the United States.
Like Danthonia decumbens, Festuca rubra, Poa annua, P. trivialis,
and a number of other species, it probably represents an early intro-
duction to Costa Rica in pasture seed. Only a few plants were seen,
and the plants have no economic utility in Costa Rica.

DACTYLIS Linnaeus

Tufted perennial, forming large clumps; culms erect; herbage generally glabrous, pale
green; sheaths keeled, with united margins; ligules prominent, membranaceous, lacer-
ate; leaf blades flat or folded; panicles simple, with few straight, stiff branches which are
naked for most of their length and bear dense tufts of nearly sessile spikelets at their
outer ends; spikelets strongly flattened, the glumes and lemmas strongly keeled, usually
pectinate-ciliate on the keels; lemmas 5-nerved, tapering into a short awn-tip; disarticu-
lation above the glumes and between the florets. (Pooideae: Poeae.)

Dactylis glomerata L., Sp. PI. 171. 1753. Figure 53.

Plants forming large tufts; culms up to 140 cm. tall, erect; blades 10-45 cm. long, 2-14
mm. wide; ligules 2-12 mm. long. Panicles up to 30 cm. long, the few stiff branches
spreading in anthesis but erect later. Spikelets 5-9 mm. long, 2-5-flowered; glumes
lanceolate, 1-3-nerved, 4-6.5 mm. long; lemmas closely imbricated, strongly keeled,
5-nerved, 4-7 mm. long; palea about equal to the lemma; keels of lemmas usually promi-
nently short pectinate-ciliate. Chromosome number n = 14 from a Costa Rican speci-
men.

Middle and higher elevations; Irazu and Turrialba. Introduced from
Europe as a pasture and hay grass and naturalized on the volcanoes.
Widespread in temperate humid areas of the world, where it is culti-
vated as a forage crop. This species is said to be used as a hay crop in
Costa Rica, but it does not appear to be abundant at the present time.
Common name: "orchard grass."

DACTYLOCTENIUM Willdenow

REFERENCE: B. E. Fisher & H. G. Schweickerdt, A critical account
of the species of Dactyloctenium Willd. in Southern Africa, Ann. Natal
Museum X:47-77. 1941.

Annual or perennial caespitose or stoloniferous grasses. Inflorescence a whorl of sev-
eral spreading or reflexed one-sided spikes, the axis prolonged as a naked point beyond
the spikelets. Spikelets sessile, densely imbricated in 2 rows along the lower side of the
rachis, laterally compressed and keeled; glumes 2, keeled, 1-nerved, broad, the second
truncate, with a short, divergent awn; disarticulation between the glumes, the second
falling with the several florets; lemmas ovate, pointed or apiculate, strongly compressed
and keeled, 3-nerved, the midnerve prominent, green, the lateral nerves obscure, sub-

FIG. 53. Dactylis glomerata. A, inflorescence and culm base; B, spikelet; C, base of
blade with ligule.

166

BURGER: FLORA COSTARICENSIS 167

marginal; second glume and lemmas disarticulating from the intact rachilla, the paleas
remaining attached; palea about as long as the lemma; lodicules 2, truncate, anthers 3,
seed broadly ovate, truncate, with strong transverse ridges; pericarp thin and delicate,
disappearing before maturity.

This is a small genus of ca. 10 species of warm climate grasses,
native to Eurasia, Africa, and Australia; introduced in warm climates
in the Americas. Dactyloctenium is closely related to Eleusine, and
the plants are similar in habit and inflorescence structure.
(Chloridoideae: Eragrosteae.)

Dactyloctenium aegyptium (L.) Beauv., Ess. Nouv. Agrost. 72; PI.
XV, Fig. 2. 1812. Cynosurus aegyptius L., Sp. PL 72. 1753. Figure 54.

Plants annual in temperate climates, of indefinite duration in the tropics; spreading by
short stolons and forming radiate mats, the erect portions of the culms 2-50 cm. tall;
branching abundant on the creeping stolons, the erect culms unbranched, 1.0-1.5 mm.
thick, glabrous, solid, the nodes with conspicuous pulvini; prophylla prominent, 10-15
mm. long, with 2 ciliate awns up to 3 mm. long; leaf sheaths carinate, overlapping on
short shoots, shorter than the internodes on the culms, glabrous to pustulose-villous;
ligule a thin brownish ciliolate membrane, ca. 0.5 mm. long; leaf blades 1-7 cm. long, 1-7
mm. wide, the uppermost much reduced; midrib prominent; blades papillose-villous on
the margins and more or less on both surfaces, occasionally glaucous. Peduncle glabrous,
exserted 1-10 (-20) cm. long; inflorescence a whorl of usually 2-4 unilateral spikes,
terminal on the culm, rarely a solitary spike in depauperate plants; spikes subsessile, 1-3
cm. long, the axis extended beyond the spikelets as a short naked point; spikelets
densely crowded in 2 overlapping rows on the lower side of the rachis. Spikelets gray to
purplish, strongly laterally compressed and keeled, ca. 4 mm. long; first glume 1-nerved,
2 mm. long, ovate, apiculate; second glume similar but longer, ca. 3 mm. long, broadly
ovate, with a short thick divergent awn; disarticulation usually above the first glume but
not between the florets; florets usually 3, the uppermost often sterile; lemmas 2-3 mm.
long, ovate, the keel strongly bowed; midnerve conspicuous, green, the lateral nerves
very inconspicuous; keel scabrid; tip acuminate; palea ca. 2 mm. long, ciliolate on the
keels; anthers 3, ca. 0.4 mm. long, yellow; pericarp very thin and fragile, soon shed, the
rugose, angular brown seed then free. Chromosome numbers 2n = 46, 48, 45, 20, 36, 40
(Gould & Soderstrom, 1974).

Savannas, pastures, beaches, weedy open areas, from sea level to
1,200 m. elevation, on both Caribbean and Pacific slopes. Blooming
yearlong. Introduced from the Old World. Southern and eastern
United States through the tropics to Uruguay.

Where plants of this species grow on bare soil, they make decum-
bent circular mats, with considerable stoloniferous spread. Extreme
dwarfing of the plants can occur under drought or poor soil conditions,
and such plants may often show glaucous leaves. Seeds from such
glaucous plants, grown in the greenhouse on sand or loam soil with
adequate moisture produced only green-leaved plants.

FIG. 54. Dactyloctenium aegyptium. A, plant with stoloniferous base and inflores-
cence; B, spikelet.

168

BURGER: FLORA COSTARICENSIS 169

DANTHONIA Lamarck & De Candolle
Nomen Conservandum

Caespitose perennial grasses; inflorescence a solitary terminal panicle; spikelets
several-flowered; glumes as long as the spikelet, equal, many-nerved; disarticulation
above the glumes and between the florets; lemmas 5-7-nerved, awned between 2 apical
teeth, or the apex of the lemma trifid; flowering mostly cleistogamous; axillary cleis-
togenes also produced inside the sheaths at the lower nodes; culms disarticulating at the
lower nodes and discharging the cleistogenes at maturity. (Arundinoideae: Dan-
thonieae.)

Danthonia decumbens (L.) Lam. & DC., F. Franc, ed. 3, Vol. 3:33.
1805. Festuca decumbens L., Sp. PI. 75. 1753. Sieglingia decumbens
(L.) Bernh., Syst. Verz. Erf. 20:44. 1800. Figure 55.

Caespitose perennial, forming dense clumps; culms 20-50 cm. tall, erect to ascending,
ca. 1 mm. thick, hollow, glabrous; leaf blades mostly at the base of the culms; sheaths
more or less hairy on the upper half; innovations extravaginal; prominent auricular hairs
present; ligule a dense circle of hairs, ca. 0.5 mm. long; blades 4-10 cm. long, 1.5-3 mm.
wide, ribbed on both surfaces, flat or inrolled, bearing scattered long weak hairs. Pani-
cles 2-6 cm. long, contracted, few-flowered. Spikelets almost entirely cleistogamous;
glumes equal, 6-12 mm. long, 5-7-nerved, broadly lanceolate, rounded on the back,
overlapping; florets 4-7; lemmas 4-6 mm. long, oval to broadly ovate, 9-nerved, rounded
on the back, bluntly 3-toothed at the tip, smooth and shining, firm, ciliate on the lower
margins, otherwise glabrous; callus projecting, bearing tufts of hairs ca. 1 mm. long;
palea 4-5 mm. long, broadly ovate, the keels prominent and conspicuously thickened
below into pulvini; rachilla segments slender, smooth, 0.6-0.7 mm. long; anthers 3, those
of cleistogamous flowers 0.2-0.3 mm. long, those of the rare chasmogamous flowers 1-2
mm. long; lodicules not developed; anthers remaining entangled with the stigmas and
persisting on the tip of the fruit; caryopsis 2.0-2.5 mm. long, elliptic, flattened, with a
terminal appendage. Basal sheaths swollen just above the nodes and containing cleis-
togenes; the cleistogene enveloped in a prominent prophyllum ca. 10 mm. long, short-
pedicellate, with 1 or 2 abortive glumes ca. 1-4 mm. long; florets 1 or rarely 2, 5-8 mm.
long, the rachilla sometimes prolonged and bearing a reduced abortive floret; culms
eventually breaking at the nodes and releasing the cleistogenes. Chromosome number
n = 18 from Costa Rican specimens; n - 28, 36, 124 also listed by Bolkhovskikh et al.
(1969).

This is an introduced European species, probably imported at an
early date in pasture seed mixtures. The only known localities from
Central America are the following: Alajuela, Volcan Poas, 1 km. below
crater on road; elevation 2,310 m., Pohl & Davidse 10813; Cartago,
Volcan Turrialba, southern slope, open pastures above the lecheria,
elevation 3,000 m., Pohl & Davidse 10858. The above two specimens
were blooming in August. Few plants were found. Danthonia decum-
bens is native in Europe and Asia Minor and Northwest Africa and has
been introduced in northeastern United States and Canada and in New
Zealand.

FIG. 55. Danthonia decumbens. A, spikelet; B, two views of a floret; C, inflorescence.

170

BURGER: FLORA COSTARICENSIS 171

This peculiar cleistogamous grass has usually been assigned to the
genus Sieglingia; however, Conert (1969) has shown that it is very
similar in morphology and biology to the other species of Danthonia,
differing only in the absence of a developed awn. It also forms spon-
taneous hybrids with Danthonia alpina, a European species. For this
reason, he assigns it to Danthonia. The generic name Sieglingia
Bernh. (1800) antedates Danthonia by five years. Because of the
necessity of combining the two genera, Danthonia, which has many
species, was conserved over Sieglingia with only one.

DESCHAMPSIA Beauvois

Caespitose, usually perennial grasses; inflorescence a terminal panicle. Spikelets
2-flowered; glumes subequal, keeled, longer or shorter than the florets; disarticulation
above the glumes and between the florets; lemmas lobed at the apex; awn inserted below
the middle of the back of the lemma; rachilla internodes short, the rachilla extended
above the base of the second floret as a short bristle.

This genus is allied to Trisetum, from which it differs in the basally
attached awns, and to Aira, which lacks the prolonged rachilla. De-
schampsia has about 35 species in cool and alpine regions of the world.
(Pooideae: Aveneae.)

KEY TO SPECIES OF Deschampsia

la. Panicle open, pyramidal, the few-flowered branches naked for their lower halves

D. flexuosa
Ib. Panicle densely cylindrical with closely overlapping spikelets D. pringlei

Deschampsia flexuosa (L.) Trin., Mem. Acad. Imp. Sci. Saint-
Petersbourg, Ser. 6, Sci. Math., Seconde Pt. Sci. Nat. 4:9. 1838. Aira
flexuosa L., Sp. PL 65. 1753.

Caespitose perennial, in dense tufts; plants 30-85 cm. tall; foliage mostly basal, the leaf
blades capillary, mostly 10-15 cm. long, less than 1 mm. wide, involute, glabrous; ligule a
firm membrane, 0.5-1.5 mm. long; culms slender, the internodes very elongate. Peduncle
elongate, exserted up to 30 cm.; inflorescence a solitary very open terminal panicle,
pyramidal, the few branches naked for the lower one-half to two-thirds, bearing few
spikelets, these borne on slender pedicels longer than the spikelets themselves.
Spikelets usually purplish, 4.0-5.8 mm. long, laterally compressed; glumes shorter than
the spikelet, rounded on the keel, 1-nerved, ovate, acuminate, the first 3.0-4.4 mm. long,
the second 3.6-5.0 mm. long; florets close to each other, the rachilla internode very short,
0.3-0.8 mm. long, bearded; lemmas scaberulous, lanceolate, faintly 5-nerved, bidentate
at the acuminate tip; callus short-bearded; awn 5-7 mm. long, inserted just above the
base of the lemma, the lower segment tightly twisted, brown, the terminal segment
exserted from the glumes; palea about as long as the lemma, scabrous on the keels;
anthers 3, purplish, 2.1-3.0 mm. long; caryopsis linear, rigid.

Collected only once in Costa Rica, from a pasture on the south slope

172 FIELDIANA: BOTANY

of Volcan Turrialba at 3,000 m. elevation. August. This is a species of
temperate and arctic North America and Eurasia. It has not previ-
ously been reported from Central America. Its presence in a high
elevation pasture along with other species of northern European origin
suggests that it was introduced in pasture seed mixtures of European
origin.

Deschampsia pringlei Scribner, Proc. Acad. Nat. Sci. Philadelphia
43:300. 1891. Figure 56.

Caespitose perennial; plants 30-100 cm. tall, erect; culms unbranched, 1-2 mm. thick,
hollow, thin- walled, glabrous and shining; nodes conspicuous, dark and shrunken; leaf
sheaths shorter than the internodes, glabrous, striate; ligule a firm truncate membrane,
1.5-2.5 (-4) mm. long; blades flat, 7-12 cm. long, 2-4 mm. wide, minutely scaberulous.
Peduncle glabrous, exserted up to 20 cm.; panicle solitary, terminal, densely cylindrical,
somewhat lobed below, 10-15 cm. long, 5-15 mm. thick, grayish or pinkish; spikelets
densely overlapping on the short erect branches, the short pedicels hispidulous.
Spikelets 4.8-5.6 mm. long, laterally compressed, the glumes subequal, keeled, 1-
nerved, longer than the florets, the keels scabrous; first glume 4.0-4.9 mm. long, ovate,
acuminate, the second similar, 4.2-5.6 mm. long; disarticulation above the glumes and
between the 2 florets; lemmas 3.3-4.3 mm. long, lanceolate, faintly 5-nerved; callus
short-bearded; apex lobed 1.0-1.5 mm., the lobes rounded or erose; awn geniculate,
exserted, 4.5-5.0 mm. long, inserted ca. one-fourth above the base of the lemma; palea
3.0-3.6 mm. long; rachilla internodes very short, bearded; anthers 1.2-1.3 mm. long,
whitish; caryopsis linear-cylindrical, soft, the endosperm pasty. Chromosome number
n = 14 from a Costa Rican specimen.

Rare, margins of a quebrada below San Juan de Chicoa at 2,600 m.
elevation. Previously known from southern Mexico and Guatemala.

Deschampsia pringlei has recently been transferred to the genus
Peyritschia by Stephen D. Koch in Taxon 28: 233, 1979. The genus
Peyritschia differs from Deschampsia in having a soft caryopsis with
liquid interior and basal shoots bursting through the base of the sub-
tending sheath. The genus Peyritschia differs from Trisetum in having
a bilobed apex on the lemma, glumes exceeding the florets and stamens
2 per floret.

DIECTOMIS Kunth
Nomen Conservandum

Caespitose; inflorescences numerous, terminal and axillary, each one a solitary rame
or a conjugate pair of rames on a bracted peduncle; rachis disarticulating readily into
individual segments, each bearing a dimorphic pair of spikelets; rachis internodes and
pedicels flattened, narrowly obtriangular, with silky-ciliate edges and an obliquely cup-
like toothed apex; sessile spikelet remaining attached to the rachis internode and
pedicel, perfect-flowered, strongly laterally compressed; first glume narrow, 2-keeled,
grooved between the keels, second glume strongly laterally compressed and keeled,

FIG. 56. Deachampsia pringlei. A, inflorescence; B, spikelet; C, florets.

173

174 FIELDIANA: BOTANY

boat-shaped, bearing a long curved awn from the tip; sterile lemma hyaline, 2-keeled,
narrowly lanceolate; fertile lemma hyaline, strongly keeled, the keel curved to fit the
second glume, bearing a long exserted twisted and geniculate brown awn from between
2 triangular teeth; palea hyaline; flower perfect; pedicellate spikelet larger than the
sessile one, readily deciduous from the pedicel, sterile or staminate; first glume broad
and flat, stiff, several-nerved, asymmetric, awned from the acute apex, the margins
narrowly and sharply inflexed, the folded edge strongly scabrous or ciliate; second glume
shorter and narrower than the first, oblong, membranaceous, bearing a short straight
apical awn. Terminal segment of the rachis bearing one sessile and 2 pedicellate
spikelets.

Diectomis is a small genus of tropical grasses of both eastern and
western hemispheres, related to Andropogon and sometimes included
as a section of that genus. It differs in the strongly laterally com-
pressed sessile spikelets with awned second glumes, and in the en-
larged pedicellate spikelets. The plants are probably annual.
(Panicoideae: Andropogoneae.)

KEY TO SPECIES OF Diectomis

la. Rames solitary on each peduncle D. fastigiata

Ib. Rames paired at tip of each peduncle D. angustata

Diectomis angustata Presl, Rel. Haenk. 1:333. 1830. Andropogon
angustatus (Presl) Steud., Syn. PL Glum. 1:370. 1854.

Duration indefinite; plants caespitose, erect, 20-100 cm. tall; culms branching from the
base and the middle and upper nodes, 1.0-1.5 mm. thick, hollow or pithy, glabrous; nodes
glabrous, not prominent; sheaths shortef than the internodes, glabrous; ligule a truncate
brown membrane, 1.0-2.5 mm. long, adnate to the upper sheath margins; leaf blades up
to 30 cm. long, 1.5-3.0 mm. wide, glabrous, flat; midrib wide, white. Peduncles mostly
enclosed in slender, bladeless sheaths; inflorescences terminal, of numerous individual
peduncles arising from upper sheaths, each bearing a conjugate pair of rames, these 2-4
cm. long. Spikelets paired, one sessile and perfect-flowered, one pedicellate and sterile
or staminate, both falling together with the rachis internode and pedicel when the rachis
disarticulates; terminal sessile spikelet of each rame accompanied by 2 pedicellate ones;
callus of sessile spikelet sharp, bearded, prolonged about 1 mm. below the insertion of
the pedicel and rachis internode; pedicels and rachis internodes similar, ca. half as long
as the sessile spikelet, very narrow at the base, wedge-shaped upward, slightly convex
on the outer side, thin-walled and hollow, lower two-thirds of the edges ciliate, apex
terminating in a very obliquely U-shaped cuplike apex, wider than the spikelet base
above. Sessile spikelet: 4.4-5.0 mm. long; first glume deeply grooved on the back, ca.
6-nerved, lacking a midrib, bifid at the tip; second glume longer than the first, strongly
keeled, boat-shaped, the spikelets appearing laterally compressed; glume faintly 3-
nerved, bearing a slender awn, 10-15 mm. long from the blunt tip; lower lemma 1-
nerved, thin, marginally ciliate, 2-keeled, lacking a midrib, 3.0-4.2 mm. long; upper
lemma fertile, 2.8-4.0 mm. long, hyaline, 1-nerved, the awn arising from the bifid tip;
awn twisted and geniculate, brown, slightly hispid, 3-5 cm. long; palea nerveless, 1.5-2.0
mm. long; lodicules 2, truncate; anthers 3, 1.7-2.1 mm. long. Pedicellate spikelets: Ovate
6:1, acute, 5.5-6.0 mm. long, dorsally compressed; first glume slightly convex, 3-7-

BURGER: FLORA COSTARICENSIS 175

nerved, its margins inrolled over the edges of the second glume, ciliate above the middle;
apex bifid, a straight awn 5-13 mm. long arising between the teeth; second glume
rounded on the keel, 3-nerved, with an awn ca. 3 mm. long; florets absent or, in some
cases, the spikelet with a lower lemma ca. 5 mm. long, thin and nerveless; upper lemma
5.1-5.3 mm. long, thin and ciliate, 1-nerved; palea 2.2-3.0 mm. long; lodicules 2, truncate;
anthers 3, 2.5-3.0 mm. long. Chromosome number n = 20 from Costa Rican specimens.

Curatella-Byrsonima savannas, Guanacaste; elevation 100-250 m.
October to December. Southern Mexico to Panama and Colombia,
Venezuela, and northern Brazil.

Diectomis fastigiata (Swartz) Beauv., Ess. Nouv. Agrost. 132, 160.
1812. Cymbachne fastigiata (Swartz) Roberty, Mon. Androp. Boissi-
era 9:255, 1960. Andropogonfastigiatus Swartz, Prodr. Veg. Ind. Occ.
26. 1788. Figure 57.

Caespitose annual; plants 30-200 cm. tall, erect; branching abundant from middle and
upper nodes; prophylla thin, brown, up to 5 cm. long; culms slender, hollow, smooth and
glabrous; nodes glabrous, impressed; lower leaf blades very elongate, up to 35 cm. long,
1-3 mm. wide, tapering into an elongated awn tip, scabrous below, puberulent above,
sometimes with scattered elongate weak hairs; upper leaves reduced to sheaths with
awnlike reduced blades; ligule stiff, erect, brown, 2-11 mm. long, decurrent on the
sheath margins; rames numerous, solitary or in small groups, exserted on slender
branches from the middle and upper leaf sheaths; peduncle bearing at its base a
spathelike sheath which includes the base of the rame, its blade reduced to an awn; an
elongated slender prophyllum borne within the spathe; rames 3-5 cm. long, of numerous
pairs of spikelets, linear, flattened, the first glumes of the pedicellate spikelets conspicu-
ous, imbricated; sessile spikelets 4-5 mm. long, deciduous with the rachis internode and
pedicel; first glume linear, 2-keeled, silky between the keels, slightly longer than the
second glume, 4.5-5.0 mm. long, awnless; second glume 4.0-5.0 mm. long, strongly
compressed and keeled, the keel bowed out; sterile lemma ca. 3.5 mm. long, narrowly
lanceolate, 2-keeled, conforming to the shape of the first glume, hyaline, the margin
ciliate, lacking flower or palea; fertile floret ca. 3.0 mm. long, the keel of the lemma
curved, conforming to the shape of the second glume, membranaceous, bifid at the apex
and bearing a long awn, 3-4 cm. long; flower perfect; anthers 3, 1.5-1.8 mm. long,
pinkish; palea 2.3-3.0 mm. long, hyaline. Pedicellate spikelet readily deciduous from the
apex of the pedicel, its first glume oblong or obovate, stiff and flat, acuminate, somewhat
asymmetric, bearing an awn ca. 10 mm. long, scabrous ciliate on the margins; second
glume 3.5-5.0 mm. long, with a straight awn 2-10 mm. long; no flower present. Chromo-
some number n = 10 from Costa Rican material.

Scattered in northern Guanacaste; savannas, tuff outcrops, sea cliffs;
Western Meseta Central; Boruca area and valley of Rio Grande de
Terraba; elevations from sea level to 800 m. Late October to March.
Mexico to Brazil; West Indies; Tropics of the Old World.

DIGITARIA Haller

REFERENCES: J. Th. Henrard, Monograph of the genus Digitaria,
Univ. Pers. Leiden. 999 pp. 1950. J. F. Veldkamp, A revision of Di-

FIG. 57. Diectomis fastigiata. A, rame; B, two views of a spikelet pair, showing
enlarged sterile pedicellate spikelets.

176

BURGER: FLORA COSTARICENSIS 177

gitaria Haller (Gramineae) in Malesia. Notes on Malesian Grasses VI,
Blumea 21:1-80. 1973.

Annual or perennial caespitose, rhizomatous, or stoloniferous grasses; leaf blades
usually flat and lax; ligules membranaceous, sometimes ciliolate. Inflorescence of several
to many unilateral racemes, these whorled or racemose along a central rachis; rachis of
racemes triquetrous or flattened and winged, the spikelets appressed in 2 rows along the
lower side of the rachis, in pairs or triads, rarely solitary or in groups of 4-5; pedicels of
each group of unequal length. Spikelets ovate or lanceolate, dorsally compressed,
planoconvex, disarticulating below the glumes, placed with the back of the fertile lemma
toward the rachis; first glume a minute nerveless scale or absent; second glume from ca.
one-fourth as long to as long as the spikelet, usually 3-5-nerved; lower floret represented
by a sterile lemma possessing a minute palea which remains attached to the base of the
fertile upper floret; sterile lemma usually about as long as the spikelet, flat on the back,
5-9-nerved; fertile floret about as long as the spikelet, its lemma stiff but not rigid, ovate
or lanceolate, convex, usually faintly 3-nerved and longitudinally striate, glabrous,
grayish, tan, brown, or chocolate colored, its margins thin and flat, not inrolled, overlap-
ping the margins of the palea and often meeting near the base; palea flat, of the same
texture and appearance as the lemma and about as long; anthers 3; stigmas 2; caryopsis
planoconvex, elliptical, whitish and opalescent.

A large genus of about 170 species (Veldkamp, 1973) of grasses of
tropical and warm temperate climates, abundant in both eastern and
western hemispheres. Digitaria is related to Leptoloma, Reimaro-
chloa, Hymenachne, and Leptocoryphium, and less closely to
Panicum and Paspalum. Many of the species of Digitaria are abun-
dant weeds of cultivated or waste areas, and a few are cultivated for
forage, notably D. decumbens (pangola grass) in Central America.
Species of Digitaria are usually easily recognizable by the very slender
simple racemose inflorescence branches and narrow, more or less
pointed spikelets. (Panicoideae: Paniceae.)

KEY TO SPECIES OF Digitaria

la. Mature fertile floret reddish brown to nearly black 2

Ib. Mature fertile floret grayish or dull tan 6

2a. Spikelets paired, densely covered with elongated silky or tan hairs which
nearly conceal the spikelet and extend several mm. beyond the tip

D. insularis
2b. Spikelets paired or in triads, the white, golden, or purple hairs short, not

extending more than 1 mm. beyond tip of spikelet 3

3a. Spikelets paired; hairs of mature spikelet purple D. pittieri

3b. Spikelets in triads or, rarely, 4-5 per group; hairs silvery or golden 4

4a. Margins and tip of sterile lemma bearing stiff, glassy, golden bristles which,

when young, extend beyond the tip of spikelet as a stiff brush D. argillacea

4b. Margins of sterile lemma and second glume bearing fine appressed silky hairs;

golden bristles not present 5

5a. Hairs of second glume and sterile lemma with blunt, club-shaped tips, readily
visible under 20 x magnification D. filiformis var. villosa

178 FIELDIANA: BOTANY

5b. Hairs of second glume and sterile lemma tapering to fine points, hair walls minutely

roughened (visible under 400 x magnification) D. violascens

6a. Spikelets 2 mm. or more long; first glume present or absent 7

6b. Spikelets less than 1.5 mm. long; second glume and sterile lemma completely

covering fertile floret; first glume absent D. longiflora

7a. First glume absent; second glume less than half as long as spikelet . D. setigera

7b. First glume present; second glume more than half as long as spikelet 8

8a. Pedicellate spikelet when mature, bearing strongly spreading fine marginal
cilia, often interspersed with thick bristles; subsessile spikelet similar or usu-
ally with appressed pubescence only D. bicornis

8b. Spikelets never possessing strongly spreading cilia; Spikelets of each pair
always alike 9

9a. Second glume and sterile lemma subequal, nearly or completely covering and con-
cealing fertile floret 10

9b. Second glume shorter and narrower than sterile lemma, exposing upper part and

sides of fertile lemma 11

lOa. Spikelets 3.5-4.0 mm. long; foliage heavily villous; inflorescence a whorl of

closely ascending racemes D. costaricense

lOb. Spikelets 1.9-2.1 mm. long; foliage more or less pubescent; inflorescence a
panicle of solitary or paired spreading racemes along a slender rachis

D. abyssinica

lla. Rachis of racemes bearing scattered elongated pustulose-based hairs 13

lib. Rachis of racemes not bearing elongated hairs 12

12a. Back of sterile lemma visibly 5-nerved, internerves scarcely wider than
nerves; coarse stoloniferous perennial, sometimes with rhizomes; leaf blades

narrowly linear, scabrous; cultivated crop D. decumbens

12b. Back of sterile lemma visibly 3-nerved, internerves broad, first pair of lateral
nerves appearing marginal; plants with decumbent stems; leaf blades short

and broad, papillose-pilose; wild plants D. ciliaris

13a. Spikelets 1.8-2.0 mm. long; inflorescence of branched racemes; sterile lemma 5-

nerved D. velutina

13b. Spikelets 2.1-2.4 mm. long; inflorescence of simple, unbranched racemes; sterile
lemma 7-nerved D. horizontalis

Digitaria abyssinica (Hochst.) Stapf, Gr. Brit. Somal. Kew Bull.
1907:213. Panicum abyssinicum Hochst., in A. Rich., Tent. Fl.
Abyss. 2:360. 1851. Syntherisma abyssinica (Hochst.) Newbold, Tor-
reya 24:8. 1924. Figure 58.

Duration indefinite; culms long-decumbent and rooting at the nodes, the erect
branches 20-40 cm. tall; plants branching freely from the base and from nodes of rooted
stems; culms 1.0-1.5 mm. thick, hollow, glabrous, often purple; nodes prominent;
prophylla 20-30 mm. long; sheaths shorter or longer than the internodes, papillose-
pilose; ligules 1-2 mm. long, membranaceous, erose, brownish or purplish; blades rather
short and broad, 4-9 cm. long, 3-11 mm. wide, papillose-pilose on both sides, rounded to a
broad base. Peduncles slender, glabrous, exserted up to 15 cm., terminal on the main
culm or on erect leafy branches; inflorescence an open panicle of racemes, 5-10 cm. long,
wider than long, the rachis 2-6 cm. long, the racemes solitary or subopposite; rachis of

FIG. 58. Digitaria abyssinica. A, two views of a spikelet; B, fertile floret; C, portion of
a raceme; D, blooming plant.

179

180 FIELDIANA: BOTANY

racemes slender, triquetrous, scabrous on the angles, less than 0.5 mm. thick; spikelets
paired, unequally pedicellate, the shorter pedicel 0.8-1.1 mm. long, the longer one
1.7-2.5 mm. long. Spikelets ovate, rather plump, barely acute, 1.9-2.1 mm. long, often
with some purple coloration; first glume prominent, ovate-deltoid, 1-nerved, 0.3-0.7 mm.
long; second glume ovate, blunt, ca. five-sixths as long as the spikelet, 1.6-1.8 mm. long,
3-6-nerved; sterile lemma as long as the spikelet and slightly exceeding the fertile one,
7-nerved, but the inner 3 nerves much more conspicuous, glabrous or with short silky
pubescence on the upper margins; fertile lemma ovate, plump, minutely striate, usually
grayish, 1.7-1.9 mm. long, the palea exposed at maturity; anthers 3, orange or purplish,
1.0-1.1 mm. long; stigmas purple; caryopsis elliptical, whitish-opalescent, 1.3-1.4 mm.
long. Chromosome number n = 18 from a Costa Rican specimen.

Becoming common in disturbed areas, particularly in cafetals;
Meseta Central, Orosi and Turrialba Valleys; probably blooming
yearlong. Native to northeastern and Central Africa and there known
as a weed in coffee plantations; not previously known from the western
hemisphere, except as a cultivated introduction in the United States
(Newbold, I.e.).

Henrard distinguishes this species from D. vestita Fig. & De-
Notaris, but Stapf, in Fl. Trop. Africa 461 (1919), included D. vestita
as a synonym of D. abyssinica. Our specimens seem very uniform
except for the slight ciliation of the second glume and sterile lemma of
some specimens.

Digitaria argillacea (Hitchc. & Chase) Fernald, Rhodora 22:104.
1920. Syntherisma argillacea Hitchc. & Chase, Contr. U.S. Natl.
Herb. 18:296. 1917. Figure 61.

Duration indefinite; plants 28-60 cm. tall, the culms erect, in small tufts; culms slen-
der, 1 mm. thick, hollow, glabrous; sheaths papillose-pilose, about as long as the inter-
nodes; ligule a lacerate, ciliolate membrane, 0.7-1.2 mm. long; blades flat, 4-9 cm. long,
2-5 mm. wide, papillose-pilose. Peduncle included or exserted, glabrous. Inflorescences
solitary, terminal on leafy culms, 6-12 cm. long, of 2-6 erect or spreading racemes along a
common rachis 1-3 cm. long; individual racemes 1-12 cm. long, the rachis slender, 0.2-0.3
mm. wide, triquetrous, strongly scabrous and sometimes with scattered elongate hairs;
spikelets in triads or pairs, the shortest pedicel 0.5-1.0 mm. long, the longest up to 2.5
mm. long. Spikelets 1.7-1.8 mm. long, not including the bristles, ovate, acute; first glume
absent; second glume triangular, 1.2-1.6 mm. long, 3-nerved; sterile lemma as long as
the spikelet, 5-7-nerved; central internerve areas glabrous, the lateral ones pubescent
with fine silky hairs which are mostly hidden by abundant thick, glassy golden bristles
which, until full maturity, are appressed and overtop the spikelet bracts up to 1 mm.;
similar bristles on the margins and tip of the second glume; bristles finally widely
spreading at maturity of the fruit; tips of bristles slightly dilated and terminating in an
abruptly acuminate point; fertile floret plump, ovate, 2.3:1, deep brown, striate; palea
similar; caryopsis elliptic, whitish-opalescent, 1.3 mm. long.

Open dry areas, savannas; rare; elevations from sea level to 1,200
m.; Bagaces, Hacienda Argentina, Carillos de Poas, Puntarenas,
Boruca, San Jose. August to December.

BURGER: FLORA COSTARICENSIS 181

This species was originally described from Puerto Rico and has been
recorded from Cuba as well as Central America. The type from Puerto
Rico has mostly basal foliage, but the spikelets are a good match for
our specimens. Our specimens have leafy culms and are vegetatively a
good match for D. hirsuta Swallen, Ann. Missouri Bot. Gard. 30:172.
1943. The latter species, however, lacks the conspicuous glassy golden
bristles found on the spikelets of D. argillacea. Spikelets of both
species have peculiar bulbous-tipped hairs ending in a sharp mucro.
Both of these entities need more field study to determine whether they
are actually distinct. Digitaria hirsuta may be a form of D. argillacea
lacking the glassy golden bristles. Similar occurrences are known in
other species of the genus.

Digitaria bicornis (Lam.) Roem. & Schult., Syst. 2:470. 1817. Pas-
palum bicorne Lam., Tabl. Encycl. 1:176. 1791. Digitaria diversiftora
Swallen, Rhodora 65:356. 1963. An extended synonomy for this species
is given by Veldkamp in Blumea 21:30-31. 1973. Figure 59.

Duration indefinite; culms long-decumbent and rooting at the nodes, the erect
branches 10-85 cm. long, branching from the lower nodes; culms 1-2 mm. thick, hollow,
glabrous; leaf sheaths longer or shorter than the internodes, bearing scattered elongate
pustulose-based hairs, sometimes nearly glabrous; ligule a thin membrane, 1.5-3.2 mm.
long; leaf blades 3-14 cm. long, 2-9 mm. wide, flat, nearly glabrous except for elongated
pustulose-based bristles on the upper surface near the base. Peduncles glabrous, ex-
serted up to 30 cm.; inflorescences terminal on the main culm or erect leafy branches,
usually consisting of a single whorl of 3-6 racemes, rarely with a secondary whorl above
these; racemes 5-14 cm. long, the rachis flattened, wing-margined, 0.7-1.0 mm. wide, the
edges scabrous, the midrib winged; spikelets paired, unequally pedicellate, the shorter
pedicel ca. 0.2 mm. long, the longer one up to 2 mm. long. Spikelets lanceolate, usually of
2 kinds; length 2.9-3.3 mm.; first glume small to obsolete, deltoid or bifid, 0.2-0.4 mm.
long; second glume 1.5-2.2 mm. long, 3-nerved, triangular 6:1, ciliate; sterile lemma as
long as the spikelet, 5-nerved; lemma of fertile floret ovate, 6:1, acute, 3-nerved, grayish
to stramineous, the palea equal to the lemma; anthers 3, purple, 0.5-0.6 mm. long;
caryopsis tan to whitish, opalescent, elliptical-ovate, 1.8-1.9 mm. long; subsessile
spikelet usually slightly marginally ciliate, the nerves of the sterile lemma equidistant;
pedicellate spikelet strongly ciliate, the hairs divergent at maturity, arising between the
lateral nerves of the sterile lemma and on its margins; silky pubescence interspersed
with yellowish papillose-based bristles; inner nerves of sterile lemma distant from the
midnerve, so that only 3 nerves are normally visible, the others obscured by the pubes-
cence. Chromosome number n = 36 from a Costa Rican specimen.

Beaches, sand bars, roadsides, disturbed open areas; sea level to
1,600 m.; common in Guanacaste and on Pacific beaches; Limon; appar-
ently less common in the interior. Probably blooming yearlong. Florida
and southern Texas southward to Costa Rica; West Indies; Colombia
and Venezuela.

FIG. 59. Digitaria species. D. bicornis: A, two rachis internodes, showing glabrous
subsessile spikelets paired with strongly ciliate pedicellate ones; B, a single spikelet; D.
horizontalis: C, a spikelet pair, rachis bearing papillose-based hairs; D. ciliaris: D, two
views of a spikelet.

182

BURGER: FLORA COSTARICENSIS 183

Digitaria ciliaris (Retz.) Koel., Descr. Gram. 27. 1802. Panicum
ciliare Retz., Obs. 4:16. 1786. Panicum sanguinale auct., non L. Di-
gitaria adscendens (H.B.K.) Henr., Mon. Digitaria 9. 1950. Digitaria
abortiva Reeder, J. Arnold Arbor. 29:291. 1948. An extended
synonomy is provided by Veldkamp, I.e. Figure 59.

Duration indefinite; plants mat-forming, the culms long-decumbent, rooting at the
nodes; erect portions 30-60 cm. long; branching abundant from the decumbent portions
of the culms; prophylla 2 cm. long, with extra marginal nerves; their margins silky
pilose; culms ca. 2 mm. thick, hollow, thin-walled, glabrous; sheaths longer or shorter
than the internodes, more or less papillose-pilose; ligules membranaceous, 2.0-3.5 mm.
long; blades flat, 5-12 cm. long, 5-9 mm. wide, more or less papillose-pilose, especially
toward the base. Peduncles exserted up to 27 cm., glabrous; inflorescence 7-15 cm. long,
of 2-10 spreading racemes, each 7-14 cm. long, borne in 1 or 2 whorls, the common rachis
up to 2 cm. long. Spikelets paired, unequally pedicellate, the shorter pedicel 0.5-1.0 mm.
long, the longer 2.0-3.1 mm. long; rachis narrowly winged, scabrous on the angles;
spikelets of each pair alike, 2.7-3.4 mm. long, narrowly ovate, 4:1; first glume deltoid,
nerveless, 0.3-0.5 mm. long; second glume triangular 4:1, 1.7-2.0 mm. long, 3-nerved,
the margins and tip silky; sterile lemma the length of the spikelet, 3-5-nerved, short-
silky between the lateral nerves and on the margins; fertile lemma slightly shorter,
2.5-3.0 mm. long, grayish, striate; anthers 3, brownish red, 1.2-1.3 mm. long; stigmas
purple. Chromosome number n = 27.

Roadsides and open areas, sea level to 1,500 m. elevation, Pacific
and Caribbean slopes. April to August, possibly yearlong. Tropics of
both hemispheres; in the New World extending from the southern
United States to Argentina.

Digitaria costaricensis Pohl, Fieldiana, Bot. 38:5. 1976. Figure 60.

Probably perennial; plants with long decumbent rooting culm bases, up to 80 cm. long,
sometimes becoming buried and appearing rhizomatous; culms branching abundantly
from lower and middle nodes, 1-3 mm. thick, hollow, thick-walled, glabrous; prophylla
up to 2 cm. long, papillose-pilose; sheaths mostly longer than the internodes, densely
retrorsely papillose-pilose, the hairs silky, up to 3.5 mm. long; ligule a thin erose mem-
brane, decurrent on the sheath margins, 1.5-2.5 mm. long; blades soft, flat, 8-15 cm.
long, 3.5-7.0 mm. wide, softly velvety. Peduncle glabrous, exserted up to 15 cm.;
inflorescences terminal on erect leafy branches, 7-14 cm. long, narrow and erect, the 4-7
racemes borne on a short rachis up to 2-3 cm. long; several short racemes of 1-several
spikelets borne at the base of the longer racemes. Spikelets paired, rather remote on the
slender triquetrous rachis which is strongly scabrous on the angles; subsessile spikelet
reaching about to the base of the spikelet next above it; spikelets of the pair equal,
3.5-4.0 mm. long; shorter pedicel 0.5-0.7 mm. long, the longer one 2.0-3.0 mm.; spikelets
acute, narrowly ovate 3.4-4.2:1; first glume a thin evanescent nerveless truncate cuff-
like scale, ca. 0.3 mm. long; second glume and sterile lemma equal, slightly longer than
the fertile floret; both with short silky white hairs on the margins and in the outer
internerves, somewhat silky on the back above the base and with scattered silky hairs on
the remainder of the back; second glume slightly narrower than the sterile lemma, but
covering the fertile floret completely, 5-7-nerved; sterile lemma similar, 7-9-nerved, the
nerves equidistant; fertile floret 3.0-3.2 mm. long, the lemma narrowly ovate, acute,

FIG. 60. Digitaria costaricensis. A, blooming plant; B, portion of a raceme; C, fertile
floret; D, two views of a spikelet.

184

BURGER: FLORA COSTARICENSIS 185

striate, grayish, faintly 3-nerved, the palea equal; stamens 3, the anthers purple, 0.9-1.5
mm. long; stigmas purple. Mature fruit not seen.

This species occurs at middle elevations in the region east and south
of Cartago. It is a member of the section Aequiglumae Henrard,
Monog. Digitaria 641. 1950. This is a group of about 16 species native
to the American tropics and subtropics, the members having paired
spikelets with the first glume weak or absent. The second glume and
sterile lemma are subequal and usually exceed the fertile floret.
Among this group, Digitaria costaricensis seems most closely similar
to D. aequiglumis (Hack, et Arech.) Parodi, from which it differs in
the following characteristics: heavily pubescent foliage, wider leaf
blades, longer racemes, presence of a cuff-like first glume on the
spikelets, more numerous nerves of the second glume and sterile
lemma, longer anthers.

Digitaria decumbens Stent, Bothalia 3:150. 1930.

Plants perennial; culms 60-100 cm. long, branching intravaginally from the lower and
middle nodes, glabrous, thin-walled, hollow, 2-3 mm. thick; bases often long-decumbent
and rooting; prophyllum firm, strongly keeled, up to 3 cm. long; upper internodes very
elongated; sheaths mostly shorter than the internodes, glabrous or more or less
papillose-pilose above the node and near the apex; ligule membranaceous, minutely
erose-ciliate, 1.8-2.5 mm. long; blades flat, firm, narrow, acuminate, somewhat keeled
near the base, 5-20 cm. long, 3-6 mm. wide, scabrid. Peduncle exserted 5-25 cm., gla-
brous, felty-puberulent at the apex; inflorescences terminal on leafy branches, usually
composed of a single whorl of 5-7 spreading racemes, these 12-16 cm. long; rachis of
racemes triquetrous, 0.5 mm. wide, the green herbaceous margins narrower than the
whitish midrib, conspicuously scabrous on all the angles; pedicels triquetrous, scabrous;
spikelets paired, or rarely solitary by abortion, unequally pedicellate, the shorter pedicel
ca. 0.5 mm. long, the longer one up to 2.2 mm. Spikelets of the pair 3.0-3.5 mm. long,
alike; first glume a deltoid to narrowly triangular nerveless scale; second glume one-half
to two-thirds as long as the spikelet, lanceolate, ciliate; sterile lemma as long as the
spikelet, 3.0-3.5 mm. long, lanceolate, acute, with 5 evident nerves and 2 inconspicuous
marginal ones; margins of the lemma and the second internerve from the midrib ap-
pressed silky; fertile lemma chartaceous, grayish, very inconspicuously nerved, lanceol-
ate, acuminate; palea equal, both striate; anthers 3, purple, 1.2-1.6 mm. long; pollen
collapsed and empty; stigmas purple; lodicules 2, fleshy, truncate. Digitaria decumbens
is a sterile triploid, its somatic chromosome number being 2n = 27 from Costa Rican
specimens.

This species is widely cultivated in Costa Rica as a forage grass at
low and intermediate altitudes, up to 2,000 m. It is especially common
in Guanacaste. Introduced from Africa; cultivated or straying from
fields by vegetative spread.

Since D. decumbens sets no seed, it is propagated by transplanting
the stolons. The common name is Pangola.

186 FIELDIANA: BOTANY

Digitaria filiform is (L.) Koel., Descr. Gram. 26. 1802. var. villosa
(Walt.) Fernald, Rhodora 36:19. 1934. Panicum filiforme L., Sp. PL
57. 1753. Syntherisma villosa Walt., Fl. Carol. 77. 1788. Digitaria
villosa (Walt.) Persoon, Syn. 1:85. 1805. Figure 61.

Duration indefinite; plants caespitose, erect; culms slender, glabrous; nodes glabrous;
sheaths shorter than the internodes, the lower ones papillose-hirsute, the upper gla-
brous; ligule a conspicuously ciliolate membrane, 1.2-1.5 mm. long; blades narrow, 3-6
mm. wide, elongate, the upper surface with scattered elongate pustulose-based hairs.
Peduncle slender, glabrous, exserted; inflorescences solitary, terminal, 9-11 cm. long, of
3-7 ascending racemes, each 6-8 cm. long; spikelets usually in triads, the pedicels of
unequal length. Spikelets elliptical-ovate, acute, 2.0-2.2 mm. long; first glume absent;
second glume ca. half as long as the spikelet, ovate, 3-nerved, ciliate with short hairs
with club-shaped blunt tips, these conspicuous against the dark brown back of the
mature fertile lemma; sterile lemma as long as the spikelet, 5-nerved, the central inter-
nerve areas glabrous, the others with appressed hairs similar to those of the second
glume; fertile floret ca. 2.0 mm. long, the lemma dark brown, striate, the wide thin
margins nearly covering a palea of similar color and texture; anthers 3, purple, ca. 0.9
mm. long.

The above description is based largely on the specimen listed below.
The determination is somewhat doubtful, since the only available
specimen is inadequate. The club-shaped hairs of the spikelets place it
in Henrard's group Clavipilae, along with such species as D . filiformis
and D. leucocoma (Nash) Urban. Our specimen differs from typical Z).
filiformis of temperate North America in its larger spikelets and from
D. villosa in having glabrous medial internerves on the sterile lemma
and in its shorter, denser racemes. Unless more adequate specimens
are collected, we cannot be sure of its identity. San Jose, San Jose,
1,100 m., Hitchcock 8498, 22-24 October 1911.

Digitaria horizontalis Willd., Enum. PL 92. 1809. Figure 59.

Duration indefinite; plants sprawling, the culms long-decumbent and rooting at the
lower nodes, branching freely from the lower nodes; prophylla prominent, 1.5-3.5 cm.
long; culms ca. 2 mm. thick, hollow, the internodes glabrous and shining; nodes rather
prominent; foliage soft, sheaths longer than the internodes, papillose-pilose, less so
toward the top of the plant; ligule a thin brownish membrane, 1.5-1.8 mm. long; blades
flat, 3-14 cm. long, 3-9 mm. wide, velvety. Peduncle slender, exserted up to 25 cm.,
glabrous; inflorescences solitary and terminal on the main culm or on leafy branches;
panicle up to 15 cm. long, very broad, the elongated slender racemes 4-12 cm. long,
borne on a common rachis up to 4 cm. long, the lower ones whorled, the upper often
paired or solitary; rachis of racemes triquetrous, ca. 0.5 mm. wide, the narrow herbace-
ous margins narrower than the midrib, scabrous on the angles, bearing scattered elon-
gated, slender, glassy, papillose-based hairs. Spikelets paired, unequally pedicellate, the
shorter pedicel 0.3-0.5 mm. long, the longer one 1.3-2.0 mm. long; spikelets narrowly
ovate, acute, 2.1-2.4 mm. long; first glume deltoid, 0.1-0.2 mm. long; second glume ca.
half as long as the spikelet, 1.0-1.1 mm. long, narrowly triangular, 3-nerved, ciliate on

J&t

FIG. 61. Digitaria species. D. velutina: A, panicle and two views of a spikelet; D.
filiformis, var. villosa: B, two views of a spikelet; D. argillacea: C, two views of a
spikelet.

187

188 FIELDIANA: BOTANY

margins and tip; sterile lemma as long as the spikelet, lanceolate, acute, 7-nerved, ciliate
with short, silky hairs; fertile lemma stramineous or grayish, minutely striate, slightly
shorter than the sterile lemma; caryopsis lanceolate, tan, ca. 1.8 mm. long. Chromosome
number n = 18 from Central American material.

Occasional on Caribbean and Pacific beaches, also at Tuis, Puerto
Viejo and Siquirres. Blooming July to February, probably yearlong.
Southern Florida; West Indies; tropical America from Guatemala to
Brazil and Paraguay.

The nomenclature of this species is much confused. Our material has
been identified by Veldkamp.

Digitaria insularis (L.) Mez ex Ekman, Beitr. Gramineenfl. Mis-
iones. Ark. Bot. 11:17. 1912. Andropogon insulare L., Syst. Nat. ed.
10:2:1304. 1759. Trickachne insularis (L.) Nees, Agrost. Bras. 86.
1829. Figure 63.

Vigorous perennial; plants 80-130 cm. tall, erect; bases of culms with swollen, woolly
bracted innovations; culms branching from middle and lower nodes, up to 3 mm. thick,
hollow, glabrous; nodes glabrous; sheaths mostly papillose-pilose, rarely glabrous;
ligules 4-6 mm. long, thin, tan, membranaceous; blades lax, flat, 20-50 cm. long, 10-17
mm. wide, scabrid. Peduncle glabrous, exserted 10-50 cm.; inflorescences terminal on
the main culm or on leafy branches, narrow, cylindric, 20-35 cm. long, 2-10 cm. wide;
racemes numerous, ascending, mostly 10-15 cm. long, the axis slender, trigonous, scab-
rous on the angles; spikelets paired, equal, one pedicel 0.7-2.0 mm. long, the other
2.5-5.0 mm. long, both slender, trigonous, scabrous. Spikelets narrowly ovate, caudate,
4.2-4.6 mm. long, densely covered with abundant fawn-colored hairs up to 6 mm. long
and extending beyond the summit of the spikelet as much as 5 mm.; first glume mem-
branaceous, nerveless, triangular to ovate; second glume lanceolate, 3.5-4.5 mm. long,
3-5-nerved, ciliate on the margins; sterile lemma as long as the spikelet (4.1-4.5 mm.
long), narrowly ovate, acuminate, 7-nerved, the nerves obscured by the dense marginal
hairs; fertile lemma narrowly ovate, acuminate, castaneous, minutely striate, 3.2-3.6
mm. long; palea about equal; anthers 3, rarely exserted, 1.0-1.2 mm. long, tan. Chromo-
some number n = 18 from Costa Rican specimens.

Beaches, roadsides and forest margins, pastures; common in
Guanacaste, also collected from Pigres, Atenas, Puente de Mulas, and
Guacimo; elevations sea level to 1,200 m.; probably blooming yearlong.
The plants are somewhat weedy. Florida and southern Texas to
Arizona, southward to Argentina; West Indies.

The fertile floret is elevated above the insertion of the second glume
and sterile lemma on a thick rachilla internode 0.2-0.4 mm. long. This
feature was formerly used as a generic character to separate
Trichachne from Digitaria.

Digitaria longiflora (Retz.) Pers., Syn. PI. 85. 1805. Paspalum
longiftorum Retz., Obs. Bot. IV:15. 1786. Figure 62.

FIG. 62. Digitaria longiflora. A, blooming plant; B, two views of a spikelet; C, verru-
cose hair from a spikelet, greatly enlarged.

189

190 FIELDIANA: BOTANY

Duration indefinite; plants forming large patches by means of long, abundant, freely
branching stolons; flowering culms ascending to erect, 10-25 cm. tall, branching occa-
sionally from the lower nodes; culms 1 mm. or less thick, hollow, glabrous; nodes dark,
contracted; leaves 3-4 per culm, mostly clustered near the base; lower sheaths overlap-
ping, the internodes short; peduncle very elongated, exserted, forming more than half
the height of the plants; ligule a thin whitish membrane, 0.5-1.0 mm. long; leaf blades
flat, 1.5-4.0 cm. long, 3-5 mm. wide, 5-8 x longer than wide, glabrous except for a few
small cilia near the subcordate base. Inflorescence of 2 or rarely 3 conjugate slender
racemes borne at the tip of the peduncle, widely spreading; racemes 4-5 cm. long; rachis
flat, green, ca. 1 mm. wide, naked for 1-2 mm. at the base; spikelets crowded, borne in
trios, these alternating along the sides of the narrow midrib. Spikelets of each trio alike,
but borne on pedicels of unequal length, elliptic or slightly obovate 2:1, acute at the
apex, 1.2-1.3 mm. long; first glume absent; second glume and sterile lemma equal,
completely covering the fertile lemma or only its tip exposed; second glume 5-nerved,
minutely pubescent between all of the nerves and on the margins; sterile lemma similar
but 7-nerved, pubescent on the margins and outer internerves, the internerves adjacent
to the midrib glabrous; fertile lemma grayish, ca. 1.2 mm. long, minutely striate, acute
at the apex, enclosing a palea of equal length; anthers 3, purple, 0.7-0.8 mm. long;
stigmas purple.

Sandy beach of the Caribbean at Tortugero, Pohl & Lucas 13030.
December. This is apparently the only collection from the mainland of
North America. West Indies. Introduced from the Old World; native
to Africa and Asia.

Digitaria pittieri (Hack.) Henrard, Monog. Gen. Digitaria 570.
1950. Panicum pittieri Hack., Oesterr. Bot. Z. 51:367. 1901. Valota
pittieri (Hack.) Chase, Proc. Biol. Soc. Wash. 19:188. 1906. Trichachne
pittieri (Hack.) Hitchc., Proc. Biol. Soc. Wash. 40:83. 1927. Figure 63.

Duration indefinite; plants erect or scrambling, the culm bases decumbent and rooting;
culms branching freely, ca. 1 mm. thick, hollow, glabrous; prophylla prominent, 2-4 cm.
long, thin and soft, with 2 minor nerves marginal to each keel; sheaths loose, longer or
shorter than the internodes, more or less papillose-hirsute; blades soft, rather short and
broad, 6-10 cm. long, 7-11 mm. wide, flat, more or less papillose-pilose on both sides;
ligule membranaceous, 1.0-2.5 mm. long. Peduncle slender, glabrous, exserted up to 25
cm. Inflorescences numerous, terminal on leafy branches, 6-12 cm. long, of 5-10 slender
ascending or rarely horizontally spreading racemes borne on a common rachis 1-4 cm.
long; rachis and branches slender, triquetrous, bearing scattered, thin, elongate,
pustulose-based hairs up to 4 mm. long; spikelets paired, rarely in triads near the base of
the raceme, or solitary and accompanied by a minute abortive spikelet; pedicels slender,
angular, the shorter one of the pair 0.2-0.3 mm. long, the longer one 1.5-3.0 mm. long.
Spikelets dorsally compressed, lanceolate, 3.0-3.7 mm. long, marginally ciliate with soft
erect purple hairs, these surpassing the tip of the spikelet up to 1 mm.; first glume
obsolete or minute, up to 0.3 mm. long, truncate, deltoid, or bidentate, glabrous; second
glume ca. three-fourths as long as the spikelet, narrowly triangular, 3-nerved, 2.0-2.7
mm. long, marginally ciliate with erect hairs; sterile lemma as long as the spikelet,
7-nerved, heavily marginally ciliate with shorter hairs in the internerves; fertile floret
lanceolate, 2.8-3.0 mm. long, firm, castaneous, longitudinally striate, acuminate, the

FIG. 63. Digitaria species. D. violascens: A, spikelet triad; B, spikelet; C, fertile
floret; D. insularis: D, two views of a spikelet; E, fertile floret; D. pittieri: F, spikelet
pair attached to the rachis.

192 FIELDIANA: BOTANY

margins thin; palea similar in color and texture, ca. as long as the lemma; caryopses
produced; anthers 3, tan, 1 mm. long.

Endemic to Costa Rica; rare, Meseta Central and Cartago Valley,
1,000-1,400 m. elevation. Pastures, roadsides, thickets, river banks.
September to February.

This species is readily distinguished from others of the genus Di-
gitaria by the dense purple marginal hairs of the spikelets. The type
number, Pittier & Durand 6945, was collected by Tonduz as his
number 749, from the banks of the Rio Tiliri near San Jose in 1892. The
species was subsequently collected in 1911 at Alajuela and San Jose, at
Dulce Nombre near Cartago in 1924, and at Ujaras in 1936. It has not
been collected since, but may persist in the Meseta Central. The elon-
gated shape of the spikelets and their hairiness suggest a relationship
toD. insularis. The elongated trichomes of the inflorescence branches
are similar to those of D. horizontalis.

Digit aria setigera Roth ex Roem. & Schult., Syst. Veg. 2:474. 1817.
var. setigera D. sanguinalis auct., non Scop. D. adscendens auct., non
Henrard. An extensive synonymy is given by Veldkamp, I.e.

Duration indefinite; plants forming mats or patches, the culms glabrous, hollow,
1.5-2.5 mm. thick, long-decumbent and rooting at the lower nodes; erect portions of the
culms up to 120 cm. long; branching free from lower nodes; prophylla up to 8 cm. long,
with multiple lateral nerves; sheaths mostly shorter than the internodes, more or less
papillose-pilose; ligule a tan membrane, 2.5-3.5 mm. long; blades flat, 4-28 cm. long, 4-12
mm. wide, usually with a few papillose hairs near the base on the upper surface, some-
times pilose all over, the surfaces usually scabrous. Peduncles long-exserted, up to 40
cm. long, glabrous; inflorescences terminal on leafy branches, usually 10-15 cm. long,
composed of 1 to several whorls of racemes borne on a common axis up to 6 cm. long;
racemes 3-11, each 5-15 cm. long, spreading; rachis of racemes winged, 0.5-1.0 mm.
wide, scabrous on the margins, the midrib keeled. Spikelets paired, unequally pedicel-
late, the shorter pedicel of the pair 0.3-0.8 mm. long, the longer 1.7-2.7 mm. long;
spikelets 2.4-3.5 mm. long, ovate 3:1 to 4:1; first glume absent or a minute cufflike scale
0.1 mm. long; second glume 0.7-1.3 mm. long, less than half the length of the spikelet,
rectangular or bilobed at the apex, 1-3-nerved, ciliate, the hairs overtopping the scale;
sterile lemma the length of the spikelet, 5-7-nerved, the central pair of nerves remote
from the midrib; lateral internerves and margins of the lemma silky-ciliate; fertile lemma
slightly shorter than the sterile lemma, tan or grayish, striate, faintly 3-nerved, acumi-
nate, its palea equal in length; anthers 3, reddish brown, 0.7-1.3 mm. long; stigmas
purple; caryopsis elliptical, whitish-opalescent. Chromosome number n = 35, 36 from
Costa Rican specimens.

Occasional in open places and roadsides; Colonia Carmona, San Jose,
Guapiles, Limon, Isla del Coco; sea level to 1,100 m. Caribbean coast of
Honduras. Not previously recognized from Central America, but

BURGER: FLORA COSTARICENSIS 193

probably occurring elsewhere in the American tropics. Tropical Asia,
Australia, Jamaica, Surinam.

Digitaria velutina (Forsk.) Beauv., Ess. Nouv. Agrost. 51. 1812.
Phalaris velutina Forsk., Fl. Aegypt. Arab. 17. 1775. NotZ). velutina
(DC) Hitchc., Proc. Biol. Soc. Wash. 40:84. 1927. Figure 61.

Duration indefinite; plants 30-60 cm. tall; bases of culms long-decumbent and rooting,
forming circular patches; branching mostly from the rooted basal portions; prophylla
2-keeled, 1.5-2.5 cm. long; culms 1.5-1.8 mm. thick, hollow, thin-walled, glabrous; nodes
contracted, glabrous; leaves 1-4 per culm; sheaths shorter or longer than the internodes,
papillose-pilose, keeled near the apex; ligule a tan membrane, 1.8-2.0 mm. long; leaf
blades thin, flat, 6-10 cm. long, 6-10 mm. wide, appressed-pilose, somewhat keeled near
the subcordate base. Peduncle slender, exserted 14-30 cm., glabrous, the interior filled
with pith; inflorescences terminal on apical peduncles. Inflorescence panicled, 8-12 cm.
long, 10-14 cm. wide, composed of 11-28 slender branches, the lowermost ones usually
whorled, the upper ones paired or solitary; lower branches up to 10 cm. long, pinnately
branched with spreading branches 2-3 cm. long, the upper branches simple; rachis
triquetrous, narrowly winged, scabrous on the angles and bearing scattered long hairs;
the spikelets paired, equal, one subsessile, the other on a pedicel up to 1.5 mm. long.
Spikelets purplish, 1.8-2.0 mm. long; first glume minute, ca. 0.1 mm. long, or obsolete;
second glume 1.5-1.7 mm. long, oblong to ovate, 3-nerved, the internerves villous;
sterile lemma as long as the spikelet, 5-nerved, villous on the marginal internerves and
edges; fertile lemma exposed near the tip, grayish, faintly nerved, ovate, acute, the
margins covering the edges of a slightly shorter palea of similar texture; caryopsis
elliptical, whitish-opalescent, 1.2-1.3 mm. long. Chromosome number n = 9.

Our only specimen is the following: San Jose, Ciudad Universitaria,
disturbed subsoil in area of new library building. Pohl & Davidse
11075, 11 September 1968. Arabia to tropical Africa. Apparently pre-
viously unreported from the western hemisphere.

Digitaria violascens Link, Hort. Berol. 1:229. 1827. Panicum vio-
lascens (Link) Kunth, Rev. Gram. 1:33. 1829. An extended synonomy
is given by Veldkamp, Rev. Digitaria Malesia 63 (1972). Figure 63.

Duration indefinite; plants erect, in small tufts; culms mostly unbranched, slender, ca.
1 mm. thick, hollow, thin-walled, glabrous; nodes glabrous, not prominent; foliage
mostly basal, the uppermost leaf blade reduced; sheaths shorter than the internodes,
glabrous; ligule an erose membrane 1.0-2.3 mm. long; blades few per culm, 4-17 cm. long,
3-5 mm. wide, glabrous, sometimes scaberulous on the upper surface or with a few
elongated papillose-based hairs on the upper surface near the base. Peduncle slender,
exserted up to 13 cm.; inflorescences solitary and terminal on leafy culms, 3-10 cm. long,
consisting of 2-7 slender, arching racemes borne in 1-2 whorls, the common rachis up to 3
cm. long; rachis of racemes flattened, 0.5-0.7 mm. wide, with a herbaceous border, the
edges scabrous. Spikelets usually borne in triads, occasionally 4 or 5 together and rarely
solitary by abortion of spikelets; pedicels of varying length, the shortest of the triad

194 FIELDIANA: BOTANY

0.2-0.3 mm. long, the middle one 0.8-1.0 mm., the longest 1.3-2.0 mm. long, scabrous,
the apex dilated into a disk. Spikelets of each group equal, ovate 2:1, 1.4-1.5 mm. long,
first glume absent, the second glume and sterile lemma thin, white; second glume 1.3-1.4
mm. long, slightly shorter and narrower than the spikelet, usually 3-nerved, rarely
5-nerved, the nerves anastomosing near the tip; sterile lemma as long as the spikelet,
usually 5-nerved, rarely 7-nerved; internerves of the sterile lemma and second glume
bearing appressed white silky hairs, their walls verrucose-roughened under 400 x
magnification; fertile floret about as long as the spikelet, deep chestnut brown at matur-
ity; lemma minutely striate, faintly 3-nerved; palea similar; caryopsis elliptical, 1.0-1.1
mm. long, white, opalescent; anthers 3, reddish, 0.4-0.6 mm. long. Chromosome number
n = 18 from Costa Rican specimens.

Open roadsides and waste ground, sea level to 1,500 m. elevation;
San Jose area, General Valley, San Vito, Golfito. Blooming yearlong.
Tropics of Asia and Australia; introduced in the western hemisphere.

This species may be confused with D. panicea (Sw.) Urban, which
differs by having a narrow triquetrous rachis, spikelets bearing capi-
tate hairs, and ciliolate ligules.

ECHINOCHLOA Beauvois

REFERENCES: F. W. Gould, M. A. Ali, & D. E. Fairbrothers, A
revision of Echinochloa in the United States, Amer. Midi. Naturalist
87:36-59. 1972. A. S. Hitchcock, The North American species of
Echinochloa, Contr. U.S. Natl. Herb. 22:133-153. 1920. K. M.
Wiegand, The genus Echinochloa in North America, Rhodora
23:49-65. 1921.

Annual or perennial, caespitose, decumbent, or rhizomatous grasses; culms usually
solid, the lumen filled with aerenchyma; ligule absent or consisting of a dense row of stiff
hairs. Inflorescence a terminal panicle, the branches mostly simple, bearing paired or
clustered subsessile spikelets. Disarticulation below the glumes, the spikelets elliptical
or ovate, dorsally compressed, plano-convex; first glume one- to three-fourths as long as
the spikelet, ovate, apiculate, 3-5-nerved; second glume and lower lemma subequal, as
long as the spikelet, apiculate or the lemma bearing a terminal awn; second glume
5-7-nerved, convex, usually hispid on the nerves; lower lemma similar but usually 5-
nerved and often tapering into a stiff, antrorsely scabrous awn; lemma containing a
well-developed flat, membranaceous palea and in some species a staminate flower; sec-
ond floret with a shiny, coriaceous, stramineous, longitudinally striate, ovate or elliptical
lemma, its flat margins covering the edges of a flat palea of similar texture, except near
the emergent tip; tip of lemma apiculate or beaklike; lodicules 2, truncate; stamens 3, the
anthers yellow or orange; stigmas 2, plumose, purple.

The species of Echinochloa frequent rich, moist, disturbed soil or
occur in shallow water. The apiculate or awned spikelets, solid culms,
and the usual absence of a ligule are marks of recognition. The genus is

BURGER: FLORA COSTARICENSIS 195

similar to Panicum in many respects, differing in the awned or apicu-
late spikelets and the flat, not inrolled, margins of the fertile lemma.
Echinochloa is similar to Hymenachne in its solid, aerenchymatous
culms and hygrophilous habit. (Panicoideae: Paniceae.)

KEY TO SPECIES OF Echinochloa

la. Ligule a dense row of stiff bristles; lower floret staminate 2

Ib. Ligule absent; lower floret neuter 3

2a. Plants with short scaly rhizomes; spikelets awnless, 2.9-3.5 mm. long; fertile

floret 2.5-2.7 mm. long; anthers 1.0-1.5 mm. long E. pyramidalis

2b. Plants not rhizomatous, culms often decumbent and rooting; spikelets 4.5-6.0
mm. long, sometimes with awn up to 18 mm. long; fertile floret 2.5-5.0 mm.

long; anthers 1.5-3.6 mm. long E. polystachya

3a. Spikelets awnless, borne in 4 rows on short racemes 1-2 cm. long; fertile floret

1.9-2.2 mm. long E. colonum

3b. Spikelets awn-tipped or awned, irregularly crowded along 4-6 cm. long racemes;
fertile floret 2.5-2.8 mm. long E. crus-pavonis

Echinochloa colonum (L.) Link, Hort. Berol. 2:209. 1833.
Panicum colonum L., Syst. Nat. ed. 10. 2:870. 1759. An extended
synonomy is given by Gould et al. Figure 64.

Plants annual, erect and caespitose, or spreading and rooting from the lower nodes;
culms usually 20-60 cm. tall, 2-3 mm. thick, hollow or filled with aerenchyma, branching
near the base; lower nodes appressed-hispid, the upper glabrous; prophylla prominent,
up to 8 cm. long; sheaths glabrous, shorter than the internodes, somewhat keeled; ligule
absent; blades flat, 8-22 cm. long, 3-8 mm. wide, glabrous or with a few papillose-based
marginal setae near the base. Peduncle exserted up to 10 cm.; inflorescence slender, 2-12
cm. long, composed of 5-10 short, spikelike erect or ascending racemes, racemosely
arranged along the slender, angular, scabrous rachis; individual racemes 0.7-2.0 cm.
long, the rachis flattened; spikelets paired, minutely pedicellate, in 4 rows along the
lower side of the rachis, which is papillose-hispid at its base and more or less along its
length. Spikelets ovate, acute, not awned or barely apiculate, flattened on the first
glume side, strongly turgid on the second glume side, often purple-blotched, 2.3-2.9 mm.
long, the visible bracts appressed-hispid along the nerves; first glume 1.0-1.5 mm. long,
3-nerved, broadly ovate, acute; second glume very convex, ovate, apiculate, 5-nerved,
as long as the spikelet; sterile lemma flat, 5-nerved, as long as the spikelet, concealing an
elliptical flat palea nearly as long; fertile lemma 1.9-2.2 mm. long, indurate, smooth and
shining, faintly longitudinally striate and 5-nerved, elliptical 3:2, terminating in a minute
greenish withering tip; palea flat, its margins overlapped by the flat edges of the lemma
except at the tip; anthers 3, yellow, 0.7-0.8 mm. long. Chromosome number n = 27 from
Costa Rican plants.

Roadsides, pastures, beaches, banana groves, sea level to 1,100 m.,
but most common at low elevations near the coasts. June to December.
Widespread in warm climates of the world, apparently introduced
from the Old World. Certain plants may have leaf blades with trans-
verse purple markings.

FIG. 64. Echinochloa colonum. A, inflorescence; B, two views of a spikelet; C, two
views of the fertile floret.

196

BURGER: FLORA COSTARICENSIS 197

Echinochloa crus-pavonis (H.B.K.) Schult., Mant. PL 2:269. 1824.
Oplismenus crus-pavonis H.B.K., Nov. Gen. & Sp. 1:108. 1816. An
extended synonomy is given by Gould et al. Figure 65.

Duration indefinite, probably annual; plants 80-150 cm. tall, the culms erect or the
bases decumbent and rooting from the lower nodes, branching from the lower nodes,
thick and spongy, often 1 cm. or more thick, glabrous; nodes swollen, glabrous; lumen of
internodes filled with aerenchyma which contains vascular bundles; prophylla promi-
nent, up to 12 cm. long; sheaths shorter than the internodes, loose, glabrous, often
purplish; ligule absent, a rounded ridge taking its place; blades flat, glabrous, usually
12-60 cm. long, 7-25 mm. wide, scabrous-margined. Inflorescences terminal on the main
culm or on erect leafy intravaginal branches, 10-30 cm. long, oblong to narrowly pyrami-
dal, the branches, except the lowermost, mostly overlapping, 4-6 cm. long. Spikelets
mostly paired, densely and irregularly clustered along the primary or secondary
branches, obscuring the axes; rachis and branches angular, scabrous, often bearing
pustulose-based stiff glassy hairs. Spikelets 2.8-3.5 mm. long, often purple, awn-tipped
or awned, ovate; first glume 1.4-1.7 mm. long, broadly ovate or orbicular, abruptly
acuminate, the margins enwrapping the base of the second glume, 3- or rarely 4-nerved;
second glume as long as the spikelet, 5-nerved, ovate, cuspidate, bulging, bearing more
or less appressed stiff hairs on the nerves and minutely hispid between them; sterile
lemma as long as the spikelet, ovate, 5-nerved, similar to the second glume, enclosing a
flat membranaceous elliptical palea two-thirds to three-fourths as long, awn-tipped or
bearing a stiff scabrous awn up to 11 mm. long; fertile lemma 2.5-2.8 mm. long, ovate,
caudate, shiny, faintly-nerved, tapering into a herbaceous withering tip; palea equal to
the lemma and similar in texture; anthers 3, dark, 1.0-1.2 mm. long; lodicules small,
truncate. Chromosome number of E. crus-pavonis is n = 18 from a number of Costa
Rican specimens.

Wet open areas and marshes, roadsides; sea level to 1,700 m. eleva-
tion. Cartago area, San Jose, Nuestro Amo, Guanacaste. June to Oc-
tober. Probably common, but little collected. Southern United States
to Argentina; tropical Africa; Australia.

This species exhibits a great deal of variation in awn length. Awn-
less specimens appear very different from long-awned types, but fun-
damental spikelet structure is the same. This species has been con-
fused with E. crusgalli (L.) Beauv., but differs from the latter in the
lack of minute bristles at the apex of the shiny part of the fertile
lemma, as well as in chromosome number. Var. macera (Wiegand)
Gould is said to have vestigial or absent palea within the sterile lemma.
All of the Costa Rican specimens have a well-developed palea and
belong to var. crus-pavonis.

Echinochloa poly st achy a (H.B.K.) Hitchc., Contr. U.S. Natl.
Herb. 22:135. 1920. Oplismenus polystachyus H.B.K., Nov. Gen. &
Sp. 1:107. 1816. Figure 65.

Duration indefinite, probably perennial; culms 1-3 m. or more long, decumbent and
rooting abundantly at the lower nodes, sometimes forming large floating patches, gla-

FIG. 65. Echinochloa species. E. cms-pavonis: A, base of leaf blade, lacking a ligule;
B, base of culm; C, inflorescence; D, two views of a spikelet; E. polystachya: E, base of
leaf blade, showing ligule; F, two views of a spikelet.

198

BURGER: FLORA COSTARICENSIS 199

brous, spongy, up to 1.5 cm. thick, the lumen filled with aerenchyma containing vascular
bundles; nodes glabrous or strongly appressed-hispid, swollen; branching intravaginal
from the middle nodes; prophylla prominent, up to 13 cm. long, hispid-margined and
with a conspicuous tuft of hispid hairs at the tip; sheaths shorter or longer than the
internodes, glabrous or appressed papillose-hispid; ligule a dense V-shaped line of stiff
tan hairs, 2-4 mm. long, continued onto the upper sheath margins as a few papillose-
hispid hairs; leaf blades soft, flat, up to 50 cm. long and 3.5 cm. wide, with a prominent
white midrib, glabrous, the margins scabrous, surfaces scabrous toward the tip.
Inflorescences terminal; peduncle ridged, glabrous, up to 15 cm. long; panicle 20-35 cm.
long, narrowly cylindrical, 2-5 cm. wide, the numerous ascending branches 2-11 cm.
long, rachis angular, scabrous, with tufts of stiff, glassy, papillose-based hairs at the
bases of the branches, along the rachises of the branches, and on the pedicels; spikelets
subsessile or on pedicels up to 1 mm. long, their apices dilated into disks. Spikelets
paired, in trios, or irregularly grouped on the lower sides of the primary branches,
4.5-6.0 mm. long, elliptic or narrowly ovate, apiculate or awned, short-hispid on the
nerves, greenish; first glume 1.9-4.2 mm. long, 5-7-nerved, broadly deltoid-ovate, clasp-
ing the base of the second glume, its margins minutely ciliate; second glume and lower
lemma about equal, as long as the spikelet; second glume convex, 5- or usually 7-nerved,
apiculate or with an awn up to 7.5 mm. long; lower lemma usually 5-nerved, flat, apicu-
late or with an antrorsely scabrous awn up to 18 mm. long, the palea elliptical, scabrous
on the nerves, ca. as long as the lemma, enclosing 3 stamens with orange anthers 1.5-3.6
mm. long (usually longer than those of the upper floret); upper floret 2.5-5.0 mm. long,
the coriaceous elliptical lemma tapering into a laterally flattened greenish herbaceous
beak up to 1 mm. long; palea similar to the lemma and about as long; lodicules 2,
truncate; anthers 3; stigma purple, laterally exserted. Chromosome number n = 54 from
Costa Rican specimens.

Marshes near the coasts, often in standing water; Limon area,
Cahuita, Tarcoles. June to September. Southern coast of the United
States, through Mexico and Central America to Argentina; Caribbean
Islands.

This is the largest of the Central American species of Echinochloa
and the most hygrophilous. Large stands are seen in marshes and
possibly are grazed by livestock. The form with pubescent nodes and
sheaths has been distinguished as var. spectabilis (Nees) Martinez,
Rev. Arg. Agron. 9:318. 1942, based upon Echinochloa spectabilis
(Nees) Link. None of our Costa Rican specimens is pubescent.

Echinochloa pyramidalis (Lam.) H. & C., Contr. U.S. Natl. Herb.
18:345. 1917. Panicum pyramidale Lam., Tabl. Encycl. 1:171. 1791.
Echinochloa guadeloupensis (Hack.) Wiegand, Rhodora 23:63. 1921.
Panicum spectabile, var. guadeloupense Hack., Notizbl. Bot. Gart.
Berl. 1:328. 1897. Figure 66.

Perennial, with short scaly creeping rhizomes; culms erect or sometimes decumbent
and floating in water, up to 2 m. long; usually unbranched except for decumbent por-
tions, lower nodes sometimes producing prop roots, glabrous, up to 1 cm. thick, solid,

FIG. 66. Echinochloa pyramidalis. A, panicle; B, base of culm with rhizome; C, two
views of a spikelet; D, two views of a fertile floret.

200

BURGER: FLORA COSTARICENSIS 201

the lumen filled with aerenchyma containing vascular bundles; nodes glabrous, swollen;
sheaths mostly shorter than the internodes, glabrous or papillose-hispid on the back;
papillose-hispid on the upper margins below the ligule, somewhat keeled above; ligule a
dense row of stiff tan hairs, 1-4 mm. long, those of the lower leaves longer, continued
onto the upper sheath margins as a row of papillose-based hairs; leaf blades flat or
somewhat keeled and folded near the base, glabrous, with a broad whitish midrib;
margins scabrous, length 15-70 cm., width 5-13 mm., apex caudate-acuminate, base
rather narrow. Peduncle smooth, cylindrical, exserted up to 30 cm.; inflorescence an
open cylindrical panicle, tapering to a narrow apex, 13-45 cm. long, 2-10 cm. wide, with
numerous simple lax ascending subverticillate branches up to 10 cm. long, the lower
much longer than the upper; rachis angular, scabrous, exposed between the lower
branches, bearing tufts of stiff pustulose-based glassy hairs around and below the bases
of the branches and scattered single hairs along the primary branches; spikelets subses-
sile in small clusters on short secondary branches, mostly below the primary branch.
Spikelets elliptical 2:1, 2.9-3.5 mm. long, turgid, apiculate, greenish, often with purple
blotches; first glume deltoid, apiculate, 1.5-2.2 mm. long, 5-nerved; second glume and
lower lemma appressed-hispid on the nerves above the middle, as long as the spikelet;
second glume 5-nerved, the nerves equidistant; lower lemma 5-nerved, the lateral
nerves in pairs near the margins; lemma containing a palea nearly as long, elliptical,
often purple; stamens 3, the anthers yellow, 1.0-1.5 mm. long; fertile floret 2.5-2.7 mm.
long; lemma shining, stramineous, faintly 5-nerved; tip greenish, acute; upper margins
minutely ciliolate; palea flat, equal to the lemma; anthers 3, shorter than those of the
lower floret; lodicules small, truncate. Chromosome number n = 18 from a Nicaraguan
specimen.

This African species is known from Costa Rica only by the following
specimen: Guanacaste, Finca La Taboga, 16 January 1969, P. & D.
11661. It also occurs around the Lago de Nicaragua and on the Carib-
bean Island of Guadeloupe. July and January.

ECHINOLAENA Desvaux

Much-branched decumbent annual; inflorescence a solitary reflexed unilateral spike
borne at the tip of a bracted peduncle; spikelets pectinately arranged in 2 rows on the
lower side of a flattened rachis, one spikelet terminating the rachis; first glume coriace-
ous, convex below but flattened toward the tip, many-nerved, much longer than the
remainder of the spikelet; second glume boat-shaped, acuminate, ca. two-thirds as long
as the first; lower lemma nearly as long as the second glume, herbaceous, 5-nerved, with
a prominent membranaceous palea and a staminate flower; upper lemma shorter than
the lower one, smooth and shining, coriaceous, cucullate at the apex, the margins thin
and exposed near the base, inrolled near the tip; basal callus prominent, truncate, rather
fleshy.

Echinolaena is a small genus of a few tropical American and African
species. (Panicoideae: Paniceae.)

Echinolaena gracilis Swallen, J. Wash. Acad. Sci. 23:457. 1933.
Figure 67.

FIG. 67. Echinolaena gracilis. A, blooming plant; B, two views of a spikelet; C, two
views of a fertile floret.

202

BURGER: FLORA COSTARICENSIS 203

Plants trailing, only the tips of the branches ascending; culms rooting at the nodes,
hollow, appressed-pilose, often purplish, up to 50 cm. long; prophylla ca. 10 mm. long;
nodes bearded; leaf sheaths 1.5-2 cm. long, much shorter than the internodes; strongly
papillose-hispid; culms hollow, appressed-pilose, often purplish; ligule an arc of stiff
hairs, ca. 0.5 mm. long; blades rather firm, 2-4 cm. long, 5-6 mm. wide, cordate at the
base, with conspicuous whitish marginal bands, papillose-hispid on the margins and
upper surface at the base, with a few scattered short hispid hairs on the upper surface,
glabrous beneath; peduncle short or included in the sheath; spike 1, reflexed, 2-2.5 cm.
long, a short stiff bract at the apex of the peduncle; spikelets 7-10.5 mm. long; first glume
stiff, coriaceous, linear- triangular, acuminate, prominently ribbed on the outer surface,
the upper third somewhat deflected to one side; outer surface prominently pustulose-
hispid with spreading hairs; second glume herbaceous, broadly ovate, convex acuminate,
9-nerved, papillose-hispid near the tip, 6-6.5 mm. long; lower lemma herbaceous, ovate,
acute, 5-nerved, slightly hispid near the tip, the palea nearly as long as the lemma;
flower staminate; second floret shorter than the first, the lemma glabrous, smooth and
shining, coriaceous, 3.6-3.7 mm. long, elliptical, faintly 5-nerved, the margins covering
the edges of the palea, thin and membranaceous near the base, somewhat inrolled above.
Chromosome number n = 10 from a Venezuelan specimen.

Known in Costa Rica only by the following specimen: Guanacaste,
open Curatella-Byrsonima savanna, road to Las Animas, 2 km. E of
Carretera Interamericana, elevation 200 m. , 4 December 1968, Pohl &
Davidse 11527. Guatemala and Belize, northwestern Costa Rica; Co-
lombia, Venezuela. Apparently rare.

ELEUSINE Gaertner

Caespitose or somewhat stoloniferous grasses; inflorescence of solitary or usually
whorled one-sided spikes; spikelets sessile, densely imbricated in 2 rows along the lower
side of a flattened rachis, laterally compressed and keeled, disarticulating above the
glumes and between the florets; first glume 1-nerved, the second 5-nerved, both shorter
than the lowermost floret; florets several; lemmas awnless, 3-nerved, the lateral nerves
close to the midnerve; seed loose in the thin pericarp, strongly ridged.

Eleusine is a small genus of less than 10 species, native to warmer
parts of Africa and Asia. Our species is widespread as a weed in warm
climates of the entire world. The genus is most closely related to
Dactyloctenium. Although both genera have unilateral spikes, their
spikelets are more similar to those of other genera of the Eragrosteae
than to the Chlorideae. (Chloridoideae: Eragrosteae.)

Eleusine indica (L.) Gaertn., Fruct. & Sem. 1:8. 1788. Cynosurus
indicus L., Sp. PI. 72. 1753. Figure 68.

Annual; culms 15-70 cm. long, erect or spreading, branching from the base, rarely
from culm nodes; lower nodes often rooting; culms glabrous, hollow, thick-walled; stems
leafy, the sheaths mostly overlapping, somewhat keeled, glabrous except for long soft
hairs on their upper margins and the throat; ligules 0.5-1.0 mm. long, membranaceous,
lacerate; leaf blades 5-30 cm. long, 2-5 mm. wide, mostly folded, glabrous beneath, with

FIG. 68. Eleusine indica. Blooming plant, spikelet, floret, seed.

204

BURGER: FLORA COSTARICENSIS 205

scattered long weak hairs above; peduncle glabrous, solid, pithy, exserted 6-20 cm., with
a tuft of conspicuous hairs at the tip; inflorescence of 2-6 spikes, either all in one whorl, or
with a solitary spike borne 1-2 cm. below; spikes 1.5-9 cm. long, the rachis flattened,
0.7-1 mm. wide; spikelets 4-5 mm. long; first glume 1.5-2.2 mm. long, 1-nerved, lanceo-
late as folded; second glume obscurely 5-nerved, 2.2-2.8 mm. long, narrowly ovate as
folded, acute; florets 4-7; lemmas 2-3 mm. long, narrowly ovate as folded, glabrous;
nerves 3, the lateral ones close to the keel, rarely an extra pair near the margins; keels
scabrid; palea slightly shorter than the lemma, the keels salient, scabrid, converging to a
boat-shaped tip; anthers 3, 0.2-0.5 mm. long, purplish. Chromosome numbers n = 9, 18.

Common; open, disturbed sites; sea level to 1,500 m. elevation.
Blooming is most common during the rainy season, but probably oc-
curs to some extent yearlong. Introduced from the Old World; wide-
spread in the Americas from the northern United States to southern
South America.

This is a very common weedy grass. Where it is trodden, it tends to
form flat circular patches. Local name: Pata de gallina. Although most
specimens have the nerves of the lemma very close to the keel, two
collections from Costa Rica have an extra pair of nerves near the
margins.

ELYTROSTACHYS McClure

Tall, hollow-stemmed bamboos; rhizomes pachymorphous; clumps of numerous elon-
gated culms, becoming dependent on trees; internodes cylindrical, thin-walled; initial
lateral bud 1 per node, but the primary branch soon rebranching from the base and
producing a tuft of numerous slender leafy branches, usually with one larger than the
rest; primary culm sheaths with narrow, attenuate, very strongly reflexed blades;
auricular bristles elongate, flattened, very conspicuous on new shoots; foliage blades not
visibly tessellate. Inflorescences borne on leafy or leafless stems, composed of pseudo-
spikelets. These are bracted structures having several orders of branches, each sub-
tended by a broad, short prophyll. The ultimate branchlets, concealed by the outer leafy
bracts, are "spikelets" composed of a pair of glumelike bracts with a stiff, flattened rachis
(pedicel) produced between them and supporting 1 or 2 perfect florets, the rachilla
usually terminating in a rudiment; lemma awnless, grasping the palea only at its base;
lodicules 3, flat; stamens 6; stigmas 2. (Bambusoideae.)

Elytrostachys, a newly recognized genus, has only two species, one
known only from Venezuela. Vegetatively, the plants can be separated
from those of the larger species of Rhipidocladum by the strongly
reflexed blades of the culm sheaths.

Elytrostachys clavigera McClure, J. Wash. Acad. Sci. 32:176. 1942.
Figure 69.

Caespitose bamboo, forming large, open clumps of 30-50 culms, their bases decumbent
and trailing, the upper parts clambering and looping up into trees; culms hollow, thin-
walled, cylindrical, green, 4-8 cm. thick, glabrous; culm sheaths up to 25 cm. long, more

FIG. 69. Elytrostachys clavigera. A, pseudospikelet; B, culm sheath showing narrow,
strongly reflexed blade and elongated auricular bristles; C, young vegetative culm with
reflexed culm blades and prominent auricular bristles; D, branch with foliage blades.

206

BURGER: FLORA COSTARICENSIS 207

or less appressed-hispid with glassy white hairs; external ligule a stiff membrane, ca. 1
mm. long, minutely ciliolate; internal ligule similar; auricular bristles numerous, erect,
flattened, dark-colored, 3-5 cm. long; blades much narrower than the sheath apex,
strongly reflexed, 4-7 cm. long, less than 1 cm. wide, hispid. Foliage-bearing branches
arising from middle and upper nodes, each node bearing a dense fascicle of 10 or more
slender branch lets, one (the primary branch) usually larger than the others; branchlets
up to 50 cm. long, bearing reduced and early deciduous blades at their basal nodes and
several larger blades, 6-18 cm. long and 13-32 mm. wide on their outer portions; blades
flat, dark green, 6-18 cm. long, 13-32 mm. wide, ovate 6-7:1, tapering rather abruptly to
a caudate apex, glabrous above, more or less hispid beneath; pseudopetiole up to 3 mm.
long, puberulent above. Inflorescences numerous, forming false whorls at the nodes of
leafy or leafless lateral branches; each inflorescence composed of a pseudospikelet
covered with overlapping bracts; ultimate branchlet with a pair of sterile glumelike
bracts at its base, a stiff, elongated, flattened puberulent pedicel extended above them,
about as long as the bracts and supporting at its apex 1 or 2 florets; glumes none; lemma
awnless, up to 17 mm. long; palea as long as the lemma or longer, grooved on the back
and clasping a rachilla that is sterile or bears a second floret or a rudiment; flower
perfect; lodicules 3, flat, unequal, vasculated; stamens 6, the anthers up to 8 mm. long;
stigmas 2; disarticulation below the floret, the old pedicels with cuplike apices protrud-
ing from the pseudospikelets.

Forests at low elevations; La Selva, Buenos Aires, Tsaki. The last
two specimens, collected in 1891 and 1895, respectively, were in fruit.
Our recent collections from La Selva and Buenos Aires were vegeta-
tive. The plants may be recognized vegetatively by their large, weak,
cylindrical culms, strongly reflexed reduced blades of the culm
sheaths, and the conspicuous elongated erect auricular bristles. Ven-
ezuela to Honduras.

ERAGROSTIS Wolf

REFERENCES: L. H. Harvey, Eragrostis in North and Middle
America, Unpubl. Ph.D. Diss. Univ. of Michigan. University
Microfilms, Ann Arbor. 269 pp. 1948. S. D. Koch, The Eragrostis
pectinacea-pilosa complex in North and Central America.
(Gramineae-Eragrostoideae), Illinois Biological Monographs 48; I-XI
+ 74 pp. Univ. of Illinois Press. Urbana. 1974.

Plants annual or perennial, caespitose, stoloniferous, or rarely rhizomatous. Inflores-
cence an open or contracted panicle; spikelets laterally compressed; florets 2-many;
glumes short, keeled, 1-nerved; lemmas ovate, blunt to acute, 3-nerved, the nerves
usually prominent; paleas at least half as long as the lemmas, with prominent keels;
disarticulation usually sequential from the base upward, the glumes dropping from the
rachilla first, followed by the lemmas; paleas usually remaining on the persistent rachilla;
anthers 2-3; caryopsis free from the lemma and palea, oblong or elliptical, brown or tan,
translucent, usually faintly striate. Some species have spikelets that regularly disar-
ticulate above the glumes and between the florets, and a few species disarticulate in
either fashion.

208 FIELDIANA: BOTANY

Eragrostis is a large genus, common in warm temperate and tropical
climates of the world. The genus contains much diversity, and various
segregate genera have been proposed. The awnless spikelets with
prominently 3-nerved lemmas and the peculiar type of disarticulation
are good marks of recognition. Many of the species are weedy, and
only a very few perennial species (e.g. , Eragrostis curvula) have value
for forage. The genus is related to Triplasis, Leptochloa, Eleusine,
and Dactyloctenium among the Costa Rican grasses. (Chloridoideae:
Eragrosteae.)

KEY TO SPECIES OF Eragrostis

la. Plants extensively stoloniferous, rooting at nodes, forming flat mats on moist

soil E. hypnoides

Ib. Plants caespitose, not stoloniferous; culms usually erect or ascending 2

2a. Keels of paleas prominently ciliate with papillose-based hairs visible from

outside of spikelets 3

2b. Keels of paleas not long-ciliate, mostly scabrous 5

3a. Panicles densely cylindrical, at least 10 x longer than wide; spikelets subsessile,
pedicels much shorter than spikelets; pulvini of branches lacking long hairs

E. ciliaris

3b. Panicles open, rachis visible, length less than 5 x width; pedicels short or long . 4
4a. Panicles open and delicate; pulvini of panicle branches bearing long, silky

hairs; plants not viscid E. tenella

4b. Panicles rather densely flowered, not delicate; pulvini of branches lacking
long hairs; plants usually viscid, particles of soil adhering to sticky areas

E. viscosa

5a. Ligule a membrane E. glomerata

5b. Ligule a dense row of minute hairs 6

6a. Plants forming large dense clumps with numerous very elongated (to 100 cm.)
arching and drooping basal leaf blades that terminate in an elongated thread-
like apex; basal sheaths closely overlapping, copiously appressed-hispid; cul-
tivated perennial E. curvula

6b. Plants in small tufts, lacking elongated basal leaves; wild plants, annuals or

perennials 7

7a. Lemmas acuminate, strongly keeled, midnerve projecting as scabrous ridge;

length of lemma usually 4-6 x folded width 8

7b. Lemmas acute, rounded on the back or slightly keeled but without projecting
midrib; length of lemmas less than 4 x folded width 10

8a. Pulvini of panicle branches bearing conspicuous tufts of long hairs 9

8b. Pulvini of panicle branches lacking tufts of long hairs; lemmas 3.4-4.0 mm.
long, 3-5-nerved; panicle branches very short, densely covered with overlap-
ping spikelets E. simpliciflora

9a. Panicle dense, longest branches up to 5 cm. long, bearing spikelets to their bases;

spikelets subsessile, overlapping E. maypurensis

9b. Panicle large and open, the branches up to 9 cm. long, naked near their bases;

BURGER: FLORA COSTARICENSIS 209

spikelets borne on pedicels up to 5 mm. long, not concealing rachis or branches

E. acutiflora
lOa. Spikelets linear, 6-9 x longer than wide, deep leaden gray or blackish; glumes

minute, the second less than 1 mm. long E. tenuifolia

lOb. Spikelets narrowly ovate or linear, less than 5 x longer than wide, greenish,

light gray, stramineous, or purplish; glumes more than 1 mm. long 11

lla. Panicle narrow, dense, 6 or more x longer than wide, branches erect, densely
flowered; larger leaf blades up to 60 cm. long; coarse, harsh perennial seashore

grasses; Pacific Coast E. prolifera

lib. Panicles open, pyramidal, 2-3 x longer than wide; branches spreading; leaf blades

usually less than 20 cm. long; small annual grasses of various habitats 12

12a. Mature spikelets 2-3 mm. wide; keels of sheaths often bearing pustulose

glands E. cilianensis

12b. Mature spikelets 1.5 mm. or less wide; sheaths lacking pustulose glands on

keels 13

13a. Spikelets closely appressed to primary branches of panicle E. pectinacea

13b. Spikelets at maturity mostly diverging strongly from branches 14

14a. Spikelets slender, delicate, ca. 1 mm. wide; pedicels of lateral spikelets 1-
several x as long as spikelets E. pilosa

14b. Spikelets linear to narrowly ovate, 1.5 mm. or more wide; pedicels of lateral

spikelets mostly equal in length to or shorter than spikelets 15

15a. Caryopsis oblong, truncate, with broad, shallow groove on side opposite embryo;

spikelets 2-3 x longer than wide, often purplish E. mexicana

15b. Caryopsis elliptic-oblong, with rounded ends, cylindrical, not grooved; spikelets

3.5-4.5 x longer than wide, green or stramineous E. tephrosanthos

Eragrostis acutiflora (H.B.K.) Nees, Agrost. Bras. 501. 1829. Poa
acutiftora H.B.K. , Nov. Gen. & Sp. PI. 1:161. 1816.

Caespitose perennial, in small, dense tufts; culms erect to ascending, 35-70 cm. long,
mostly unbranched; internodes 1.5-2.0 mm. thick, hollow, glabrous; nodes glabrous;
sheaths glabrous except at the long-ciliate throat; ligule a minute ciliolate membrane, ca.
0.2 mm. long; leaf blades 6-25 cm. long, 2-4 mm. wide, mostly folded or involute, gla-
brous beneath, more or less pubescent with scattered long weak hairs on the ridged,
scaberulous upper surface. Inflorescence solitary, terminal; panicle ovoid 2:1, 17-28 cm.
long, ca. half as wide, open, the branches solitary, the longest one up to 10 cm. long;
pulvini silky-ciliate with conspicuous hairs; spikelets more or less appressed along the
primary branches; pedicels of lateral spikelets up to 5 mm. long. Spikelets oblong 3-6:1,
5-10 mm. long, with 9-17 florets; the bracts strongly flattened and keeled, usually purple
near the keels and whitish near the margins, the spikelets thus appearing bicolored;
disarticulation from the base upward, the glumes dropping, followed by the lemmas, the
paleas persistent on the flexuous rachilla; the florets rarely disarticulating individually;
glumes ovate 4-5:1 as folded, the keels scabrous; first glume 0.9-1.5 mm. long; 1-nerved;
second glume similar but wider, 1.3-1.9 mm. long; lower lemmas 2.0-2.2 mm. long, ovate
5:1, the margins nearly straight, surface smooth or scaberulous; palea ca. three-fourths
as long as the lemma, the keels bowed-out, short-scabrous; anthers 2, purple, 0.3 mm.
long; caryopsis ca. 0.7 mm. long, hah9 as wide, amber. Chromosome number n - 20 from
a Venezuelan specimen.

210 FIELDIANA: BOTANY

Ocean beaches, open roadsides, cultivated fields, savannas, sea level
to 450 m. elevation; Guanacaste; General Valley; both coasts. June to
December. Southern Mexico to Panama, Brazil, and Bolivia; Trinidad.

Eragrostis cilianensis (All.) Lutati, Malpighia 18:386. 1904. Poa
cilianensis Allioni, Fl. Fed. 2:246. 1785. Eragrostis megastachya
(Koel.) Link, Hort. Berol. 1:187. 1827. Figure 70.

Caespitose annual; plants erect, sprawling, or decumbent; culms simple or branched
from the lower nodes, the internodes glabrous, up to 2 mm. thick, with a thick wall, the
lumen usually filled with pith; nodes glabrous, enlarged; sheaths longer or shorter than
the internodes, glabrous except for elongated silky auricular hairs; flat, circular pus-
tulose glands usually present just above the nodes or more commonly on the keel of the
sheath; ligule a dense ring of white hairs, ca. 0.5 mm. long; leaf blades 5-20 cm. long, up
to 7 mm. wide, glabrous, sometimes bearing pustulose glands on their lower margins.
Inflorescences terminal or sometimes axillary, 6-16 cm. long, 2-8.5 cm. wide, ovoid,
dense to open, greenish to leaden color, becoming stramineous when dry, with numerous
spikelets. Spikelets 6-20 mm. long, linear or ovate, 2-4 mm. wide, with 12-40 florets;
disarticulation usually sequential from the base upward, the glumes dropping first,
followed by the lemmas, the paleas remaining on the rachilla; occasionally disarticulating
between the florets; glumes strongly keeled, scabrous on the keel, the first 1-nerved,
1.2-2.0 mm. long; second similar but broader, sometimes weakly 3-nerved, 1.2-2.6 mm.
long; lower lemmas 2.0-2.8 mm. long, ovate, rather blunt, the 3 nerves conspicuous, back
sometimes scabrid near the tip; palea ca. 0.6 as long as its lemma, scabrous on the keels,
bidentate at the tip; anthers 3, yellow, 0.3-0.5 mm. long; styles 2; caryopsis broadly
ellipsoid, 0.6-0.7 mm. long and more than two-thirds as wide, reddish brown.

Rare in Costa Rica; known from Finca la Pacifica, Canas, Hacienda
Tenorio, and Puntarenas. June to October. Pastures and disturbed
open ground at low elevations. This introduced European species is
very common in warmer parts of the United States, extending south-
ward to northwestern Costa Rica; Cuba and Bermuda; to temperate
South America (Argentina).

Like most species of Eragrostis, this one has spikelets that first
appear with only the basal florets visible and continue to grow and
develop more florets at the apex for some time. Because of this, young
panicles with juvenile spikelets appear very different from mature
ones. The tendency to shed glumes and lower lemmas is not as strong
in this species as in some others, and the rachilla occasionally disar-
ticulates. The plants have a fetid odor when fresh, presumably because
of the secretions of the pustulose glands. In Central American mate-
rial, these glands appear to be restricted largely to the keels of the
sheaths, whereas in specimens from the temperate zone, they are
much more abundant and occur on the sheath bases, panicle branches,
and keels of the lemmas.

FIG. 70. Eragrostis cilianensis. Blooming plant, young and mature spikelets, segment
of rachilla with two florets and a persistent palea.

211

212 FIELDIANA: BOTANY

Eragrostis ciliaris (L.) R. Br. in Tuckey, Narr. Exp. Congo 478.
1818. Poa ciliaris L., Syst. Nat. ed. 10. 2:875. 1759. Figure 71.

Caespitose annual in small tufts; culms 3-40 (65) cm. long, erect, ascending, or decum-
bent, branching from the base or lower nodes; internodes less than 1 mm. thick, hollow,
glabrous; nodes glabrous; sheaths glabrous except papillose-pilose on the overlapping
margin; auricular hairs abundant, to 4 mm. long, silky; ligule a minute ciliate rim, 0.2-0.5
mm. long. Peduncle exserted up to 11 cm.; panicle solitary, terminal on the main culm
or occasionally on leafy branches, 4-14 cm. long, 3-8 mm. thick, densely cylindrical,
spikelike, more than 10 x longer than wide; branches mostly less than 1 cm. long,
densely flowered to their bases, the lower ones sometimes remote from the main body of
the panicle; axils of the branches glabrous; pedicels erect, 0.2-0.6 mm. long, shorter than
the spikelets. Spikelets numerous, densely clothing the branches, 2.2-2.5 mm. long,
mostly 6-9-flowered, disarticulating above the glumes and between the florets or, rarely,
the rachilla remaining intact and the lemmas dropping; first glume 0.8-1.2 mm. long,
1-nerved, ovate, acute; second glume similar, 1.0-1.3 mm. long, the keels sometimes
ciliolate or scabrous; lower lemmas 1.0-1.3 mm. long, ovate, acute, the internerves
scabrid; palea about equal to the lemma, papillose-ciliate on the keels with divergent
straight hairs to 0.6 mm. long; anthers 3, purplish, ca. 0.2 mm. long; caryopsis elliptical
2:1, amber, 0.5 mm. long. Chromosome number n = 10, 20.

Common on weedy open ground and disturbed soils, from sea level
to 1,500 m. elevation; most common at low elevations. Blooming ap-
parently all year. Florida and Gulf Coast of the United States to north-
ern Mexico and southward to Peru and Brazil. Apparently introduced
from the tropics of the Old World.

Eragrostis curvula (Schrad.) Nees, Fl. Afr. Austral. 1:397. 1841.
Poa curvula Schrad., Goett. Anz. Ges. Wiss. 3:2073. 1821.

Long-lived perennial, densely caespitose and forming large circular clumps with very
numerous, densely crowded leafy innovations with elongated drooping blades; culms
unbranched, up to 150 cm. long, arching, the inflorescence drooping; internodes gla-
brous, up to 2.5 mm. thick, solid, the lumen filled with pith; nodes glabrous; foliage
mostly basal, the basal leaf sheaths densely overlapping, their surfaces covered with flat
longitudinal ridges, copiously appressed-hispid with hairs arising in the grooves between
the ridges; blades of the basal leaves flat or involute, very elongated, up to 1 m. long, ca.
2 mm. wide, tapering to an elongated caudate tip, the aspect of the clump fountain-like
from the numerous drooping and trailing basal leaf blades; ligule a dense fringe of short
hairs, ca. 0.5 mm. long; a tuft of elongated silky hairs at the throat and behind the ligule.
Peduncle long-exserted, silky-bearded at the apex; panicle solitary, terminal, usually
17-23 cm. long, open, ovoid-cylindrical, the length 3-7 x the width; pulvini silky-bearded;
branches mostly paired, naked near the base, the spikelets clustered on short secondary
branches and appressed along the primary branches; lateral pedicels usually shorter
than the spikelets. Spikelets leaden-gray, 4-7.5 mm. long, usually with 5-9 florets; disar-
ti culation either sequential from the base upward, the glumes falling first, followed by
the lemmas, the paleas usually persistent on the intact rachilla; or in some cases, the
rachilla disarticulating between the florets; rachilla internodes ciliate at the tip; glumes
1-nerved, the first 1.5-2.1 mm. long, narrowly triangular, the second similar but wider,
2.0-2.5 mm. long; lower lemmas 2.4-3.4 mm. long, oblong-ovate, acute, the nerves not

FIG. 71. Eragrostis species. E. ciliaris: A, panicle; B, spikelet; C, floret showing
ciliate palea; E. tenella: D, blooming plant.

213

214 FIELDIANA: BOTANY

conspicuous; palea nearly equal to its lemma; anthers 3, purple, 1.1-1.6 mm. long;
caryopsis elliptical, amber, 1.4-1.5 mm. long, flattened on the back; embryo dark, ca. half
as long as the grain. A wide variety of chromosome numbers has been reported for the
group.

This African species has been widely cultivated in the southern half
of the United States for forage, stabilization of embankments, and
revegetation of abandoned lands. It is also cultivated in temperate
South America (Uruguay and Argentina). To a limited extent, it is
currently being cultivated as an ornamental in the cities of the Meseta
Central. Our only specimen with inflorescences was obtained from the
campus of the University of Costa Rica. Several related forms or
species occur in Africa and are poorly separable from E. curvula.
Because of the drooping leaf blades, it has been called "weeping love
grass" in English and Pasto lloron in Spanish.

Eragrostis glomerata (Walt.) L. H. Dewey, Contr. U.S. Natl.
Herb. 2:543. 1894. Poa glomerata Walt., Fl. Carol. 80. 1788. Dian-
drochloa glomerata (Walt.) Burk., Fl. Illus. Entre Rios 168. 1969. Col.
Cient. del I.N.T.A. VI, II. Figure 72.

Caespitose annual; culms erect, 25-90 cm. long, branching from the lower and middle
nodes; prophylla 3.5-6.0 cm. long, bidentate at the tip; culm internodes 1.5-4.0 mm.
thick, glabrous, hard, very thick-walled, with a small lumen that is empty or filled with
loose sheets of parenchyma; sheaths glabrous, shorter or longer than the internodes;
ligule an erose membrane, 0.4-0.5 mm. long; leaf blades flat, up to 25 cm. long and 7 mm.
wide, glabrous or scaberulous above. Peduncle included or exserted; inflorescence a
solitary panicle terminal on the main culm or on leafy branches; panicles congested,
densely cylindrical, 13-25 cm. long, 2-3 cm. thick; branches fascicled, erect to ascending,
densely flowered to their bases; spikelets crowded, overlapping, the pedicels usually
much shorter than the spikelets, erect. Spikelets laterally compressed, 2.8-3.4 mm. long,
whitish, disarticulating above the glumes and between the florets; glumes ovate, acute,
scabrous on the keels, the first 0.7-0.9 mm. long, the second slightly longer than the first;
florets usually 8-9; .lemmas 1.0-1.1 mm. long, ovate, acute, the nerves conspicuous,
green, the internerves whitish or translucent; palea slightly shorter than its lemma,
ciliolate at the tip; anthers 2, white, 0.2 mm. long; caryopsis obovoid 3:2, ca. 0.4 mm.
long, amber. Chromosome number n = 10 from a Costa Rican specimen.

Disturbed open areas, rare in Costa Rica. November and December.
The only two specimens known from Costa Rica are from the Cariari
Club and La Guacima. Southeastern United States to northwestern
South America, southward to Bolivia and Argentina.

Eragrostis hypnoides (Lam.) B.S.P., Prelim. Cat. N.Y. 69. 1888.
Poa hypnoides Lam., Tabl. Encycl. 1:185. 1791. Figure 73.

Diminutive creeping annual, forming flat circular patches; stolons much-branched,
rooting at the nodes; flowering culms fascicled from the rooted nodes, usually ascending,
less than 10 cm. long; nodes glabrous; internodes glabrous, less than 0.5 mm. thick,

V ':\i ?!

FIG. 72. Eragrostis species. E. glomerata: A, panicle; B, group of spikelets; C, leaf
base and ligule; E. prolifera: D, disarticulating spikelet showing persistent paleas.

215

216

FIELDIANA: BOTANY

FIG. 73. Eragrostis hypnoides. Blooming plant, portion of a spikelet showing one
floret, persistent paleas, one caryopsis.

hollow; sheaths glabrous except for the finely ciliate overlapping margin; ligule a dense
row of minute hairs, ca. 0.5 mm. long; leaf blades 4-30 mm. long, 1.0-1.5 mm. wide, flat
or folded, the lower surface glabrous, the upper finely papillose-puberulent. Inflores-
cences numerous, on short leafy culms arising from the stolons, rather dense, broadly
ovoid, 2-4 cm. long and nearly as wide; branches very short, bearing 1-few spikelets;
lateral pedicels less than 1 mm. long. Spikelets compressed and keeled, linear, 8-14 mm.
long, up to 3 mm. wide, with 15-32 florets; disarticulation sequential from the base
upward, the glumes falling first, followed by the lemmas, the paleas remaining on the

BURGER: FLORA COSTARICENSIS 217

intact rachilla; glumes 1-nerved, narrowly ovate, acute, scabrous on the keel, the first
0.6-0.8 mm. long, the second 0.9-1.2 mm. long; lower lemmas narrowly ovate or trullate,
1.8-2.2 mm. long, strongly 3-nerved, glabrous; palea ca. half as long as its lemma;
anthers 2, white, ca. 0.2 mm. long; caryopsis elliptical, 0.4-0.5 mm. long and ca. half as
wide.

Sand and mud bars along streams, flat wet beach areas around lakes;
apparently rare in Costa Rica. None of our collections is recent. Tucur-
rique, San Jose. Throughout its range, this species occupies moist,
recently exposed shores. Suitable habitats for its establishment may
be rare in Costa Rica. Nearly all of the United States, southward
through Mexico, Central America to Argentina.

This delicate little creeping grass fruits so abundantly that at
maturity, the entire plant consists primarily of the elongated spikelets,
which probably carry on the majority of the photosynthesis, since
foliage is so sparse.

Eragrostis maypurensis (H.B.K.) Steud., Syn. PL Glum. 1:276.
1854. Poa maypurensis H.B.K., Nov. Gen. & Sp. 1:161. 1816. Figure
74.

Duration indefinite, probably annual; plants caespitose, erect to prostrate, culms 15-70
cm. long, mostly unbranched or in larger plants with a few branches; internodes 0.5-1.0
mm. thick, hollow, glabrous; nodes glabrous; sheaths about as long as the internodes,
varying from nearly glabrous to densely papillose-pilose on the back and collar; auricles
usually long-ciliate with hairs to 4 mm. long; ligule a minute stiff fringe of hairs, 0.2-0.3
mm. long; leaf blades 4-15 cm. long, up to 4 mm. wide, densely papillose-pilose to nearly
glabrous on the upper surface or both sides. Peduncle exserted up to 15 cm., glabrous to
densely papillose-pilose; inflorescence a solitary terminal panicle, 4-20 cm. long, open,
narrowly pyramidal, the branches solitary, up to 4.5 cm. long, simple or rebranched;
rachis and branches from heavily pilose to nearly glabrous; axils of main panicle branches
bearing tufts of long silky hairs; spikelets rather densely clustered and divergent along
the branches; pedicels mostly 0.2-0.5 mm. long. Spikelets oblong, strongly keeled and
compressed, 7-12 mm. long, ca. 3-4 x longer than broad, glabrous, stramineous to
reddish, with up to 27 florets; disarticulation from the base upward, the glumes and then
the lemmas dropping, leaving the paleas on the persistent rachilla; glumes 1-nerved,
strongly keeled, scabrous on the keel; first glume 1.5-2.5 mm. long, 1-nerved, narrowly
triangular, usually acuminate; second glume similar, 1.7-2.5 mm. long; lower florets
1.9-2.7 mm. long, the lemmas ovate 2:1, caudate, the nerves conspicuous, usually green;
keel scabrous; palea ca. two-thirds as long, bowed out above the base; the keels scab-
rous; anthers usually 2, purple, 0.2 mm. long; caryopsis oblong, reddish, ca. 0.5 mm.
long. Chromosome number n = 10 from Costa Rican and South American specimens.

Dry savannas, pastures, roadsides; common on the savannas of
northwestern Guanacaste; dryer western parts of the Meseta Central;
Buenos Aires; Boruca. Elevations to 600 m. Baja California and South-
ern Mexico to Bolivia and Brazil. This species is extremely variable in
stature and pubescence.

218

FIELDIANA: BOTANY

FIG. 74. Eragrostis species. E. maypurensis: A, group of spikelets; E. simpliciflora:
B, panicle; C, spikelet.

Eragrostis mexicana (Hornem.) Link, Hort. Berol. 1:190. 1827.
Poa mexicana Hornem., Hort. Hafn. 2:953. 1815. Eragrostis limbata
Fourn., Mex. PL 2:116. 1881. Figure 75.

Plants caespitose, annual, erect or the lower nodes of the culms geniculate, up to 80
cm. tall but usually much smaller; culms unbranched or branched from the lower nodes,
ca. 1 mm. thick; internodes glabrous, hollow or the lumen filled with pith; nodes gla-
brous, dark; sheaths keeled, mostly shorter than the internodes, glabrous or with a few
papillose-based silky hairs on the overlapping margins; auricles and collar densely
bearded with elongated silky hairs; ligule a minute membrane, densely ciliate with short
white hairs, in total 0.2-0.5 mm. long; leaf blades flat or somewhat involute, 10-25 cm.
long, 3-9 mm. wide, smooth beneath, minutely scaberulous above, occasionally with a
few delicate elongated hairs on the upper surface near the base. Inflorescences solitary,
terminal; panicle open but with numerous spikelets, ovoid, 2-3 x longer than wide, 15-40

BURGER: FLORA COSTARICENSIS

219

FIG. 75. Eragrostis mexicana. Portion of a panicle, portion of a spikelet showing a
floret and two persistent paleas.

cm. long, the longest branch ca. 12 cm. long; spikelets strongly divergent from the
primary or secondary branches, the stiff, flexuous pedicels longer or shorter than the
spikelets. Spikelets laterally compressed, 4.5-6.0 mm. long, 2-3 x longer than wide,
greenish or purplish; disarticulation sequential from the base upward, the glumes drop-
ping first, followed by the lemmas, the paleas remaining on the intact rachilla; glumes
1-nerved, strongly keeled, scabrous on the keels, the first narrowly ovate, 1.6-1.9 mm.
long, acuminate; second glume similar but slightly wider, 1.7-2.2 mm. long; florets usu-
ally 6-8; lower lemmas 1.9-2.2 mm. long, ovate 3:1 as folded, the 3 nerves green, con-
spicuous, tip acute; tip and sometimes the margins scaberulous; palea ca. three-fourths
as long as its lemma; anthers 3, purplish, ca. 0.4 mm. long; caryopsis oblong, the ends
truncate, 0.6-0.7 mm. long, dark reddish brown, with a longitudinal groove on the side
opposite the embryo. Chromosome number n = 30 from Costa Rican specimens.

Occasional in coffee and sugarcane plantations, on roadsides and
streets, and in gardens. Occasional in the Meseta Central, at eleva-
tions of 500 to 1,500 m.; Turrialba; Zarcero. June to February. Arizona
and New Mexico to Costa Rica; Venezuela and Brazil.

Eragrostis pectinacea (Michx.) Steud., Syn. PL Glum. 1:272. 1854.
Poa pectinacea Michx., Fl. Bor. Amer. 1:69. 1803. Figure 76.

Caespitose annual, 10-60 cm. tall, mostly in small tufts; culms erect to spreading,
branching from the base and lower nodes; prophyllum to 3 cm. long; internodes glabrous,
either solid, with pith filling the lumen, or partly hollow; nodes glabrous, dark; sheaths
mostly shorter than the internodes, glabrous except for a tuft of elongated auricular
hairs; ligule a dense line of minute hairs, 0.2-0.5 mm. long; leaf blades 2-15 cm. long,
1.0-4.5 mm. wide, flat or involute, glabrous. Inflorescences solitary, terminal on the
main culm or leafy branches; panicles 5-25 cm. long and ca. half as wide; branches
solitary or paired, simple or occasionally branched, naked near the base, the spikelets
closely appressed to the branches, grayish. Spikelets laterally compressed, linear, 4.5-11
mm. long, with 6-22 florets; disarticulation sequential from the base upward, the glumes
dropping first, followed by the lemmas, the paleas remaining on the persistent rachilla;
glumes 1-nerved, the first subulate, 0.5-1.1 mm. long, the second narrowly triangular,
1.1-1.7 mm. long; lemmas grayish or with a purplish band near the apex, ovate 4:1 as
folded, acute, the nerves evident; palea at least three-fourths as long as its lemma; lower

FIG. 76. Eragrostis pectinacea. Blooming plant, partially disarticulated spikelet with
persistent lower paleas.

220

BURGER: FLORA COSTARICENSIS 221

lemmas 1.7-1.9 mm. long; anthers 3, purple, ca. 0.3 mm. long; caryopsis elliptical, 0.7
mm. long, ca. half as wide, amber.

Roadsides, railroad embankments, cultivated fields, disturbed open
areas generally; occasional at elevations from sea level to 800 m. , both
Pacific and Caribbean slopes. June to March. Possibly introduced from
the United States. Northern United States to Panama; West Indies;
introduced in Argentina.

Eragrostis pilosa (L.) Beauv., Ess. Nouv. Agrost. 71, 162, 175.
1812. Poa pilosa L., Sp. PI. 68. 1753.

Caespitose annual in small tufts; plants 15-45 cm. tall; culms erect, branched from the
base and lower nodes; internodes glabrous, hollow, ca. 0.5 mm. thick; nodes glabrous,
dark; sheaths glabrous except for a tuft of long, stiff auricular hairs; leaf blades flat or
involute, 5-15 cm. long, 2-3 mm. wide, glabrous beneath, scaberulous above. Inflores-
cences terminal on the main culm or on leafy branches; panicles ovoid 2:1, open and
delicate; branches spreading; pedicels strongly divergent, capillary, flexuous, longer
than the spikelets. Spikelets grayish, linear, laterally compressed, 2-6 mm. long; disar-
ticulation sequential from the base upward, the glumes dropping first, followed by the
lemmas and often the paleas; first glume 0.8-1.0 mm. long, 1-nerved, narrowly ovate,
acute, the keel scabrid; second glume similar but wider, 1.2-1.6 mm. long; florets usually
3-8; lemmas 1.2-1.6 mm. long, ovate, rather faintly 3-nerved, sometimes somewhat
scabrid toward the tip; palea at least three-fourths as long as its lemma; anthers 3,
purple, 0.2-0.3 mm. long; caryopsis elliptical 2:1, brown, ca. 0.7 mm. long.

Known in Central America only by the following specimen:
Guanacaste, dry savanna, 21 km. NW of Liberia, 75 m. elevation, Pohl
& Calderdn 12167, 31 July 1966. This introduced European species is
widely established in the United States and has previously been re-
ported as far south as southern Mexico. Caribbean Islands.

Eragrostis prolifera (Swartz) Steud., Syn. PI. Glum. 1:278. 1854.
Poa prolifera Swartz, Nov. Gen. & Sp. PI. Prod. 27. 1788. Eragrostis
domingensis (Pers.) Steud., Syn. PI. Glum. 1:278. 1854. Poa
domingensis Pers. , Syn. PL 88. 1805. Figure 72.

Caespitose perennial, in dense, hard clumps; culms erect or ascending, mostly un-
branched, to 2 m. long; internodes glabrous, up to 4 mm. thick, hard, very thick-walled,
with a small lumen; nodes glabrous; lower sheaths mostly overlapping; sheaths glabrous;
ligule a minute ciliate rim, 0.3-0.5 mm. long; leaf blades harsh, up to 60 cm. long, to 5
mm. wide, flat or involute, glabrous except for the occasional presence of a few long cilia
at the throat or at the base of the blade; lower surface glabrous; upper surface minutely
scaberulous, apex tapering to an elongate scabrous caudate tip. Inflorescence a solitary
terminal panicle; peduncle glabrous, to 40 cm. long; panicle up to 44 cm. long, usually 3
cm. or less thick; branches solitary or fascicled of various lengths together, the longest 9
cm. long, strict, erect, densely flowered to their bases; primary branches bearing
numerous erect short secondary branches; spikelets borne on erect pedicels much
shorter than the spikelets. Spikelets oblong, stramineous when mature, 4.5-11.5 mm.
long, 1.2-2.0 mm. wide; disarticulation sequential from the base upward, the glumes first

222 FIELDIANA: BOTANY

dropping, followed by the lemmas, the paleas persistent on the persistent flexuous
rachilla; first glume 1.2 mm. long, subulate, 1-nerved, scabrous on the keel; second
glume narrowly ovate, 1-nerved, 1.2-1.5 mm. long; florets 8-24; lower lemmas 1.3-1.5
mm. long, ovate, acute, plainly 3-nerved, keeled toward the apex; palea about equal to
the lemma; anthers 2, purple, 0.5-0.6 mm. long; caryopsis ovoid, ca. 0.8 mm. long and
half as wide, amber, minutely striate.

Salinas and sandy beaches of the Pacific; Puerto Castillo, Puerto
Soley, Chomes, Puntarenas. October to January. Southern Mexico to
Colombia.

Eragrostis simpliciflora (Presl) Steud., Syn. PI. Glum. 1:278. 1854.
Megastachya simpliciflora Presl, Rel. Haenk. 1:283. 1830. Figure 74.

Duration indefinite, probably annual; plants caespitose, the culms erect to prostrate,
10-30 cm. long, branching freely from the base and also from the lower and middle nodes;
prophylla 9-15 mm. long; internodes 0.7-1.0 mm. thick, hollow, glabrous; sheaths mostly
overlapping, glabrous except for auricular hairs up to 4 mm. long, keeled; ligule a row of
minute stiff hairs, to 0.1 mm. long; leaf blades up to 15 cm. long, 2-4 mm. wide, more or
less involute, the upper surface ridged, scaberulous, bearing scattered elongate weak
hairs. Panicles terminal and axillary, mostly 4-8 cm. long, ovoid to narrowly pyramidal,
the few branches stiffly spreading or ascending, up to 4 cm. long, bearing few spikelets
that are appressed to the branches or divergent. Spikelets purplish or stramineous,
linear, 9-24 mm. long, very flattened and keeled, subsessile along the branches, the
lateral pedicels 0.2-0.5 mm. long; glumes and lemmas at maturity dropping from the
flexuous rachilla, the paleas persistent; rachilla only very tardily disarticulating; first
glume ovate, acute, 1-nerved, 1.6-2.0 mm. long; second glume similar, 2.1-2.5 mm. long;
florets 12-24; lower lemmas 3.4-3.8 mm. long, ovate 5:1 as folded, acuminate, usually
3-nerved, or with a fainter pair of secondary nerves just inside of the principal lateral
nerves; surface minutely scabrid; keel scabrous; paleas ca. two-thirds as long as the
lemmas, bowed outward above the base, the scabrous-ciliate keels prominent, the area
between the keels deeply infolded; anthers purplish, 0.3 mm. long; caryopsis oval 2:1,
0.8-1.0 mm. long. Chromosome number n = 20 from a Costa Rican specimen.

Open dry areas in full sun, roadsides, pastures, savannas; western
Meseta Central (Guadalupe, Nuestro Amo, San Pedro de Poas); Hda.
Las Animas, Guanacaste. December to March. Southern Mexico to
Panama.

Eragrostis tenella (L.) Beauv. ex R. & S., Syst. Veg. 2:576. 1817.
Poa tenella L., Sp. PL 69. 1753. Poa amabilis L., Sp. PL 68. 1753.
Eragrostis amabilis (L.) Wight & Arn. ex Hook. & Am., Bot.
Beechey Voy. 251. 1838. For discussion of the nomenclature of this
species, See N. L. Bor, 1960. The Grasses of Burma, Ceylon, India,
and Pakistan, pp. 513-514. 1960. Figure 71.

Delicate sprawling caespitose annual in small tufts; culms 5-25 cm. long, branching
from the base; internodes glabrous, less than 0.5 mm. thick, hollow or pithy; nodes
glabrous; sheaths glabrous except for papillose pilosity on the overlapping margins;

BURGER: FLORA COSTARICENSIS 223

ligule a dense row of minute stiff erect hairs; leaf blades flat, mostly 3-5 cm. long, 2-3
mm. wide, glabrous, scabrous on the margins; collar and auricles beset with straight
papillose-based hairs up to 4 mm. long. Peduncle exserted to 4 cm.; inflorescence a
solitary, terminal, open cylindrical panicle, 1.5-9 cm. long, up to 3 x longer than wide;
rachis bearing silky hairs on the pulvini and scattered flat glandular spots on the
internodes; branches spreading; at least some of the pedicels 1-3 x as long as the
spikelets. Spikelets whitish or purple, oblong, mostly 1.7-2.0 mm. long, mostly with 4-6
florets; disarticulation above the glumes and between the florets; first glume 0.5-0.6 mm.
long, ovate, acute, 1-nerved; second glume similar, 0.7-0.8 mm. long; lemmas mostly
0.8-1.0 mm. long, oblong, usually blunt; nerves conspicuous, the lateral ones submargi-
nal, converging only slightly toward the blunt apex; internerves scabrid; palea nearly as
long as its lemma, the keels prominently ciliate with strongly divergent papillose-based
straight hairs up to 0.3 mm. long, these conspicuous on the spikelets; anthers 3, purplish,
0.2 mm. long; caryopsis elliptic 2:1, clear reddish amber colored, 0.5 mm. long.

Casual weed in open areas, mostly near the Caribbean; Limon,
Limon airport; Isla Uvita; Puerto Viejo (S of Cahuita); Turrialba. June
to September. Introduced from the Old World. Southeastern United
States to Texas; west coast of Mexico; Central America to Panama and
tropical South America; West Indies.

Eragrostis tenuifolia (A. Rich.) Hochst. ex Steud., Syn. PI. Glum.
1:268. 1854. Poa tenuifolia A. Rich., Tent. Fl. Abyss. 2:425. 1851.
Figure 77.

Caespitose perennial; clumps dense, hard; culms 30-75 cm. long, erect to prostrate,
unbranched or branched from the lower nodes; internodes hollow, glabrous; nodes gla-
brous; prophylla up to 2.5 cm. long; sheaths about as long as the lower internodes,
strongly compressed and keeled, glabrous, the overlapping margin softly pilose; throat
pilose with hairs to 2 mm. long; ligule a dense line of minute hairs, to 0.25 mm. long; leaf
blades flat or folded, up to 20 cm. long, 2-3 mm. wide. Peduncle exserted up to 18 cm.,
glabrous; inflorescence a solitary terminal panicle, 5-19 cm. long, narrowly pyramidal,
very open; rachis angular, grooved, scabrous on the angles, the pulvini prominent,
strongly ciliate with fine silky hairs to 2 mm. long; branches solitary, strongly divergent,
thin and stiff; pedicels strongly divergent from the branches, the lateral ones 3-13 mm.
long, the terminal ones longer. Spikelets linear, leaden-colored, 6-14 mm. long, 1.5-2.0
mm. wide, laterally compressed but not strongly keeled; disarticulation sequential from
the base upward, the glumes dropping first, followed by the lemmas, the paleas remain-
ing on the flexuous persistent rachilla; glumes much reduced, subulate, the first 0.3-0.6
mm. long, separated from the second by a visible internode; second glume similar,
0.5-1.0 mm. long; florets 6-15; lemmas ovate 4:1 as folded, acute, faintly nerved; palea
more than three-fourths as long as the lemma, bowed out above the base; anthers 3,
whitish, 0.4-0.5 mm. long; flowers apparently cleistogamous, the anthers remaining
tangled with the style branches and not exserted; caryopsis oblong, 0.6-1.0 mm. long,
blunt, amber, about half as wide as long. Chromosome number n = 20 from a Costa
Rican specimen.

Soccer fields, roadsides, streets, disturbed open areas generally;
very common in the Meseta Central, but now known from La Cruz on

FIG. 77. Eragrostis tenuifolia. A, panicle; B, spikelet; C, floret.
224

BURGER: FLORA COSTARICENSIS 225

the Nicaraguan border to San Vito and Agua Buena on the Panama-
nian frontier. Introduced from Africa or India. This species is appar-
ently of recent introduction and is spreading rapidly. It is as yet little
known from the Caribbean slope (Juan Vinas, La Tirimbina). The
plants form a wiry, tough turf that virtually excludes other species on
areas such as playing fields, where they are trampled extensively. Not
previously recorded from the western hemisphere.

Eragrostis tephrosanthos Schultes, Mant. 2:316. 1824. Eragrostis
arida Hitchc., J. Wash. Acad. Sci. 23:449. 1933.

Caespitose annual in small tufts; plants erect, 15-90 cm. tall; culms branched from the
base or lower nodes; internodes glabrous, hollow; nodes glabrous, dark; leaf sheaths
glabrous except for a tuft of elongated auricular hairs; ligule a dense row of short white
hairs, 0.5-0.7 mm. long; leaf blades flat or involute, 3-21 cm. long, 1-5 mm. wide, gla-
brous. Inflorescences solitary, terminal on the main culm or leafy branches; panicle open,
pyramidal, 4-25 cm. long, 2-18 cm. wide, about twice as long as wide; branches mostly
solitary or paired, strongly divergent from the rachis, the largest ones secondarily
branched; pulvini and branch axils with tufts of elongated hairs; pedicels strongly diver-
gent from the branches, stiff and flexuous, often longer than the spikelets. Spikelets
linear-ovate, 4-10.5 mm. long, 1.2-1.5 mm. wide, with 7-20 florets; disarticulation se-
quential from the base upward, the glumes dropping first, followed by the lemmas, the
paleas remaining on the intact rachilla; glumes 1-nerved, scabrous on the keel, the first
0.5-1.4 mm. long, narrowly ovate, acute, the second 0.9-1.7 mm. long, ovate, acute;
lower lemmas 1.1-2.1 mm. long, ovate, acute, the nerves evident; keel scabrid; surface
slightly scabrid near the tip; paleas at least three-fourths as long as their lemmas;
anthers 3, purplish, 0.2-0.3 mm. long; caryopsis elliptic-oblong, 0.6-0.7 mm. long, more
than half as wide, reddish brown, minutely striate.

Occasional; fields, roadsides, railroad embankments; elevations from
sea level to 600 m. Southern General Valley; Piedras Blancas; San
Jose; La Garita; Turrialba. March to October. Florida and southwest-
ern United States to Panama; West Indies; in South America to Brazil.

This species is very similar to E. pectinacea in most respects, dif-
fering chiefly in the spreading pedicels of the spikelets. Koch states
that he has not observed hybrids between the two. Some immature
specimens are difficult to identify definitely.

Eragrostis viscosa (Retz.) Trin., Mem. Acad. Imp. Sci. St.
Petersbourg Hist. Acad. 1:397. 1830. Poa viscosa Retz., Obs. Bot.
4:20. 1786.

Caespitose annual; culms numerous, ascending to erect, branching from the lower and
middle nodes, 20-50 cm. tall; internodes less than 1 mm. thick, hollow, thick-walled,
glabrous; nodes glabrous; prophylla 2.0-2.5 cm. long; sheaths more or less keeled above,
shorter than the internodes, more or less viscid, the overlapping margins and auricles
papillose-pilose with hairs up to 4 mm. long; ligule a dense row of stiff hairs, ca. 0.5 mm.
long; leaf blades 5-13 cm. long, up to 4 mm. wide, bearing scattered weak papillose-based

226 FIELDIANA: BOTANY

hairs on the upper surface; stems and leaves often viscid and coated with adherent soil
particles. Inflorescence terminal on the main culm or on leafy branches; panicle open
cylindrical, 11-13 cm. long, ca. 2 cm. wide; lower panicle branches solitary and remote,
the upper more or less whorled; axils lacking tufts of elongated hairs; spikelets rather
densely arranged on the short lateral branches, the pedicels of lateral spikelets shorter
than the spikelets. Spikelets ovate, 3.0-5.5 mm. long, disarticulating above the glumes
and between the florets; first glume ovate, acute, 0.8-1.4 mm. long, 1-nerved; second
glume similar, 1.0-1.5 mm. long; florets 6-12; lower lemmas 1.1-1.8 mm. long, ovate,
rather blunt, the lateral nerves submarginal, the internerves scabrid; palea about equal
to the lemma, the keels ciliate with divergent papillose-based hairs to 0.6 mm. long;
anthers 3, purple, 0.2-0.3 mm. long. Caryopsis elliptical, 2:1, ca. 0.5 mm. long, reddish
brown.

Bluffs, Playas del Coco; disturbed pasture 20 km. N of Liberia on the
CIA. August to November. Southern Baja California to the Yucatan
and southward to Panama. Introduced from southeastern Asia.

Eragrostis ekmanii Hitchc., Man. Gr. W. Ind. 43. 1936.

A specimen of this species in US bears a label indicating that it was
collected in Costa Rica (0. Jimenez 713, San Francisco de Guadalupe,
Jan. 1913). The identification is correct, but the geographic data is
extremely suspect. The type, which is the only other specimen known,
was collected on the Isle of Pines, Cuba.

EREMOCHLOA Biise

Stoloniferous and rhizomatous perennial; inflorescences are slender terminal or axil-
lary dorsiventral rames, the sessile awnless fertile spikelets all on one side of the rachis,
each overlapping the base of the one above, each accompanied by a flattened leathery
pedicel, bearing at its apex a minute rudimentary spikelet. First glume of sessile
spikelet oblong, barbed along the lower margins, dorsally flattened, many-nerved,
bearing a papery apical wing, notched at the midrib, and two narrow flanges on the inner
side which clasp the margins of the slightly keeled dorsally flattened second glume;
florets 2, the lower staminate, with membranaceous nerveless lemma and palea, the
upper similar but perfect-flowered; lodicules 2, fleshy, forked at the apex.

A small genus of ca. 10 species, native from eastern Asia to Au-
stralia. The following species is sometimes cultivated in warm cli-
mates. (Panicoideae: Andropogoneae.)

Eremochloa ophiuroides (Munro) Hack., in DC., Monogr. Phan.
6:261. 1889. Ischaemum ophiuroides Munro, Proc. Amer. Acad. Arts
4:363. 1860. Sehima ciliare (L.) G. Rob., subvar. ophiuroides (Munro)
G. Rob., Monogr. Androp. 318. 1960. Figure 78.

Plants extensively stoloniferous, the stolons with short internodes and numerous
short erect flowering branches; rhizomes also produced; erect flowering culms 10-20 cm.

FIG. 78. Eremochloa ophiuroides. A, blooming plant; B, rame; C, a sessile spikelet; D,
portion of a rame, showing two flattened pedicels with rudimentary spikelets at their
tips.

227

228 FIELDIANA: BOTANY

tall, ca. 1 mm. thick, hollow, glabrous; nodes dark, with a short ciliate fringe at the base;
leaves 2-3 per culm, the uppermost with a short or rudimentary blade; sheaths mostly
overlapping, strongly keeled; ligule a short ciliate membrane, 0.5-1.0 mm. long; blades
short, linear, 3-5 (8) cm. long, abruptly rounded to a scabrid tip, contracted into a short
pseudopetiole at the rounded, ciliate base. Peduncles slender, 1-5 cm. long, terminal and
axillary. Inflorescence a stiff slender rame, 3-5 cm. long, ca. 2 mm. thick, the overlapping
first glumes of the fertile spikelets all on one side of the rachis, the rachis joints and
pedicels of the abortive pedicellate spikelets on the other. Rachis flattened, tough,
scarcely disarticulating. Spikelets paired, the sessile ones 3.2-4.0 mm. long, 1.5-2.0 mm.
wide, often purplish near the apex; second glume equal in length to the first, but nar-
rower, elliptical, acute, not winged, 3-nerved; florets 2, the lower staminate, the upper
perfect-flowered; lemma of lower floret 2.5-3.0 mm. long, ovate, acute, nerveless; palea
about equal; upper lemma 2.5-2.8 mm. long, similar to the first, its palea about equal to
the lemma; anthers 3, 1.7-2.0 mm. long, purple. Chromosome number n = 9.

This Asiatic species is often cultivated as a lawn grass in warm moist
climates and is fairly common in the southeastern United States. Our
only collection from Costa Rica is from Finca Las Cruces near San Vito
de Java, where it makes up a lawn. It makes a strong, erosion-
resisting turf, but the numerous, wiry inflorescences may be objec-
tionable. It also occurs at El Zamarano, Honduras. Blooming time in
Central America is in June and July.

ERIOCHLOA Humboldt, Bonpland & Kunth

Annual or perennial caespitose or stoloniferous grasses; inflorescence of 1-many
spikelike racemes borne on a common rachis; spikelets solitary or paired, subsessile or
short-pedicellate, borne along the lower side of the rachis. Spikelets disarticulating
below the glumes, dorsally compressed, ovate, acute; the thickened basal rachilla joint
and first glume united to form a protruding knoblike structure at the base of the spikelet;
first glume abortive or reduced to a minute cufflike scale embracing the rachilla joint;
second glume and sterile lemma subequal, completely covering and concealing the
shorter fertile floret; fertile lemma cartilaginous, minutely rugose-striate, the margins
not inrolled, covering the edges of the flat palea of similar texture; tip of the lemma
minutely bristly or prolonged into a minute awn.

About 25 species in warm climates of both eastern and western
hemispheres. (Panicoideae: Paniceae.)

KEY TO SPECIES OF Eriochloa

la. Inflorescence of 1-3 simple racemes, each 1-2 cm. long E. distachya

Ib. Inflorescence of numerous usually branched primary branches, the longer ones 5-8
cm. long E. polystachya

Eriochloa distachya H.B.K., Nov. Gen. & Sp. 1:95, Tab. 30. 1816.
Helopus brachystachys Trin., Sp. Gram. Icon. & Descr. II, Tab. 277.
1829. Figure 79.

FIG. 79. Eriochloa species. E. polystachya: A, panicle; B, two views of a spikelet; C,
fertile floret; E. distachya: D, inflorescences; E, spikelet; F, fertile floret.

229

230 FIELDIANA: BOTANY

Caespitose annual; plants 25-50 cm. tall, erect, or the culm bases decumbent; branch-
ing freely from the base and the culm nodes; prophylla 2-3 cm. long; culms 1 mm. thick,
hollow, glabrous; nodes bearded with ascending or retrorse hairs; leaf sheaths glabrous
or villous on the back and margins; ligule a minute fringe of white hairs, 0.4-0.5 mm.
long; leaf blades flat, 2-13 cm. long, 2-6 mm. wide, mostly glabrous, the uppermost
sometimes reduced. Peduncle slender, 5-12 cm. long, glabrous near the base, increas-
ingly villous toward the apex; inflorescence of 1-2 silky racemes, these 1-2 cm. long,
usually arched, 1-sided, the spikelets alternating in 2 rows along the lower side of the
densely silky-villous rachis; pedicels minute, villous, with a ring of longer hairs near
their apex; spikelets placed with the sterile lemma facing toward the midline of the
rachis and the backs of fertile lemmas facing outward. Spikelets elliptic-ovate, 2.5-3.5
mm. long, acute, dorsally compressed, with a protruding basal knob ca. 0.3 mm. long and
0.5 mm. wide formed of the thickened basal rachilla joint surrounded by an abortive
cuplike first glume; surface of disarticulation umbrella-shaped, smooth and shiny; second
glume and sterile lemma equal, similar, 2.3-3. 1 mm. long, completely covering the fertile
floret; the glume 5-nerved, the lemma 3-nerved, both bearing stiff erect to spreading
hairs, those toward the apex much longer than the rest; fertile lemma stiff, minutely
rugulose, elliptical, 1.9-2.3 mm. long, faintly 3-nerved, bearing a few minute spicules at
the tip, the flat margins barely covering the edges of a flat palea of similar texture;
anthers 3, tan, 1.2-1.5 mm. long; caryopsis elliptic-oblong, 1.5 mm. long, white, opaque.
Chromosome number n = 9 from a Costa Rican specimen.

Rare; savannas of Boruca and Buenos Aires. December. Guatemala
and Costa Rica to Panama, Brazil and Paraguay.

Eriochloa polystachya H.B.K., Nov. Gen. & Sp. 1:95. Tab. 31.
1816. Figure 79.

Duration indefinite but probably perennial; culm bases long-decumbent and rooting at
the nodes; upper parts of culms ascending, 1-2 m. long, branching freely, glabrous,
hollow, thin-walled, 3-4 mm. thick; nodes conspicuously bearded with spreading or re-
trorse hairs; sheaths more or less papillose-hispid; ligule a minute stiff membrane,
crowned with a longer dense row of silky white hairs, totaling 0.8-1.2 mm. long; collar of
the sheath and base of the upper blade surface minutely velvety; blades glabrous or
sparsely papillose-hairy, 10-25 cm. long, 8-15 mm. wide. Peduncles exserted up to 12
cm., glabrous except for the heavily bearded apex; inflorescences terminal on leafy
culms; panicles narrowly ellipsoidal, 15-25 cm. long, 2-3 x longer than wide; rachis and
branches more or less papillose-hirsute; branches straight, ascending, usually re-
branched, the spikelets racemose, solitary or paired along the undersides of the primary
or secondary branches; members of a pair unequally short-pedicellate; backs of the
fertile lemmas placed away from the rachis. Spikelets narrowly ovate, 2.5:1, acute,
3.2-3.6 mm. long with a small protruding basal knob; first glume 0.2 mm. long, truncate,
cufflike, usually purple; second glume and sterile lemma equal, sparsely appressed-
hairy, 3.0-3.5 mm. long, ovate, acute; the second glume 5-nerved; sterile lemma with 3
strong nerves and 2 weak marginal ones; fertile floret 2.2-2.5 mm. long, noticeably
shorter than the glume and sterile lemma, elliptical, faintly 3-nerved, with a minute
apical awn ca. 0.1 mm. long; lemma and palea white, stiff, faintly striate, the margins of
the lemma flat, covering the edges of the palea; anthers 3, greenish, 1.0-1.5 mm. long;
stigmas purple. Chromosome number n = 18 from Costa Rican specimens.

BURGER: FLORA COSTARICENSIS 231

Cultivated as a forage crop and commonly escaped to roadsides and
margins of ponds; elevations up to 1,200 m.; most common in humid
areas. March to September. West Indies and northern South America.
Not previously reported as a wild plant in Central America. Common
name in Costa Rica is Janeiro. The plants are very similar to
Brachiaria mutica ("Para grass").

ERIOCHRYSIS Beauvois

REFERENCE: J. R. Swallen, Notes on grasses: Eriochrysis,
Phytologia 14:88-91. 1966.

Caespitose erect perennial; inflorescence a dense silky cylindrical intricately branched
panicle of short rames; spikelets awnless, paired at each node of the rachis, one sessile
and the other short-pedicellate; disarticulation at the bases of the sessile spikelets, the 2
spikelets of the pair falling together or the pedicellate one dropping from the pedicel.
Glumes, rachis internodes, and pedicels all densely brown-silky. Spikelets of each pair
similar, but the pedicellate one slightly smaller; glumes equal, chartaceous, completely
covering and concealing the inner spikelet parts; outline of spikelet narrowly ovate,
acute; first glume flat on the back, with inflexed margins which cover the edges of the
keeled second glume; callus, margins, and tip of the first glume and the keel and tip of
the second glume fringed with long, silky, golden-brown hairs. Sterile lemma and fertile
lemma thin, nerveless, slightly shorter than the glumes; no paleas present; lodicules
thick and fleshy, truncate. Sessile spikelet with a perfect flower; pedicellate spikelet
with a pistillate flower only.

Species about 10, from tropical America, Africa, and Asia.

Eriochrysis cayanensis Beauv., Ess. Nouv. Agrost. 8. PL 4, f. 11.
1812. Saccharum cayennense (Beauv.) Benth., J. Linn. Soc. Bot.
19:66. 1881. S. cayennense Benth., Roberty, Mon. Syst. Androp.,
Boissiera 9:360. 1960. Figure 80.

Perennial, in small, dense clumps from a deep-seated base; plants 90-300 cm. tall; basal
leaves numerous, their blades very elongate, up to 50 cm. long and 6 mm. wide, often
folded; bases of culms clothed with the fibrous remains of the old sheaths; culms erect,
2-4 mm. thick, hollow, glabrous; nodes densely bearded with straight ascending hairs;
foliage as a whole copiously velvety-pubescent; sheaths densely hairy on the collar; ligule
a short ciliate membrane, 1-2 mm. long; blades of culm leaves shorter and wider than the
basal ones, up to 12 mm. wide; uppermost blade much reduced; inflorescence included at
the base or the peduncle exserted up to 15 cm. Inflorescence dense, cylindrical, lobulate,
lustrous golden-brown, the densely clustered spikelets mostly concealed by the long
silky pubescence of spikelets, rachis internodes and pedicels; length 12-18 cm., width 1-3
cm.; branches short, ascending, concealed by the spikelets and hairs. Pedicels and rachis
joints silky-pubescent, very short, 1.0-1.3 mm. long. Spikelets paired, or the terminal
segment of a rame bearing a sessile spikelet and 2 pedicellate ones. Spikelets 2.0-4.4
mm. long, the pedicellate member of the pair usually shorter than the sessile one; glumes

FIG. 80. Eriochrysis cayanensis. Blooming plant.
232

BURGER: FLORA COSTARICENSIS 233

subequal and the full length of the spikelet, concealing the inner parts; lower floret
sterile, represented by an empty lemma slightly shorter than the first glume; upper
floret with a keeled lemma ca. as long as the second glume but no palea; flower of sessile
spikelet perfect, that of the pedicellate spikelet pistillate; lodicules 2, large and fleshy,
truncate; anthers 3, yellow, 1.3-1.7 mm. long. Chromosome number n = 10 from Costa
Rican specimens.

Open marshy places, from near sea level to 1,400 m. July to October.
Uncommon in Costa Rica; known from General Viejo and Canas Gor-
das. Mexico to Bolivia and Argentina.

This is one of the most striking of the tropical American grasses,
easily recognized by its beautiful brown inflorescence, somewhat re-
sembling a small cattail. The specific epithet was spelled cayanensis by
Beauvois in two separate places in his work. Later authors have usu-
ally spelled it cayennensis, referring to Cayenne. Beauvois, however,
makes no such reference.

EUCLASTA Franchet

Inflorescences terminal on the main culm or on leafy lateral branches. Peduncle very
slender, flexuous; rames several, slender, borne racemosely along a slender central
rachis, each rame on a filiform naked flexuous branch. Spikelets dorsally compressed,
the basal 1-several pairs sterile, the members of the pair alike and awnless; rachis
between sterile pairs not disarticulating, the sessile spikelets remaining on the rachis
after the upper parts of the rame have disarticulated; pedicellate spikelets of basal pairs
disarticulating; upper spikelet pairs of the rame dimorphic, the sessile perfect-flowered
spikelet bearing an exserted twisted and geniculate awn, the pedicellate one awnless,
sterile. Disarticulation at the apex of each internode of the rachis, the paired spikelets
falling together or the pedicellate spikelet deciduous; rachis segments and pedicels flat,
ciliate, with a very thin, translucent band down the length of the center; terminal rachis
segment bearing 1 sessile spikelet and 2 pedicellate ones; glumes membranaceous, the
first flat on the back, many-nerved, ciliate and slightly keeled on the margins of the
upper half, the lower margins incurved; second glume shorter than the first, boat-
shaped, 3-nerved; sessile spikelets usually with a thin, nerveless lower lemma lacking
palea or flower; upper fertile lemma reduced to the flattened whitish base of the awn;
lodicules 2, truncate; anthers 3, linear.

The genus Euclasta consists of a single species, distributed in the
tropics of Africa and America. It is related to Andropogon, Hypar-
rhenia, and Bothriochloa, being closest to the last in the possession of
rachis segments and pedicels with thin translucent centers. The per-
sistent basal portion of the rames, bearing persistent sessile spikelets,
along with the delicately peduncled rames, are characteristic of
Euclasta. The spikelets are much softer than is usual in this tribe.
(Panicoideae: Andropogoneae.)

Euclasta condylotricha (Hochst.) Stapf, Fl. Trop. Africa 9:181.

234 FIELDIANA: BOTANY

1917. Andropogon condylotrichus Hochst. in Steud., Syn. PL Gram.
377. 1855. Amphilophis piptatherus (Hack.) Nash, N. Amer. Fl.
17:127. 1912. Figure 81.

Weak sprawling annual, the decumbent stems rooting at the lower nodes, branching
freely from the lower nodes; internodes glabrous, pithy; nodes bearded; sheaths longer
or shorter than the internodes, glabrous except pilose on the collar; ligule a firm brown-
ish membrane, ca. 1 mm. long, ciliate with white hairs longer than the membranaceous
part; leaf blades flat, 7-20 cm. long, 3-8 mm. wide, hirsute beneath, usually glabrous
above, usually with a few long, pustulose-based hairs on the basal margins. Peduncles
very slender, terminal or axillary from the upper culm nodes, heavily bearded at the
apex and on the rachis nodes. Rames usually 2-6, solitary or paired at the rachis nodes,
2-4 cm. long, forming a fan-shaped cluster. Basal spikelet pairs: spikelets about equal,
4.6-6.0 mm. long, sterile; ovate 3:1, first glume 5-7-nerved, narrowly truncate at the
apex; second glume shorter, boat-shaped, 3-nerved; basal portions of the glumes bearing
stiff spreading hairs. Upper spikelet pairs: sessile spikelets 3.5-3.8 mm. long, the first
glume 5-7-nerved, flat on the back, bristly hirsute on the lower half, slightly truncate at
the apex; second glume ca. 3.5 mm. long, 3-nerved; sterile lemma thin and nerveless, ca.
half as long as the spikelet; upper lemma reduced to the brown, twisted and geniculate
awn, 3-4 cm. long; anthers 1.0-1.2 mm. long. Chromosome number n = 10 from a
Venezuelan specimen.

Tuff outcrops in savanna and rocky sea cliffs, sea level to 300 m.,
Hacienda Murcielago. October to December. Mexico to Venezuela and
Brazil; West Indies; tropical Africa.

EUSTACHYS Desvaux

REFERENCE: G. V. Nash, A revision of the genera Chloris and Eus-
tachys in North America, Bull. Torrey Bot. Club 25:432-450. 1898.

Caespitose perennial grasses, often with short stolons; foliage glabrous; leaves mostly
aggregated near the bases of the culms, the sheaths strongly keeled; culms hollow;
inflorescence solitary, terminal, of several whorled ascending spikes; spikelets densely
arranged on the lower sides of a slender triquetrous rachis, alternating in 2 rows but
forming a single file, oriented at right angles to the rachis. Spikelets strongly laterally
compressed, the glumes and lemmas keeled; first glume narrow, acuminate, 1-nerved;
second glume oblong, flattened on the back, markedly bifid at the apex, the single nerve
protruding as a short awn; fertile lemma broad, blunt, awnless or nearly so, dark brown
and shining, with a short truncate callus; nerves 3, the lateral marginal; palea equalling
the lemma; rachilla inflated, bearing a club-shaped truncate rudimentary lemma.

This small genus of ca. 10 species of warm climates of the western
hemisphere is closely related to Chloris, with which it is often united.
It differs in the broad, dark brown, awnless florets, in the placement of
the spikelets perpendicular to the rachis rather than appressed to it, in
the single file, the oblong, bifid second glume, and the hollow culms.
(Chloridoideae: Chlorideae.)

FIG. 81. Euxlasta condylotricha. A, inflorescence; B, old inflorescence with persistent
sessile spikelets; C, rame with awnless basal spikelets and awned upper sessile
spikelets.

236 FIELDIANA: BOTANY

Eustachys petraea (Swartz) Desv., Nouv. Bull. Sci. Soc. Philom.
Paris 2:189. 1810. Chloris petraea Swartz, Prodr. Veg. Ind. Occ. 25.
1788. Figure 82.

Perennial, in clumps, the bases with short stout stolons; plants 30-100 cm. tall, erect;
culms compressed, glabrous, 2-3 mm. thick, hollow, thick-walled; nodes glabrous; leaves
mostly clustered near the bases of the culms, the basal sheaths much overlapping,
strongly keeled; foliage glaucous; ligule a minute strongly ciliate membrane, ca. 0.2 mm.
long; blades 6-15 cm. long, 4-7 mm. wide, flat or folded, glabrous, scabrous on margins
and midrib, strongly keeled beneath, the uppermost much reduced; tip blunt and apicu-
late. Inflorescence solitary, terminal, vase-shaped, of 3-8 slender spikes, each 4-9 cm.
long, the spikelets attached in 2 rows along the lower sides of a slender triquetrous
rachis, crowded, placed approximately perpendicular to the rachis; adjacent spikelets
intercalated with each other, thus forming a single file. Spikelets 1.6-2.0 mm. long,
disarticulating above the persistent glumes; first glume 0.9-1.3 mm. long, 1-nerved,
lanceolate, the scabrous keel curved; second glume 1.1-1.5 mm. long, oblong, strongly
lobed at the tip, the back rather flat, short-awned from between the lobes; awn 0.3-0.5
mm. long; fertile floret 1.6-2.0 mm. long, the lemma rotund, strongly laterally com-
pressed, dark brown and shining, awnless or minutely apiculate, short-ciliate on the
blunt callus, the keel, and the marginal nerves; palea as long as the lemma, obovate,
brown and shining, flat; anthers 3, ca. 0.6 mm. long, yellow; rudimentary floret reaching
the tip of the fertile lemma, consisting of a club-shaped, truncate, hollow empty lemma,
contracted at the base into a thick, fleshy whitish rachilla. Chromosome number n = 20
from Costa Rican material.

Sandy beach of the Caribbean Sea, Limon Airport to Boca Banano;
Estero Negro; Playa Westfalia. Blooming yearlong. Southeastern
United States to Texas and eastern Mexico, Belize, Honduras, Costa
Rica and Panama; West Indies. The sporadic occurrence of this species
near Caribbean ports in Central America suggests that it may have
been introduced. It has grown at Limon at least since 1895.

FESTUCA Linnaeus

Perennial grasses; inflorescence a terminal panicle; spikelets several-many-flowered,
laterally compressed, disarticulating above the glumes and between the florets; lemmas
with a hard callus, slender, usually 5-nerved, tapering to an acuminate apex or an awn;
palea mostly as long as the lemma; anthers 3; flowers chasmogamous.

A large genus of perennial grasses of cold and temperate climates, in
the tropics restricted to upper elevations. The genus is often united
with Vulpia, which differs in containing annual species with one anther
and cleistogamous flowers. A few instances of intergeneric hybridiza-
tion between Festuca and Vulpia are known. Species of Festuca may
be confused with certain species of Bromus. The latter genus, how-
ever, has leaf sheaths with united edges and lemmas with apical teeth,
the awn arising between them. (Pooideae: Poeae.)

FIG. 82. Eustachya petraea. A, stolon with a cluster of keeled basal leaf sheaths; B,
inflorescence; C, portion of a spike; D, a spikelet.

237

238 FIELDIANA: BOTANY

KEY TO SPECIES OF Festuca

la. Leaf blades flat, 3-12 mm. wide 2

Ib. Leaf blades involute or less than 3 mm. wide 5

2a. Lemmas awnless or with awn less than 4 mm. long 3

2b. Lemmas long-awned, awn 10-15 mm. long F. breviglumis

3a. Bases of leaf blades wider than sheath, auricled; florets 3-10 F. arundinacea

3b. Bases of leaf blades as wide as sheath, lacking auricles; florets 3-5; native species of

forests and alpine sites 4

4a. Lemmas awnless, lowermost 5.5-7.0 mm. long; anthers 2.0-2.8 mm. long, pur-
ple; lower panicle branches in 5's; spikelets very numerous . . F. amplissima
4b. Lemmas short-awned, lowermost 9-11 mm. long; anthers 3-4 mm. long, yellow;
lower panicle branches paired; spikelets few F. chiriquensis

5a. Lemmas less than 3.5 mm. long, awnless; plants 10-25 cm. tall; leaf blades thread-
like F. tenuifolia

5b. Lemmas 5-8 mm. long, usually awned; plants 15-110 cm. tall 6

6a. Ligule minute; introduced grasses in upper elevation pastures of volcanoes 7
6b. Ligule 1.0-2.5 mm. long; native grasses of paramos above 3,000 m. elevation 8

7a. Clumps dense, basal leafy shoots (innovations) arising within the basal sheaths;
lower sheaths stramineous, persistent F. ovina

7b. Clumps loose, sprawling, basal leafy shoots bursting through basal sheaths near

their bases; lower sheaths reddish, breaking down into fibers F. rubra

8a. Basal leaf blades less than 2.0 mm. wide, with 3-4 coarse ridges on upper

surface F. toliicensis

8b. Basal leaf blades 2-4 mm. wide, with 6-12 ridges on upper surface

F. dolichophylla

Festuca amplissima Rupr. ex Fourn., Mex. PL 2:125. 1881. Figure
85.

Tall, stout perennial; plants 110-150 cm. tall; culms erect from hard bases; basal leaves
numerous, their sheaths breaking down into stiff fibers; culms unbranched, stiff, 2-3 mm.
thick, hollow, glabrous or scabrous; nodes dark, contracted, glabrous; sheaths nearly as
long as the internodes, faintly scabrous; ligules membranaceous, 0.5-1.8 mm. long, the
basal ones very short; blades 20-50 cm. long, 7-8 mm. wide, stiff and erect, scabrous
beneath, tapering into a long involute tip. Peduncle scabrid, exserted up to 40 cm.;
panicle solitary, terminal, up to 30 cm. long, narrowly elliptical; branches up to 5 per
node, usually 10-12 cm. long, ascending, naked for several centimeters near the base;
rachis, branches, and pedicels angular, scabrous on the edges; spikelets appressed along
the branches, their pedicels mostly short. Spikelets laterally compressed, ca. 10 mm.
long; first glume 3.0-4.5 mm. long, linear, 1-nerved; second glume 4.8-6.0 mm. long,
3-nerved, lanceolate; florets 3-5, often with a small terminal rudiment; lemmas lanceo-
late, scabrid, evidently 5-nerved, keeled, awnless, acuminate, often purplish on the
back, bronzy near the tip, 5.5-7.0 mm. long; palea nearly as long as its lemma, tapering
abruptly to a point, scabrid between the keels; rachilla slender, scabrous; anthers 3,
purple, 2.0-2.8 mm. long.

Rare; known from the devastated area at the head of the Rio Reven-
tado on Irazu, and from the upper canyon of the Rio Talari on Chirripo
Grande, at the margin of the paramo; elevations 2,700-3,250 m.

BURGER: FLORA COSTARICENSIS 239

January to April; November. Southern Mexico; Guatemala; Costa
Rica; Volcan Chiriqui in Panama. Our specimens have somewhat
smaller spikelets and longer ligules than the Pringle specimens 3945
and 9555 cited by Piper in N. Am. Sp. Festuca, from Mexico, but are
generally similar.

Festuca arundinacea Schreb., Spic. Fl. Lips. 57. 1771. Figure 83.

Perennial, forming large clumps; plants to 150 cm. tall; culms erect to spreading,
unbranched, to 5 mm. thick, glabrous; nodes dark, glabrous, shrunken; sheaths elon-
gate, striate; ligules membranaceous, up to 2 mm. long; leaf blades 2-5 per culm, 10-60
cm. long, 3-12 mm. wide, glabrous, coarse and tough, flat, strongly ridged above, the
upper surface and margins scabrous, base auricled; basal blades numerous, lying flat on
the ground in cropped or grazed plants. Peduncle exserted 10-50 cm.; inflorescence a
solitary terminal panicle, erect or nodding, rather narrow and dense; rachis and
branches angled and scabrous; spikelets rather densely clustered along the branches,
short-pedicellate. Spikelets 10-18 mm. long, the florets crowded because of the short
rachilla segments; first glume 3-6 mm. long, 1-nerved, lanceolate; second glume 4.5-7.0
mm. long, 3-nerved, lanceolate-ovate; florets 3-10; lemmas 6-9 mm. long, glabrous,
lanceolate-oblong, 5-nerved, tapering to an acuminate apex of a short awn 1-3 mm. long;
palea ca. as long as the lemma, the keels scabrous, rachilla segments ca. 1 mm. long,
upwardly scabrous; anthers 3, purple, 3.5-4.0 mm. long. Chromosome number n = 21.

Moist pastures, Irazii and Turrialba, 1,800-2,800 m. elevation. Au-
gust to November, probably yearlong. Introduced from Europe as a
pasture grass; naturalized in various parts of North America. This
species was apparently reported as F. elatior L. in the Grasses of
Central America.

Festuca breviglumis Swallen, Contr. U.S. Natl. Herb. 29:398.
1950. Figure 84.

Perennial; culms erect or the bases decumbent; plants to 130 cm. tall; culms un-
branched, 3 mm. thick, glabrous, hollow; nodes dark, shrunken, glabrous; culm leaves
ca. 4, their sheaths very elongate, up to 25 cm. long, glabrous; ligules 0.5-0.8 mm. long,
membranaceous, minutely ciliolate; blades flat or folded, up to 35 cm. long, 5-7 mm.
wide, glabrous, the upper surface finely nerved; lower surface scaberulous. Panicle
solitary, terminal, up to 27 cm. long, 15 cm. wide, open, nodding; branches paired, the
longest 18 cm. long; rachis and branches scabrous, the lower third to half of the branch
devoid of spikelets. Spikelets few, 15-20 mm. long without the awns; first glume 3-5 mm.
long, 1-nerved, acicular; second glume 6.5-8.5 mm. long, narrowly lanceolate, 3-nerved;
florets 4-5; lemmas narrowly lanceolate, rounded on the back, the upper portion folded
and keeled, evidently 5-nerved, but with an extra pair of weak marginal nerves near the
base, scabrid on the back, tapering to an awn up to 15 mm. long; lowermost lemma
14.0-15.5 mm. long, the upper ones shorter; palea narrowly elliptical, tapering to a
narrow tip, scabrous on the nerves, two-thirds to three-fourths as long as the lemma;
rachilla scabrous, the ultimate segment sterile or bearing a long-awned rudiment at its
tip; anthers 3, purple, 4.0-4.5 mm. long.

Rare; known in Costa Rica only from the type from Copey, and from

FIG. 83. Festuca species. F. arundinacea: A, portion of panicle and ridged upper
surface of leaf blade; F. tenuifolia: B, panicle and threadlike leaf blades; F. ovina: C,
portion of panicle; D, leafy shoot with intravaginal branching; F. rubra: E, panicle; F,
base of plant with extravaginal branching.

240

FIG. 84. Festuca species. F. breviglumis: A, panicle; B, culm base; C, spikelet; F.
chiriquensis: D, spikelet.

241

242 FIELDIANA: BOTANY

a recent specimen collected along the Carretera Interamericana north
of San Cristobal Norte; elevations 2,000-2,200 m. September to De-
cember. Also known from Guatemala.

Festuca chiriquensis Swallen, Ann. Missouri Bot. Gard. 30:116.
1943. Figure 84.

Perennial, in small clumps from a deep-seated base; plants 80-130 cm. tall; culms un-
branched, 2-3 mm. thick, glabrous, hollow; culm leaves ca. 4; sheaths glabrous, much
shorter than the internodes, scabrid; ligule a minutely ciliolate membrane, 0.7-2.0 mm.
long; blades soft, flat, dark green and shining, slightly scabrid, 15-50 cm. long, 4-7 mm.
wide. Peduncle exserted to 15 cm.; inflorescence a solitary terminal panicle, open, nod-
ding, few-flowered, 15-30 cm. long; branches few, paired, the longest 15 cm. long, the
spikelets borne on the outer third. Spikelets 3-4-flowered, 15-17 mm. long; first glume
subulate, 1-nerved, 5.5-6.7 mm. long; second glume linear-lanceolate, 3-nerved, scab-
rous on the keel, 8.0-9.5 mm. long; lowermost lemma 9-11 mm. long, lanceolate, con-
spicuously 5-nerved, scabrous, minutely toothed at the apex; awn stiff, scabrous, 1-4
mm. long; palea equal to the lemma, scabrous on the keels, nerves prolonged into awns
up to 1 mm. long; rachilla scabrous; anthers 3, yellow, 3.0-3.9 mm. long.

Moist oak forests, Chirripo Grande, 3,000-3,200 m. elevation. The
type was from Volcan Chiriqui in Panama. September to April. This
rare species was previously known only from the type. It is very
similar to F. breviglumis, from which it differs in having much longer
glumes, shorter lemmas, longer paleas which are awned, and smaller
yellow anthers.

Festuca dolichophylla Presl, Rel. Haenk. 1:258. 1830. Figure 85.

Perennial, in large, dense clumps; plants erect, 65-110 cm. tall; culms unbranched,
hollow, glabrous, 2-4 mm. thick; internodes very elongated; nodes dark, shrunken,
glabrous; sheaths glabrous, about as long as the internodes; ligules membranaceous,
1.0-2.5 mm. long; leaves mostly basal; blades elongate, up to 50 cm. long, erect, involute,
glabrous or scabrous beneath, puberulent or glabrous above, 2-5 mm. wide, upper sur-
face with 6-12 strong ridges. Peduncle glabrous or slightly scaberulous, up to 15 cm.
long; panicle terminal, solitary, narrowly elliptical, nodding, 10-25 cm. long, 3-4 cm.
wide; lower branches usually paired, up to 12 cm. long, ascending; spikelets appressed
along the branches. Spikelets 10-17 mm. long, usually purple, with 5-7 florets; first
glume linear-triangular, 1-nerved, 4-6 mm. long; second glume linear-lanceolate, 3-
nerved, 6.0-7.2 mm. long; lemmas obscurely 5-nerved, narrowly lanceolate, more or less
scaberulous, 6.5-8.0 mm. long, rounded on the back, the margins infolded; apex acumi-
nate or short-awned, the awn less than 1 mm. long; palea nearly as long as the lemma,
narrowed to the tip, scabrous on the keels; rachilla segments slender, scabrous, the
terminal one half as long as the floret below, naked or bearing an abortive floret at its tip.
Chromosome number n = 21 from Costa Rican material.

Volcanic cinders and mud about the craters of Irazu and Turrialba,
Chirripo Grande; elevations 3,100-3,400 m. June to August. Costa
Rica; Volcan Chiriqui in Panama; to Chile.

This species is similar to F. amplissima, but differs in the stiff,

FIG. 85. Festuca species. F. dolichophylla: A, panicle and leaf blades; B, spikelet; F.
amplissima: C, panicle; D, leaf sheath and blade; E, spikelet.

243

244 FIELDIANA: BOTANY

involute narrow leaves, paired panicle branches, larger spikelets with
more florets. It also resembles F. tolucensis of Mexico, but differs in
the much coarser foliage.

Festuca ovina L., Sp. PI. 73. 1753. Figure 83.

Densely caespitose perennial; intravaginal innovations numerous, most of the foliage
borne near the base of the plants; culms 15-60 cm. tall; leaf blades of innovations and
culms stiff, folded; foliage glabrous. Inflorescence a solitary terminal panicle, usually
5-10 cm. long, with few ascending branches, the spikelets clustered near the tips.
Spikelets with 3-9 florets; lemmas short-awned, rounded on the back, stiff.

This is a widespread and extremely polymorphous European
species, not previously reported from Central America and known only
from the following Costa Rican specimen. A number of European pas-
ture grasses occur in these alpine pastures, and were evidently intro-
duced long ago in pasture seed mixtures. Cartago, in pasture, upper
slopes of Volcan Irazii, Godfrey 66649, 24 February 1965.

Festuca rubra L., Sp. PI. 74. 1753. Figure 83.

Perennial, in loose, sprawling tufts; plants 15-90 cm. tall; the bases of the culms often
decumbent or creeping; foliage mostly basal, the innovations extravaginal; culms ca. 1
mm. thick, hollow, ridged, glabrous; old basal sheaths becoming dark reddish, eventu-
ally breaking down into loose fibers; ligule a minute membrane; blades 3-40 cm. long,
mostly folded, appearing 0.5-1.0 mm. wide as folded, as much as 2 mm. wide when flat.
Peduncle elongate, as much as half the height of the plant; panicle solitary, terminal,
3-17 cm. long, slender, erect or nodding; branches solitary or paired, the longest up to 6
cm. long, angled and scabrous, few-flowered; spikelets overlapping. Spikelets 5-14 mm.
long, with 3-9 florets; first glume 2.0-3.5 mm. long, 1-nerved, narrowly lanceolate; sec-
ond glume 3.5-5.0 mm. long, 3-nerved, lanceolate; lemmas 5-6 mm. long, lanceolate,
5-nerved, glabrous or scabrid toward the tip, tapering into a stiff awn 1-3 mm. long;
palea equal to the lemma, scabrid on the keels; anthers 3, 2-3 mm. long, purple.

Pastures and clearings, upper slopes of Volcan Barba and Volcan
Turrialba; elevations 2,400-2,800 m., rare. June to August. This
species is widespread in cooler regions of the northern hemisphere and
is extensively cultivated as a lawn grass. In Central America, it is
known only from Costa Rica. Our collections are undoubtedly survivals
from pasture seed mixtures imported from Europe, since they grow in
areas harboring numerous European plants.

Festuca tenuifolia Sibth., Fl. Oxon. 44. 1794. F. capillata Lam.,
Fl. Franc. 3:597. 1778. Figure 83.

Perennial, in dense clumps with numerous erect basal blades; plants 10-25 cm. tall;
culms thin, hollow, glabrous or scaberulous; leaf blades hairlike, rolled, less than 0.5
mm. thick; ligule a minute membrane; sheaths with small auricles; peduncle slender, half
the height of the plant. Inflorescence a solitary terminal panicle, 2-10 cm. long, linear,

BURGER: FLORA COSTARICENSIS 245

with short, erect, few-flowered scabrous branches. Spikelets 3-7 mm. long, 3-8-flowered;
first glume 1-nerved, lanceolate, 1.5-2.5 mm. long; second glume 3-nerved, ovate, 2.5-3.5
mm. long; lemmas 2.5-3.5 mm. long, ovate, acuminate, awnless, 5-nerved, glabrous or
scabrid near the tip; palea as long as the lemma; anthers 3, 1-2 mm. long, yellow or
purple.

Moist pasture, south slope of Volcan Turrialba, elevation 3,000 m.
August. This species is European and has been introduced sparingly in
the northern United States. The collection indicated above is appar-
ently the first from Central America. The plants occurred in an area
where numerous grasses of European origin grow. Probably, this
species was introduced in pasture seed mixtures.

Festuca tolucensis H.B.K., Nov. Gen. & Sp. 1:153. 1816.

Caespitose perennial in dense tufts; culms erect, up to 100 cm. tall; unbranched;
foliage mostly aggregated near the base of the plants; internodes glabrous, 1.5-2.0 mm.
thick; nodes dark, contracted; leaf sheaths glabrous, granular-roughened; ligule a thin
membrane, 1.0-2.5 mm. long; basal leaf blades up to 25 cm. long, scabrous, involute,
1.0-1.5 mm. wide, the upper surface 3-4-ridged, scaberulous; basal foliage reaching
one-half to two-thirds the height of the plants, the upper portions of the culms nearly
leafless. Peduncles exserted up to 30 cm.; inflorescences solitary, terminal; panicles
11-20 cm. long, open but narrow, few-flowered; branches paired or solitary. Spikelets
usually purplish, 9-14 mm. long; 6-8-flowered; first glume 4.5-6.3 mm. long, narrowly
triangular, 1-nerved; second glume 6.0-7.4 mm. long, ovate, acute, 3-nerved; lemmas
narrowly ovate, acuminate or awn-tipped, 6-8 mm. long, scaberulous; palea slightly
shorter, bifid at the tip; anthers 3, yellow, 2.8-3.4 mm. long.

Rare; summit of Irazu; Valle de los Conejos, Chirripo. Apparently
blooming yearlong. Southern Mexico (Toluca); Guatemala; Costa Rica.

This species is difficult to distinguish with certainty from F.
dolichophylla. The very slender, elongate, scabrous basal foliage
blades are the best character, but some individuals are intermediate.
The chromosome number of n = 21 has been previously reported and is
the same as that of Costa Rican F. dolichophylla. The spikelets of our
material are a good match for type fragments of F. tolucensis in US.

GLYCERIA R. Brown

Perennial aquatic or paludose grasses; sheaths with united edges; inflorescence a
panicle; spikelets several-many-flowered, terete or compressed, disarticulating very
readily above the glumes and between the florets; glumes usually 1-nerved, blunt; lem-
mas 5-9-nerved, the nerves conspicuous, not converging but running parallel from base
to the usually blunt apex. (Pooideae: Meliceae.)

Glyceria plicata (Fries) Fries, Nov. Fl. Suec. Mant. 111:176. 1842.
G. fluitans var. plicata Fries, Nov. Mant. 11:6. 1839. Figure 86.

FIG. 86. Glycerin plicata. A, spikelet; B, lemma; C, panicle.

246

BURGER: FLORA COSTARICENSIS 247

Culms 30-75 cm. long, the basal portion creeping and much-branched, the upper part
ascending, not branched, glabrous, rather succulent, hollow; sheaths mostly overlap-
ping, slightly roughened; ligules brownish, membranaceous, 2-8 mm. long, decurrent on
the sheath margins; blades 5-30 cm. long, 3-14 mm. wide, flat or folded, scabrid beneath,
tapering abruptly to an acute apex. Peduncle mostly included, smooth; inflorescence
solitary, terminal, 20-25 cm. long, cylindrical, strict when young but the branches
spreading in fruit; branches whorled, with up to 7-8 spikelets; pedicels 1.0-7.5 mm. long;
spikelets mostly appressed to the branchlets, nearly terete, 10-25 mm. long; florets 7-15;
first glume 1.5-2.5 mm. long, 1-nerved; second glume 2.5-4.0 mm. long, 1-nerved, both
glumes ovate, blunt; lemmas 3.5-5.0 mm. long, oblong, blunt, conspicuously 7-nerved,
scabrid on the nerves, with a purple band below the whitish, membranaceous apex; palea
nearly as long as the lemma, glabrous, with thickened keels, the apex blunt; anthers 3,
0.8-1.5 mm. long, yellow or rarely purplish. Chromosome number n = 20.

This European species has not previously been reported from the
western hemisphere. At the spot where we collected it, it was growing
in a moist meadow along with Poa trivialis, another European species.
It is probable that this species, like a number of others from highland
pastures, represents a survival from accidental introduction in Euro-
pean pasture seed mixtures. The following is our only collection: Car-
tago, Hacienda Las Virtudes, SE of Volcan Irazu, 2,650 m., 14 Feb-
ruary 1969, Pohl & Davidse 11715.

GOUINIA Fournier

REFERENCE: J. R. Swallen, The grass genus Gouinia. Amer. J. Bot.
22:31-41. 1935.

Caespitose perennial grasses; inflorescence a terminal panicle, the branches mostly
simple, the spikelets pedicellate in 2 rows along the lower side of the slender branches.
Spikelets with 2 or more florets, disarticulating above the glumes and between the
florets; glumes 1-several-nerved, shorter than the spikelets; lemmas 3-nerved, lanceo-
late, long awned from the acuminate apex, ciliate on the callus and nerves; rachilla
slender, the internodes long; palea bidentate or awned, glabrous or pubescent.

The genus, containing 13 species of tropical American grasses, is
related to Leptochloa. (Chloridoideae: Eragrosteae.)

Gouinia virgata (Presl) Scribn., Bull. U.S.D.A. Div. Agrost. 4:10.
1897. Bromus virgatus Presl, Rel. Haenk. 1:263. 1830. Figure 87.

Culms erect, 30-150 cm. tall, unbranched, glabrous, solid, pithy; nodes glabrous;
sheaths slightly keeled above, shorter or longer than the internodes, glabrous or slightly
hispid about the collar and base of the blade; ligule a ciliate membrane, 0.5-1.5 mm. long;
blades up to 25 cm. or more long, 4-15 mm. wide, glabrous, tapering to a narrow base,
margins scabrous. Panicle 10-15 cm. long, open, with few, solitary, mostly simple
branches, stiffly spreading, 8-20 cm. long, spikelets lying parallel to the lower sides of
the branches; pedicels 1-4 mm. long, angular. Spikelets 10-12 mm. long, excluding the
awns, slender; disarticulation above the glumes and between the florets; first glume

FIG. 87. Gouinia virgata. A, panicle; B, glumes, C, floret.

248

BURGER: FLORA COSTARICENSIS 249

3.9-5.2 mm. long, 3-4-nerved, lanceolate; second glume 5.7-7.2 mm. long, 5-7-nerved,
narrowly ovate; florets 2-3; lemmas 8-10 mm. long, lanceolate, acuminate, with a sharp
bearded callus, the nerves and margins silky-ciliate on the lower half; awn from the tip,
8-15 mm. long; upper florets shorter than the lowermost; palea 7-8 mm. long, silky-ciliate
on the keels; anthers 3, 0.5-0.6 mm. long. Chromosome number n = 20 from Costa Rican
specimens.

Open forests near the Pacific Ocean, elevations below 100 m.;
Cuajiniquil and Puerto Castillo, Hacienda Murcielago; Finca la
Pacifica, Canas, Isla de Chira. October to January. Mexico to
Guanacaste; Colombia to Peru and Ecuador; Cuba and Haiti.

GYMNOPOGON Beauvois

REFERENCE: J. P. Smith, Jr., Taxonomic revision of the genus
Gymnopogon (Gramineae), Iowa State Univ. J. Sci. 45:319-385. 1971.

Perennial or annual caespitose or rhizomatous grasses; culms simple or sparingly
branched; leaf blades lacking a midrib, usually stiffly spreading. Inflorescence a panicle
of several erect or spreading slender spikelike racemes; rachis of racemes triquetrous;
spikelets alternating in 2 rows on 2 sides of the rachis and parallel to it. Spikelets
1-2-flowered, the ultimate floret reduced to a thin awnlike body; disarticulation above
the glumes; glumes 1-nerved, narrow, acuminate, keeled, both longer than the florets;
lemma very faintly 3-nerved, its apex minutely bifid, usually bearing an awn that arises
below the tip; palea 2-nerved, equal to the lemma; rachilla prolonged above the fertile
floret and usually bearing a slender rudiment; caryopsis terete to angular.

Gymnopogon is a small genus of about 13 species, confined to warm
regions of the western hemisphere, with one species in Southeast Asia.
The genus is closely related to Chloris, differing mostly in the stiff leaf
blades, lacking midribs, the long, equal glumes, and the absence of a
well-developed sterile upper floret. (Chloridoideae: Chlorideae.)

Gymnopogon fastigiatus Nees, Agrost. Bras. 430. 1829, ssp. fas-
tigiatus. Figure 88.

Caespitose perennial; culms glabrous, erect to spreading, 35-80 cm. long, simple or
sparingly branched from the middle nodes; sheaths glabrous except for sparse auricular
pilosity at the throat; ligule a minute ciliolate membrane, ca. 0.1-0.2 mm. long; leaf
blades glabrous, flat or involute, 2.0-4.5 cm. long, 1-4 mm. wide, subcordate at the base,
stiffly ascending. Peduncle included or exserted up to 7 cm.; inflorescence a raceme of
3-11 spikes, each 3-7 cm. long, spikelet-bearing to the base, ascending; axis triquetrous,
scabrous. Spikelets 1-flowered; glumes subequal, acuminate, 1-nerved, the keel scab-
rous; lemma faintly 3-nerved, glabrous on the back and sides, the margins pubescent,
long-pilose at the summit; apex bifid, bearing a tortuous awn 8-15 mm. long from just
below the bifid tip; palea membranaceous, 2-nerved; rachilla segment nearly as long as
the lemma, lying between the keels of the palea, lacking a rudimentary second floret;
anthers 3, ca. 0.7 mm. long; caryopsis 1.3-1.8 mm. long. Chromosome number n = 20.

FIG. 88. Gymnopogon fastigiatus ssp. fastigiatus. A, inflorescence; B, portion of a
spike; C, floret with prolonged rachilla internode.

250

BURGER: FLORA COSTARICENSIS 251

Rare; in steep gullies, savannas of Boruca; reported from this area by
Standley. The following is the only recent specimen: Puntarenas,
Savanas de Boruca, elevation 380 m., P. & D. 11614. Blooming during
the short days of the dry season. Costa Rica, Panama, northern South
America from Colombia to Bolivia and Brazil.

GYNERIUM Humboldt & Bonpland

REFERENCE: H. J. Conert, Die Systematik und Anatomic der Arun-
dineae, Cramer Verlag. Weinheim. 208 pp. 1961.

Giant rhizomatous perennial grasses, forming large colonies; culms erect to arching,
solid and semi-woody, the lower parts clothed with bladeless sheaths, the upper end
with a large fan-shaped cluster of distichous leaves; dioecious, the staminate and the
pistillate plants frequently in separate colonies. Inflorescence a very large terminal
panicle borne on an elongated solid peduncle, the branches drooping along the rachis;
pistillate panicles plumose; spikelets laterally compressed, disarticulating above the
glumes and between the florets, usually 2-flowered. (Arundinoideae: Arundineae.)

Gynerium sagittatum (Aubl.) Beauv., Ess. Nouv. Agrost. 138.
1812. Saccharum sagittatum Aubl., PI. Gui. 1:50. 1775. Figure 89.

Culms up to 10 m. tall, 2-5 cm. thick, simple or with extravaginal branches; leaf blades
with a conspicuous midrib, 40-200 cm. long, 2-8 cm. wide, cottony on the midrib above
the base, very scabrous on the margins; ligule a minute ciliolate membrane; nodes level
with surface of the culm, glabrous. Peduncle 1 m. or more long, 1 cm. or more in
diameter, smooth; panicles up to 1.5 m. long, the very slender branches emerging from
the rachis in clusters, drooping along the rachis; spikelets pedicellate, in dense clusters
along 3rd- or 4th-order branches. Pistillate spikelets: 8-10 mm. long, plumose; first
glume 1-nerved, narrow, hyaline, ca. 3 mm. long; second glume longer than the florets,
linear, faintly 3-nerved, 7-10 mm. long, light brown, thinly membranous, the upper
two-thirds with inrolled margins, the keel recurved. After the fall of the florets, the
glumes may also disarticulate. Florets 2; disarticulation at the base of the rachilla joints;
lowermost lemma ca. 5 mm. long, the upper shorter; lemmas tapering into a slender
inrolled awnlike beak, abundantly long-silky hairy on the basal half, the beak portion
glabrous; callus bearing short erect hairs; palea ca. 1 mm. long, linear, glabrous except
at the tip; lodicules 2, truncate; pistil with 2 terminal styles, terminating in feathery
purple stigmas; staminodia may be present. Staminate spikelets: not plumose, ca. 3 mm.
long, laterally compressed, disarticulating above the glumes and at the base of the upper
floret; glumes about equal, 2 mm. long, 1-nerved, lanceolate, hyaline, brownish; lemmas
2.0-2.5 mm. long, narrowly ovate, 1-nerved, purplish, sparsely puberulent at the base or
occasionally with a few long hairs on the upper portion; palea blunt, nearly as long as the
lemma; lodicules 2, truncate; anthers 2, 1.5-2.0 mm. long, yellow. A rudimentary ovary
may be present. Chromosome number n = 22 from Costa Rican specimens.

This species forms conspicuous large colonies along the margins of
major streams and occasionally elsewhere, from sea level up to about
1,100 m. The stems are harvested in large quantities and used in rustic
construction and as banana props. Blooming is apparently yearlong.

FIG. 89. Gynerium sagittatum. A, panicle; B, branchlet from a pistillate panicle; C,
pistillate spikelet; D, branchlet from a staminate panicle; E, staminate spikelet.

252

BURGER: FLORA COSTARICENSIS 253

Southern Mexico to Peru and northern Paraguay and Brazil; West
Indies. Common name: Cana brava.

HACKELOCHLOA Kuntze

Caespitose, much-branched annual; inflorescences numerous, terminal and axillary
solitary dorsi ventral pedunculate rames, exserted in clusters from the middle and upper
sheaths; spikelets paired at each node of a flat disarticulating rachis; sessile spikelet of
each pair spheroidal, rigid, the first glume much inflated, the upper portion round,
blackish, its surface covered with square pits in transverse rows, its margins clasping
the edges of the united rachis joint and pedicel, the base smooth and white, contracted;
second glume appressed to the rachis joint, oblong, blunt, slightly keeled, chartaceous,
3-nerved; flower perfect. Pedicellate spikelet very different from the sessile one and
larger, its first glume flat, ovate, acute, green and herbaceous, many-nerved, clasping
the margins of the second glume by 2 flanges borne near the margins on the inner side;
second glume folded, strongly wing-keeled, as long as the first; inner parts usually
absent. Occasional spikelets may possess sterile lemma, fertile lemma and palea, and a
staminate flower. All the inner bracts are hyaline and nerveless.

One species, native to the tropics of the Old World but widespread in
the warmer regions of both hemispheres. (Panicoideae: An-
dropogoneae.)

Hackelochloa granularis (L.) Kuntze, Rev. Gen. PL 2:776. 1891.
Cenchrus granularis L., Mant. PI. 2:575. 1771. Rottboellia granularis
(L.) Roberty, Monogr. Androp. 79. 1960. Figure 90.

Tufted, much-branched annual; erect, often with prop-roots; culms from very short to
120 cm. long, solid, pithy, more or less pustulose-hispid, especially toward the apex of
the internodes; sheaths much shorter than the internodes, inflated, keeled, the margins
silky, the surface prominently pustulose-hispid; ligule arched, a ciliate membrane 1.0-1.5
mm. long; leaf blades flat, 2-20 cm. long, 4-15 mm. wide, pustulose-hispid on both
surfaces and on the margins. Peduncles bracted, arising in small groups from all the
middle and upper nodes of the culms, slightly exserted; rames slender, stiff, 7-15 mm.
long. Spikelets paired, the sessile ones in 2 rows alternating along one side of the rachis,
the pedicellate ones on the opposite side. Sessile spikelets 1.3-1.7 mm. long, falling
attached to the rachis joint, pedicel, and pedicellate spikelet; first glume rigid, sub-
spherical or turbinate, its opening completely closed off by the chartaceous second
glume; second glume 0.8-1.0 mm. long; fertile lemma and palea hyaline, nerveless, ca.
0.9 mm. long; flower perfect; anthers 0.2-0.3 mm. long. Pedicellate spikelet 1.5-2.0 mm.
long. Chromosome number n = 1 from Costa Rican specimens.

Open dry weedy areas, common at low elevations and ascending to
1,100 m.; both Caribbean and Pacific slopes; particularly common in
Guanacaste. July to December. This species occurs in the western
hemisphere as an introduction, from southern United States through
Central America; Caribbean Islands.

This peculiar grass is at once recognizable by the tiny spheroidal,

FIG. 90. Hackelochloa granularis. A, B, two views of a spikelet pair; C, flowering
culm.

254

BURGER: FLORA COSTARICENSIS 255

blackish, pitted, fertile spikelets. The sheaths are pungent-bristly to
the touch.

HIEROCHLOE R. Brown
Nomen Conservandum

Rhizomatous perennials; culms simple; inflorescence a terminal panicle; spikelets of 3
florets, disarticulating only above the subequal enlarged membranaceous glumes, the
florets remaining attached to each other; lower 2 florets subequal, longer than the fertile
floret, staminate or neuter; lemmas 5-nerved, usually awned below the tip or from the
back; palea usually present (absent in our species); stamens, if present, 3, the anthers
large; terminal floret with a blunt, 3-5-nerved lemma, awnless or nearly so; palea some-
what shorter than the lemma, 1-nerved; stamens 2, usually rudimentary; stigmas 2;
plants with the odor of coumarin.

A small genus of Arctic, alpine and cool temperate grasses, mostly in
the northern hemisphere but extending to South America. The sweet
vanilla-like odor of the plants, due to the presence of coumarin, aids in
their recognition. (Pooideae: Phalarideae.)

Hierochloe davidsei Pohl, Iowa State J. Res. 47:71. 1972. Figure
91.

Rhizomatous perennial; culms erect, 30-60 cm. tall, unbranched, glabrous, hollow, 2-3
mm. thick, arising singly or in small clumps from slender rhizomes; the rhizomes up to 9
cm. long, often giving rise to leafy innovations; leaves 5-7 per culm; lower sheaths short
and overlapping, the upper one or two much shorter than the internode, strongly ribbed,
glabrous or occasionally retrorsely pilose, especially near the apex; ligules 1.5-5 mm.
long, the upper ones longer than the lower, whitish, membranaceous, densely retrorsely
pilose on the outer surface, truncate; leaf blades 5-8 mm. wide; 6-15 cm. long, the
mid-culm blades largest, all rather blunt, pilose above; peduncle 10-15 cm. long, slender,
erect, glabrous; inflorescence a single narrowly cylindrical terminal panicle, sometimes
slightly lobulate below, 3-11 cm. long, the branches erect; pedicels 1-3 mm. long, slightly
pilose; spikelets 5.5-6.5 mm. long, ovate, laterally compressed, brownish; glumes thin
and membranaceous, ovate, acute, overlapping, the first 4-4.5 mm. long, 1-nerved, the
second 5.5-6.5 mm., 3-nerved; florets 3; lower 2 florets sterile, lacking flower and palea,
both ca. 5 mm. long; sterile lemmas 5-nerved, brownish, ciliate; first lemma with a short
straight awn born ca. 1 mm. below the lobed apex and reaching to the tip; second lemma
similar, but bearing a bent awn attached slightly below the middle of the lemma, below a
lobed apex; awn 4-5.5 mm. long, twisted below, exserted laterally from the glumes 1-2
mm.; fertile lemma 3 mm. long, thin and membranaceous, glabrous, 5-nerved, blunt,
cucullate, awnless, or with a short straight awn, bifid at the apex; palea about equal,
oblong, acute; anthers 2, ca. 1.5 mm. long, yellow; lodicules minute, evidently function-
less.

Chromosome number n = 28, determined from microsporocytes of
the type: Prov. de San Jose, Paramo along Carretera Interamericana
at km. 86, elevation 3,030 m., 23 August 1968, Pohl & Davidse 11004.

FIG. 91. Hierochloe davidsei. A, blooming plant; B, spikelet; C, two lower sterile
florets and fertile terminal floret.

256

BURGER: FLORA COSTARICENSIS 257

This species is similar to H. mexicana, from which it differs in the
following characteristics:

Character H. davidsei H. mexicana

leaf blade LAV ratio 11/1-12/1 20/1-30/1

ligule very pilose glabrous

lower 2 florets without flower and often with flower

palea and palea

anther length (mm.) 1.5 4

In having sterile lower florets, this species resembles species of
Anthoxanthum. The latter genus, however, has a basic chromosome
number of 10, and the spikelets have very unequal glumes. Hierochloe
davidsei has a basic chromosome number of X = 7 (n = 28) and sub-
equal glumes. Certain specimens from Guatemala approach the Costa
Rican species, but have anthers 2.5-3 mm. long and are probably best
assigned to H . mexicana on other characters. This species is named for
Gerrit Davidse, who discovered the plants. It is known from the type
locality and from La Asuncion (Burger & Gomez 7936) and Chirripo
Grande (Burger & Gomez 8212). It should be looked for elsewhere on
the high paramos. Elevations 3,000-3,450 m. Blooming in August from
the three known specimens.

HOLCUS Linnaeus

Caespitose or rhizomatous perennials; inflorescence a terminal panicle; spikelets com-
pressed and keeled, 2-flowered; glumes equal, longer than the florets; disarticulation
below the glumes; florets similar, but the lower one with a perfect flower, the upper
staminate; upper lemma bearing a short, thick awn. (Pooideae: Aveneae.)

Holcus lanatus L., Sp. PL 1048. 1753. Figure 92.

Caespitose perennial; culms 20-100 cm. tall, erect from decumbent bases, unbranched,
hollow and thin-walled, velutinous; nodes velvety; leaves 3-5 per culm; sheaths mostly
overlapping; ligules 1.5-3 mm. long, membranaceous, decurrent on the sheaths, ciliolate,
puberulent on the back; blades soft, grayish-green, velutinous, 4-20 cm. long, 3-10 mm.
wide. Panicle solitary, contracted or lax, cylindrical to pyramidal, pale or pinkish or
purplish. Spikelets closely arranged, overlapping, short-pedicellate, strongly com-
pressed and keeled; glumes about equal in length, 4.0-4.5 mm. long, overlapping; first
glume ovate, 1-nerved, second broadly ovate, 3-nerved; both ciliate on nerves and keel,
puberulent on the internerves; florets 2, smooth and shining, completely hidden in the
glumes; lower floret awnless, the upper with a short, hook-shaped awn from just below
the apex; lemmas 2.0-2.3 mm. long, faintly 3-nerved; paleas slightly shorter than the
lemmas, scabrid on the keels; anthers 3 in each floret, purplish, 1.7-2.2 mm. long.
Chromosome number n = 1 from Costa Rican specimen.

FIG. 92. Holcux lanatus. A, panicle; B, spikelet; C, florets.
258

BURGER: FLORA COSTARICENSIS 269

Pastures, open areas, roadsides; common in moist areas from 1,600-
3,200 m. elevation, Cordillera Central and Cerro de la Muerte.
Blooming is probably yearlong. This species is native in Eurasia and
northwest Africa. It is widely naturalized in temperate North
America. In Costa Rica, it was introduced as a forage crop, but is
probably little used as such now.

HOMOLEPIS Chase

Stoloniferous grasses; inflorescence a terminal panicle. Disarticulation below the
glumes; spikelets lanceolate, acuminate, dorsally compressed; glumes concealing the
florets, subequal or the first somewhat longer than the second, its margins covering the
edges of the second; first glume 7-9-nerved, ovate; second glume 7-nerved; sterile lemma
7-nerved, strongly ciliate between the marginal nerves, its palea small, membranaceous;
fertile floret chartaceous, acuminate, the lemma obscurely nerved, glabrous and shining,
with thin exposed margins overlapping the margins of a palea of similar length and
texture. (Panicoideae: Paniceae.)

Homolepis aturensis (H.B.K.) Chase, Proc. Biol. Soc. Wash.
24:146. 1911. Panicum aturense H.B.K., Nov. Gen. & Sp. 1:103. 1816.
Figure 93.

Duration indefinite; plants extensively stoloniferous; erect or ascending floriferous
branches 20-50 cm. long arising from the stolons; culms glabrous, hollow, 1-2 mm. thick;
nodes glabrous; sheaths usually shorter than the internodes, glabrous or pilose, silky-
ciliate on the margins, keeled; ligule a minutely ciliate membrane, 0.4-0.7 mm. long; a
puberulent line across the collar; blades cordate above a brief pseudopetiole, flat, 4-12
cm. long, 7-20 mm. wide, glabrous to pilose or velutinous on the surfaces; peduncle
included or exserted up to 12 cm.; uppermost leaf blade much reduced; panicles terminal
on the culms or on leafy branches, narrowly elliptical, 6-9 cm. long, 2-5 x longer than
wide; spikelets on slender pedicels, rather crowded, 7.0-7.7 mm. long; first glume 7-9-
nerved, ovate, the margins overlapping the edges of the second; second glume 6.4-6.8
mm. long, 7-nerved, the margins ciliate near the base; sterile lemma 7-nerved, 5.2-6.8
mm. long, 7-nerved, strongly silky-ciliate between the marginal pairs of nerves; fertile
lemma 4.8-6.0 mm. long, lanceolate, the nerves faint, its palea similar; anthers 3, purple,
1.3-1.6 mm. long. Chromosome number n = 10 from Costa Rican material.

Moist pastures, shaded roadsides, sea beaches, from sea level to
1,200 m. elevation, on both Caribbean and Pacific slopes. June to
March. Southern Mexico to Bolivia and Brazil.

HYMENACHNE Beauvois

Aquatic or paludose perennials of tall stature; culm internodes filled with spongy
aerenchyma. Inflorescence a dense narrowly cylindrical or spikelike terminal panicle.
Spikelets lanceolate-acuminate, dorsally compressed; first glume 1-3-nerved, much
shorter than the spikelet, a definite internode of the rachilla between the first and second
glumes; second glume and sterile lemma 3-5-nerved, subequal, both longer than the

FIG. 93. Homolepis aturensis. A, panicle; B, stolon with leafy shoots; C, two views of
a spikelet.

BURGER: FLORA COSTARICENSIS 261

perfect terminal floret; sterile lemma lacking a pa lea; fertile lemma lanceolate, chartace-
ous, smooth and glabrous, very faintly nerved, its margins thin, not inrolled; palea
nearly as long as the lemma and of similar texture.

A genus of about 10 species of New World and Asiatic tropics,
closely related to Sacciolepis and differing from it in having solid in-
temodes. (Panicoideae: Paniceae.)

KEY TO SPECIES OF Hymenachne

la. Spikelets 3.5-5.5 mm. long; second glume and sterile lemma 5-nerved, acuminate;

panicles spikelike H. amplexicaulis

Ib. Spikelets 2.5-2.9 mm. long; second glume and sterile lemma 3-nerved, acute; panicle

narrowly cylindrical, tapering, with ascending branches H. donacifolia

Hymenachne amplexicaulis (Rudge) Nees, Agrost. Bras. 276.
1829. Panicum amplexicaule Rudge, PI. Gui. 1:21, pi. 27. 1805. Figure
94.

Tall perennial, the culms to 3.5 m. long, arising from long decumbent rooting bases;
culms thick and spongy, the interior filled with stellate aerenchyma, glabrous; nodes
glabrous, with swollen sheath pulvini; sheaths much shorter than the internodes, gla-
brous, or the margins papillose-ciliate; ligule a thin brownish membrane, 1.0-2.5 mm.
long; blades soft, flat, glabrous, 15-33 cm. long, 12-28 mm. wide, the margins strongly
scabrous, pustulose-ciliate on the cordate-clasping basal lobes. Peduncle glabrous, usu-
ally included in the upper sheath; panicles spikelike, solitary, 10-40 cm. long, 1-2 cm.
thick, dense, sometimes lobed near the base; spikelets densely crowded, short-pedicel-
late, ascending along the short erect branches of the panicle. Spikelets lanceolate,
acuminate; 3.5-5.5 mm. long, scabrous on the nerves; first glume 1.0-1.7 mm. long,
ovate, 3-nerved, sometimes caudate; second glume 5-nerved, 2.8-3.9 mm. long, caudate;
sterile lemma 5-nerved, longer than the second glume, caudate, 3.6-4.6 mm. long, lack-
ing palea or flower; fertile lemma shorter than the sterile lemma, 2.5-3.5 mm. long;
anthers 3, 1.1-1.2 mm. long, yellowish or pinkish; caryopsis elliptical, tan, free from the
floret. Chromosome number n = 10 from Costa Rican material.

Marshes, ditches, lakes, riverbanks; occasional at low elevations
from 20-850 m., mostly under 300 m., on both Caribbean and Pacific
slopes. Apparently blooming yearlong. Southern Mexico to Argentina.

Hymenachne donacifolia (Raddi) Chase, J. Wash. Acad. Sci.
13:177. 1923. Panicum donacifolium Raddi, Agrost. Bras. 44:1823.

Succulent perennial; culms 3-4 m. tall, from long decumbent rooting bases, un-
branched above, 4-6 mm. thick, glabrous, solid, the interior filled with stellate aeren-
chyma; nodes with swollen sheath pulvini; sheaths shorter than the internodes, gla-
brous, the margin somewhat pustulose-ciliate; ligule a minute membrane, ca. 0.4-0.5
mm. long; blades 25-27 cm. long, 27-40 mm. wide, glabrous, with cordate-clasping basal
lobes, the margins scabrous. Peduncle included; panicles narrowly cylindrical, tapering
to a narrow tip, the branches ascending, strict, the lower ones as much as 6 cm. long, the
rachis exposed between whorls of branches. Spikelets short-pedicellate, densely clus-
tered along the lower sides of the branches, 2.5-2.9 mm. long, lanceolate; first glume
ovate, acute, 1-nerved, 0.9-1.1 mm. long; second glume 2.0-2.1 mm. long, lanceolate,

FIG. 94. Hymenachne amplexicaulis. Blooming plant, rooting culm base.

262

BURGER: FLORA COSTARICENSIS 263

acute, 3-nerved; sterile lemma 2.3-2.6 mm. long, lanceolate, acute, 3-nerved; fertile
lemma 2.0-2.2 mm. long, narrowly ovate, obscurely nerved; palea about equal in length;
anthers 3, 0.5 mm. long, purplish. The foliage has a deep green to olivaceous coloration.
Chromosome number n = 20 from a Costa Rican specimen.

Rare; elevations below 800 m.; riverbanks. General Valley near San
Isidro (Skutch 3963), near San Vito de Java (Pohl & Davidse 11161).
Southern Costa Rica, Panama; Cuba and Trinidad; Bolivia to Argen-
tina.

HYPARRHENIA Andersson in Stapf

Perennial caespitose grasses; inflorescence usually complex, of numerous individually
pedunculate spathaceous partial inflorescences, each of a pair of nearly conjugate rames
at the tip of a slender peduncle; rames, or some of them, having a basal pair of sessile
awnless spikelets that are staminate or sterile, followed by 1 or more spikelet pairs, each
consisting of 1 sessile, awned, perfect-flowered spikelet and 1 pedicellate, nearly awn-
less, usually staminate spikelet; rame terminating in a triad of 1 sessile spikelet and 2
pedicellate spikelets. Spikelets dorsally compressed; glumes equal, lanceolate, the first
flat on the back, 7-9-nerved, its margins incurved over the edges of the second glume and
slightly keeled and ciliolate near the bifid tip; second glume 3-nerved, bulging on the
back; florets usually 2, shorter than the glumes and completely concealed by them; lower
lemma thin, membranaceous, faintly nerved; upper lemma in staminate or sterile
spikelets similar to the first; upper lemma in perfect-flowered spikelets very narrow,
membranaceous, 2-lobed at the tip, scarcely wider than the broad flat base of the stout,
twisted and geniculate exserted awn. Disarticulation usually above the basal pair of
spikelets and at the tip of each internode of the flattened, ciliate rachis, the spikelet pairs
or triads falling as units. (Panicoideae: Andropogoneae.)

Hyparrhenia is a large genus of more than 75 species, nearly all
confined to tropical and subtropical Africa, with a few species, some
introduced, in tropical and subtropical America. The genus is closely
related to Andropogon, differing mostly in the rounded and incurved,
not keeled, margins of the first glume, and in the presence of a basal
pair of sessile, equal, and usually staminate or sterile spikelets.

KEY TO SPECIES OF Hyparrhenia

la. Rames of each pair ascending, diverging at an acute angle from each other; spikelet
pairs usually 5 or more per rame; common cultivated forage grass, widely es-
caping H. rufa

Ib. Rames of each pair strongly reflexed away from each other; spikelet pairs or triads
usually 1-2 per rame; rare; Boruca H. bracteata

Hyparrhenia bracteata (Willd.) Stapf in Prain, Fl. Trop. Africa
9:360. 1919. Andropogon bracteatus Willd., Sp. PL ed. 4. 914. 1806.
Figure 95.

Perennial, in dense tufts; plants up to 2.5 m. tall, caespitose; culms erect, unbranched
except in the inflorescence, up to 5 mm. thick, solid or with a small lumen, glabrous or

FIG. 95. Hyparrhenia bracteata. A, compound inflorescence; B, a rame and its
spatheole; C, triad of a sessile, perfect-flowered spikelet and two awnless, pedicellate
staminate spikelets.

264

BURGER: FLORA COSTARICENSIS 265

appressed-silky below the contracted nodes; basal leaf sheaths keeled, overlapping;
sheaths appressed-hirsute; ligule a firm brown membrane, 1-3 mm. long, densely short-
ciliate on the margin; leaf blades up to 5 mm. wide, the margins revolute, lower surface
appressed-hirsute like the sheath, upper surface glabrous or puberulent; midrib wide,
flat above. Inflorescence an elongate virgate mass, up to 50 cm. long, much branched
with several orders of ascending branches, each with a bladeless spathe; ultimate
inflorescences borne on slender, heavily papillose-hirsute peduncles, each subtended by
a spatheole longer than the peduncle, which protrudes laterally from it; rames paired,
reflexed at the tip of the peduncle, a dense tuft of elongated glassy hairs between them;
one rame subsessile and with a pair of sessile awnless staminate spikelets at its base;
rachis bearing an oblong bract just above the pair of staminate spikelets; disarticulation
just above this bract, the remainder of the rame usually a triad of one sessile perfect-
flowered awned spikelet, accompanied by 2 pedicellate awnless or awn-tipped staminate
spikelets. Callus of the sessile spikelet slender, pointed, heavily bearded; pedicels thin
and flat, heavily bearded on the margins, extremely oblique at their tips. Basal awnless
spikelets 5.0-5.5 mm. long, lanceolate; first glume 7-nerved, its edges infolded, slightly
keeled and ciliolate near the tip; second glume 4.5-5.0 mm. long, 3-nerved; lower lemma
membranaceous, 4.0-4.2 mm. long, firm, ciliate, 1-nerved; upper lemma 3.0-3.2 mm.
long, ciliate; lodicules 2, ciliate; anthers 0-3, ca. 2 mm. long. Sessile spikelet of the
terminal triad 5.5-6.5 mm. long, lanceolate; first glume ca. 7-nerved, grooved on both
sides of the midrib, bifid at the tip, the teeth acute, keels ciliolate near the tip; second
glume convex, lanceolate, 3-nerved, awn-tipped; sterile lemma 3.5-4.5 mm. long, mem-
branaceous, faintly nerved; fertile lemma scarcely wider than the flattened awn base;
awn ca. 3 cm. long, geniculate, the 2 basal segments strongly twisted and hispid; anthers
3, yellow, 1.5 mm. long; stigmas purple. Pedicellate spikelets similar, ca. 4.5 mm. long;
first glume with an awn up to 1.8 mm. long, lower lemma ca. 2.5 mm. long; upper lemma
3.5-4.0 mm. long; anthers 3, 2.0-3.0 mm. long. Second rame of the pair similar to the
first, but lacking the basal pair of sessile spikelets. Occasionally, 1 rame may contain
more spikelet pairs.

Dry hilly savannas, Boruca and Buenos Aires; elevation 380-480 m.;
rare. December. Southern Mexico to Brazil and Paraguay. Tropical
Africa. Willdenow cited a specimen from Cumana, Venezuela, and
credited the species to Humboldt and Bonpland; however, he indicated
that the description was his own and that he had seen a dry specimen.

Hyparrhenia rufa (Nees) Stapf in Prain, Fl. Trop. Africa 9:304.
1919. Trachypogon rufus Nees, Agrost. Bras. 345. 1829. Figure 96.

Perennial; densely caespitose, forming large clumps with numerous innovations and
elongate drooping basal leaves; culms mostly 1-2 m. tall, unbranched except in the
inflorescence, internodes round, glabrous, solid or with a small lumen; nodes contracted,
glabrous or slightly puberulent, a swelling just above the node; leaf sheaths shorter than
the internodes, keeled near the apex, from glabrous to marginally papillose-hirsute
above, rarely hirsute all over; ligule a firm brownish membrane, 1.0-2.5 mm. long; blades
flat, narrow at the base, glabrous, or hirsute above, especially near the base; basal
blades up to 70 cm. long, 7 mm. wide, the culm blades smaller. Inflorescence a large
compound mass, up to 50 cm. long, open, composed of numerous axillary branches, the
ultimate inflorescences being paired slender rames borne on slender weak hairy pedun-
cles exserted from bladeless sheaths. One of the pair of rames subsessile at the tip of the

FIG. 96. Hyparrhenia rufa. A, compound inflorescence; B, a pair of awnless spikelets
from the base of a rame; C, pair with sessile, awned spikelet and pedicellate awnless
spikelet.

266

BURGER: FLORA COSTARICENSIS 267

peduncle, the other on a short rachis, one or both with a pair of equal awnless spikelets
at the base. Rames 1-4 cm. long, with up to 8 pairs of spikelets, the terminal segment of
the rachis bearing one sessile spikelet and a pair of equal awnless pedicellate ones.
Rachis internodes, pedicels, and spikelets heavily bearded with rusty colored ascending
hairs; rachis disarticulating at the base of the internodes and the tips of the pedicels;
internodes thin, flat, ca. 3 mm. long. Basal pair of spikelets usually awnless, subequal,
4.5-5.5 mm. long, lanceolate in outline; first and second glumes equal in length, the first
flattened on the back, the edges inrolled but not keeled except near the ciliate bidentate
tip; nerves 9-11; second glume 3-nerved, tapering to the tip; lower lemma empty, 1-3-
nerved, hyaline, ciliate; upper lemma similar, enclosing a staminate flower with 2
lodicules and 3 yellow to reddish anthers, 2.5-3.0 mm. long. Succeeding pairs of spikelets
dimorphic, the sessile spikelet with a conspicuous geniculate awn, the 2 basal segments
twisted and appressed-hispid, the terminal segment thin and straight; pedicellate
spikelet 3.7-5.5 mm. long, lacking an awn but similar in shape to the other. Sessile
spikelet 3.7-4.5 mm. long, with an empty lower lemma, the upper lemma very narrow,
membranaceous, 2-lobed at the apex, the wide flat awn arising between the lobes;
lodicules 2, truncate; anthers 3, yellow or reddish, usually smaller than those of the basal
pair; stigmas purple. Pedicellate spikelets sterile or with minute staminodes.

Abundant in open areas, pastures, and savannas; elevations up to
900 m.; widely cultivated for forage and freely escaping to the wild,
becoming a dominant species in Guanacaste. The principal season of
bloom is from late October to December, when the tall culms develop
synchronously over large areas. During most of the rest of the year,
the plants remain vegetative, producing much basal foliage but only
scattered and somewhat dwarfed blooming culms. Hyparrhenia rufa is
of African origin, but is now widespread in the American tropics;
Mexico to Brazil. Common name: Jaragud.

HYPOGYNIUM Nees

Caespitose perennial grasses; inflorescence a compound mass of numerous individually
spathaceous racemes, each of few pairs of similar awnless spikelets; rachis internodes
thin, disarticulating at the nodes; racemes terminating in a single staminate spikelet;
subsessile spikelet of each pair pistillate, with 2 stigmas and 3 minute staminodes;
pedicellate spikelet of each pair staminate, with 3 fertile anthers; spikelets dorsally
compressed, lanceolate, awnless; glumes equal in length, coriaceous, completely con-
cealing the 2 florets; first glume flattened on the back, the margins sharply inflexed over
the edges of the convex second glume; lower floret consisting of a thin membranaceous
lemma, shorter than the glumes, lacking flower or palea; upper floret similar, consisting
of a membranaceous lemma containing a pair of truncate lodicules and a staminate
flower.

A small genus of two species, one in tropical Africa and the other in
the American tropics. The genus was formerly united with Andropo-
gon, from which it differs in having both spikelets of the pair externally
equal, awnless, and pedicellate, and also in the unisexual spikelets.
(Panicoideae: Andropogoneae.)

268 FIELDIANA: BOTANY

Hypogynium virgatum (Desv.) Dandy, J. Bot. 69:54. 1931. An-
dropogon virgatus Desv. in Hamil., Prodr. PI. Ind. Occ. 9:1825. Figure
97.

Perennial, caespitose in large dense tufts; culms erect, 95-165 cm. tall, unbranched
except in the inflorescence, up to 4 mm. thick, glabrous; internodes mostly solid, filled
with parenchyma or with a small lumen; nodes dark, glabrous, slightly contracted; basal
leaf sheaths keeled and longer than the internodes, glabrous, the basal blades up to 90
cm. long, 3 mm. wide, the upper leaves with sheaths shorter than the internodes and
much smaller blades that are pilose on the upper surface near the ligule, erect and flat
near the base, involute above; ligule an inverted U-shaped stiff membrane, less than 1
mm. long. Inflorescence an elongated ellipsoidal compound mass, terminal on the main
culms or axillary from upper leaf nodes, in total 15-40 cm. long, up to 6 cm. thick,
repeatedly branching, each branch and the individual racemes subtended by a bladeless
sheath or spathe. Individual racemes solitary on a short peduncle which is enveloped by
a spatheole that envelops the lower portion of the raceme; racemes 1.0-1.5 cm. long,
usually of 5-6 internodes, each bearing a pair of spikelets; rachis slender, scabrous,
disarticulating at the bases of the internodes, bearing a solitary terminal staminate
spikelet at the tip. Pistillate spikelet of each pair 2.8-3.1 mm. long, subsessile, on a
thickish pedicel ca. 0.2 mm. long; first glume 2-3-nerved, hispid on the angles above;
second glume 3-5-nerved; florets similar, the lemmas ca. 2.0 mm. long, staminodes
minute; stigmas large, plumose, purple. Staminate spikelet similar to the pistillate
spikelet, borne on pedicel ca. 1 mm. long; anthers 3, yellow or reddish, 1.1-1.2 mm. long.
Chromosome number n = 10 from a Costa Rican specimen.

Savannas at Buenos Aires; roadsides near San Isidro de El General.
December to February. British Honduras and Guatemala; northeast-
ern Nicaragua; Costa Rica to Argentina; West Indies.

The plants are reddish in all their parts. Harlan (Rhodora 58:138.
1956) has reported a chromosome number of n = 15 for a Brazilian
specimen designated as H. spathifolius.

ICHNANTHUS Beauvois

REFERENCES: K. E. Rogers, A taxonomic study of the genus
Ichnanthus (Gramineae), Section Foveolata Pilger, Unpubl. Ph.D.
Diss., Univ. of Tennessee. University Microfilms 69-16, 528. vii + 187
pp. 1969. Michael Stieber, A revision of the genus Ichnanthus
(Gramineae) based on the morphology and anatomy, Unpubl. Ph.D.
Diss., Univ. of Maryland. University Microfilms 75-29, 136. 211 pp.
1975. A. S. Hitchcock, The North American species of Ichnanthus,
Contr. U.S. Natl. Herb. 22:1-12. 1920.

Perennial, usually decumbent or creeping grasses; leaf blades flat, often ovate; ligule a
membrane; panicles terminal and axillary. Spikelets usually paired and unequally
pedicellate, more or less dorsally compressed, but the glumes keeled; disarticulation
below the glumes; glumes and lower lemma membranaceous, strongly nerved, acute or
acuminate; first glume shorter than the spikelet, 3-5-nerved; second glume and lower

FIG. 97. Hypogynium virgatum. A, compound inflorescence; B, rame with base en-
veloped in a spatheole; C, terminus of a rame with a single staminate spikelet; D,
spikelet pair.

270 FIELDIANA: BOTANY

lemma subequal, acute or acuminate, as long as the spikelet, surpassing and mostly
concealing the upper (fertile) floret; second glume 5-9-nerved; lower lemma similar, with
a well-developed palea and often a staminate flower; upper floret cartilaginous or rigid,
dorsally compressed, awnless, ovate or elliptical, smooth and shining; lemma with in-
rolled margins, bearing on its lower curved margins depressed scars or winglike ap-
pendages, these continued downward into a minute stipe (rachilla internode). These
scars or wings are usually considered to be appendages of the rachilla internode, al-
though they fall with the easily detached fertile floret. Palea flat, its margins covered by
the inrolled edges of the lemma.

The genus is common in moister parts of tropical America, and oc-
curs in western Africa and tropical Asia as well. The plants usually
occur in forests or forest margins, at low or middle altitudes. Ichnan-
thus is only weakly differentiated from Panicum, the best mark of
distinction being the scars or appendages of the upper (fertile) lemma.
The plants are extremely variable, and two recent authors have esti-
mated the number of species as 27 and over 100, respectively. Some
species, in addition to their great morphological variation, exhibit sev-
eral levels of polyploidy. Chromosomal abnormalities and aneuploidy
are known as well. It is evident that the genus needs continued biosys-
tematic study. Occasional plants of various species may have weirdly
proliferated, greatly elongated spikelets with numerous sterile, over-
lapping bracts, the whole resembling a multi-flowered spikelet of a
pooid or chloridoid grass. (Panicoideae: Paniceae.)

KEY TO SPECIES OF Ichnanthus

la. Mature upper lemma, including basal stipe (rachilla) 2 mm. or less long; terminal
panicles with lower branches more than 5 cm. long, usually rebranched; upper

lemma usually rotated 90° within spikelets when mature /. pallens

Ib. Mature upper lemma 2-3 mm. long; terminal panicles with branches less than 5 cm.

long, mostly simple; upper lemma usually not rotated within mature spikelet . . 2

2a. First glume narrowly triangular, 3-nerved, tapering gradually into a caudate

tip, the length, including the awn, 6.5-9 x the folded width; peduncles very

slender, arching, exserted up to 19 cm /. tennis

2b. First glume ovate, 3-5-nerved, tapering abruptly to a cuspidate tip, length
3.2-4.7 x the folded width; peduncles stiff, usually exserted 3-6 cm.

/. nemorosus

Ichnanthus nemorosus (Swartz) Doell in Mart., Fl. Bras. 2 (2):289.
1877. Panicum nemorosum Swartz, Prodr. PL Ind. Occ. 22. 1788. For
a detailed synonomy, see Stieber, I.e. Figure 98.

Duration indefinite, probably perennial; plants creeping, forming patches, the culms
rooting at the lower nodes and branching freely below; internodes 1.5 mm. or less thick,
hollow, glabrous or papillose-pilose in lines or overall; nodes mostly bearded; sheaths
shorter than the internodes, more or less papillose-pilose, especially on the margin;
ligule a short-ciliate membrane, 0.5-1.3 mm. long; leaf blades flat, asymmetric at the

FIG. 98. Ichnanthus species. /. nemorosus: A, flowering shoot; B, spikelet; /. tennis:
C, flowering shoot; D, spikelet.

271

272 FIELDIANA: BOTANY

sometimes subcordate base, mostly 2-7 cm. long, 7-12 mm. wide, usually ovate 3.5-7:1,
more or less papillose-pilose to nearly glabrous. Terminal peduncle exserted 3-6 cm.;
terminal panicle 3-5 cm. long, 1.5-3 cm. wide, open pyramidal, with few short branches;
terminal panicle usually accompanied by a smaller axillary barely exserted one from the
terminal sheath, and often a small axillary one from the sheath below. Spikelets paired,
unequally pedicellate, few on one branch, appressed, green or purple, 3.0-4.5 mm. long,
ovate; first glume 1.8-3.6 mm. long, 3- or rarely 5-nerved, acute or cuspidate, the length
3.2-4.7 x the folded width; second glume 2.8-4.2 mm. long, ovate, acute, 5-nerved,
sometimes with scattered weak hairs near the margin; lower (sterile) lemma 2.8-3.5 mm.
long, ovate, acute, 5-nerved, enclosing a membranaceous palea at least three-fourths as
long and usually a staminate flower with 3 stamens; rare individuals may have a pistillate
lower flower; upper (fertile) lemma 2.1-2.6 mm. long, elliptic, blunt, cartilaginous, its
lower margins scarred, the scars continued downward as wings on the short stipelike
rachilla; palea similar and equal in length, its edges covered with the inrolled margins of
the lemma; lodicules 2, truncate; anthers 3, yellow, 1.2-1.5 mm. long.

Moist forests; 600-2,200 m. elevation; mountains from Guanacaste to
the Panamanian Border. June to October. Southern Mexico to Argen-
tina; West Indies. We have recorded several chromosome counts of n
= 20 for this species, as well as an aneuploid count of n = 27, and have
observed cases of abnormal meiosis as well. This species is weedy and
displays a great deal of variation in leaf shape and pubescence.

Ichnanthus pallens (Swartz) Munro ex Benth., Fl. Hongk. 414.
1861. Panicum pallens Swartz, Prodr. Ind. Occ. 23:1788. Ichnanthus
axillaris (Nees) Hitchc. & Chase, Contr. U.S. Natl. Herb. 18:334.
1917. Panicum axillare Nees, Agrost. Bras. 141. 1829. Figure 99.

Perennial, the plants mostly decumbent and creeping, or the culms ascending into
brush and up to 2-3 m. long; lower nodes rooting; branching abundant; culms usually
1.0-1.5 mm. thick, the internodes hollow, thick-walled; sheaths mostly shorter than the
internodes, usually glabrous but with pilose upper margins; ligule a ciliate membrane,
1-2 mm. long; leaf blades flat, thin, dark green, usually ovate 2.3:1-5:1, rarely to 9:1,
asymmetric and subcordate at the base, usually glabrous or scabrid. Inflorescences
1-several from the terminal sheath, one larger and longer-pedunculate than the other;
axillary panicles usually present from several upper sheaths; panicles usually 5-10 cm.
long, ovoid, the longest branch 5-7 cm. long, often somewhat congested, the larger
branches secondarily branched, rather densely flowered, the spikelets appressed to the
branches. Spikelets keeled, slightly laterally compressed, glabrous or scabrous, 3-4 mm.
long, disarticulating entire, but the upper floret very weakly attached and frequently
separating; first glume usually at least three-fourths as long as the spikelet, 3-nerved,
triangular 3-4:1 as folded, acuminate; second glume and lower (sterile) lemma subequal
or the glume slightly longer; second glume 5-nerved, the lateral pairs remote from the
midrib, acuminate; lower lemma similar, enclosing a palea at least three-fourths as long
and often a staminate flower with 3 stamens; upper (fertile) floret shorter than the
glumes and lower lemma, 1.5-2.2 mm. long, elliptical, blunt, lemma cartilaginous, gla-
brous, dorsally compressed, its margins inrolled over the edges of the palea of equal
length; lower margins of lemma bearing depressed scarred areas, these extending
downward to the stipelike attached rachilla internode; stamens 3, the anthers yellow,

FIG. 99. Ichnanthus pollens. A, stoloniferous base; B, young panicle; C, mature
panicle; D, spikelet; E, fertile floret, showing scars on basal lemma margins.

273

274 FIELDIANA: BOTANY

0.8-1.0 mm. long. Fertile floret when mature often rotating 90° within the spikelet, its
back visible from the side of the spikelet.

Common in moist forested areas from near sea level to about 1,500
m. elevation, most common at lower elevations; rain forest, forest
margins, clearings, coffee and cacao plantations, usually in areas with
some disturbance, on both Pacific and Caribbean slopes; rare in
Guanacaste. Blooming mostly July to December. Central America to
northern Argentina; West Indies.

This species is somewhat weedy. The plants are astonishingly di-
verse, but it appears quite impossible to select separable types.
Chromosome numbers among our Costa Rican collections were n = 10,
20, 27, ca. 30, and 30; however, no clear correlation was seen between
ploidy level and morphological type. The two counts of n = 10 were
from plants collected near sea level, and the higher counts were from
greater elevations.

Ichnanthus tenuis (Presl) Hitchc. & Chase, Contr. U.S. Natl.
Herb. 18:334. 1917. Oplismenus tenuis Presl, Rel. Haenk. 319. 1830.
See Stieber, I.e. for an extended synonymy. Figure 98.

Duration indefinite, possibly annual; plants creeping, the lower nodes rooting; culms
10-70 cm. long, branching freely; internodes very slender, elongated, hollow, glabrous or
pubescent, especially in longitudinal stripes; nodes usually bearded; sheaths much
shorter than the internodes; more or less papillose-pilose; ligule a short, thin membrane,
long-ciliate, in total up to 1.5 mm. long; leaf blades flat, thin, ovate 3.5-7:1, asymmetrical
at the subcordate base, mostly 2.5-5.0 cm. long, 6-13 mm. wide, the surfaces scabrous to
heavily papillose-pilose. Peduncles very slender, arched, elongated, up to 19 cm. long,
usually several from the terminal sheath, with others arising from the axils of most of
the lower sheaths. Terminal inflorescence usually 2-7 cm. long, open, the branches
usually solitary, ascending; spikelets mostly paired, unequally pedicellate, appressed
along the usually simple branches. Spikelets 3.5-4.5 mm. long, disarticulating entire,
narrowly ovate, acuminate; first glume 2.1-3.6 mm. long, 3-nerved, narrowly triangular,
the length 6.5-9 x the folded width, caudate; second glume about as long as the spikelet,
3.2-4.2 mm. long, 5-nerved, ovate, caudate, often bearing scattered weak slender hairs
near the upper margins; lower (sterile) lemma similar, 2.6-3.5 mm. long, 5-nerved,
enclosing a membranaceous palea at least three-fourths as long, usually with a staminate
flower; upper (fertile) lemma elliptical, blunt, cartilaginous, light-colored, 1.9-2.6 mm.
long, its lower margins with depressed scars that continue downward as wings onto the
stipelike rachilla internode; margins inrolled over a palea of equal length; anthers 3,
yellow, 0.8-1.5 mm. long. Chromosome numbers n = 10, 20 from Costa Rican specimens.

Along trails and streams in forests, mostly at elevations up to 300
m., but occasionally to 1,100 m., on both Pacific and Caribbean slopes.
October to March. Southern Mexico to Brazil. The plants are some-
what weedy. They are best recognized by the small leaves and slender,
whiplike peduncles, and the caudate, pubescent spikelets.

BURGER: FLORA COSTARICENSIS 275

IMPERATA Cyrillo

Rhizomatous perennials; inflorescence a dense cylindrical terminal panicle, the
spikelets mostly concealed by long, silky hairs borne on the axis, branches, pedicels, and
spikelets. Spikelets paired, alike, unequally pedicellate, disarticulating from the disklike
apex of the pedicels; callus truncate, bearing a ring of numerous elongate silky hairs
several times as long as the spikelets; spikelets narrowly ovoid in outline; glumes nearly
equal or the first slightly shorter than the second, membranaceous, 3-7-nerved, nar-
rowly triangular, bearing scattered long silky hairs; sterile lemma and fertile lemma
much shorter than the glumes, hyaline and nerveless, their apices erose-jagged; stamen
usually 1.

A small genus of about seven species of warm climate grasses of both
eastern and western hemispheres, related to Saccharum and Erio-
chrysis. The plants are often regarded as weeds with little forage
value. (Panicoideae: Andropogoneae.)

KEY TO SPECIES OF Imperata

la. Inflorescence 25-50 cm. long; culms 1-2 m. tall, leafy, bearing elongated leaf blades;

spikelets 2.9-3.5 mm. long /. contructa

Ib. Inflorescence 6-15 cm. long; culms up to 80 cm. tall, the foliage mostly near the base,

the blades of stem leaves small; spikelets 3.5-4.5 mm. long /. brasiliensis

Imperata brasiliensis Trin., Mem. Acad. Imp. Sci. St.-
Petersbourg, Ser. 6, Sci. Math. 2:331. 1832. I. caudata Cyr. ex
Chapm., Fl. S. U.S. ed. 2. 668. 1883.

Perennial from scaly, creeping rhizomes; culms unbranched, 1 mm. thick, glabrous,
25-75 cm. tall, the interior more or less filled with parenchyma; nodes more or less
bearded with tufts of appressed elongated silky hairs; foliage mostly basal, the 2-3 stem
leaf blades usually small and the uppermost one very reduced; sheaths glabrous, the
basal ones breaking down into stiff fibers; ligule a ciliolate brown membrane, 0.3-1.0 mm.
long; larger leaf blades 6-15 cm. long, 8-10 mm. wide, glabrous except for prominent
silky marginal hairs at the base, a few scattered long hairs on the upper surface near the
base. Peduncle slender, glabrous, exserted up to 20 cm.; inflorescence a solitary terminal
panicle, densely silvery-silky, 6-15 cm. long, 1-2 cm. thick, cylindrical and little tapered;
rachis, branches, and pedicels bearing elongated silky hairs; apex of pedicels dilated,
disciform. Spikelets paired, equal, narrowly ovoid, 3.5-4.0 mm. long; callus truncate,
bearing a ring of elongate silky white hairs up to 12 mm. long; first glume slightly shorter
than the second, narrowly triangular, ciliolate at the tip, bearing elongated silky hairs on
the back; nerves 3-5; second glume similar but 5-7-nerved; sterile lemma hyaline, nerve-
less, triangular, the margins erose-jagged; fertile lemma similar, 0.5-1.1 mm. long;
anther single, 1.8-2.8 mm. long, orange.

Rare; Buenos Aires savanna; El Paraiso. An old Oersted specimen is
stated to have come from Guanacaste, but bears no other locality data.
February to April. Florida; West Indies; southern Mexico to Brazil.

Imperata contracta (H.B.K.) Hitchc., Rep. Missouri Bot. Gard.

276 FIELDIANA: BOTANY

4:146. 1893. Saccharum contractum H.B.K., Nov. Gen. & Sp. 1:182.
1816. Figure 100.

Tall, coarse, erect perennial, 1-2 m. tall, forming large colonies by abundant scaly
creeping rhizomes; culms unbranched, hollow, glabrous, 1-2 mm. thick; lower sheaths
without blades; sheaths mostly overlapping, glabrous, with prominent auricles; ligule a
firm brown ciliate membrane, 0.5-1.5 mm. long; blades up to 70 cm. long, 5-11 mm. wide,
widest at the middle, tapering to a narrow base; midrib wide, white; blades scabrous on
the margins, glabrous on the surfaces or occasionally with a few long papillose-based
hairs on the auricles and behind the ligule; uppermost leaf blade much reduced. Inflores-
cence a solitary terminal panicle, narrowly cylindrical, dense, 25-50 cm. long, tapering
toward the apex, the numerous branches ascending, usually 5 cm. or less long; panicle
densely silky because of the numerous long hairs of the branches and spikelets, white or
purplish. Spikelets unequally pedicellate, the shorter pedicel of each pair ca. 0.5 mm.
long, the longer ca. 1.5 mm.; rachis, branches, and pedicels scabrous and bearing scat-
tered long silky hairs. Spikelets of each pair equal, narrowly ovoid, acute, 2.9-3.5 mm.
long; callus truncate, bearing numerous silky hairs up to 12 mm. long; glumes nearly
equal or the first slightly shorter, lanceolate or triangular, 3-nerved, sometimes scab-
rous, their backs bearing scattered silky hairs, the tips sometimes minutely ciliolate;
lower lemma sterile, a hyaline nerveless oblong scale 1.5-1.8 mm. long, its tip erose or
lobed and bearing minute marginal spicules; fertile lemma similar, shorter, 0.7-1.1 mm.
long; lodicules not seen; anther one, 1.6-2.0 mm. long; caryopsis ca. 0.7 mm. long,
obovate-cylindrical, 2:1. Chromosome number n = 10 from Costa Rican material.

Beaches and open areas, roadsides, near the Pacific Coast; Moin;
Puriscal; San Jose area; mostly under 500 m. elevation. Blooming ap-
parently yearlong. Southern Mexico to Peru and Brazil; West Indies.

The plants are coarse and weedy, forming large colonies by
rhizomatous spread; probably of little value for forage. Common name
Zacate talquesa.

ISACHNE R. Brown

REFERENCE: A. S. Hitchcock, The North American species of
Isachne. Contr. U.S. Natl. Herb. 22:115-122. PL 25-32. 1920.

Inflorescence a panicle; spikelets biconvex, 2-flowered; glumes subequal, shorter than
the florets, 5-7-nerved, a definite internode between the 2 glumes; florets similar or
somewhat dimorphic, the second slightly shorter than the first, both containing flowers;
lower flower staminate or perfect, the upper pistillate in our species; disarticulation
above or below the glumes; florets joined by a very short rachilla segment and falling
together.

Although this genus is obviously panicoid in many features, the fact
that both florets are well developed causes the spikelets to be more or
less globose, rather than dorsally compressed as in most other panicoid
genera. (Panicoideae: Paniceae.)

FIG. 100. Imperata contracta. A, inflorescence; B, rhizomatous plant base; C, portion
of an inflorescence branch with unequal pedicels.

277

278 FIELDIANA: BOTANY

KEY TO SPECIES OF Isachne

la. Low creeping plants; leaves cordate, 2-4 cm. long; upper floret puberulent

I. polygonoides

Ib. Tall erect or scrambling plants; leaves not cordate, 9-20 cm. long; both florets gla-
brous I- o/rundinacea

Isachne arundinacea (Swartz) Griseb., Fl. Brit. W. Ind. 553. 1864.
Panicum arundinaceum Swartz, Prodr. Veg. Ind. Occ. 24. 1788. Fig-
ure 101.

Perennial from hard, knotty crowns; culms hard, woody, scrambling, in brush or
reclining on steep slopes and rooting from lower nodes, much branched, up to 5 m. long;
main culms hard and woody, 4-8 mm. thick, thick-walled, glabrous, resembling bamboo
canes; branches much thinner; young canes bearing nearly bladeless sheaths which are
deciduous at maturity; sheaths of main culms shorter than the internodes, those of
smaller lateral branches overlapping; sheaths usually glabrous except for the ciliate
overlapping margin, rarely papillose-hispid; prophylla prominent, 2-3 cm. long; ligule of
stiff white hairs, 0.5-3.5 mm. long; blades scabrous, rarely appressed-hispid below or on
both surfaces, 9-20 cm. long, 7-22 mm. wide, rather firm; inflorescences mostly born on
leafy branches from the elongated main culms; peduncle glabrous, 4-11 cm. long; panicles
dome-shaped, nearly as wide as long when fully expanded, 8-12 cm. long, 8-11 cm. wide,
the branches spreading, much branched above the middle, the spikelets crowded at the
periphery of the panicle; spikelets obovoid to subspherical, scarcely compressed, 1.4-1.8
mm. long, disarticulating below the glumes, above the glumes, or the glumes dropping
before the florets; glumes shorter than the spikelet, subequal, but the first somewhat
narrower than the second, glabrous or with a few stiff hairs near the tips; first glume
ovate, 5-nerved; 1.0-1.4 mm. long; second glume broadly ovate, 7-nerved, 1.0-1.7 mm.
long; florets elliptical-obovoid, obscurely nerved; first floret 1.4-1.7 mm. long, the second
1.0-1.3 mm. long, on a very short rachilla segment; anthers 2-3, ca. 1 mm. long, yellow to
purple. Chromosome number n = 20 from Costa Rican material.

Occasional; steep embankments, cliffs above streams, roadsides,
forest margins; 30 to 1,900 m. elevation; more common on the Pacific
slope, but also collected in the Limon area and at BriBri. Blooming
yearlong. Southern Mexico to Peru; Caribbean Islands.

Isachne polygonoides (Lam.) Doell in Mart., Fl. Bras. 2:273. 1877.
Panicum polygonoides Lam. , Encycl. 4:742. 1798. Figure 102.

Duration indefinite; total length of culms to 50-60 cm.; plants widely decumbent, the
culms rooting at the lower nodes, the terminal portions erect; branching abundant;
prophylla ca. 10 mm. long; culms hollow, soft, glabrous; nodes glabrous or papillose-
pubescent; leaves numerous; sheaths shorter than the short internodes, papillose-ciliate
on the overlapping margin, often papillose-hispid all over; ligule of rather sparse stiff
hairs, 1-2.5 mm. long; leaf blades lanceolate, cordate-based, 2-4 cm. long, 7-13 mm. wide,
thin, scabrous above and on the margins, papillose-ciliate at the base, sometimes to the
tip, puberulent beneath; base of panicle included in the uppermost sheath; panicles
terminal on leafy branches, 2-6 cm. long, pyramidal, the branches solitary, perpendicu-
lar to the rachis; branches and pedicels bearing yellowish glandular bands; spikelets
biconvex, on stiff spreading pedicels; spikelets 1.3-2.0 mm. long, disarticulating below or
above the glumes, the 2 florets remaining together; a definite internode between the first

FIG. 101. Isachne arundinacea. A, flowering culm; B, base of plant; C, cluster of
spikelets.

279

FIG. 102. Isachne polygonoides. A, panicle; B, spikelet, showing dimorphic florets.

280

BURGER: FLORA COSTARICENSIS 281

and second glumes, the first glume 1.2-1.8 mm. long, 5-nerved, broadly ovate; second
glume 1.3-1.9 mm. long, 7-nerved, broadly ovate; glumes glabrous or with a few stiff
papillose hairs near the tips; lower floret with a glabrous, chartaceous lemma and palea;
lemma 1.5-1.7 mm. long, oval, convex, faintly 5-nerved, the palea subequal, the flower
staminate; anthers 3, 0.4-0.5 mm. long, yellow; upper floret with lemma 1.2-1.5 mm.
long, hemispherical, puberulent, stiff, the palea plane, its margins narrowly overlapped
by the lemma; flower pistillate, its truncate lodicules bearing abundant bicellular hairs.
Chromosome number n = 10 from Costa Rican material.

Pond margins, ditches, swamps, often in shallow water; fairly com-
mon in Guanacaste; Tuis; Volcan; 270-400 m. elevation. September to
February; possibly yearlong. Guatemala and Honduras to Peru and
northern Brazil; West Indies.

ISCHAEMUM Linnaeus

Annual or perennial grasses; inflorescence of 2-many digitate racemes or rames borne
at the apex of a terminal peduncle; individual rame or raceme composed of many inter-
nodes, each bearing 2 similar spikelets; disarticulation at the base of each internode,
which falls with the 2 attached spikelets; one spikelet of each pair sessile or subsessile,
the other pedicellate, the 2 similar, but the pedicellate one often somewhat smaller or
reduced. First glume flattened, usually rigid and often cross-wrinkled below, thin and
veiny above, its marginal flanges clasping the boat-shaped second glume of equal or
slightly longer length; florets 2, concealed by the glumes; lower floret hyaline, awnless,
with a staminate flower; upper floret shorter, the lemma hyaline, deeply bifid, the
twisted awn arising at the juncture of the lobes; palea usually longer than the lemma.
Pedicellate spikelet equal or smaller, often somewhat reduced and shorter-awned, in
some species disarticulating from the pedicel.

The genus is unusual in the Andropogoneae in having a well-
developed, staminate lower floret. About 50 species, almost all native
to the Old World, a few of these occurring as weeds in the American
tropics. (Panicoideae: Andropogoneae.)

KEY TO SPECIES OF Ischaemum

la. Rames 2, closely appressed to each other, appearing as a single cylindrical spike;
lower part of first glume of sessile spikelet strongly transversely corrugated

/. rugosum
Ib. Racemes 2-many, spreading apart; first glume of subsessile spikelet stiff but

smooth, not corrugated 2

2a. Racemes 3-many; nodes and leaf blades glabrous; blades 10-33 mm. wide

/. latifolium

2b. Racemes 2; nodes upwardly bearded; blades pubescent, less than 10 mm.
wide /. indicum

Ischaemum indicum (Houtt.) Merrill, J. Arnold Arbor. 19:320.
1938. Phleum indicum Houtt., Nat. Hist. II: 13:198. t. 90, f. 2. 1782.
Ischaemum ciliare Retz., Obs. Bot. 6:36. 1791. Figure 103.

FIG. 103. Ischaemum species. /. latifolium: A, inflorescence; /. indicum: B, portion of
a raceme; I. rugosum: C, spikelet pair and rachis internode.

282

BURGER: FLORA COSTARICENSIS 283

Duration indefinite; plants sprawling, the lower parts of the culms long decumbent and
rooting at the lower nodes; upper portions of culms ascending, branching freely;
prophylla 2.5-6 cm. long; internodes ca. 1 mm. thick, hollow, glabrous; nodes wide, dark,
upwardly bearded; sheaths keeled, papillose-pilose on the margin and on the surfaces,
especially toward the apex; ligule a thin, brownish membrane, 0.5-1.0 mm. long; leaf
blades flat, 4-9 cm. long, 4-8 mm. wide, papillose-pilose on the surfaces, with a few stout
hispid hairs at the base. Peduncles slender, glabrous, exserted 5-15 cm.; inflorescence a
conjugate pair of diverging racemes, 6-8 cm. long. Spikelets paired at each node of the
disarticulating rachis, one subsessile, on a pedicel ca. 0.5 mm. long, the other on a
pedicel ca. 3 mm. long; rachis internode and pedicel similar, triangular in cross section,
stiffly ciliate on the external angles. Disarticulation at the base of the internodes, the
spikelet pair falling together with the internode. Subsessile spikelet biconvex, ovate 3:1,
tapering to a short, narrow base; first glume ca. 4 mm. long, its basal third stiff, yellow,
smooth, very broad, its marginal flanges covering the base of the second glume; upper
two-thirds of the first glume thin, with many green nerves, most of them paired; apex
bidentate; surface with numerous stiff spreading hairs; second glume longer than the
first, bulging near the base, slightly winged near the tip, 5-nerved, tapering into a short
straight awn; lower lemma ovate, acute, hyaline, ca. 3.5 mm. long, with a similar palea of
about equal length; lodicules 2, truncate; stamens 3, the anthers yellow, 1.6-2.2 mm.
long; pistil absent; upper floret perfect-flowered; lemma thin, hyaline, apex bifid to the
middle, the awn arising between the teeth; basal segment of awn brown, tightly twisted,
3-4 mm. long; upper segment thin, only slightly twisted, purple, 6-7 mm. long; palea
thin, hyaline, acute, longer than the lemma; lodicules 2, truncate; stamens 3, the anthers
similar to those of the lower floret but longer; pistil with 2 separate naked style
branches; stigmas purple. Pedicellate spikelet: Similar to the subsessile one, but usually
smaller, the flower sometimes abortive. Chromosome number n = 9.

The only Costa Rican collection is the following: Puntarenas, Golfito;
very common on sand along a stream, elevation 2m., 11 December
1968, P. & D. 11571. Introduced from the Old World; reported from
Panama and Guyana.

Ischaemum latifolium (Spreng.) Kunth, Rev. Gram. 1:168. 1829.
Andropogon latifolius Spreng., Syst. Veg. 1:286. 1825. Figure 103.

Perennial; plants sprawling or erect, the culms 45-150 cm. long, sometimes rooting at
the decumbent lower nodes, freely branching; internodes solid, pithy, glabrous; nodes
wide, glabrous; sheaths glabrous except for the bearded collar, keeled toward the apex;
ligule a brown membrane, 0.5-2.0 mm. long, tipped with cilia 0.5-2.0 mm. long; leaf
blades flat, broad, 6-10 x longer than wide, 6-24 cm. long, 10-33 mm. wide, narrowed
abruptly to the base, bearded on the collar and lower side at the base, otherwise gla-
brous. Peduncle slender, glabrous, exserted 3-10 cm.; uppermost leaf blade reduced;
peduncle forking once or twice at the tip, the branches bearing a fan-shaped cluster of
5-17 racemes, each 6-12 cm. long. Spikelets paired, one subsessile, its pedicel ca. 0.3 mm.
long, the other on a pedicel ca. 3 mm. long; rachis internodes and pedicels bearded on the
angles and at the tip; disarticulation at the base of the internodes, the spikelet pair
falling; sometimes the pedicellate spikelet disarticulates from its pedicel. Subsessile
spikelet: 4.5-7.0 mm. long; first glume narrowly ovate, 4.5:1, acute, flat to convex on the
back; margins slightly keeled and ciliate near the bifid tip; basal portion firm, smooth;
upper portion herbaceous, 5-7-nerved, some of the nerves forking; second glume convex,

284 FIELDIANA: BOTANY

awn-tipped, slightly longer than the first; lower lemma nearly as long as the first glume,
4.0-5.5 mm. long, hyaline, acute, ciliate above, its palea slightly shorter; lodicules 2,
truncate; anthers 3; upper floret with a hyaline, bifid lemma 3.5-4.0 mm. long, bearing an
awn 5.0-9.5 mm. long from the sinus; palea about as long as the lemma; lodicules 2,
truncate; anthers 3, yellow, 2.1-2.3 mm. long; caryopsis 1.5 mm. long, clear amber, with
a large embryo. Pedicellate spikelet: Similar to the subsessile one, but becoming later-
ally compressed by the folding of the first glume along one keel, the other scarcely
developed; florets similar to those of the subsessile spikelet, but somewhat red-iced and
the fertile lemma shorter-awned.

Brushy roadside, Canton de Dota, 1,400-1,800 m.; Buenos Aires;
stream banks, northern Guanacaste. September to February. Mexico
to Ecuador and Brazil. Chromosome number n = 18 from a Costa
Rican specimen (P. & D. 11067) that is smaller and has narrower
blades than most specimens of this species.

Ischaemum rugosum Salisb., Icon. Stirp. Rar. 1, pi. 1. 1791. Fig-
ure 103.

Caespitose annual; culms 55-130 cm. tall, erect or the bases decumbent and rooting;
branching freely from most nodes; prophylla prominent, 4-8 cm. long, with several
accessory nerves on each lateral flange; culms 2-3 mm. thick, hollow, glabrous; nodes
wide, dark, bearded at the lower margin with a circle of appressed, ascending, silky,
white hairs; sheaths shorter than the internodes, glabrous except on the margin below
the apex, slightly keeled above; ligule a thin brown membrane, 2.0-5.5 mm. long, adnate
to the erect sheath auricles; leaf blades flat, 8-20 cm. long, 7-15 mm. wide, softly
papillose-pilose on both surfaces; base of blade usually contracted into a short, woolly
pseudopetiole. Peduncle glabrous, erect, exserted 3-11 cm.; inflorescences several,
borne on the culm apex and from the upper leaf axils, consisting of a pair of conjugate
rames, closely appressed to each other and appearing as single cylindrical spike ca. 5
mm. in diameter, 3-10 cm. long, the 2 rames at maturity somewhat spreading apart near
the apex. Spikelets paired, one sessile and one pedicellate at each node; rachis inter-
nodes thick, 2.8-3.5 mm. long, triangular in cross section, the external faces yellowish,
rigid, the inner side hyaline, thin, the interior hollow; external angle of the surface with
a Line of stiff appressed hairs; base of the internode and callus of the sessile spikelet
bearded with short ascending hairs; pedicel similar to the rachis internode, usually
shorter, 1.5-2.5 mm. long; rames disarticulating freely at the base of each internode, the
rachis internode, pedicel, and the 2 spikelets falling as a unit. Sessile spikelet: First
glume 3.8-5.0 mm. long, ovate, acute, 2.5:1, slightly convex, the lower three-fifths rigid,
yellowish, very strongly transversely corrugated, the upper two-fifths flat, herbaceous,
longitudinally striate with many fine green nerves; margins of the glume bearing 2
inflexed flanges that clasp the margins of the second glume; second glume keeled, boat-
shaped, slightly longer than the first, acute; lower lemma thin, ovate, acute, faintly
nerved, awnless, its palea a hyaline nerveless scale, shorter than the lemma; stamens 3,
the anthers 1.5-1.8 mm. long, pink; pistil rarely present; upper floret perfect-flowered or
pistillate, its lemma hyaline, 3-4 mm. long, bifid to the middle, the awn attached on the
outer side at the junction of the acuminate teeth; awn 1.5-2.0 cm. long, bent, the basal
half brown, strongly twisted, the upper segment thin, white, loosely twisted; palea
hyaline, nerveless, shorter than the lemma. Pedicellate spikelet: Similar to the sessile

BURGER: FLORA COSTARICENSIS 285

spikelet but smaller, the first glume asymmetric, ovate 2:1, the lower half yellow, rigid,
sometimes slightly undulate, the upper portion green, herbaceous, finely striate; flower
usually staminate. Chromosome number n = 9 from Costa Rican specimens. A base
number of x = 10 is also reported for this genus.

Occasional but locally abundant; Curatella-Byrsonima savannas in
northern Guanacaste, in road ditches, pastures, sometimes in shallow
water; sea level to 600 m. elevation; also collected at Los Angeles (Rio
Penas Blancas), Chomes, and Turrialba. This Old World species is
apparently a recent introduction in Costa Rica, the earliest collection
dating to 1950. Panama, Venezuela, Trinidad, Cuba, and Jamaica.

IXOPHORUS Schlechtendal

Caespitose perennial; inflorescence a panicle with simple spreading or ascending
branches racemosely arranged along the rachis; spikelets subsessile in 2 rows along the
lower sides of the triquetrous branches; each spikelet subtended by a single bristle
longer than the spikelet; disarticulation below the glumes. Spikelets dorsally com-
pressed; first glume much shorter than the spikelet, 3-nerved; second glume and sterile
lemma subequal, as long as the spikelet and concealing the fertile floret; second glume
many-nerved; lower lemma 5-nerved, containing 3 stamens; palea 2-keeled, as long as
the lemma or slightly longer, at full maturity of the fruit becoming circular with a
cordate base and broad chartaceous wings, much wider than the remainder of the
spikelet; upper floret shorter than the spikelet, elliptical, the lemma indurate, apiculate,
with margins inrolled over the edges of the indurate palea; flower of upper floret pistil-
late, rarely with rudimentary stamens.

Ixophorus is similar to Setaria in possessing sterile branches (bris-
tles) in the inflorescence, but differs in the winged spikelets.
(Panicoideae: Paniceae.)

Ixophorus unisetus (Presl) Schlecht., Linnaea 31:421. 1861-62.
Urochloa uniseta Presl, Rel. Haenk. 1:319. 1830. Figure 104.

Coarse caespitose perennial; culms 50-140 cm. tall, up to 1 cm. thick, rather succulent,
erect, unbranched; sheaths mostly overlapping, somewhat keeled, glabrous; nodes
glabrous or slightly appressed-pubescent; ligule a lacerate or ciliate membrane, 1.0-2.5
mm. long; blades lax, with a conspicuous white midrib, glabrous, 10-25 mm. wide, up to
75 cm. long; panicles 10-25 cm. long, ovoid-cylindrical, of numerous racemosely arranged
simple racemes, the lower ones 2-8 cm. long, the upper successively shorter, often naked
near the base; spikelets dorsally compressed, 3.5-4.7 mm. long, each subtended by a
scabrid purple bristle (sterile branch), 1-2 x as long as the spikelet; outline of young
spikelets lanceolate; first glume broadly ovate, acute, 3-nerved, 0.7-1.5 mm. long; second
glume many-nerved; lower lemma 5-nerved; palea of lower lemma at maturity becoming
circular, with a cordate-auriculate base, expanding the spikelet to circular outline; sta-
mens 3, 2-3 mm. long; upper lemma indurate, papillose, brownish. Chromosome number
approximately n = 31-33 from Costa Rican material. Other counts of n = 17 are known.

Sea level to 1,200 m. elevation; common in Guanacaste, San Jose
area, Limon area, Turrialba, Siquirres, Palmar Norte. Mexico to

FIG. 104. Ixophorus unisetus. A, panicle; B, young spikelet; C, mature spikelet with
winged palea of the lower floret; D, mature spikelet from second glume side, showing
winged palea of lower floret; E, winged palea of lower floret, F, upper (pistillate) floret.

286

BURGER: FLORA COSTARICENSIS 287

Costa Rica; Colombia and Venezuela; Cuba. This species is used for
forage production under the names Zacate de Honduras and Zacate
bianco.

JOUVEA Fournier

Stoloniferous, pungent-leaved perennial maritime grasses of coastal dunes and mud
flats; dioecious, the staminate and pistillate inflorescences very different. Staminate
plants: Inflorescences clustered from upper few leaf axils, 1-3 peduncles arising in each
axil, forming a cylindrical or flabellate group; individual inflorescence a spike on a slen-
der, short-exserted peduncle. Spikelets sessile, many-flowered; first glume absent or a
minute scale; second glume 1-nerved, shorter than the first floret; lemmas faintly 3-
nerved; palea nearly as long as the lemma, 2-keeled; rachilla not disarticulating; anthers
3; lodicules 2, truncate, vasculated. Pistillate plants: Pistillate inflorescence a cluster of
stiff, sharp-pointed hornlike bodies, subtended closely by foliage leaves, the horns in-
terspersed with prominent prophylls; individual horns falcate, cylindrical, hard,
acerose-pointed, containing several pistils in alternating succession, each sealed within a
linear cavity in the spongy interior of the horn, the style emerging through a small apical
ostiole; caryopsis linear, naked within the cavity or accompanied by a small nerveless
scale.

The horns have been interpreted as spikelets by Weatherwax (Bull.
Torrey Club 66:315-325. 1939), but their structure and their aggrega-
tion into prophyllate clusters are so unusual as to make the homology
dubious.

Jouvea is a genus of only two species, ranging from Baja California
to Panama. Because of the highly unusual structures of the female
inflorescences, the relationship of the genus to others is obscure. Leaf
anatomy and chromosome size and number indicate that it is
Chloridoid. (Chloridoideae: Aeluropodeae.)

KEY TO SPECIES OF Jouvea

la. Plants of sand dunes on open beaches, forming dense, leafy mounds; stolons thick
and stiff (often becoming buried in the sand), usually with an erect branch at each
node; their internodes usually 2-6 cm. long, leaf sheaths covering one-third or more
of their length; leaf blades persistent J. pilosa

Ib. Plants of saline mud flats behind the beaches or in estuaries, forming sparse flat
mats on surface of soil; stolons thin and wiry, not becoming buried; their internodes
usually 6-10 cm. long, leaf sheaths usually less than one-third as long as internodes,
the leaf blades usually deciduous from the sheath J. straminea

Jouvea pilosa (Presl) Scribn., Bull. Torrey Bot. Club 23:143. 1896.
Brizopyrum pilosum Presl, Rel. Haenk. 1:280. 1830.

Plants forming mats or mounds on sandy beaches; strongly Stoloniferous, the stolons
often buried in sand, profusely branching; flowering on branches or raised tips of the
stolons; culms hollow, glabrous, strongly ridged; nodes yellowish, smooth; leaf sheaths
keeled, shorter or longer than the internodes, 1-3 cm. long, glabrous except for a cluster

FIG. 105. Jouvea straminea. A, staminate plant with inflorescence; B, pistillate
inflorescence; C, pistillate horn with emergent stigmas.

288

BURGER: FLORA COSTARICENSIS 289

of tuberculate-based auricular hairs; prophylls prominent, 2-keeled, up to 2 cm. long;
ligules membranous, crowned with a dense fringe of white cilia, less than 1 mm. long;
leaf blades stiff, often folded, 5-15 cm. long, or much shorter in the female inflorescence,
2-4 mm. wide, glabrous beneath, with scattered long hairs above, the upper surface
strongly ridged. Staminate inflorescence: Spikes 1-several, terminal and axillary from
upper sheaths; peduncle included or slightly exserted; groups of spikes forming a cylin-
drical cluster; individual spikes 5-7 cm. long, oblong, the spikelets borne alternately in 2
rows on 2 sides of a triquetrous rachis. Spikelets overlapping, often proliferous and with
up to 30 florets, 1.5-4.0 cm. long; first glume absent or a minute scale less than 1 mm.
long; second glume 3.5-4.0 mm. long, 1-nerved, keeled, lance-linear; rachilla persistent,
the florets not disarticulating; lemmas with prominent midrib and several faint lateral
nerves, ovate, keeled, 3.5-4.5 mm. long, acute, glabrous; palea as long as or slightly
longer than the lemma, prominent, scabrid on the keels; anthers 3, 2.5 mm. long,
purplish; lodicules 2, truncate, lacerate, vasculated. Spikelets continue to produce new
florets at the tip after flowering has ceased in the lower ones. Pistillate inflorescence: a
dense, flabellate cluster of stiff, sharp-pointed hornlike bodies, these subtended by
short, stiff leaf blades and interspersed with prominent prophylls; individual horns fal-
cate, cylindrical, 2-4 cm. long, acerose-pointed, containing usually 2-5 caryopses, each
sealed within a cylindrical cavity in the spongy interior of the horn, the style emerging
through a small apical ostiole; caryopsis linear, tan, filling the cavity of the horn, naked
or rarely accompanied by a small nerveless bract. Chromosome number n = 10 from
Costa Rican material.

Pacific beaches of Guanacaste, on low sand dunes; Playa Tamarindo,
Playa Naranjo in Parque Nacional de Santa Rosa, Puerto Soley. Prob-
ably blooming yearlong. Pacific beaches; Mexico, Guatemala, El Sal-
vador, Honduras, and Costa Rica.

Jouvea straminea Fourn., Bull. Soc. Roy. Bot. Belgique 15:475.
1876. Figure 105.

Plants caespitose in dense, hard tufts; the culms arising from prophyllate bases,
reclining, forming extensive flat open mats on dry mud flats; stolons numerous, thin and
wiry, sparsely branched, up to 150 cm. long; culms arising in small clumps from the
stolons, glabrous, the nodes dark-colored; leaf sheaths 0.5-2.0 cm. long, usually less than
one-third as long as the internodes, glabrous except at the auricles, not keeled; ligules
0.5-1.0 mm. long, dilate; leaf blades 1.5-5.0 cm. long, 2-3 mm. wide, often folded, tending
to disarticulate from the sheaths on stolons. Staminate inflorescence: A cluster of several
terminal or axillary spikes from the apex of the culms and the upper nodes, the pedun-
cles mostly included; individual spikes 2-4 cm. long, slender. Staminate spikelets usually
2-4, appressed along 2 sides of a thin triquetrous rachis, strongly laterally compressed
and keeled, 1-4 cm. long, proliferous, the rachilla producing new florets at the tip after
the lower ones have shed their pollen; first glume usually absent or up to 5 mm. long and
1-nerved, acicular, second glume lance-linear, 1-nerved, sometimes with an additional
weak lateral nerve, 4-6 mm. long, stiff, scabrid on the keel; florets up to 30, not disar-
ticulating; lemmas 3.5-4.0 mm. long, narrowly ovate, acute, glabrous, 3-nerved, rarely
with additional faint nerves, awnless; palea about as long as the lemma, scabrid-ciliate on
the keels; flower staminate; stamens 3, the anthers ca. 2.5 mm. long, yellowish or
purplish; lodicules 2, truncate, fleshy, prominently vasculated. Pistillate inflorescence:
Plants bearing at the upper several nodes of the culms axillary and terminal clusters of

290 FIELDIANA: BOTANY

several rigid hornlike cylindrical bodies, their bases concealed by the subtending leaf
sheath and several papery prophylls; horns 1.5-3.0 cm. long, ca. 1.5 mm. thick, curved,
rigid, tapering to a pointed base and apex, readily disarticulating at the base; pistillate
flowers 2-3, concealed within the horn by an adnate narrowly triangular flap of tissue,
the single flattened style emerging through a small apical ostiole; stigmas 2, not strongly
plumose; ovary naked or accompanied by a narrow hyaline bract. Chromosome number
n = 10 from Costa Rican material.

Drying mud flats behind beaches and in estuaries, Pacific Coast of
Guanacaste, Puerto Castillo, Puerto Soley, Playa Naranjo in Parque
Nacional de Santa Rosa. Blooming sparsely in December and January;
staminate plants only seen in Costa Rica. Mexico to Panama, on the
Pacific beaches.

LASIACIS (Grisebach) Hitchcock

REFERENCE: G. Davidse, A systematic study of the genus Lasiacis
(Gramineae: Panicoideae), Unpubl. Ph.D. Diss., Iowa State Univ. Li-
brary. 231 pp. 1972.

Perennial, erect, scandent, or prostrate grasses; caespitose or creeping; culms much-
branched, often thick and semi- woody; internodes solid or hollow; ligules membrana-
ceous; leaf blades linear to ovate, sometimes borne on a short pseudopetiole. Inflorescence
an open or contracted panicle, terminal on the culm or on leafy branches. Spikelets
subglobose to globose, ovate, or elliptic, placed obliquely on the pedicel, disarticulating
entire; glumes and lower (sterile) lemma broad, abruptly apiculate, many-nerved, mem-
branaceous, but becoming black and shiny at maturity, woolly at the apex; first glume
one- to two-thirds as long as the spikelet, 5-13-nerved, its lower margins overlapping;
second glume and sterile lemma subequal, ca. as long as the spikelet, 7-15-nerved; lower
(sterile) lemma enclosing a palea one-fourth as long to equalling the lemma; staminate
flower present or absent; fertile lemma hard, rigid, obtuse, its margins inrolled and
enclosing the edges of a similar palea; floret usually dark brown when mature, broadly
elliptic to obovate; palea convex above, concave near the base; both lemma and palea
with a tuft of wool at the tip; stamens 3; styles 2, separate; lodicules 2, fleshy, truncate,
vasculated.

Lasiacis is a genus of 16 species of grasses native to tropical and
subtropical parts of North and South America and the West Indies.
The plants are distinguished from all other panicoid grasses by their
rotund black spikelets, set obliquely on the pedicel and woolly-tufted
at the tip. Individuals of most of the species are large, somewhat
woody plants, vaguely resembling small bamboos or Olyra latifolia.
They are abundant in somewhat disturbed sites on roadsides, in brush,
or on the margins of forests. Recent studies by Davidse have shown
that the mature, black spikelets store oil droplets in the inner linings of
the bracts. They are consumed by fruit-eating birds, who obtain nutri-
tion from this oil, rather than from the heavily protected and undi-

BURGER: FLORA COSTARICENSIS 291

gested grain. This peculiarity of the spikelets, which immediately sets
the genus off from all other grasses, undoubtedly accounts for the
abundance of the plants on the forest margins where birds frequently
perch. The genus is most closely related to Acroceras. (Panicoideae:
Paniceae.) It is commonly called carrizo.

KEY TO SPECIES OF Lasiacis

la. Culms solid, pithy; plants sprawling or creeping and rooting at lower nodes . . 2
Ib. Culms hollow or mostly so; plants creeping, ascending, or clambering on brush or

trees 5

2a. Ligules 1.4 mm. or less long 4

2b. Ligules 2.0-6.0 mm. long; leaf blades linear-lanceolate, 13-29 cm. long ... 3
3a. Sheaths glabrous; spikelets paired or clustered near ends of panicle branches;

lower floret staminate, with long palea L. oaxacensis var. oaxacensis

3b. Sheaths puberulent or pubescent; spikelets solitary on long pedicels; lower floret

sterile, its palea two-thirds or less as long as lemma L. linearis

4a. Foliage glabrous; blades 16-25 cm. long; lower floret staminate

L. oaxacensis var. maxonii
4b. Foliage pubescent; blades 8-17 cm. long; lower floret sterile

L. rhizophora

5a. Plants creeping and rooting at the lower nodes; ligules 4.5-9.0 mm. long; palea of

lower floret less than half as long as lemma L. standleyi

5b. Plants erect or scrambling; culms hollow 6

6a. Leaf blades conspicuously cordate-based, clasping stem, 14-42 cm. long; lower
nodes decumbent, producing conspicuous thick wiry prop roots; panicles very

large, 20-120 cm. long, very open and dome-shaped L. procerrima

6b. Blades not conspicuously cordate-based, smaller; plants without prop roots;

panicles less than 30 cm. long, mostly compactly flowered 7

7a. Ligules of upper leaves readily visible, usually 2-7 mm. long 8

7b. Ligules of upper leaves not readily visible, usually less than 1.5 mm. long 9

8a. Ligules mostly 4-6 mm. long; panicle spherical, less than 9 cm. long; upper

leaf surface scabrous L. scabrior

8b. Ligules mostly less than 3.5 mm. long; panicles large, ovoid, 9-30 cm. long;
upper surfaces of blades glabrous or pubescent

L. sorghoidea var. sorghoidea

9a. Leaf blades glabrous on both surfaces 10

9b. Leaf blades with some pubescence on at least one surface 14

lOa. Blades linear to narrowly lanceolate, 7-11 x longer than wide, usually less

than 2 cm. wide 11

lOb. Leaf blades broadly lanceolate to ovate, 3-6 x longer than wide, more than 2

cm. wide 13

lla. Panicles few-flowered, branches spreading or reflexed; mature pedicels sharply

divergent; culms zigzag L. divaricata var. divaricata

lib. Panicle branches not reflexed; culms straight or zigzag 12

1 -a. Base of panicle included in uppermost sheath; pedicels and branches short

L. divaricata, var. leptostachya

292 FIELDIANA: BOTANY

12b. Base of panicle usually exserted; pedicels slender, widely spreading,
flexuous L. nigra

13a. Main inflorescence branches sparsely branched, bearing few spikelets; pedicels
appressed, short; blades with short, puberulent pseudopetioles L. sloanei

13b. Main inflorescence branches much branched; pedicels not appressed; leaf blades

lacking a distinct pseudopetiole L. ruscifolia var. ruscifolia

14a. Leaf blades lanceolate, 6-11 x longer than wide 15

14b. Leaf blades ovate, 3-6 x longer than wide 16

15a. Panicles 5-12 cm. long; pedicels spreading; spikelets 4.0-5.0 mm. long . L. nigra

15b. Panicles 9-25 cm. long; pedicels not spreading; spikelets 3.4-4.1 mm. long

L. sorghoidea var. sorghoidea

16a. Blades 6-14 cm. long, 18-44 mm. wide L. ruscifolia var. ruscifolia

16b. Blades 4-7 cm. long, 8-15 mm. wide L. rugelii var. pohlii

Lasiacis divaricata (L.) Hitchc., Contr. U.S. Natl. Herb. 15:16.
1910, var. divaricata. Panicum divaricatum L., Syst. Nat. ed. 10.
2:871. 1759.

Robust perennial; caespitose; culms erect or arching and clambering in brush, up to 7
m. long, the upper portions of the culms and main branches usually zigzag; internodes
hollow, 5-9 mm. thick, glabrous or puberulent; nodes glabrous; sheaths glabrous or
puberulent, ciliate on the margin; auricular hairs up to 3 mm. long; ligule inconspicuous,
usually less than 0.6 mm. long, ciliolate or glabrous; leaf blades usually 5-12 cm. long,
6-14 mm. wide, linear or narrowly lanceolate, glabrous, scabrous, or puberulent.
Inflorescence usually 2-12 cm. long, the longest branch 2-8 cm. long; branches spreading
or reflexed; pedicels strongly divergent. Spikelets obovate, 3.5-4.5 mm. long; first glume
1.2-2.5 mm. long, 7-11-nerved; second glume 9-11-nerved; lower (sterile) lemma lacking
a flower, 9-13-nerved, its palea half or more as long; upper (fertile) lemma 3.4-4.0 mm.
long, whitish to brown; anthers white, ca. 2 mm. long; stigmas purple; caryopsis 2.2-2.4
mm. long, whitish. Chromosome number n = 18.

Caribbean lowlands, in brushy margins of forests. Southern Florida;
West Indies and northern South America; Mexico to Panama. Usually
fruiting from June to March.

Var. leptostachya (Hitchc.) Davidse, Ann. Missouri Bot. Gard.
64:375. 1977. Lasiacis leptostachya Hitchc., Contr. U.S. Natl. Herb.
22:19. 1920.

This variety differs from the typical var. divaricata in its narrower leaf blades, occa-
sionally heavily pubescent culm internodes, somewhat larger spikelets, and smaller,
denser panicles which are included at the base and lacking divaricate branches except at
full maturity.

Northwestern Costa Rica. Oaxaca and Veracruz to Panama.

Lasiacis linearis Swallen, Phytologia 4:427. 1953.

Creeping perennial; the culms solid, 2-5 mm. thick, the lower nodes decumbent and
rooting, the terminal portions erect, up to 100 cm. long, freely branching, forming large
tangled colonies; internodes glabrous or with a line of pubescence; nodes glabrous;

BURGER: FLORA COSTARICENSIS 293

sheaths puberulent or pubescent, the overlapping margin ciliate; ligules tan to dark
brown, ciliate, 1.4-4.8 mm. long, conspicuous; leaf blades linear, asymmetric at the base,
13-22 cm. long, 8-18 mm. wide, glabrous, scabrid, or puberulent. Inflorescence 19-30 cm.
long, the branches spreading, up to 23 cm. long, naked on the lower half, the long-
pedicellate spikelets borne toward the tips. Spikelets narrow, obovate, 3.9-4.5 mm. long;
first glume 2.0-2.5 mm. long, 7-9-nerved; second glume 8-11-nerved; lower (sterile)
lemma empty, 9-11-nerved, its palea one- to two-thirds as long as the lemma or rarely
absent; upper (fertile) lemma 3.9-4.1 mm. long; anthers white; stigmas purple; caryopsis
2.2-2.4 mm. long. Chromosome number n = 18.

Cloud forests, oak and pine forests, forest margins, elevation 1,400-
2,400 m. San Gabriel. June through March. Southern Mexico to North-
ern Panama.

Lasiacis nigra Davidse, Phytologia 29:152. 1974. Figure 106.

Caespitose perennial; culms erect at the base, arching above and clambering into
vegetation, up to 12 m. long; internodes hollow, up to 10 mm. thick, glabrous to densely
papillose-pubescent; nodes glabrous; sheaths glabrous to pilose, the margin ciliate with
hairs to 3 mm. long; auricular hairs to 4 mm. long; ligule 0.5-2.0 mm. long, glabrous to
ciliate; leaf blades linear to lanceolate, 5-15 cm. long, 6-26 mm. wide, glabrous or com-
monly pilose. Panicle usually 5-12 cm. long, the longest branch to 8 cm. long; spikelets
few, long-pedicellate; panicle branches ascending to diverging, glabrous to pilose.
Spikelets obovate, 3.6-5.5 mm. long; first glume 1.6-3.2 mm. long, 5-13-nerved; second
glume 7-13-nerved; lower (sterile) lemma 9-11-nerved, its palea half as long as the lemma
or longer; flower absent or staminate with anthers rudimentary or up to 2.7 mm. long,
white; stigmas white; caryopsis 2.4-2.7 mm. long, light brown. Chromosome number n =
18.

Forest margins, thickets, and brush; elevations 900-2,300 m. This
species is common in Costa Rica, mostly on the Pacific slope. It is not
known from the lower and dryer parts of Guanacaste. Flowering most
commonly from June to January. Central Mexico to northwestern
South America (Colombia, Venezuela, and Ecuador).

This species has usually been included in L. sorghoidea until re-
cently, but differs in the delicate, open panicle with few spikelets.

Lasiacis oaxacensis (Steud.) Hitchc., Proc. Biol. Soc. Wash. 24:45.
1911, var. oaxacensis. Panicum oaxacense Steud., Syn. PL Glum.
1:73. 1854.

Perennial; culms extensively creeping and rooting at the nodes, 0.5-2.0 m. long, much
branched, the terminal portions more or less ascending; internodes 2-5 mm. thick, usu-
ally solid, glabrous; nodes glabrous; sheaths glabrous or rarely somewhat puberulent
when young; margins usually ciliate; ligule prominent, 2-6 mm. long (see also var.
maxonii with short ligules), brown, often puberulent or hispid on the back, the edges
ciliate or glabrous; leaf blades 13-29 cm. long, 12-24 mm. wide, narrowly linear-
lanceolate, glabrous, usually scabrous on edges and midrib, rarely puberulent when
young. Inflorescence mostly terminal, 16-31 cm. long, the longest branch 4-24 cm. long;
branches widely spreading, mostly naked on lower two-thirds; spikelets pedicellate in

FIG. 106. Lasiacis nigra. A, culm segment; B, base of plant; C, inflorescence; D,
spikelet.

294

BURGER: FLORA COSTARICENSIS 295

pairs or small clusters toward the ends of the branches. Spikelets 3.8-4.2 mm. long; first
glume 1.6-2.3 mm. long, 4-9-nerved; second glume 7-11-nerved; lower lemma with an
equal palea and a staminate flower with well-developed lodicules; anthers 1.0-2.3 mm.
long, sometimes rudimentary; upper (fertile) lemma 3.2-3.6 mm. long; anthers 1.7-2.3
mm. long; stigmas purple; caryopsis 2.0 mm. long. Chromosome number n = 18.

Forest margins and openings, roadsides, sometimes in cafetales,
mostly on the Pacific slope. This species is more weedy than most of
the others of the genus, and may form sizable patches in disturbed
sites. Mostly blooming from November to April. Southern Mexico to
Peru, Ecuador, Venezuela, and Colombia; Greater Antilles.

Var. maxonii (Swallen) Davidse, Ann. Missouri Bot. Gard. 64:375.
1977. L. maxonii Swallen, loc. cit. 30:231. 1943.

This variety differs in having short ligules, 1.5 mm. or less long.

Costa Rica and Panama; Honduras.

Lasiacis procerrima (Hack.) Hitchc., Proc. Biol. Soc. Wash. 24:145.
1911. Panicum procerrimum Hack., Oesterr. Bot. Z. 51:431. 1901.
Figure 107.

Short-lived perennial or annual; culms decumbent at the base and producing conspicu-
ous unbranched prop roots from lower nodes; culms in clumps, 0.5-5 m. long, simple or
sparingly branched, 4-12 mm. thick; internodes hollow, glabrous or rarely puberulent
below the glabrous nodes; sheaths glabrous or puberulent, glaucous; ligule 0.5-1.5 mm.
long; leaf blades 14-42 cm. long, 14-57 mm. wide, the base cordate and clasping the stem,
ciliate; surfaces glabrous to velutinous, rarely hispid, glaucous beneath. Inflorescence a
large, very open panicle, 20-120 cm. long, about as wide; spikelets mostly borne toward
the ends of the branches. Spikelets 3.0-4.8 mm. long; first glume 1.4-3.0 mm. long,
7-11-nerved; second glume 9-11-nerved; lower (sterile) lemma 9-11-nerved, usually en-
closing a palea at least three-fourths as long; flower usually staminate, rarely perfect;
anthers 1.8 mm. long, rarely rudimentary; upper (fertile) lemma 3.1-3.4 mm. long,
1.8-2.1 mm. wide; lemma black to grayish brown at maturity, its upper margins not
inrolled; anthers 1.6-1.9 mm. long; stigmas white; caryopsis 2.3 mm. long, dark brown.
Chromosome number n = 18 from Costa Rican specimens.

Common on exposed road embankments and brushy open slopes, up
to 1,800 m. elevation, most common on the Pacific Slope. Blooming
from June to January. Mexico to Northern South America, from Peru
to Guyana. Common names: Alajuela, Cariuela.

Lasiacis rhizophora (Fourn.) Hitchc. Proc. Biol. Soc. Wash. 24:145.
1911. Panicum rhizophorum Fourn., Mex. PI. 2:31. 1881.

Perennial; culms creeping, rooting at the nodes, freely branching; upper parts of culms
erect to 1 m. tall; culms slender, 2-3 mm. thick, solid; internodes puberulent toward the
apex; nodes glabrous or puberulent; sheaths shorter than the internodes, puberulent,
hirsute, or papillose- hispid, the overlapping margin ciliate above; auricular hairs of
sheath apex prominent; ligule a ciliate membrane, 0.4-1.1 mm. long, tipped with hairs

FIG. 107. Lasiacis procerrima. A, culm base with prop roots; B, leaf blade with
cordate base; C, portion of inflorescence; D, spikelet; E, two views of an upper (fertile)
floret.

296

BURGER: FLORA COSTARICENSIS 297

1.5-3.5 mm. long; leaf blades lanceolate, 8-17 cm. long, 16-37 mm. wide; surfaces hispid,
puberulent, scabrous or glabrous; base asymmetrical, one side cordate-clasping.
Inflorescence 10-24 cm. long, the longest branch up to 11 cm. long; branches ascending or
spreading, scabrous or puberulent; spikelets clustered in pairs or small groups toward
the tips of the branches. Spikelets 3.1-4.0 mm. long; first glume 1.4-2.1 mm. long,
5-7-nerved, second glume 7-9-nerved; lower (sterile) floret lacking a flower or rarely with
rudimentary stamens, the lemma 7-9-nerved, its palea three-fourths or less as long;
fertile lemma 2.9-3.2 mm. long, black to dark brown; anthers 1.6-1.9 mm. long; stigmas
purple; caryopsis 2.2-2.4 mm. long. Chromosome number n = 18 from a Costa Rican
specimen.

Pacific slope, 850-1,400 m. elevation. Known from Tilaran, Mon-
teverde, the Meseta Central, and Canas Gordas. Blooming July to
February. Central Mexico to Colombia.

Lasiacis rugelii (Griseb.) Hitchc., Bot. Gaz. (Crawfordsville)
51:302. 1911, var. pohlii Davidse, Ann. Missouri Bot. Gard. 64:375.
1977. Panicum rugelii Griseb., Cat. PI. Cuba 233. 1866. Figure 108.

Perennial; culms caespitose, 1-5 m. long, erect below, weak and arching and climbing
into brush, occasionally in part procumbent and rooting, internodes hollow, 3-6 mm.
thick, usually glabrous or with a line of hairs on one side or entirely puberulent; nodes
glabrous; sheaths densely puberulent; overlapping margin ciliate; auricular hairs 1.5
mm. long, pseudopetiole 1-3 mm. long; ligule an inconspicuous whitish membrane, 0.4
mm. or less long; leaf blades ovate-lanceolate to lanceolate, 4-7 cm. long, 8-15 mm. wide,
glabrous or minutely puberulent; base asymmetric, abruptly narrowed to nearly trun-
cate. Panicle usually not fully exserted, 3-7 cm. long, the longest branch 3.5 cm. or less
long; branches ascending to spreading, pubescent or scabrid. Spikelets globose, 3.6-4.2
mm. long; first glume 1.7-2.5 mm. long, 7-9-nerved; second glume 9-nerved; lower
(sterile) lemma 9-nerved, with a palea at least half as long but lacking a flower, upper
(fertile) lemma 3.8-4.0 mm. long, brown; caryopsis 2.2-2.4 mm. long.

Rain forests, shaded roadsides, riverbanks; elevation 500-700 m.
Blooming July to January. Known in Costa Rica from Pejibaye (the
type), Turrialba, and La Palma (Volcan Arenal). Guatemala to
Panama.

This variety replaces var. rugelii in Central America. It differs from
var. rugelii in having the culm internodes glabrous or with only a line
of puberulence, var. rugelii having pubescent internodes, as well as in
having smaller, more globose spikelets.

Lasiacis ruscifolia(H.B.K.) Hitchc., Proc. Biol. Soc. Wash. 24:145.
1911, var. ruscifolia. Panicum ruscifolium H.B.K., Nov. Gen. & Sp.
PL 1:101. 1816. Lasiacis glabra Swallen, Ceiba 4:287. 1955.

Caespitose perennial; culms 1-8 m. long, erect at the base, arching, the upper parts
leaning on brush; internodes woody, usually hollow, 5-12 mm. thick, variously glabrous
or with a single line of pubescence, or puberulent, or papillose-pubescent; nodes glabrous
or puberulent; sheaths papillose-hispid with hairs up to 3.5 mm. long, or puberulent or
glabrous; overlapping sheath margin ciliate; auricular hairs up to 3 mm. long; ligule

FIG. 108. Lasiacis rugelii var. pohlii. A, base of plant; B, flowering branch; C,
spikelet.

298

BURGER: FLORA COSTARICENSIS 299

usually inconspicuous, 0.3-1.0 mm. long, glabrous or ciliate; leaf blades ovate to lance-
olate, 4-16 cm. long, 10-56 mm. wide, with an asymmetric clasping base that is usually
ciliate with hairs to 3 mm. long. Panicle rather dense, 2-22 cm. long, the longest branch
1-9 cm. long, the lower branches widely separated and spreading. Spikelets globose,
2.6-4.0 mm. long; first glume 1.0-2.2 mm. long, 9-13-nerved; second glume 11-13-nerved;
lower (sterile) lemma lacking a flower, 11-13-nerved, its palea at least two-thirds as long
as the lemma; upper (fertile) lemma 2.8-3.6 mm. long, dark brown to grayish black;
anthers 1.4-2.3 mm. long, white; stigmas white; palea usually deeply concave; caryopsis
2.0-2.5 mm. long. Chromosome numbern = 18.

Dry, rocky savannas, gallery forests; common in northern
Guanacaste; Barranca; La Garita; elevations usually below 500 m.
Blooming mostly June to February. Northern Mexico to northwestern
South America (Colombia, Venezuela, and Ecuador); Cuba and
Jamaica.

Var. velutina (Swallen) Davidse, Ann. Missouri Bot. Gard. 64:375.
1977. L. velutina Swallen, Ceiba 4:288. 1955.

This variety has velutinous leaf blades and pilose panicle branches.

Some of our specimens from Guanacaste approach this in leaf pubes-
cence, but lack pilose panicle branches. Honduras; Venezuela.

Lasiacis scabrior Hitchc., Proc. Biol. Soc. Wash. 40:85. 1927.

Caespitose perennial; culms erect or arching and clambering over vegetation, 1-6 m.
tall; internodes up to 13 mm. thick, hollow, woody, papillose-pubescent or puberulent
near the apex or in a vertical line; nodes glabrous; sheaths Usually pubescent or villous,
the hairs up to 2 mm. long, rarely becoming glabrous with age; overlapping margin and
throat ciliate, the hairs 2.0-3.5 mm. long; ligule a conspicuous, usually dark brown
lacerate membrane, 3.5-7.0 mm. long, glabrous, appressed-pubescent or ciliate, the hairs
to 3.0 mm. long; leaf blades linear to lanceolate, 6-16 cm. long, 10-30 mm. wide; upper
surface scabrid or puberulent along the midrib, especially toward the base; lower surface
usually densely puberulent, or becoming glabrous; base asymmetric; margin scabrid.
Panicle usually 4-9 cm. long, rather dense, nearly spherical, the longest branch 1-5 cm.
long; base always included in the upper sheath. No large terminal inflorescence present,
but numerous inflorescences borne on secondary branches; panicle branches usually
pubescent or densely puberulent below, scabrid above. Spikelets obovoid, 3.5-4.5 mm.
long; first glume 1.2-2.8 mm. long, 7-11-nerved; second glume 9-13-nerved; lower
(sterile) lemma 11-13-nerved, its palea two-thirds as long or longer; flower lacking or
rudimentary; upper (fertile) lemma 3.5-3.6 mm. long, dark brown; anthers ca. 2 mm.
long, white; caryopsis 2.1-2.3 mm. long.

Clearings, trails, margins of wet forests; sea level to 1,100 m. eleva-
tion. Northern Costa Rica to the Panamanian border. July to April.
Oaxaca and Vera Cruz, Mexico, to Colombia, Ecuador, and Peru.

Lasiacis sloanei (Griseb.) Hitchc., Bot. Gaz. (Crawfordsville)
57:302. 1911. Panicum sloanei Griseb., Fl. Brit. W. Ind. 551. 1864.

300 FIELDIANA: BOTANY

Panicum latifolium Hamilt. Prodr. PI. Ind. Occ. 10. 1825, non P.
latifolium L., 1753.

Caespitose perennial; culms erect or clambering, 1-6 m. long; internodes hollow, 4-10
mm. thick, glabrous or with a vertical line of puberulence; nodes glabrous; sheaths
glabrous except for dilation on the upper margin and throat; auricular hairs up to 3 mm.
long; pseudopetioles up to 3 mm. long, usually pubescent; ligule membranaceous, 0.5-1.0
mm. long, ciliolate or ciliate; leaf blades 8-18 cm. long, 13-45 mm. wide, ovate to lance-
olate; upper surface puberulent or scabrous at the base of the midrib or along its length,
otherwise shiny and glabrous on both surfaces; base asymmetrical. Panicle open, with
relatively few, short-pedicellate spikelets appressed to the branches; length 6-34 cm.;
longest branch 2-15 cm. long. Spikelets 4.0-5.3 mm. long, first glume 1.5-2.6 mm. long,
7-9-nerved; second glume 9-13-nerved; lower (sterile) lemma 9-13-nerved, with a palea at
least three-fourths as long; flower lacking or staminate; anthers 1.5-2.0 mm. long or
sometimes rudimentary; upper (fertile) lemma 3.8-4.3 mm. long; anthers 1.8-2.2 mm.
long, white; stigmas white; caryopsis 2.3-2.6 mm. long, whitish. Chromosome number
n = 18.

Moist forest margins, in brush and thickets along roadsides. Eleva-
tions below 1,000 m. Northwestern Guanacaste; Pandora; Rio Terraba
below Boruca; common in the canyon of the Rio Reventazon at CATIE
at Turrialba. July to March. Northeastern Mexico to Colombia, Ven-
ezuela, and Ecuador; Greater Antilles.

Lasiacis sorghoidea (Desv. ex Hamilt.) Hitchc. & Chase, Contr.
U.S. Natl. Herb. 18:338. 1917., var. sorghoidea. Panicum sor-
ghoideum Desv. ex Hamilt. , Prodr. PI. Ind. Occ. 10. 1825.

Caespitose perennial; culms 1-10 m. long, erect at the base, often coarse, arching and
leaning on vegetation; internodes woody, 5-15 mm. thick, hollow, variously glabrous,
papillose-pubescent, or with a single line of pubescence; nodes glabrous; sheaths often
papillose-pubescent, especially toward the apex, the hairs up to 3.5 mm. long, rarely
glabrate; overlapping margin and throat ciliate, the hairs up to 3 mm. long; collar
densely pubescent; ligule inconspicuous, usually 0.3-1.5 mm. long, usually ciliate; leaf
blades elliptic-lanceolate to linear-lanceolate, 6-23 cm. long, 6-46 mm. wide, the upper
surface usually puberulent, rarely heavily pubescent; lower surface usually velutinous or
puberulent. Panicle usually large and prominent, 5-35 cm. long, the branches usually
ascending, spreading at maturity. Spikelets obovate to elliptic, usually purple when
immature, 3.0-4.3 mm. long; first glume 1.2-2.7 mm. long, 7-11-nerved; second glume
9-13-nerved; lower (sterile) lemma 9-11-nerved, with a palea half or more as long as the
lemma; with or without a staminate flower; anthers 1.7-2.0 mm. long; upper (fertile)
lemma 2.9-3.8 mm. long, dark brown, with a dorsal indentation; anthers 1.9-2.3 mm.
long; caryopsis 1.8-2.3 mm. long. Chromosome number n = 18.

Forest margins, brushy areas, roadsides; mostly at elevations below
1,100 m. Mountains of western Costa Rica, from Guanacaste to the
Panamanian border. October through May. Oaxaca and Veracruz,
Mexico, to Brazil and Argentina; West Indies.

Lasiacis standleyi Hitchc., Proc. Biol. Soc. Wash. 40:86. 1927. L.

BURGER: FLORA COSTARICENSIS 301

longiligula Swallen, Ann. Missouri Bot. Gard. 30:232. 1943. L. lucida
Swollen, Ann. Missouri Bot. Gard. 30:231. 1943.

Creeping perennial, the culms rooting at the nodes, the plants lacking strong central
canes; culms with terminal growths erect or scrambling in brush for several meters;
internodes 2-4 mm. thick, hollow, thin- walled, puberulent toward the apex and with a
longitudinal line of puberulence or rarely pubescent; nodes glabrous; sheaths variously
puberulent, pubescent, or papillose-hispid with hairs to 3 mm. long, occasionally gla-
brous; overlapping margin ciliate with hairs to 2.5 mm. long; collar glabrous or puberu-
lent; ligule a prominent, usually dark brown lacerate membrane, 4.5-9.0 mm. long,
ciliate on one or both margins with hairs to 3 mm. long; leaf blades 10-18 cm. long, 8-35
mm. wide, broadly elliptic-lanceolate to linear, upper surface usually strongly scabrous,
puberulent, hispidulous, or glabrous; base asymmetric; margins sometimes undulate.
Panicle rather compact, 7-27 cm. long, the longest branch 2-15 cm. long. Spikelets
3.7-5.0 mm. long; first glume 9-13-nerved; lower (sterile) lemma 11-13-nerved, with a
palea one-fourth or less as long, lacking a flower; upper (fertile) lemma 3.4-4. 1 mm. long;
anthers white; stigmas purple; caryopsis 2. 1-2.4 mm. long. Chromosome number n = 18.

Cloud and montane forests, from 600 to 2,000 m. elevations; in for-
ests, clearings, along trails and in brush. Mountains of western Costa
Rica, from northern Guanacaste to the Panamanian border. October to
April. Guatemala to Colombia, Venezuela, and Ecuador.

LEERSIA Swartz
Nomen Conservandum

REFERENCE: G. L. Pyrah, Taxonomic and distributional studies in
Leersia (Gramineae), Iowa State J. Sci. 44:215-270. 1969.

Perennial caespitose or rhizomatous grasses; inflorescence a terminal panicle.
Spikelets consisting of a naked laterally compressed and keeled awnless floret; glumes
reduced to minute ridges or a minute cupule at the tip of the pedicel; lemma strongly
keeled, 5-nerved; palea keeled, 3-nerved; stamens 1-6; disarticulation below the floret,
the cupule remaining on the pedicel.

Leersia is a genus of about 17 species, most of them occurring on wet
soil or in marshes in temperate or tropical regions of the entire world.
The genus is apparently closely related to Oryza, from which it differs
in lacking sterile florets below the fertile one, and in the lack of awns.
The plants often form large, tangled colonies in marshy areas. The
foliage in some species, notably L. hexandra, bears minute barbs that
cause painful scratches in the human epidermis. (Oryzoideae:
Oryzeae.)

KEY TO SPECIES OF Leersia

la. Spikelets pectinate-ciliate, narrowly elliptical, 3-5 mm. long; stamens 6; plants
rhizomatous, in wet places L. hexandra

302 FIELDIANA: BOTANY

Ib. Spikelets not ciliate, usually glabrous, broadly elliptical, 2-3 mm. long; stamens 2;
plants caespitose, in upland forests L. ligularis var. grandifiora

Leersia hexandra Swartz, Prodr. Veg. Ind. Occ. 21. 1788. Figure
109.

Plants perennial; culms 25-150 cm. long, decumbent and rooting at lower nodes;
rhizomes slender, elongated; plants sometimes floating in shallow water, branching
common from rhizomes or decumbent portions of stems; culms 1.0-3.5 mm. thick, hollow,
glabrous or retrorsely scabrous; nodes retrorsely pubescent; sheaths strongly scabrous
to glabrous, the margins ciliate, midrib somewhat keeled, upper margins auriculate, the
auricles acute, joined to the ligule; ligules membranaceous, 1-6 mm. long; blades flat,
5-25 cm. long, 3-15 mm. wide, from strongly scabrous to glabrous. Peduncle smooth, up
to 11 cm. long; panicle narrow, open, rather simple, 5-15 cm. long, the branches few.
Spikelets subsessile, imbricated along the slender, zigzag branchlets, elliptic-oblong,
apiculate, 3-5 mm. long, 1.0-1.5 mm. wide; lemma and palea of equal length, but the
lemma much wider; keels of lemma and palea strongly scabrous-ciliate; margins, nerves,
and internerves of lemma somewhat scabrid; spikelets whitish or pink; stamens 6, 2-3
mm. long. Chromosome number n = 24 from Costa Rican material.

Common in wet places, ditches, moist pastures, marshes, sometimes
floating in shallow water, often forming enormous stands in marshes,
as at Laguna de Arenal. Widespread in Costa Rica from sea level to
1,400 m. elev. Blooming probably yearlong. Subtropical and tropical
regions of both hemispheres; in North America from the southeastern
United States to Texas; southern Mexico to southern South America.

Pyrah has pointed out that there is practically no seed set in this
species. In the sites where it grows, it is able to spread very freely by
vegetative means. Because of the strongly scabrous sheaths, the
plants often cause severe scratches, which readily become infected.

Leersia ligularis Trin., Mem. Acad. Imp. Sci. St.-Petersbourg,
Ser. 6, Sci. Math., Seconde Pt. Sci. Nat. 5:168. 1839. var. grandiflora
(Doell) Pyrah, Iowa State J. Sci. 44:236. 1969. L. distichophylla Bal.
and Poit, Bull. Soc. Hist. Nat. Toulouse 12:221. 1878. L. grandiflora
(Doell) Prodoehl, Bot. Arch. 1:219. 1922. Figure 109.

Plants perennial; culms decumbent to erect, to 2 m. tall, sometimes rooting at lower
nodes, unbranched, hollow; nodes glabrous to retrorse-pubescent; leaves numerous, the
lower ones with overlapping sheaths; upper sheaths shorter than the internodes; midribs
of sheaths somewhat keeled above; sheath auricles present, acute, united to the edges of
the ligule; ligules 1-4 mm. long, membranaceous; blades up to 40 cm. long and 25 mm.
wide, glabrous or hispid on the upper surface. Peduncle glabrous; panicle up to 45 cm.
long, ovoid, very open; branches 1-4 at the lower nodes. Spikelets broadly elliptical, 2-3
mm. long, 1.2-1.6 mm. wide, subsessile along the outer fourth of the spreading branches,
glabrous or slightly scabrid; anthers 2, 1.0-1.5 mm. long.

Occasional in the Meseta Central; Rincon de la Vieja; elevations

FIG. 109. Leersia species. L. hexandra: A, inflorescence; B, spikelet; L. ligularis, var.
grandiflora: C, inflorescence; D, spikelet.

303

304 FIELDIANA: BOTANY

900-1,100 m., in rocky open woods or brush. Blooming October to
June. Guatemala to Colombia; Brazil, Paraguay, Argentina.

LEPTOCHLOA Beauvois

Annual or perennial grasses. Inflorescence a panicle of slender, 1-sided racemes,
arranged racemosely along an elongated common rachis; spikelets short-pedicellate,
appressed in 2 rows along the lower sides of a slender triquetrous rachis, somewhat
overlapping. Spikelets laterally compressed and keeled, of 2-6 florets, disarticulating
above the glumes and between the florets, the rachilla extended above the ultimate
fertile floret and often bearing a minute or moderate-sized rudiment at its apex; glumes
1-nerved, narrow, acuminate; lemmas 3-nerved, the lateral nerves close to the margins,
the apex bifid and sometimes bearing a short awn from the split; palea nearly as long as
the lemma; anthers 2 or 3, small; caryopsis free, angular, grooved on the side opposite
the embryo.

Leptochloa is a genus of about 20 species of rather weedy grasses,
distributed in warm temperate and tropical regions of both hemi-
spheres. In spikelet structure, it is similar to such genera as Gouinia,
Triplasis, and Eragrostis. Because of the arrangement of the nearly
sessile spikelets in two rows along the simple panicle branches, au-
thors have sometimes placed the genus in the tribe Chlorideae.
(Chloridoideae: Eragrosteae.)

KEY TO SPECIES OF Leptochloa

la. Sheaths more or less papillose-hirsute; glumes nearly as long as spikelet

L. filiformis

Ib. Sheaths glabrous; glumes much shorter than spikelet 2

2a. Ligule a ciliolate membrane 0.3-0.7 mm. long; lemmas often awned L. virgata
2b. Ligule a dense row of stiff white hairs, 1.5-3.0 mm. long; lemmas awnless

L. scabra

Leptochloa filiformis (Lam.) Beauv., Ess. Nouv. Agrost. 71, 166.
1812. Festuca filiformis Lam., Tabl. Encycl. 1:191. 1791. Figure 110.

Caespitose annual; plants 10-130 cm. tall; culms erect, unbranched or branched from
the base, up to 3 mm. thick, hollow, glabrous; nodes glabrous; sheaths mostly overlap-
ping, more or less papillose-hirsute; ligule a lacerate-ciliate membrane, 0.5-1.5 mm. long,
decurrent on the sheath margins; blades flat, glabrous or minutely scabrid, 4-23 cm.
long, 3-9 mm. wide. Peduncle glabrous, exserted 3-15 cm.; inflorescence solitary, termi-
nal, oblong, 5-50 cm. long, a raceme of simple racemose branches, borne singly or several
at one node along the rachis; branches up to 10 cm. long, stiffish, slender, the rachis
triquetrous, bearing short-pedicellate appressed spikelets in 2 rows along the lower 2
sides. Spikelets 2-3-flowered, 1.8-3.0 mm. long; glumes nearly as long as the spikelet;
first glume subulate, keeled, 1-nerved, 1.3-2.0 mm. long; second glume narrowly lan-
ceolate, keeled, 1-nerved, 1.5-2.0 mm. long; lemmas 1.1-1.8 mm. long, ovate, acute,
keeled, slightly bifid at the apex, awnless, the keel and lateral nerves finely ciliate; palea
nearly as long as the lemma; rachilla prolonged beyond the upper floret and bearing a
minute rudiment at its tip; anthers 2, 0.2-0.3 mm. long, yellow.

FIG. 110. Leptochloa species. L. filiformis: A, panicle; B, spikelet; L. virgata: C,
spikelet; L. scabra: D, spikelet.

305

306 FIELDIANA: BOTANY

Weedy open areas at low elevations; common in Guanacaste. June to
October, probably yearlong. Southern United States to Panama; West
Indies; South America.

Leptochloa f il i form is X L. virgata.

A large, vigorous specimen intermediate between these species and
possessing defective pollen, was collected from Finca la Taboga (Pohl
& Davidse 10133). It is a probable hybrid of these species, which are
common in the immediate area.

Leptochloa scabra Nees, Agrost. Bras. 435. 1829. Figure 110.

Caespitose annual, in small clumps; plants 90-120 cm. tall; culms erect, branching from
the lower nodes, up to 6 mm. thick, hollow, glabrous; nodes glabrous, constricted;
prophylla up to 12 cm. long; sheaths mostly overlapping, glabrous; ligule a dense row of
stiff, white hairs, 1.5-3.0 mm. long; blades up to 50 cm. long, 6-14 mm. wide, minutely
scabrid, the margins very scabrous; dewlap purple. Peduncle mostly included in the
upper sheath; inflorescence solitary, terminal, open-cylindrical, up to 40 cm. long, com-
posed of numerous lax racemes attached singly or in pairs along the length of the rachis;
racemes 7-10 cm. long; spikelets rather densely arranged in 2 rows along the lower sides
of the rachis of the simple branch, overlapping at about 30° inclination to the rachis.
Spikelets pale, 3.7-4.5 mm. long, with 3-6 florets, narrowly elliptical in outline; glumes
and florets keeled; first glume ovate, acuminate, 1-nerved, 0.7-1.1 mm. long; second
glume similar, 1-nerved, 1.2-1.7 mm. long; lemmas 2.3-1.4 mm. long, the upper ones
shorter than the lower, ovate-oblong, abruptly acuminate or apiculate, 3-nerved, the
lower part of keel and marginal nerves softly ciliate; palea equal to the lemma or slightly
exceeding it; anthers 3, 0.2-0.3 mm. long; rachilla prolonged beyond the uppermost floret
as a naked bristle.

Uncommon; railroad yard at Limon, Siquirres, Zent, Rio San Car-
los; open areas at low elevations. June to December. Louisiana and
Mexico to Costa Rica; West Indies; Venezuela and Colombia to Peru
and Brazil.

Leptochloa virgata (L.) Beauv., Ess. Nouv. Agrost. 71, 166. 1812.
Cynosurus virgatus L., Syst. Nat. ed. 10, 2:876. 1759. Figure 110.

Caespitose, in small clumps; plants 40-110 cm. tall, erect; branching mostly from base
and lower nodes; basal portions of culms sometimes decumbent and rooting; culms 2-3
mm. thick, hollow, glabrous; sheaths glabrous, shorter or longer than the internodes;
ligule a ciliolate membrane, 0.3-0.7 mm. long; blades 10-26 cm. long, 7-10 mm. wide,
glabrous. Peduncle exserted 5-28 cm.; inflorescence solitary, terminal, 10-22 cm. long, of
few to many lax racemes, attached singly or whorled, floriferous to the base, 7-11 cm.
long; spikelets overlapping, appressed laterally to the lower sides of the rachises.
Spikelets often purplish, 2.5-3.6 mm. long; glumes scabrous on the keel, the first 1.2-1.6
mm. long, 1-nerved, subulate to narrowly lanceolate, second glume 1.8-2.3 mm. long,
1-nerved, narrowly lanceolate; florets 3-5; lowermost lemma 1.8-2.2 mm. long, the upper
ones shorter, keeled, narrowly ovate, slightly bifid at the apex, sometimes bearing an
awn up to 2.2 mm. long (often only the lowermost lemma awned); lateral nerves margi-
nal, softly ciliate on the upper half, the keel glabrous; palea nearly as long as the lemma;

BURGER: FLORA COSTARICENSIS 307

ultimate segment of the rachilla bearing a rudiment of varying size; anthers 2, 0.2-0.3
mm. long, yellow or purplish. Chromosome number n = 20 from Costa Rican material.

Disturbed soil of fields, roadsides, pastures, and forest margins; low
elevations, mostly near the Pacific Coast; Limon area. March to De-
cember, possibly yearlong. Southern United States and Mexico to
Argentina; West Indies.

LEPTOCORYPHIUM Nees

Caespitose perennial from deeply buried hard cormose bases; inflorescence a terminal
panicle. Spikelets dorsally compressed, disarticulating whole from the pedicel; first
glume lacking or represented only by a cupule at the tip of the pedicel; second glume and
sterile lemma subequal, about as long as the fertile floret, both strongly ribbed and
covered with long silky hairs arising from the nerves; sterile lemma lacking a palea or
flower; fertile floret chartaceous, brown, its edges not inrolled; palea similar, about equal
to the lemma, its tip not enclosed by the lemma.

A small genus of one or two species of savanna grasses, ranging from
Mexico to Argentina. The genus appears to be closely related to An-
thaenantia of the southern United States. (Panicoideae: Paniceae.)

Leptocoryphium lanatum (H.B.K.) Nees, Agrost. Bras. 84. 1829.
Paspalum lanatum H.B.K. , Nov. Gen. & Sp. 1:94, pi. 29. 1816. Fig-
ure 111.

Perennial, in small hard clumps, the bases of the plants hard, cormose, buried in soil;
plants 60-90 cm. tall, erect, the leaves mostly basal, their sheaths breaking down into
harsh fibers; culms unbranched, 1-2 mm. thick, smooth, pithy; nodes dark colored,
glabrous; leaf sheaths glabrous except long-pilose on the sheath auricles; ligule a minute
ciliate membrane, ca. 0.2 mm. long; leaf blades mostly involute, up to 40 cm. long, 2-3
mm. wide, glabrous except long-pilose on their lower margins, the upper surface
strongly ridged; uppermost blade much reduced. Peduncle elongated, slender, glabrous.
Panicle solitary, terminal, slender, cylindrical but loose, 8-15 cm. long, 1-3 cm. wide, the
short branches ascending; aspect grayish and fuzzy. Spikelets ascending, appressed to
the branches, dorsally compressed, 3.5-4.0 mm. long, silky because of the long grayish or
white hairs which densely cover them. The tip of the pedicel is dilated into a hollow
cupule from which the spikelet disarticulates, and which may represent a reduced first
glume. Second glume and sterile lemma 3.2-3.7 mm. long, strongly 5-7-nerved, the
internerves thin and translucent; nerves densely beset with papillose-based silky hairs
up to 2 mm. long, either appressed or spreading at right angles to the spikelet; fertile
floret narrowly ovate, acute, the lemma and palea similar, faintly nerved, their tips
hyaline; margins of the lemma covering the lower portions of the palea but not the tip;
anthers 3, purple, ca. 2.5 mm. long. Chromosome number n = 10 from a specimen from
Honduras. South American reports indicate n = 20 as well.

This is one of the most xeric of the savanna grasses, found on very
dry sites, especially on volcanic tuff deposits. The deeply buried plant
bases afford protection from fires. Many specimens have charred basal

FIG. 111. Leptocoryphium lanatum. A, panicle; B, buried plant base; C, spikelet; D,
caryopsis; E, fertile floret.

308

BURGER: FLORA COSTARICENSIS 309

leaves, indicating the frequency of fires in these habitats. Flowering,
as in many savanna grasses, is synchronous over large areas and is
completed quickly. Dry savannas, in Costa Rica under 300 m. but
elsewhere to 1,000 m.; northern Guanacaste, Buenos Aires, Boruca,
Carias Gordas; not common. February to July. Mexico to Argentina.

LITHACHNE Beauvois

Caespitose herbaceous perennials. Spikelets unisexual. Pistillate spikelets: Solitary,
terminal on slender clustered axillary peduncles, sometimes with 1-several pedicellate
staminate spikelets below the pistillate one; glumes of pistillate spikelets equal, green,
herbaceous, many-nerved, caudate-ovate, much exceeding the floret; floret 1, bony,
shining, the lemma obpyramidal, truncate, cucullate, laterally compressed, borne on a
thick attached rachilla internode; margins of lemma clasping a bulging palea of bony
texture; disarticulation above the glumes which may later fall from the pedicel; pedicel
flattened, keeled, enlarged below the tip. Staminate spikelets: Either borne below the
pistillate one on axillary peduncles or in a small terminal panicle. Staminate spikelet: A
naked floret lacking glumes, borne on a short, thickened stipe above the point of disar-
ticulation; lemma and palea about equal, narrowly lanceolate, thin and membranaceous,
white; lemma 3-nerved, awnless; palea similar, 2-nerved; anthers 3, nearly as long as the
floret, borne on very short filaments; floret disarticulating from the pedicel after flower-
ing.

Lithachne is a small genus of forest-inhabiting bambusoid grasses of
the tropics of the western hemisphere. The genus is related to Olyra,
Raddia, Cryptochloa, and other herbaceous bambusoids. The asym-
metric, truncate-based leaf blades and the rigid, helmet-shaped fertile
florets are distinctive. Earlier authors interpreted the spikelets as
panicoid in structure, and assigned the genus to the Panicoideae. Leaf
anatomy indicates that it is bambusoid. (Bambusoideae: Olyreae.)

Lithachne paud flora (Swartz) Beauv. ex Poir., Diet. Sci. Nat.
27:60. 1823. Olyra pauciflora Sw., Prodr. Veg. Ind. Occ. 21. 1788.
Figure 112.

Caespitose perennial; clumps usually small; culms erect or arching, 20-75 cm. tall,
simple; internodes glabrous, ca. 1 mm. thick, hollow; nodes shrunken in dry specimens,
with a sharp ridge below and above the node; lower internodes elongated, the upper
much shorter; lower sheaths bladeless or with reduced blades, much shorter than the
internodes; upper sheaths overlapping, the foliage clustered near the apex of the culms;
sheaths sparsely hispidulous, slightly keeled; ligules membranaceous, minute, ca. 0.5
mm. long; leaf blades 4-10 cm. long, 1.5-3 cm. wide, lanceolate, asymmetric, one side
broad and truncate at the base, the other narrow and rounded; pseudopetiole present
between sheath and blade, ca. 1 mm. long, flattened, sparsely hirsute above; midrib of
the blade ends just above the apex of the pseudopetiole. Successive leaf blades on a culm
are of two types. If one leaf has the broad truncate base to the left of the midrib, the
leaves above and below it will have it to the right. Pistillate spikelets: Glumes green,
herbaceous, 9-11 mm. long, about equal; first glume 9-nerved, the second 7-nerved;
floret bony, at first shining white, at maturity dark brown with whitish veins, truncate,

JE/I

FIG. 112. Lithachne pauciflora. A, blooming culm; B, pistillate spikelet; C, staminate
spikelet; D, pistillate floret on its rachilla internode.

310

BURGER: FLORA COSTARICENSIS 311

cucullate, 4-5 mm. long, including the short projecting basal stipe; edges of lemma
inrolled and concealing the margins of the bulging palea; both lemma and palea glabrous;
caryopsis rotund, completely filling the floret. Staminate inflorescence, if present, soli-
tary at the tip of the culm, a simple, few-flowered panicle, borne on a short peduncle;
staminate spikelets also born racemosely on the peduncles of the pistillate ones. Stami-
nate spikelets: Consisting of a naked floret on a short stipe; lemma and palea ca. 5-6 mm.
long, thin, white, membranaceous, glabrous, the lemma lance-acuminate, 3-nerved;
palea 2-nerved. Chromosome number n = 11 from Costa Rican material.

Moist forests and cacao groves, Atlantic and Pacific slopes 20-
1,250 m. elevation; scattered in forests but not rare; apparently
blooming yearlong. Terminal staminate inflorescences are rarely found
on specimens. Mexico to Ecuador, Brazil, and northern Argentina.

LOLIUM Linnaeus

Annual or weakly perennial caespitose or rhizomatous grasses; inflorescence a bal-
anced terminal spike; spikelets placed edgewise, with the backs of the lemmas toward
the rachis; first glume lacking except in the spikelet at the end of the rachis; second
glume placed away from the rachis; florets several; glume and lemmas several-nerved;
disarticulation at base of each floret; lemmas awned or awnless.

In the past, this genus was usually placed in the barley tribe
(Triticeae). Since numerous spontaneous hybrids with members of the
genus Festitca of the tribe Poeae are known, but none with genera of
the Triticeae, it is better placed in the Poeae. Ryegrass, Zacate ray,
Ray Ingles.

Lolium perenne L., Sp. PI. 83. 1753. Figure 113.

Perennial or annual; mostly caespitose but producing rhizomes in wet sites; plants
10-90 cm. tall; culms glabrous, 1-3 mm. thick, hollow; nodes glabrous; sheaths glabrous;
ligule a thin membrane, up to 2 mm. long; leaf blades 3-20 cm. long, 2-6 mm. wide, with
prominent auricles; inflorescence slender, to 30 cm. long; spikelets appressed to the
rachis, the lower ones remote, the upper ones longer than the rachis internode adjacent,
7-20 mm. long, with 4-14 florets; second glume oblong, 5-7-nerved, shorter than the
spikelet; lemmas 5-7 mm. long, narrowly elliptical, glabrous, 5-nerved, acute, sometimes
awned; palea equal to the lemma, scabrid on the nerves; anthers 3, 3-4 mm. long.

Awned forms of this species occur, and have been given names.
These forms interbreed freely with the awnless type, and are best
regarded as agronomic forms of the species. If given taxonomic recog-
nition, they are to be called var. aristatum Willd. (= var. italicum
Parn.). Such awned plants are usually distinguished as "Italian rye-
grass," and the awnless ones as "English" or "perennial ryegrass."

This species, especially the awned form, has been cultivated for
forage on the volcanoes of the Cordillera Central. It can be found in
moist pastures from 1,800 to 2,600 m. elevation on Irazu and Turrialba.

FIG. 113. Lolium perenne. A, inflorescence; B, plant base; C, awned and awnless
spikelets.

312

BURGER: FLORA COSTARICENSIS 313

Native to Europe, but now widely naturalized in humid temperate
climates.

LORENZOCHLOA J. & C. Reeder

Densely caespitose perennial tussock grass; leaf blades usually basal, erect, involute,
terete, rigid, pungent; ligules membranaceous, decurrent; inflorescence a few-flowered
terminal panicle; spikelets 1-flowered; glumes short, equal, firm, truncate or emargi-
nate, very broad, very faintly nerved; disarticulation above the glumes; floret much
longer than the glumes; lemma awned, obscurely 5-nerved, more or less pubescent at the
acuminate base; awn thickish, stiff, antrorsely scabrid; palea slightly shorter than the
lemma; lodicules 3, oblong-elliptical. (Pooideae: Stipeae.)

Lorenzochloa erectifolia (Swallen) J. & C. Reeder, Bol. Soc. Ar-
gent. Bot. 11:239. 1969. Muhlenbergia erectifolia Swallen, J. Wash.
Acad. Sci. 21:15. 1931. Parodiella erectifolia (Swallen) J. & C.
Reeder., Bol. Soc. Argent. Bot. 12:279. 1968. Figure 114.

Perennial, densely caespitose; culms erect, glabrous, 15-35 (38) cm. tall; leaves mostly
basal; sheaths smooth or somewhat scabrous; ligule membranous, acute, 2-4 mm. long,
decurrent onto the somewhat hyaline sheath margins; blades erect, rigid, terete, scab-
rous, pungently pointed, 5-15 (18) cm. long, narrower than the sheaths at the base;
panicles narrow, erect, 5-8 cm. long, rather few-flowered, the branches with rather
conspicuous pulvini in their axils; spikelets appressed to the branches, the pedicels 1-4
mm. long, rather stout; glumes firm, subequal, 1-1.3 (1.5) mm. long, truncate and usually
emarginate, obscurely 3-nerved, tinged with bronze and purple; lemma firm, obscurely
5-nerved, 2.5 mm. long, pubescent along the lower half of the midnerve, and often along
the margins, pointed and pubescent at the base, the slightly scabrous apex tapering into
a stout erect or slightly flexuous scabrous awn 3-5 mm. long, with a distinct line of
demarcation between it and the body of the lemma; palea firm, nearly equalling the
lemma, often pubescent between the nerves; anthers purplish, 0.6-0.8 mm. long; caryop-
sis broadly fusiform, light brown, ca. 1.2-1.4 mm. long. Chromosome number 2n = 22.

The above description was quoted from the description of Parodiella
erectifolia, since our specimens are too weathered to provide many
details. This South American species has been collected only twice in
North America, from the alpine paramo of Chirripo Grande. The
specimens are: Prov. de San Jose, Chusquea subtessellata paramo,
elevation 3,500 m., between Refugio and lake at head of Rio Ditkebi,
G. Davidse 1562, 3 April 1969; Chirripo-Massiv, Quellgebiet des Rio
Talari, "Valle de los Conejos," chusqueafreie Vegetationsflachen des
Talbodens, Kaltluftsee, ca. 3,500 m., 16 March 1971, Kuhbier 0401.
Paramos, 3,400-4,200 m.; Venezuela, Colombia, Peru; southern Costa
Rica.

LUZIOLA Jussieu ex Gmelin

REFERENCE: J. R. Swallen, The grass genus Luziola, Ann. Missouri
Bot. Card. 52:472-75. 1965.

JZZt

FIG. 114. Lorenzochloa erectifolia. A, spikelet; B, floret; C, portion of a plant with
rigid basal leaves; D, inflorescence.

314

BURGER: FLORA COSTARICENSIS 315

Monoecious aquatic or paludose grasses; spikelets unisexual, in usually separate
inflorescences, the pistillate inflorescence an axillary panicle (reduced to 2 conjugate
racemes in L. fragilis), the staminate a terminal panicle or raceme; glumes reduced to a
minute cupule or absent; floret single, disarticulating from the cupule or pedicel apex;
pistillate spikelets with equal, many-nerved lemma and palea; lodicules not functional,
the stigmas laterally exserted from the lemma and palea; caryopsis ovoid or spherical,
striate, crowned with the persistent style bases, retained within the floret, which usu-
ally decays into a circle of fibers attached to the caryopsis; staminate spikelets with thin,
membranous, faintly-nerved lemma and palea; stamens 6. (Oryzoideae: Oryzeae.)

KEY TO SPECIES OF Luziola

la. Pistillate inflorescence a single pair of few-flowered reflexed racemes at tip of
peduncle; staminate inflorescence a simple raceme; culms weak, leafless, submerged
in water, foliage leaves floating on water surface L. fragilis

Ib. Pistillate and staminate inflorescences panicles with several to many branches;
culms ascending or erect, stiff, leafy L. subintegra

Luziola fragilis Swollen, Ann. Missouri Bot. Gard. 52:474. 1965.
Figure 115.

Aquatic; duration indefinite; culms weak and slender, rooted in soil of ponds; sub-
merged internodes with thin membranaceous, bladeless sheaths; foliage leaves floating
on top of the water during wet seasons; plants forming dense mats of foliage on drying
mud during dry seasons; internodes of submerged culms up to 11 cm. long, the inter-
nodes of the floating portions very short, frequently less than 1 cm. long; nodes slightly
bearded; culms less than 1 mm. thick, apparently solid. Floating foliage: Sheaths ca. 2
cm. long, densely villosulous, or the uppermost sparsely so; ligules membranaceous,
white, 1-2 mm. long; blades 3-6 cm. long, 2-2.5 mm. wide^strongly ridged above, the
ridges densely covered with minute thick blunt spicules; usually 3-4 floating leaves at the
tip of the culm; branching abundant just below the water surface; plants monoecious.
Staminate inflorescence a simple terminal raceme of 3-5 spikelets which are appressed to
the rachis; raceme borne on a slender, erect, intravaginal peduncle, exserted ca. 1 cm.
from the mouth of the sheath; pedicels ca. 0.5 mm. long. Glumes lacking; floret 5-7 mm.
long; lemma and palea very thin and membranaceous, the lemma ca. 7-nerved, the palea
ca. 4-nerved, both with abundant blunt tricellular microhairs; stamens 6, the anthers
yellow, 3-4 mm. long. Pistillate inflorescences axillary, from 1 or more nodes below the
terminal staminate inflorescence; peduncle mostly included in the sheath, up to 3 cm.
long; branches 2, bijugate at the apex of the peduncle and strongly reflexed in fruit, one
usually slightly longer than the other; pedicels 0.5 mm. long, appressed to the branches.
Spikelets 1-9 per branch, 1.8-2.3 mm. long, lanceolate at anthesis, becoming ovoid in
fruit; glumes absent; lemma stramineous, broader than the palea and enveloping its
base, with ca. 12-14 nerves; internerve tissue very thin, rotting away after maturity, the
caryopsis remaining surrounded by the vascular bundles; palea ca. 6-nerved, similar to
the lemma but narrower; caryopsis broadly ellipsoidal , brown, longitudinally striate, ca.
2 mm. long, crowned with the persistent style bases. Chromosome number n = 12 from a
Costa Rican specimen.

This unusual aquatic grass closely resembles Hydrochloa
caroliniensis in general aspect and ecology, but differs in the bijugate
pistillate inflorescence. We have found it in permanent ponds near

FIG. 115. Luziolafragilis. A, floating culm with inflorescences; B, pistillate inflores-
cence; C, pistillate spikelets; D, staminate inflorescence; E, staminate spikelet.

316

BURGER: FLORA COSTARICENSIS 317

Buenos Aires, Prov. de Puntarenas, and in several similar ponds in
Guanacaste, as at Laguna la Calavera. Another colony occurs on the
road to Hacienda Los Inocentes. Blooming has been observed in De-
cember and January. Examination of dried pond bottoms later in the
year showed extensive growth of turfy colonies of the plant, but no
sign of flowering. I have been able to germinate seed, but the seedlings
died.

This species has previously been known only from the type collec-
tion, from Aquidauana, Mato Grosso, Brazil. Although large gaps are
common in the distribution patterns of aquatic grasses, it seems likely
that L. fragilis will eventually be found in intermediate localities. The
plants seem to require standing water that is permanent or nearly so.
Finding the plants in such very scattered localities suggests that the
seeds are transported by water fowl.

Luziola subintegra Swallen, Ann. Missouri Bot. Gard. 30:165. 1943.
Figure 116.

Duration indefinite; plants sprawling and stoloniferous on wet, muddy soil, branching
abundantly from the rooted nodes of the thick, spongy stolons; culms ascending, 2-4 mm.
thick, hollow, glabrous and shining; nodes glabrous, conspicuous, brownish; prophylla
many-nerved, 3-6 cm. long; leaf sheaths mostly longer than the culm internodes, over-
lapping, somewhat inflated; ligules membranaceous, usually 3-4 cm. long, acuminate to a
fine point, adnate to the erect sheath auricles; blades stiffish, up to 35 cm. long, 12 mm.
wide near the middle and tapering to a base narrower than the sheath apex. Pistillate
inflorescences: 1-several, borne at successive lower nodes of the culms; peduncle short,
fleshy, strongly bent and emerging extravaginally from the overlapping edges of the
sheath just above the node; length ca. 4 cm. and broader than long; branches crowded,
several per node; rachis soft, fleshy, angular; branches stiff, fleshy, strongly retrorse at
maturity; pulvini prominent, ciliate at their edges. Spikelets appressed to the main
branches, or 1 or more on a secondary branch, more or less terete, 5-5.5 mm. long;
glumes reduced to a minute cupule; disarticulation above the cupule; lemma and palea
equal, lanceolate, blunt; lemma 7-nerved, the nerves prominent, nearly contiguous when
the spikelet is immature, spreading when distended with the fruit; nerves scabrid; palea
similar to the lemma, 5-nerved; caryopsis ovoid, olivaceous, shining, slightly striate,
tipped with the persistent bases of the styles, 1.5-2 mm. long at maturity, remaining
within the floret; mature spikelet ovoid, tapering to a narrow apical beak; internerve
tissue not disintegrating. Staminate inflorescence: Single, terminal on the culm, up to
7 cm. long, narrowly ovoid, with strongly ascending subverticillate branches. Spikelets
racemose along the panicle branches, more or less terete, narrowly ovoid in outline, 5-6
mm. long; glumes reduced to a minute cupule; floret disarticulating above the cupule;
lemma and palea equal, thin, white, membranaceous, faintly 5-nerved; stamens 6, the
filaments very short, less than 1 mm. long; anthers 3.5-4 mm. long, sulfur yellow to
reddish.

Rare; wet meadows and sand bars, at sea level; Las Playitas del Rio
Bebedero and Barro de Colorado. Blooming in December and January.
El Salvador to Ecuador, Brazil, and Paraguay; Caribbean Islands.

FIG. 116. Luziola subintegra. A, staminate inflorescence; B, staminate spikelet; C,
culm with axillary pistillate inflorescence; D, pistillate spikelet.

318

BURGER: FLORA COSTARICENSIS 319

MELINIS Beauvois

Plants sprawling, leafy, the foliage densely viscid-hairy and strongly aromatic;
inflorescence a panicle; spikelets somewhat laterally compressed, oblong in outline, dis-
articulating below the glumes; first glume minute, nerveless; second glume and sterile
lemma subequal, lanceolate, strongly ribbed, both bifid at the tip; second glume 7-
nerved, with a minute awn arising between the lobes; sterile lemma 3-5-nerved, with an
elongated awn arising between the lobes; palea absent; fertile floret shorter than the
sterile lemma; its lemma and palea subequal, smooth and shining, thin and translucent;
lemma ovate, 1-nerved. (Panicoideae: Paniceae.)

Melinis minuti flora Beauv., Ess. Nouv. Agrost. 54. 1812. Figure
117.

Sprawling perennial; culms decumbent and often rooting near the base, up to 180 cm.
long but usually much shorter, much branched, with erect flowering branches; culms
solid, pithy, papillose-pilose with spreading hairs; nodes bearded with appressed erect
hairs; sheaths, except the upper ones, mostly overlapping, densely papillose-pilose, the
hairs with viscid blobs of odorous resinous material; ligule a dense arc of silky white
hairs, ca. 1 mm. long; blades velvety on both surfaces, papillose-ciliate on the margins,
5-15 cm. long, 5-12 mm. wide, flat; peduncle glabrous, 4-10 cm. long; panicles terminal on
leafy branches, 9-22 cm. long, 2-7 cm. wide, purple, narrow, the branches spreading only
during anthesis, delicate, densely flowered; spikelets slightly laterally compressed,
1.9-2.5 mm. long; first glume rotund, 0.2-0.3 mm. long; second glume lanceolate, 5-7-
nerved, 1.9-2.5 mm. long; sterile lemma similar to the second glume, 1.8-2.4 mm. long,
3-5-nerved, the awn 5-12 mm. long; fertile floret 1.7-2.0 mm. long, the lemma and palea
about equal or the palea slightly longer; anthers 3, 1-1.5 mm. long, purple. Chromosome
number n = 18.

Roadsides and pastures, especially in the Meseta Central and Gen-
eral Valley; 700-1,900 m. elevation. This species blooms en masse
during the short days of November and December, but small amounts
of bloom may be seen at other times of the year. This species is of
African origin, but has become widely distributed in the American
tropics through its use as a forage grass. It is popularly believed that
Melinis traps ticks by its stickiness and repels mosquitoes by its
strong odor. Common names: "Molasses grass," Gordura, Calinguero.

MEROSTACHYS Sprengel

Caespitose, nonthorny bamboos; rhizomes pachymorphous; internodes cylindrical,
hollow; culm sheaths with a narrow, reflexed blade; leaf-bearing branches equal, fasci-
cled, arising from the margins of a flat, plate like me ri stem adnate to the base of the
internode. Inflorescence a one-sided, rather dense spike, the spikelets solitary or paired,
in 2 rows along the lower side of the rachis. Glumes usually rudimentary or absent;
sterile lemmas 2; fertile florets 1-several, the rachilla prolonged beyond the fertile florets
and bearing a rudimentary floret at its apex; disarticulation below the fertile floret; palea
grooved, the keels clasping the rachilla internode; lodicules 3, flat, vasculated; anthers 3;
stigmas 2. (Bambusoideae: Arthrostylideae.)

FIG. 117. Melinis minutiftora. A, panicle; B, culm internode and leaf; C, hairs with
sticky globules; D, spikelet; E, apex of sterile lemma; F, fertile floret.

320

BURGER: FLORA COSTARICENSIS 321

This genus is known in Costa Rica by two flowering specimens. They
are too fragmentary for specific determination, although M. mul-
tiramea Hack, has been reported from La Palma de San Ramon by
Standley on the basis of a specimen in the National Museum of Costa
Rica.

Merostachys sp. indet. Figure 118.

Specimens fragmentary, represented by fascicles of up to 10 flowering branchlets,
these up to 60 cm. long, including the inflorescences; internodes cylindrical, up to 8 mm.
thick, glabrous; leaves with blades 4-7, borne on the outer portion of the branchlets;
lower internodes glabrous, naked or with bladeless sheaths; apex of internodes finely
appressed-silky; sheaths glabrous; auricular bristles conspicuous, 7-12 mm. long; ligule a
short, thick, minutely ciliolate membrane, ca. 0.5 mm. long; blades flat, ovate 6-9:1,
acuminate, the base rounded to a pseudopetiole ca. 4 mm. long; blade surfaces glabrous,
the marginal nerves finely scabrous. Inflorescences terminal on leafy branchlets; spikes
falcate, one-sided, 4.5-6.5 cm. long, ca. 1 cm. wide; peduncle and rachis finely white-
silky; spikelets mostly paired and subsessile, one each side of the rachis. Spikelets 11-13
mm. long, falcate, crowded, brown or purplish; disarticulation above the 2 basal bracts
(glumes or sterile lemmas); first bract triangular 2.5:1, acute, 1-3-nerved; second bract
ovate ca. 2.5:1, acute, 7-nerved, rounded on the back, acute, the margins ciliolate near
the tip; fertile lemma 9.5-10 mm. long, 11-nerved, the margins overlapping at the base;
surface sparsely pubescent; palea slightly longer, broad, 10-nerved, the 2 ciliolate keels
close together, clasping a flattened slender rachilla, ca. 8 mm. long, with a minute
rudiment at its tip; lodicules 3, flat; anthers not seen.

This species is represented in the Field Museum Herbarium by the
following flowering specimens from Costa Rica. I have not seen other
specimens from the country. Prov. Puntarenas, Zapotel, Montes de
Oro, altitude 1,500 m., May 1961, Otdn Jimenez s.n.; Prov. Alajuela,
La Palma de San Ramon, altitude 1,050 m., 17 April 1927, Brenes
5433. Common names are given as Canuela or Carrizo, but these
names are rather widely applied to different plants.

MESOSETUM Steudel

REFERENCE: J. R. Swallen, The grass genus Mesosetum, Brittonia
2:363-392. 1937.

Caespitose or stoloniferous grasses; inflorescence a solitary terminal dorsiventral
spike or spikelike raceme, the spikelets solitary, erect, appressed to the flattened rachis,
alternating in 2 rows along one side of it, with the first glumes placed toward the midrib.
Spikelets laterally compressed, the glumes subequal, stiff, nearly as long as the sterile
lower lemma, folded and sometimes wing-keeled near the tips; first glume 3-nerved;
second glume 5-nerved; lower lemma usually lacking a flower, its palea well developed;
upper floret shorter than the lower, with a perfect flower, its lemma coriaceous, boat-
shaped, 5-nerved, the margins not inrolled, the tip tapering into a narrow blunt beak;
palea of similar texture, broad, infolding the flower, convex on the back.

FIG. 118. Merostachys species. A, branch complement, showing one flowering branch;
B, pair of spikelets; C, terminal floret, showing elongated rachilla internode with a
terminal rudiment.

322

BURGER: FLORA COSTARICENSIS 323

A small genus of about 30 species, mostly in South America, a few in
the West Indies and Central America. The genus is related to
Echinolaena and Eriochloa. (Panicoideae: Paniceae.)

Mesosetum pittieri Hitchc., Proc. Biol. Soc. Wash. 40:85. 1927.
Figure 119.

Duration indefinite; culms 15-40 cm. long, erect or trailing and rooting at the lower
nodes, unbranched; culms glabrous, hollow, ca. 1 mm. thick; foliage mostly near the
bases of the culms, the upper 1 or 2 leaf blades much reduced; sheaths somewhat keeled,
the lower ones pubescent, the upper glabrous except for the papillose-ciliate margins;
ligule a dense row of stiff short hairs, 0.2-0.5 mm. long; leaf blades 3-4 per culm, the
uppermost much reduced; blades stiff, the larger ones 5-9 cm. long, 3-5 mm. wide, with a
thick white marginal band, papillose-pilose above and below or nearly glabrous. Pedun-
cle included in the upper sheath or exserted up to 7 cm. , slender, stiff, glabrous; spike 3-7
cm. long, linear, 3-5 mm. wide, the rachis slightly zigzag, ca. 1 mm. wide, flattened, with
a prominent midrib. Spikelets laterally compressed, the flat sides appressed to the
rachis; outline V-shaped, the base narrowed into a short narrow stipe ca. 0.5 mm. long
enveloped by the bases of the glumes; length of spikelet, including the stipe, 5.5-6.2
mm.; first glume 4.9-5.5 mm. long, oblong-spatulate, winged at the obtuse tip, silky
along the keel near the base, scabrid above; second glume and sterile (lower) lemma
subequal, 5.5-6.2 mm. long, both green-mottled and cross-wrinkled near the tip; second
glume narrowly ovate, slightly winged at the tip, silky along the keel and margins;
sterile lemma narrowly oblong, blunt and slightly winged at the tip, silky between the
lateral nerves on the lower half and on the margins near the middle, a conspicuous tuft of
hairs on the keel one-third below the tip; palea of sterile lemma linear, nearly as long as
the lemma; fertile floret 4.7-4.8 mm. long, stramineous, minutely roughened; anthers 3,
ca. 2 mm. long, purple; caryopsis obovate, tan, the embryo prominent, ca. half the
length of the grain; opposite side of the caryopsis with a dark line running its entire
length. Chromosome number n = 8.

We have collected this species in Byrsonima-Curatella savannas of
Hacienda Murcielago and Hda. Las Animas. In both cases, the plants
were growing in slightly moist depressions. Elevations 200-300 m.
Late July, December. This species was previously known only from
the type locality, near Chepo, Panama and from San Lorenzo, Hon-
duras.

MUHLENBERGIA Schreber

REFERENCES: T. R. Soderstrom, Taxonomic study of subgenus
Podosemum and section Epicampes of Muhlenbergia (Gramineae),
Contr. U.S. Natl. Herb. 34:75-189 + pi. 1-14. 1967. J. R. Swallen, The
awnless annual species of Muhlenbergia, Contr. U.S. Natl. Herb.
29:203-208. 1947.

Caespitose or rhizomatous annual or perennial grasses; ligules membranaceous, often
ciliate; inflorescence an open or contracted panicle; spikelets 1-flowered, disarticulating
above the glumes, laterally compressed or terete; glumes shorter than or equal to the
lemma, 1-3-nerved, or nerveless if minute, the first usually smaller than the second;

FIG. 119. Mesosetum pittieri. A, blooming plant; B, inflorescence; C, spikelet.

324

BURGER: FLORA COSTARICENSIS 325

lemma slender, 3 (-5)-nerved, membranaceous, rounded on the back, tapering to a point,
usually awned, rarely with minute teeth at the base of the awn; callus short, usually
bearded; palea about equal to the lemma, 2-nerved. (Chloridoideae: Sporoboleae.) The
basic chromosome number in Muhlenbergia is consistently x = 10, whereas that of
Sporobolus is x = 9 or x = 6.

A genus of about 100 species, mostly of North America, some
species in South America and a few in temperate Asia. Muhlenbergia
is similar to Sporobolus, differing in the 3-nerved lemma and usual
possession of lemma awns, and in the adherent pericarp. Awnless
species have sometimes been transferred from one genus to the other.

KEY TO SPECIES OF Muhlenbergia

la. Spikelets awnless or the lemmas with short awns less than 1 mm. long 2

Ib. Spikelets awned, awn longer than lemma 4

2a. Dwarf, much-branched perennials, less than 20 cm. tall 3

2b. Culms erect, unbranched, 70-100 cm. tall M. nigra

3a. Panicles exserted, many-flowered M. ramulosa

3b. Panicles hidden in the densely fascicled leaves, with 3-7 spikelets; paramos of

Chirripo Grande M . calcicola

4a. Plants 70-170 cm. tall; culms unbranched; leaf blades 40-70 cm. long; inflores-
cence 20-40 cm. long „ M . lehmanniana

4b. Plants much shorter or culms branched; leaf blades less than 15 cm. long;

inflorescences less than 15 cm. long 5

5a. Ligules 1.5-8.0 mm. long (usually over 2.0 mm.) 6

5b. Ligules less than 1.2 mm. long 8

6a. Glumes minute, less than 0.5 mm. long, rounded, nerveless; panicles open and
delicate, spikelets on diverging pedicels longer than the spikelets

M. implicate,
6b. Glumes more than 1 mm. long, 1-3-nerved; panicles narrow or congested,

spikelets short-pedicellate 7

7a. Leaves mostly basal, sheaths strongly keeled, forming fan-shaped tufts, only one
small blade at midculm; second glume 3-nerved, obtuse or 3-lobed at apex; paramos

over 3,000 m M . flabellata

7b. Leaves distributed along the culms; glumes acuminate, 1-nerved; moist forests,

1,500-2,100 m M. setarioides

8a. Glumes of all spikelets similar 9

8b. One glume of terminal spikelet on inflorescence branches awned, others ob-
tuse, nerveless M diversiglumis

9a. Ligules 0.8-1.2 mm. long; panicles very open; pedicels very slender, divergent,
longer than spikelets M. tenuissima

9b. Ligules less than 0.5 mm. long; spikelets short-pedicellate, appressed to rachis or

branches of rather condensed panicles 10

lOa. Lemmas ciliate; primary panicle branches spreading M. ciliata

lOb. Lemmas not ciliate; primary panicle branches appressed to rachis

M. tenella

326 FIELDIANA: BOTANY

Muhlenbergia calcicola Swallen, Contr. U.S. Natl. Herb. 29:407.
1950. Figure 122.

Perennial, forming flat tufts up to 15 cm. broad, dying in the center; plants 3-4 cm. tall,
densely crowded; culms branching profusely, their internodes only 2-5 mm. long, a short
branchlet with fascicled leaves borne at each node; culms 0.5 mm. thick, solid; prophylla
3.5-4.0 mm. long, broad; sheaths glabrous, ridged, flattened by the densely fascicled
branches and leaves within; ligule a membrane 0.7-0.9 mm. long; blades 3-14 mm. long,
1.0-1.5 mm. wide, thick and stiff, flat or folded, ridged on both surfaces, tapering ab-
ruptly to a boat-shaped tip; the midrib prominent beneath; upper surface bearing minute
erect spicular hairs. Inflorescence a few (3-7) flowered raceme or simple panicle, con-
cealed in the upper sheaths, or barely exserted; pedicels stiff, thick, erect, scabrous.
Spikelets blackish; glumes ovate, acute, the first 1-nerved, 1.4-1.7 mm. long, the second
sometimes 3-nerved, 1.7-1.9 mm. long; lemma ovate, somewhat keeled, 3-nerved,
2.5-3.0 mm. long; callus truncate, glabrous; lemma tapering to a short, thick, scabrous
awn up to 1.0 mm. long; palea flat between the keels, equal to the lemma; caryopsis
cylindrical, ca. 1 mm. long.

Known in Costa Rica only from the Valle de Conejos, Chirripo
Grande, at elevations between 3,400 and 3,800 m. The plants formed
large mats or tufts in flat moist depressions. November to January.
Previously known only from the highlands of northwestern Guatemala.
Muhlenbergia breviculmis Swallen is doubtfully distinct from M . cal-
cicola, the specimens probably representing young plants of the latter.

Muhlenbergia ciliata (H.B.K.) Kunth, Rev. Gram. 1:63. 1829.
Podosaemum ciliatum H.B.K., Nov. Gen. & Sp. 1:128. 1816. Figure
120.

Sprawling, delicate, short-lived annual; tufted; culms slender, 15-25 cm. long, 0.3 mm.
thick, glabrous, branching freely from the lower and middle nodes; prophylla 5-8 mm.
long; sheaths and blades hispid or nearly glabrous; sheaths much shorter than the inter-
nodes; ligule a lacerate membrane, ca. 0.3 mm. long; blades reflexed, mostly folded or
involute, 1.5-3.0 cm. long, 1-2 mm. wide. Inflorescences numerous, terminal on the main
culm or on leafy branches; panicles 5-9 cm. long, the slender exposed axis bearing 5-8
slender spreading or reflexed solitary branches, each 1-2 cm. long; spikelets appressed to
the branches, overlapping. Spikelets 2-3 mm. long, excluding the awns; first glume
linear to lanceolate, 1-nerved, 0.7-1.2 mm. long, the midnerve often excurrent as a short
awn; second glume similar, 1.2-1.7 mm. long; lemma slender, lanceolate, strongly 3-
nerved, 2.1-3.0 mm. long, the callus minutely bearded; marginal nerves more or less
papillose-ciliate, sometimes nearly glabrous; awn slender, flexuous, 7-17 mm. long; palea
equal to the lemma; anthers 3, yellow, ca. 0.3 mm. long. Some descriptions state that the
lemmas are 5-nerved. Examination with the microscope shows that the supposed inter-
mediate nerves are not vascular bundles, but merely rows of short barbs.

Moist rocky banks and roadsides. Our only Costa Rican specimen
was collected along the CIA, 14 km. S of Division, at 1,500 m. eleva-
tion. December. Mexico to Panama.

Muhlenbergia diversiglumis Trin., Mem. Acad. Imp. Sci. St.-

FIG. 120. Muhlenbergia species. M . tenella: A, inflorescence; B, glumes and floret; M.
ciliata: C, glumes and floret; M. diversiglumis: D, glumes and floret.

327

328 FIELDIANA: BOTANY

Petersbourg, Ser. 6, Sci. Math., Seconde Pt. Sci. Nat. 4:298. 1845.
Figure 120.

Delicate short-lived annual; plants sprawling, the culms 25-60 cm. long, long-
decumbent and rooting, with erect flowering branches arising from the decumbent por-
tions; prophylla 8-10 mm. long; culms slender, 0.5-0.7 mm. thick, hollow, thin-walled,
glabrous; nodes retrorsely bearded; foliage glabrous to papillose-hirsute; sheaths mostly
shorter than the internodes; ligule a rather prominent membrane, 0.7 mm. long; blades
flat, thin, 2-6 cm. long, 1.5-2 mm. wide. Inflorescences terminal on erect branches of the
culms, open cylindrical, 5-12 cm. long, the numerous short, slender spreading or droop-
ing branches borne racemosely along the slender rachis, mostly directed to one side;
basal portion of each branch forming a weak, often contorted, hispid stipe, the branches
disarticulating from the rachis when mature; lowermost branches with several distant
appressed spikelets, the upper ones mostly with 2 spikelets. Spikelets dimorphic; lower
spikelets of each branch with 2 subequal minute orbicular 1-nerved glumes, ca. 0.2-0.3
mm. long; terminal spikelet of each branch with an awned second glume, the awn from
1-6 mm. long; lemma lanceolate, 3.5-4.2 mm. long, strongly 3-nerved, the internerves
white, the nerves green, extending into short teeth on either side of the awn; callus
minutely bearded; awn usually purple, flexuous, 7-10 cm. long; palea equal to the lemma
or slightly longer, prominent, the nerves prominent, green, approaching near the nar-
rowed tip and excurrent as minute awn-tips; anthers 3, yellow-orange, 0.4-0.6 mm. long.

Meseta Central and Canton de Dota; Zarcero; roadsides and ditches,
1,100-2,000 m. elevation; late November to January. Southern Mexico
to Panama.

Mexican specimens of this species are more robust than ours and
have longer awns on the second glumes of the terminal spikelets. The
plants are similar to M . tenella and M . ciliata.

Muhlenbergia flabellata Mez, Repert. Sp. Nov. 17:213. 1921. Fig-
ure 121.

Perennial; plants sprawling, forming large clumps, the culms 25-45 cm. long; lower
parts of the culms reclining and branching profusely from the lower nodes; foliage mostly
clustered on the lower portions of the plants, the sheaths much overlapping; a single
small leaf borne at midculm; culms thin, rigid, the interior filled with vascular bundles
imbedded in sclerenchyma; lower sheaths becoming flattened and papery with age; ligule
an erect pointed membrane, 2.5-8.0 mm. long, decurrent on the sheath margins; blades
2-4 cm. long, strongly ridged and puberulent above, mostly involute. Peduncle slender,
stiff, ridged, scabrid, up to 18 cm. long; inflorescence solitary, terminal, a slender few-
flowered panicle, 3-9 cm. long, the branches erect; axis and branches scabrous; spikelets
short-pedicellate, appressed to the branches. Spikelets blackish, 3-4 mm. long, excluding
the awn; first glume ovate, blunt, 1-nerved, 1.2-1.6 mm. long; second glume oblong-
obovate, 3-nerved, truncate or 3-lobed at the apex, the slightly scabrid nerves parallel,
ending in the lobes; floret 3-4 mm. long; lemma lanceolate, rounded on the back, with a
truncate callus, firm, 3-nerved; callus short-bearded; margins of lemma and lower back
appressed-pubescent, the tip scabrid; awn stiff, scabrous, flexuous, arising from the tip
of the lemma, 4.0-7.5 mm. long; palea equal to the lemma; anthers 3, purple, 1.8-2.1 mm.

FIG. 121. Muhlenberffia flabellata. A, blooming plant; B, glumes; C, floret.

330 FIELDIANA: BOTANY

Paramos of Cerro Buena Vista (type locality); Chirripo Grande; ele-
vations 3,300-3,500 m. Blooming sparse, but apparently yearlong. En-
demic to Costa Rica.

This species is listed as M. quadridentata (H.B.K.) Kunth by Hitch-
cock in Grasses of Central America; however, that is a distinct species
and is not found in Costa Rica.

Muhlenbergia implicata (H.B.K.) Kunth, Rev. Gram. 1:63. 1829.
Podosaemum implicatum H.B.K., Nov. Gen. & Sp. 1:127. 1816.

Sprawling tufted annual plants, the culms mostly 30-50 cm. long, the lower portions
decumbent and rooting, the numerous branches erect and bearing terminal inflores-
cences; prophylla 10-25 mm. long; culms ca. 0.5 mm. thick, hollow, angular, the upper
portions of the internodes minutely retrorsely puberulent; nodes dark, contracted,
glabrous; sheaths mostly longer than the internodes but rather loose, keeled near the
apex, glabrous; ligule a firm, pointed membrane, 2.0-3.0 mm. long; blades mostly folded,
4-8 cm. long, 1.0-1.4 mm. wide, puberulent above. Peduncle included; inflorescences
terminal on the main culms or on leafy branches; panicles open, delicate, ovoid, 5-15 cm.
long, 4-8 cm. wide; spikelets long-pedicellate, the pedicels filiform, flexuous, diverging
strongly from the branches, thickened just below the spikelet. Spikelets mostly
purplish, 2.8-3.2 mm. long; glumes rotund, nerveless, minute, the first 0.2-0.3 mm. long,
the second 0.4-0.5 mm. long; lemma 2.8-3.2 mm. long, narrowly lanceolate, 3-nerved, the
lateral nerves close to the midrib, scabrous; 2 extra rows of barbs, simulating nerves,
also present; tip of lemma bearing 2 minute slender teeth at the base of the awn; callus
minutely bearded; awn slender, 12-20 mm. long; palea equal to the lemma; anthers 3,
purple, 0.4-0.7 mm. long. Chromosome number n = 10 from a Costa Rican specimen.

Dry, rocky roadsides, Meseta Central and Canton de Dota; San
Isidro area; elevations 1,100-1,800 m.; October to April. Mexico to
Venezuela and Colombia.

This species is similar in general appearance to M . tenuissima, but
differs in its larger spikelets, blunt glumes, and nonciliate lemmas.

Muhlenbergia lehmanniana Henr., Med. Rijksherb. Leiden 40:59.
1921. M. attenuata Swallen, Fl. Panama, Ann. Missouri Bot. Gard.
30:138. 1943.

Vigorous perennial, caespitose in large, dense clumps; culms arching, 70-170 cm. long,
unbranched, 2 mm. thick, hollow, glabrous, with 3-4 nodes above the base; foliage mostly
basal, the lower sheaths strongly keeled and densely overlapping, forming fan-shaped
clusters, their blades often disarticulating; culm sheaths mostly longer than the inter-
nodes; blades mostly 60 cm. or more long, 1-4 mm. wide, harsh and scabrous, folded,
tapering to elongated threadlike points; the midrib prominently keeled. Inflorescence a
solitary terminal panicle, usually 20-40 cm. long, oblong-ovoid, open and up to 10 cm.
wide when the branches spread at flowering time, later dense and contracted, 2-3 cm.
wide; color rosy or purplish when young, brownish later; spikelets appressed along the
slender branches. Spikelets 2.5-3.0 (3.5) mm. long; glumes subequal, usually longer than
the floret, 1-nerved, lanceolate, scabrous on the keel and usually on the surface, blunt or
slightly bifid at the apex, usually with a minute awn tip; lemma lanceolate, 2.4-3.0 mm.

BURGER: FLORA COSTARICENSIS 331

long, rounded on the scabrous back, the lateral nerves slightly excurrent as minute teeth
at the base of the awn; callus oblique, minutely bearded; awn slender, flexuous, scabrid,
mostly 2-3 cm. long; palea equal to the lemma, glabrous between the evident nerves;
anthers 3, purplish, 1.5-1.7 mm. long.

Occasional on steep rocky banks and road cuts, usually in full sun;
Meseta Central; General Valley, Boruca, Canas Gordas. November
and December. Elevations from 400-2,000 m. Costa Rica, Panama, and
Colombia.

This handsome species forms colonies on steep slopes. The plants are
conspicuous when they bloom at the beginning of the dry season. It has
usually been included in M. emersleyi Vasey (Epicampes emersleyi
(Vasey) Hitchc.) in older publications.

Muhlenbergia minutissima (Steud.) Swallen was reported (as
Sporobolus minutissimus (Steud.) Hitchc.) by Hitchcock in Gram.
Cent. Amer. as occurring in Costa Rica. We have not found specimens
in US or F to substantiate this report.

Muhlenbergia nigra Hitchc., N. Amer. Fl. 17:468. 1985.

Densely caespitose harsh perennial; plants 90-100 cm. tall, erect; culms unbranched;
internodes up to 3 mm. thick, hollow, minutely scabrous-puberulent, finely silky below
the nodes; nodes dark, not prominent, glabrous; sheaths mostly overlapping, smooth,
faintly scabrous; ligules decurrent on the sheath margins, wider than the blade base,
firm and plainly vasculated near the base, white and membranaceous toward the apex,
7-20 mm. long, the apex pointed or lacerate; leaf blades involute, scaberulous, strongly
ridged above, up to 25 cm. long, 2-3 mm. wide, tapering to a caudate-acuminate, scab-
rous tip. Peduncle cylindrical, exserted up to 30 cm., scabrous, especially toward the
apex; inflorescences terminal on the culms; panicles densely cylindrical, 10-14 cm. long,
5-10 mm. thick, tapering to both ends, leaden gray; branches short, few-flowered, the
spikelets borne on very short, minutely puberulent pedicels, densely overlapping and
concealing the puberulent rachis. Spikelets narrow, 4-5 x longer than wide, 6.0-7.0 mm.
long, strongly laterally compressed; bracts all scaberulous; glumes subequal, slightly
longer than the floret, narrowly triangular 7:1 as folded, acuminate, 1-nerved, strongly
keeled; floret 6.0-6.5 mm. long, ovate 6:1 as folded, acuminate or awn-tipped; 3-nerved;
callus sparsely short-bearded; palea 2-nerved, slightly shorter than the lemma; anthers
2.5-3.0 mm. long, whitish; caryopsis linear-cylindric, red-brown.

This rare species was previously known only from southern Mexico
and northern Guatemala. It occurs only at high altitudes. The only
identifiable Costa Rican specimen is cited below. A previously col-
lected specimen from the same site had completely smutted inflores-
cences. The current specimen is mostly smutted, but has one normal
inflorescence. Prov. San Jose, Valle de los Conejos, elevation ca. 3,200
m., 5-13 November 1976, R. A. Ocampo U92 (CR, ISC).

Muhlenbergia ramulosa (H.B.K.) Swallen, Contr. U.S. Natl.

332 FIELDIANA: BOTANY

Herb. 29:205. 1947. Vilfa ramulosa H.B.K., Nov. Gen & Sp. 1:137.
1816. Sporobolus ramulosus Kunth, Rev. Gram. 1:68. 1829. Figure
122.

Densely tufted annual, 5-15 cm. tall; culms decumbent at the base, upper portions
erect; branching at all nodes; prophylla 6-8 mm. long; culms less than 0.5 mm. thick,
solid, glabrous or puberulent below the nodes; sheaths mostly longer than the inter-
nodes, strongly ridged, glabrous; ligule a minute ciliate membrane, 0.3-0.5 mm. long;
blades mostly folded, puberulent above, 1-2 cm. long, 0.6-0.8 mm. wide, narrowed to a
blunt tip. Peduncle included; inflorescences numerous, terminal and axillary; terminal
panicles 1-5 cm. long, open-cylindrical, up to 1 cm. wide; branches solitary, spreading,
few-flowered; spikelets borne on stiff spreading pedicels about as long as the spikelet.
Spikelets 1.0-1.2 mm. long; glumes about equal, rounded, nerveless, 0.4-0.6 mm. long;
lemma ca. 1 mm. long, ovate, obscurely 3-nerved, blackish, glabrous, awnless; palea
equal to lemma, convex on the back; both lemma and palea cartilaginous, smooth; palea
occasionally with a few scattered hairs; anthers minute, ca. 0.2 mm. long, rounded.
Many spikelets dwarfed or abortive. Chromosome number n = 10 from the Costa Rican
specimen.

Cultivated field, San Juan de Chicoa, Irazu, at 2,600 m. elevation.
November. An old Jimenez specimen (1151) was from the Crater of
Irazii, the locality probably now destroyed. Southern Mexico to Costa
Rica.

Muhlenbergia setarioides Fourn., Mex. PI. 2:84. 1881. M.
polypogonoides Hack., Ann. K. K. Naturhist. Hofmus. 17:255. 1902.
Figure 123.

Sprawling perennial; culms up to 1 m. long, long-decumbent and rooting at the lower
nodes; unbranched ascending flowering culms arising from the rooted portions; culms
hollow, ca. 1.5 mm. thick, smooth and shining, glabrous; sheaths slightly keeled, gla-
brous, shorter or longer than the internodes; leaves numerous; ligule a lacerate-ciliate
membrane, auricled, 1.5-3.5 mm. long; blades flat, lax, dark green, 4-12 cm. long, 4-9
mm. wide, slightly scabrid. Peduncle up to 6 cm. long; panicles terminal on the culm
branches, 8-11 cm. long, 1.5-5 cm. wide, loosely cylindrical, interrupted below, the axis
exposed; branches up to 3 cm. long, ascending, densely flowered to their bases; spikelets
densely clustered on the branchlets, subsessile. Spikelets laterally compressed, 1-
flowered, disarticulating above the glumes, 2.7-3.0 mm. long, excluding the awns; the
bracts whitish with prominent green nerves; glumes 1-nerved, acute, keeled, lanceolate
to narrowly ovate; first glume 1.1-1.5 mm. long, the second slightly broader, 1.5-2. 1 mm.
long; lemma 2.2-3.0 mm. long, prominently 3-nerved, lanceolate, rounded on the back,
the short callus oblique and minutely bearded; lemma sparsely pilose on the lower third
of the back, scabrid on and between the nerves; awn terminal, somewhat flexuous, 5-9
mm. long, purple; palea equal to the lemma, pilose between the keels on the lower half;
anthers 3, 1.0-1.2 mm. long, yellow. Chromosome number n = 20 from a Costa Rican
specimen.

Rare, moist shaded roadbanks, eastern Meseta Central, Irazu and
Barba; elevations from 1,500 to 2,100 m.; blooming in February. Ver-
acruz, Mexico; Guatemala and El Salvador; Costa Rica and Panama.

FIG. 122. Muhlenbergia species. Af. ramulosa: A, blooming plant; B, spikelet; Af.
calcicola: C, blooming plant; D, spikelet.

FIG. 123. Muhlenbergia setarioides. A, decumbent base of plant; B, panicle; C,
spikelet; D, floret.

334

BURGER: FLORA COSTARICENSIS 335

This species is in many ways similar to the rhizomatous mesophytic
species of this genus common in temperate climates, such as M.
schreberi and M. frondosa. It has no close relatives in Central
America.

Muhlenbergia tenella (H.B.K.) Trin., Gram. Unifl. 192. 1824.
Podosaemum tenellum H.B.K., Nov. Gen. & Sp. 1:128. 1816.
Trichochloa tenella (H.B.K.), Roem. & Schult., Syst. Veg. 2:385.
1817. Trinius refers only to the Roemer & Schultes name, which is
based in turn on P. tenellum H.B.K. Figure 120.

Short-lived annual; plants in small tufts, the culms erect or more commonly sprawling,
15-35 cm. long, branching freely from the lower and middle nodes; prophylla 8-10 mm.
long; culms 0.2-0.3 mm. thick, hollow, glabrous; nodes glabrous; leaf sheaths shorter
than the internodes, glabrous or sometimes hirsute, especially near the apex; ligule a
minute lacerate membrane, ca. 0.3 mm. long; leaf blades flat, 2.0-3.5 cm. long, 0.8-2.0
mm. wide, from nearly glabrous to appressed-hirsute on one or both surfaces. Peduncle
mostly included in the upper sheath; inflorescences numerous, terminal on the main
culms or on leafy branches; panicle slender, 3-7 cm. long, the branches solitary, ap-
pressed to the rachis, bearing spikelets to their bases; pedicels from very short to as long
as the spikelets, appressed to the branches. Spikelets overlapping, 2.2-2.7 mm. long;
first glume 0.6-1.2 mm. long, 1-nerved, lanceolate, acuminate or short-awned; second
glume similar, 0.9-1.7 mm. long; lemma narrowly lanceolate, 1.8-2.7 mm. long; nerves
prominent, green; internerves white in immature spikelets; callus minutely bearded;
awn terminal, 15-25 mm. long, thin, flexuous; palea equal to the lemma; anthers 3,
yellow, 0.3-0.4 mm. long. Chromosome number n = 10 from Costa Rican specimens.

Moist cliffs and rocky banks, especially in stream valleys, road cuts;
Meseta Central to Guanacaste; Valley of Rio Pacuare on the Caribbean
slope; elevations from 50 to 1,200 m. October to mid-January. Mexico
to Panama.

This delicate little annual grass begins to grow during the rainy
season, but remains vegetative for a long time. The onset of blooming
is simultaneous over large areas, suggesting that blooming is con-
ditioned by photoperiod. All of the species of this annual group (M .
ciliata, M. diversiglumis, M. implicata, M. tenella, and M . tenuis-
sima) are very similar and may not all merit specific recognition. Some
of our specimens of M. tenella exhibit large pyriform swellings at some
of the lower nodes, each containing an insect grub.

Muhlenbergia tenuissima (Presl) Kunth, Rev. Gram. 1, Suppl.
XVI. 1830. Podosaemum tenuissimum Presl, Rel. Haenk. 1:230.
1830. Muhlenbergia nebulosa Scribn., Beal, Gr. N. Amer. 2:247. 1896.

Delicate, short-lived annual; culms sprawling, 7-30 cm. long, much branched, the
internodes slender, hollow, thick-walled, dull, scabrid below the puberulent nodes; leaf
sheaths shorter than the internodes, puberulent or glabrous; ligule a thin membrane,

336 FIELDIANA: BOTANY

0.8-1.2 mm. long; blades mostly folded, puberulent above, 3-7 cm. long, 0.5-1.0 mm.
wide. Peduncle included or exserted up to 3 cm. Inflorescences numerous, terminal on
the culm and leafy branches; panicles 4-8 cm. long, open cylindrical, 1-2 cm. wide;
branches delicate, filiform, the spikelets long-pedicellate on stiff filiform pedicels which
diverge strongly from the branches and are thickened just below the spikelets. Spikelets
1.7-1.9 mm. long; glumes ovate-acuminate, 1-nerved, rarely awn-tipped, the first 0.5-0.7
mm. long, the second similar, 0.8-1.0 mm. long; lemma narrowly lanceolate, 3-nerved,
1.7-1.9 mm. long, ciliate on the margins, the callus not bearded; awn thin, 6-11 mm. long;
palea equal to the lemma, ciliate on the keels; anthers 3, purple, 0.5-0.6 mm. long.

Savannas of Guanacaste, near the CIA, Liberia and Las Animas;
elevations 100-200 m. December. Southwestern Mexico; Honduras;
Costa Rica and Panama.

This delicate little grass resembles M. implicata, but differs in the
ciliate lemmas, pointed glumes, and smaller spikelets.

NASSELLA Desvaux

Perennial grasses; caespitose; culms branching below; inflorescence a terminal panicle.
Spikelets 1-flowered, disarticulating above the equal, elongated glumes; lemma ovoid or
obovoid, round in cross-section, rigid, the edges overlapping and concealing a short,
flattened palea; callus short, oblique, bearded; apex of lemma with a blunt beak at the
overlap; awn often eccentrically inserted, geniculate, the basal segment twisted, readily
deciduous from the body of the lemma.

This genus is very closely allied to Stipa and is sometimes regarded
as a section of that genus. It differs in the readily deciduous awn that is
often eccentrically attached and in microscopic characters of the an-
thoecium. (Pooideae: Stipeae.)

Nassella linearifolia (Fourn.) Pohl, comb. nov. Stipa linearifolia
Fourn., Mex. PI. 2:73. 1881. Oryzopsis fiorentula Pilger, Bot. Jahrb.
Syst. 27:26. 1899. Stipa florentula (Pilger) Parodi, Revista Mus. La
Plata, Secc. Bot. 6:228. 1944. Figure 207.

Perennial, in dense clumps; culms erect, freely branching from the lower nodes, the
branches mostly short, erect, and very leafy; culms slender, hollow, glabrous; nodes
prominent, glabrous, yellowish; sheaths glabrous, firm; ligule a white membrane, 0.5
mm. long; blades stiff, strongly ridged above, involute, 5-17 cm. long, 2-3 mm. wide,
glabrous, with a few short auricular hairs. Peduncle 6-12 cm. long, thin, stiff, wiry,
glabrous; panicles solitary on the culm or on erect leafy branches, 8-17 cm. long, ovoid,
open, the branches paired, naked below, the longest 4-6 cm. long; spikelets appressed
along the outer half or third of each branch. Spikelets terete; glumes equal, 4.2-5.0 mm.
long, longer than the floret, narrowly ovate, acuminate, rounded on the back, 3-nerved,
often purplish, connivent until the floret is shed, then spreading; lemma narrowly
obovate-cylindrical, somewhat quadrate; apex obliquely truncate, 2.8-3.0 mm. long,
surface brown, minutely roughened, the body appressed-pubescent with white hairs, the
short callus white-bearded; margins strongly overlapping and concealing an oblong

BURGER: FLORA COSTARICENSIS 337

membranaceous palea ca. 1 mm. long; awn readily deciduous, 13-15 mm. long, twice
geniculate, the lower segment tightly twisted, the second segment less so, both minutely
pubescent; floret apparently never opening, the flower cleistogamous; lodicules 3, flat;
anther 1, ca. 0.5 mm. long, placed between the stigmas.

Collected once in Costa Rica, from a gully 1 km. below San Juan de
Chicoa, elevation 2,600 m. Blooming in November. Southern Mexico;
Guatemala; Costa Rica; Colombia and Bolivia.

Recent studies of the anatomy of the anthoecia of fossil and living
Stipeae by Thomasson indicate that the epidermis of the lemmas of this
species is much more similar to that of species ofNassella than it is to
that of typical species of Stipa. This difference is supported by the
deciduous nature of the awn and the plump, somewhat flattened floret.

OLYRA Linnaeus

Caespitose perennial grasses, the culms usually elongated, often thick and hardened;
leaf blades with short pseudopetioles, often oblique-based; plants monoecious. Inflores-
cence a panicle, usually bearing pistillate spikelets toward the tips of the branches and
staminate ones near the bases. Pistillate spikelets: Glumes equal, several-many-nerved;
floret single, disarticulating above the glumes (except in O. lateralis); lemma rigid,
bony, obtuse, its margins usually inrolled over the edges of a palea of similar texture.
Staminate spikelets: Soft-textured; glumes absent; floret 1, disarticulating from the
pedicel; lemma 3-nerved, keeled; palea 2-keeled, equal to the lemma; anthers 3.

The plants are somewhat bamboo-like in general aspect, but usually
have foliage leaves on the main stem as well as on the branches. They
usually bloom annually, in contrast to the woody bamboos, which
bloom very irregularly or at long intervals. The leaf anatomy and the
possession of pseudopetioles indicate that the genus is bambusoid,
although in older systems, it was placed in the tribe Paniceae. In such
treatments, the pistillate spikelets were described as missing a first
glume and possessing only a second glume and a sterile lemma below
the floret. (Bambusoideae: Olyreae.)

KEY TO SPECIES OF Olyra

la. Tall, erect, or scrambling plants; leaf blades 12-22 cm. long, 1.5-8.5 cm. wide . . 2
Ib. Weak trailing plants; leaf blades 3.5 cm. or less long, 5-10 mm. wide

O. lateralis

2a. Sheath auricles spreading, purple, forming horizontal collar around the culm;
leaf blades with triangular purple zone at base of nearly symmetrical blade

O. standleyi

2b. Sheath auricles erect, inconspicuous, not spreading; leaf blades very oblique-
based, not purple-marked at base O. latifolia

Olyra lateralis (Presl) Chase, Proc. Biol. Soc. Wash. 21:179. 1908.

338 FIELDIANA: BOTANY

Panicum laterale Nees, Agrost. Bras. 213-214. 1829, var. a. 0. sar-
mentosa Doell, Mart. Fl. Bras. 2:819. 1877. Figure 124.

Sprawling perennial, the culms up to 4 m. long, branching freely, trailing over banks
and low vegetation; internodes 1.0-1.5 mm. thick, hollow, thin-walled, glabrous or pu-
berulent below the nodes; nodes prominent, with 2 circular ridges and a groove between
them, retrorsely puberulent; leaf sheaths shorter than the internodes, appressed-pu-
berulent especially toward the apex; ligule a short membrane, 0.2-0.5 mm. long;
pseudopetiole puberulent, 0.7-1.0 mm. long; blades flat, rather stiff, narrowly triangular
3-5:1, cordate-based, 1.5-4.0 cm. long, 5-13 mm. wide, sparsely puberulent or scabrid,
the margins sometimes ciliate, tapering abruptly to a rather rounded tip; underside
glaucous. Inflorescences paniculate, terminal on the culm and also axillary from the
upper leaf sheaths, 2-4 cm. long, open-pyramidal, to 3 cm. wide, few-flowered. Pistillate
spikelets: Few, at branch tips; dorsally compressed, 2.4-3.0 mm. long, the length 2.0-2.8
x the width; disarticulation below the equal glumes that completely cover the floret; first
glume 5-nerved, stiff, minutely woolly; second glume similar, 3-nerved; floret ovate 3:2,
1.4-1.5 mm. long; lemma rigid; stramineous, striate, with a basal areole; margins thick
but not conspicuously inrolled; palea 1.2 mm. long; lodicules 3; style 1; stigmas 3; cary op-
sis elliptical 3:2, reddish brown, with a persistent style. Staminate spikelets: Borne on
lower portions of the branches, 3-4 mm. long, ovate 4.5:1, acute; glumes subequal,
3-4-nerved; anthers 3, purple, 2.0-2.3 mm. long.

This species is rare in Costa Rica, and only one specimen has been
collected in the twentieth century. Puntarenas, Cienaga de Agua
Buena, Canas Gordas, Pittier 11008; February 1897, Helechales del
General, vallee du Diquis, 700 m., 3 February 1898, Pittier 12058;
Cordoncillal, Pittier 3641; San Jose, Vicinity of El General, Skutch
2254- Peru and Bolivia to Venezuela, Colombia, Panama, and Southern
Costa Rica.

Olyra latifolia L., Syst. Nat. ed 10, 2:1261. 1759. Figure 125.

Caespitose perennial, the plants forming clumps of up to 20 culms from a hard, knotty
crown; culms up to 6 m. long, erect, arching, scrambling in brush and trees, or decum-
bent; branching abundant from middle and upper nodes; internodes up to 1 cm. thick,
hollow, thick-walled; internodes usually glabrous or, exceptionally, pubescent near the
apex, often purplish-spotted; lower sheaths deciduous, those of the branches usually
persistent and overlapping, glabrous to hispid and puberulent, the overlapping edge
ciliate; apex of sheath prolonged into an auricle; ligule a thick membrane, up to 4 mm.
long; pseudopetiole 1-3 mm. long, puberulent to heavily bearded; leaf blades flat, oval 3-7
x longer than wide, very oblique, one side of the blade narrow and the other wide at the
base, these dimensions reversed toward the apex of the blade; apex rather abruptly
short-caudate; length 8-22 cm.; width 1.5-8.5 cm.; upper surface usually glabrous, lower
surface velvety or glabrous. Inflorescences paniculate, numerous at the apex of the culm
and the tips of leafy branches, ovoid or pyramidal, up to 18 cm. long and about a third as
wide, open to rather congested. Spikelets unisexual, the pistillate ones usually solitary
at the tips of the branches, sometimes several on a branch; pistillate spikelets more
abundant toward the apex of the panicle, the staminate ones toward the base of the
panicle and on lower parts of the branches. Peduncle, rachis, and branches scabrous to
softly hirsute. Staminate spikelets: Borne on appressed pedicels 1-3 x as long as the

FIG. 124. Olyra lateralis. A, blooming plant; B, leaf blade base, showing
pseudopetiole; C, two views of a pistillate spikelet; D, pistillate floret within a glume; E,
pistillate floret.

339

FIG. 125. Olyra latifolia. Blooming plant, pistillate spikelet, floret, staminate
spikelet.

340

BURGER: FLORA COSTARICENSIS 341

spikelet; membranaceous, ca. 5 mm. long, ovate 6:1, acute; glumes absent; lemma
keeled, 3-nerved, bearing a straight awn up to 4 mm. long; palea of equal length,
2-nerved; lodicules 3, truncate, vasculated, bearing 2-3-celled microhairs at the tip;
anthers 3, 2.7-3.5 mm. long, brown. Pistillate spikelets: Borne on flattened, thickened
pedicels at the tips of branches, or several in a series along a branch, dorsally com-
pressed, 8-15 mm. long, not including the awns; glumes usually glabrous, rarely pu-
berulent; first glume ovate, caudate, tapering gradually into a thick awn up to 20 mm.
long; nerves 7-9; second glume similar but with a shorter awn, 5-7-nerved; floret readily
deciduous; lemma 4.8-5.2 mm. long, elliptical 1.5-2:1, glabrous, rigid, blunt, white,
shiny, rounded on the back, with an evident basal germination lid; margins distinctly
inrolled over the edges of a rigid convex palea of similar color and texture, 3.7-4.0 mm.
long; lodicules truncate, vasculated; caryopsis filling the cavity of the floret, with a stiff
brown pericarp; endosperm opalescent, white, horny. Chromosome number n = 11, 22
from Costa Rican and Venezuelan material.

Common in forests and forest margins, at elevations up to 850 m., on
both Pacific and Caribbean slopes. New growth is initiated during the
rainy season, and the primary panicles bloom then. The development
of smaller panicles on the lateral branches, however, prolongs the
blooming season throughout the year. Mexico to Brazil, Bolivia, and
northern Argentina; West Indies; introduced in Africa. This species is
somewhat weedy and thrives in the disturbed margins of forests. It is
amazingly variable in stature, leaf size and shape, and pubescence.

Olyra stand ley i Hitchc., Proc. Biol. Soc. Wash. 40:87. 1927.

Perennial from hard crowns, the new buds at the base covered with shining overlap-
ping scales; plants 2-3 m. tall, the culms arching, branching from the middle nodes, the
branches solitary; prophyllum inserted above the node, to 6 cm. long, ciliate on the keels;
internodes to 3 mm. thick, glabrous, thick-walled; nodes conspicuous, with a swollen
purplish band overlapped above by the base of the sheath, glabrous or retrorsely pu-
berulent; sheaths glabrous to sparsely retrorsely papillose-hispid; lower sheaths shorter
than the internodes, the upper longer and overlapping; sheath auricles present, purple,
spreading horizontally and forming a sort of collar around the culm, the margins hispid-
ciliate; ligule inconspicuous, a stiff purple membrane ca. 1 mm. long; pseudopetiole ca. 2
mm. long, pubescent; leaf blades flat, glabrous, ovate 4-5:1, nearly symmetrical, 12-24
cm. long, 2.5-5.0 cm. wide, the base cordate, with a conspicuous deltoid purple area at
the midrib; surfaces glabrous, the upper dark green, the lower glaucous. Inflorescences
terminal on leafy branches; panicle to 15 cm. long and about as wide, open, pyramidal,
with successive whorls of stiff ascending branches, the longest 11 cm. long. Staminate
spikelets: Numerous, appressed along the lower parts of the panicle branches, short-
pedicellate, ca. 1 cm. long; glumes absent; lemma acuminate; palea about equal to the
lemma. Pistillate spikelets: 1-10 borne at branch tips, on thickened pedicels; first glume
ca. 2 cm. long, including the awn, 5-nerved, glabrous; second glume slightly shorter,
5-nerved; floret 8 mm. long, obtuse, the surface of the lemma minutely pitted, its mar-
gins inrolled over the edges of the palea.

The type specimen, which is fruiting, was collected at El Muneco by
Standley and Torres in March 1926 (50982). We have collected vegeta-
tive material from what is apparently the same stand, on the road S of

342 FIELDIANA: BOTANY

El Muneco. The plants are conspicuous because of the large size of the
leaf blades and are readily identifiable by the purple auricular collar at
the apex of the sheath and the purple triangle at the base of the leaf
blades. The only other Costa Rican collection is the following: Prov. de
Cartago, Moravia de Chirripo, 8 km. camino el Rio Chirripo, altitude
1,400 m., January 1976, R. Ocampo 1212. This specimen, like recent
material from El Muneco, is vegetative. The distance between these
two localities is over 25 km. , indicating that the species may probably
be found in other intermediate sites. Recent collections from Cerro
Jefe, Panama, by Calderon, may be the same species. No other collec-
tions are known.

OPLISMENUS Beauvois

REFERENCE: A. S. Hitchcock, The North American species of Op-
lismenus, Contr. U.S. Natl. Herb. 22:123-132. 1920.

Creeping grasses, the lower portions of the culms decumbent and rooting; blooming
from ascending leafy branches. Duration indefinite, the plants forming large patches by
vegetative spread. Inflorescence a slender terminal panicle of short, spikelike racemes;
spikelets paired, very short-pedicellate, the pairs borne alternately in 2 rows along the 2
lower sides of the triquetrous rachis of the racemes. Spikelets disarticulating below the
glumes, more or less laterally compressed; glumes keeled, subequal, membranaceous,
shorter than the spikelet, awned from a bifid tip, the first usually 3-nerved, the second
5-nerved; lower (sterile) lemma 5-9-nerved, awn-tipped or awnless, without a flower or
palea, enfolding the fertile floret; upper (fertile) floret shorter than the sterile lemma and
concealed by it; lemma dorsally compressed, narrowly ovate, acute, coriaceous, shining,
longitudinally finely striate, the margins incurved, flat, overlapping the edges of the
equal, slightly convex palea; lodicules 2, truncate; anthers 3; style branches separate,
naked at the base.

A small genus of 10-15 species, occurring in the subtropics and
tropics of both Old and New Worlds. The plants appear similar to
Pseitdechinolaena in growth habit and to Echinochloa in spikelet
structure. (Panicoideae: Paniceae.)

KEY TO SPECIES OF Oplismenus

la. Awns upwardly scabrous; racemes conspicuously whitish, hispid; glumes and sterile

lemma longitudinally ridged 0. burmannii

Ib. Awns smooth; racemes not hispid; glumes and sterile lemma not ridged 2

2a. Racemes very short, appearing wider than long, the rachis 2-6 mm. long;

spikelets usually 7 or fewer per raceme O. setarius

2b. Racemes longer than wide, the rachis of lower racemes 1 cm. or more long,
bearing numerous spikelets O. hirtellus

Oplismenus burmannii Beauv., Ess. Nouv. Agrost. 54. 1812. Fig-
ure 126.

FIG. 126. Oplismenus species. 0. burmannii: A, inflorescence; B, spikelet; 0. hirtel-
lus: C, spikelet.

343

344 FIELDIANA: BOTANY

Duration indefinite, probably annual; plants decumbent, forming large patches, the
culms long-decumbent and rooting from the nodes, branching freely, the branches
spreading or ascending, 10-30 (50) cm. long, mostly leafy only on the lower half, the
naked peduncle comprising more than half of the length; internodes ca. 1 mm. thick,
pubescent in a single villous line below the overlapping edge of the sheath above, some-
times also papillose-hispid all over; sheaths shorter than the internodes, densely short-
ciliate on the overlapping margin, more or less papillose-hispid as well; ligule a thin
ciliate membrane, in total 0.7-1.2 mm. long; leaf blades flat, ovate, 3-4:1, 2-5 cm. long,
9-15 mm. wide, scabrous, puberulent, hirsute, or papillose-hispid. Peduncle 3-18 cm.
long, slender, bearded at the apex; inflorescence rather dense, 3-6 cm. long, the 3-7
ascending racemes overlapping; axis and the rachises of the racemes densely papillose-
hispid; spikelets paired, subsessile on the lower 2 sides of the triquetrous rachis, often
one of the pair reduced or obsolete. Spikelets whitish, conspicuously hispid, 2.8-3.7 mm.
long; first glume narrowly ovate, 2.0-2.7 mm. long, 3-nerved, notched at the apex, the
purplish antrorsely scabrous awn 5-10 mm. long, attached at the notch; second glume
ovate, 5-nerved, the awn 2.5-5 mm. long; lower (sterile) lemma 2.6-3.5 mm. long, ellipti-
cal, 7-9-nerved, heavily hispid-bearded in a wide band across the middle, pubescent
below the apex on the inner side; palea and flower lacking; upper (fertile) floret 1.9-2.1
mm. long, ovate 3:1, acute, coriaceous, shining, striate; palea equal; lodicules 2, trun-
cate; anthers 3, orange, 1 mm. long; stigmas purple. Chromosome numbern = 18 from a
Costa Rican specimen.

Open dry areas and open shade, roadsides, pastures, stream banks;
sea level to 1,900 m. elevation, most common at lower elevations on the
Pacific slope, apparently uncommon on the Caribbean slope. October
to May. Southern Mexico to northern South America and the Carib-
bean Islands. Introduced from Asia.

The binomial 0. burmannii is usually stated to have been based
uponPamc^m burmannii Retz., Obs. Bot. 3:10, 1783. Beauvois, how-
ever, makes no reference to the Retzius name.

Oplismenushirtellus(L.) Beauv., Ess. Nouv. Agrost. 54:168. 1812.
Panicum hirtellum L., Syst. Nat. ed. 10. 2:870. 1759. Figure 126.

Duration indefinite; culms 59-90 cm. long, the bases long-decumbent and rooting from
the nodes, forming large patches, the rooted portions branching freely; internodes 1 mm.
thick, hollow, glabrous or pubescent below the nodes; prophylla broad, up to 1.6 cm.
long; nodes glabrous or bearded; sheaths shorter than the internodes, glabrous, pilose,
or papillose-hispid, their exposed margins softly ciliate; ligule a ciliate membrane,
0.6-1.2 mm. long; blades flat, thin, lanceolate 4.5-7.5:1, 4-12 cm. long, 7-20 mm. wide,
somewhat asymmetric; surfaces glabrous, scabrous, velvety-pubescent, or with a few
papillose-hispid bristles at the base. Inflorescences terminal on leafy, ascending or erect
branches; peduncles slender, exserted 1.5-12 cm., glabrous or appressed-pilose; inflores-
cence 7-14 cm. long, composed of 3-7 spikelike 1-sided racemes, arranged racemosely
along the central rachis; racemes 1-3 cm. long, the rachis glabrous, pilose, or papillose-
hispid; spikelets compactly arranged, in pairs, these attached alternately in 2 rows on
the 2 lower sides of the triquetrous rachis; 1 spikelet of some pairs reduced or abortive;
pedicels very short. Spikelets laterally compressed, 3.0-4.0 mm. long; glumes keeled,
the first 1.8-2.5 mm. long, ovate, 3-5-nerved, bearing a smooth, stiff awn 4-10 mm. long,
attached just below the summit; second glume 2.0-2.7 mm. long, ovate, 5-7-nerved, with

BURGER: FLORA COSTARICENSIS 345

a short awn 2-4 mm. long, attached just below the summit; lower (sterile) lemma 3.0-3.5
mm. long, ovate, 5-9-nerved, lacking palea or flower, glumes and sterile lemma glabrous,
scabrous, or papillose-hirsute; upper (fertile) floret dorsally compressed, 2.5-3.0 mm.
long, elliptical 3:2; lemma faintly 5-nerved, shiny, striate, coriaceous, acute, the thin
margins covering the margins of the broad palea of equal length; lodicules 2, truncate;
anthers 3, yellow-orange, 1.5-1.7 mm. long; caryopsis elliptical 8:3, white.

Usually in shade of brush or open forests, roadsides; sea level to
2,000 m. elevation. Meseta Central, Canton de Dota, Turrialba,
Pejivalle, General Valley, Limon area, Tilaran, Hda. Inocentes. May
to February, probably yearlong. Mexico to Argentina; Caribbean Is-
lands.

This rather weedy species is amazingly variable in the pubescence of
leaves, sheaths, and rachis of the spikes; however, all of our chromo-
some counts from Costa Rica and Venezuela indicate a single number,
rc = 45.

Oplismenus setarius (Lam.) Roem. & Schult., Syst. Veg. 2:481.
1817. Panicum setarium Lam., Tabl. Encycl. 1:170. 1791.

Duration indefinite; culms long-decumbent, rooting at the nodes; erect portions 20-30
on. long; internodes 1 mm. thick, hollow, glabrous or pilose with scattered hairs, espe-
cially in a line below the margins of the leaf sheath above; nodes bearded or glabrous;
sheaths shorter than the internodes, more or less papillose-pilose or hispid, especially
toward the apex; margins ciliate; ligule a thin membrane, ciliate at the apex, ca. 1.5 mm.
long; leaf blades 3-5 cm. long, 4-14 mm. wide, appressed-pilose or with scattered
papillose-hispid hairs. Inflorescences terminal on leafy erect branches; peduncle slender,
exserted 1-11 cm.; panicle 4-9 cm. long, made up of 4-7 short racemes borne singly at the
nodes of the rachis; individual racemes very short, the rachis 2-6 mm. long, puberulent,
bearing 7 or fewer spikelets, in pairs along the lower sides of the triquetrous rachis; one
member of a pair often reduced or abortive. Spikelets more or less laterally compressed,
2.7-3.3 mm. long; first glume 1.7-2.2 mm. long, 3-5-nerved, ovate, rounded or tapered to
the tip; awn smooth, 4-5 mm. long, inserted just below the tip; second glume 1.8-2.3 mm.
long, 5-nerved, ovate; awn 1.5-2 mm. long; lower (sterile) lemma 2.4-3.0 mm. long,
ovate, broad, partially enveloping the fertile floret, 5-7-nerved; awn very short or lack-
ing; palea and flower absent; upper (fertile) floret 2.3-2.7 mm. long, the lemma elliptical,
acute, 2.5-3.5:1, cartilaginous, shining, longitudinally striate; palea of equal length,
similar; lodicules 2, truncate; anthers 3, 1.3 mm. long, orange.

Rare or overlooked; shaded roadsides and cafetales; Meseta Central,
Turrialba, 1,000-1,700 m. August to December. Southeastern United
States to Guatemala and Honduras; West Indies; northern South
America to Paraguay.

ORTHOCLADA Beauvois

Leaf blades borne on prominent pseudopetioles; blades conspicuously cross-veined;
plants bearing numerous hook-shaped microhairs. Inflorescence a large panicle.
Spikelets 2-flowered, laterally compressed and keeled, disarticulating below the glumes

346 FIELDIANA: BOTANY

and below the second floret; glumes subequal, the first 3-nerved, the second 5-nerved;
lemmas 5-7-nerved, acuminate or awn-tipped; rachilla slender, elongate, held by the
keels of the palea.

The genus has one species in tropical America and a second in
Africa. It belongs to the Centosteceae, a tribe of uncertain relation-
ships, probably close to the bamboos.

Orthoclada laxa (L. Rich.) Beauv., Ess. Nouv. Agrost. 70, 149,
168. 1812. Aira laxa L. Rich., Actes Soc. Hist. Nat. Paris 1:106. 1792.
Figure 127.

Perennial; caespitose; culms erect or decumbent and rooting at the basal nodes, un-
branched, glabrous or slightly puberulent below the nodes; plants mostly 50-120 cm. tall,
the panicle making up ca. hah0 the total; leaf sheaths 5-15 cm. long, mostly overlapping,
slightly keeled above, densely covered with uncinate microhairs and a few long slender
trichomes; sheath auricles prominent, erect; ligule a thickish lacerate-ciliolate membrane
less than 1 mm. long; leaf blades borne on pseudopetioles 0.5-4.0 cm. long; blades nar-
rowly ovate, the larger ones 10-20 cm. long, 17-35 mm. wide. Inflorescence a large open,
dome-shaped terminal panicle; peduncle included or exserted up to 25 cm., bearing
uncinate microhairs; panicle up to 35 cm. long and about as wide, extremely open, the
slender branches bearing a few spikelets near their tips; rachis short, usually 4-10 cm.
long, abruptly terminating in an acicular bract up to 3 cm. long; major branches up to 25
cm. long, very slender; spikelets borne in small groups near the branch tips and ap-
pressed to them. Spikelets 8-10 mm. long, laterally compressed and keeled, disar-
ticulating below the glumes, the second floret also disarticulating; first glume 3.5-4.5
mm. long, lanceolate, 3-nerved; second glume 4-5 mm. long, narrowly ovate, 5-nerved;
florets 2, equal, 5-6 mm. long, ovate, acute or awn-tipped, scabrid on upper parts; palea
prominent, nearly as long as the lemma, scabrid on the keels near its tip, grasping the
slender rachilla by its keels; rachilla 2-3 mm. long, the ultimate segment usually bearing
a rudimentary third floret up to 3 mm. long. Chromosome number n = 12.

Common in wet forests, forest margins, and cacao groves; elevations
below 550 m. near both Atlantic and Pacific coasts, Provinces of
Heredia, Limon, and Puntarenas; somewhat weedy; apparently
blooming yearlong. Southern Mexico to northern South America.

ORYZA Linnaeus

REFERENCES: D. Chatterjee, A modified key and enumeration of the
species ofOryza L., Indian J. Agric. Sci. 18:185-192. 1948. T. Tateoka,
Taxonomic studies of Oryza, I. The 0. latifolia complex, Bot. Mag.
(Tokyo) 75:418-427. 1962.

Aquatic or paludose grasses; inflorescence a terminal panicle. Spikelets 1-flowered,
strongly laterally compressed and keeled; glumes reduced to minute ridges or a cupule at
the tip of the pedicel; spikelet with 2 reduced sterile lemmas at the base, the fertile floret
terminal, all 3 florets disarticulating from the cupule as a unit; lemma 5-nerved, coriace-
ous, apiculate or awned, the involute margins clasping the marginal ridges of the palea;
palea keeled, 3-nerved, similar to the lemma, apiculate; stamens 6.

FIG. 127. Orthoclada laxa. Blooming plant.

347

348 FIELDIANA: BOTANY

Several interpretations of the spikelet of Oryza have been made.
Some authors consider the sterile lemmas as glumes. The fertile floret
has also been interpreted as the result of the fusion of two florets, the
lower one contributing a lemma and a flower having 3 anthers and a
pistil, the upper contributing a lemma and 3 anthers. Species 23,
mostly in the tropics of the Old World. The genus is closely related to
Leersia, differing in the well-developed lower sterile lemmas.
(Oryzoideae: Oryzeae.)

KEY TO SPECIES OF Oryza

la. Spikelets readily deciduous; ligules 3-6 mm. long; wild plants O. latifolia

Ib. Spikelets persistent on pedicel; ligules at least 10 mm. long; cultivated crop

O. saliva

Oryza latifolia Desv., J. Bot. Desv. II. 1:77. 1813.

Caespitose perennial, rather succulent, in small tufts; culms erect, to 2 m. tall, usually
simple, hollow, thin-walled, 5-10 mm. thick, glabrous; nodes glabrous, shrunken; sheaths
mostly longer than the internodes and overlapping, glabrous; ligule a stiff membrane, 3-6
mm. long, ciliate at the apex and pubescent on the back; blades of larger plants up to 55
cm. long, 35 mm. wide, usually glabrous, rarely hirsute, scabrous on margins and sur-
faces; lower leaves with prominent ciliate blade auricles, the upper ones somewhat
pseudopetiolate, the pseudopetiole hirsute, the blades tapering to a narrow base. Panicle
open, many-flowered, up to 40 cm. long and 20 cm. wide; lower branches verticillate, up
to 30 cm. long, with a tuft of short hairs at the bases, the basal portions naked, the
secondary branches and spikelets appressed. Spikelets short-pedicellate along the
branches, 6-7 mm. long; glumes reduced to 2 minute excrescences at the tip of the
pedicel; sterile lemmas awl-shaped, 1-nerved, the first 1-2 mm. long, the second 1.5-2.0
mm.; lemma 5.5-7.0 mm. long, 2.0-2.5 mm. wide, elliptic-oblong, apiculate or with an
awn up to 3.5 cm. long, rugose, hispid-ciliate on the margins, nerves, and sometimes the
internerves; palea oblong, apiculate, much narrower than the lemma, the pubescence as
on the lemma; anthers 6, 2-3 mm. long, yellow. Chromosome number n = 24 from Costa
Rican material.

Occasional, wet muddy banks, marshes, wet pastures, forest open-
ings; low elevations, 5-300 m.; both Caribbean and Pacific slopes. April
to October, probably yearlong. Southern Mexico and the Caribbean
Islands to Brazil and Paraguay.

Oryza sativa L., Sp. PI. 333. 1753. Figure 128.

This is the common cultivated rice, widely cultivated at low eleva-
tions in Costa Rica. There are a myriad of cultivated strains, differing
mostly in agronomic characteristics. The spikelets may be awned or
awnless. As in all cultivated cereals, the spikelets are retained on the
plant past maturity, allowing efficient harvesting. Common names:
Arroz, "rice."

FIG. 128. Oryza saliva. Culm base, inflorescence, spikelet.

350 FIELDIANA: BOTANY

PANICUM Linnaeus

REFERENCES: S. T. Blake, New criteria for distinguishing genera
allied to Panicum (Gramineae), Proc. Roy. Soc. Queensland 70:15-19.
1958. Agnes Chase, Notes on genera of Paniceae IV, Proc. Biol. Soc.
Wash. 24:103-160. 1911. R. W. Freckmann, Taxonomic studies in
Panicum subgenus Dichanthelium, Unpubl. Ph.D. Diss., I.S.U. Li-
brary. 175 pp. 1967. F. W. Gould, Nomenclatural changes in the
Poaceae, Brittonia 26:59-60. 1974. A. S. Hitchcock & Agnes Chase,
The North American species of Panicum, Contr. U.S. Natl. Herb.
15:1-396. 1910; and Tropical North American species of Panicum,
Contr. U.S. Natl. Herb. 17:459-539 + XII. 1915. Chien-Chang Hsu,
The classification of Panicum (Gramineae) and its allies with special
reference to the characters of lodicule, style-base and lemma, J. Fac.
Sci. Univ. Tokyo, Sect. 3, Bot. 9:3:43-150. 1965. M. G. LeLong,
Studies of reproduction and variation in some Panicum subgenus
Dichanthelium, Unpubl. Ph.D. Diss., I.S.U. Library. 228pp. 1965. L.
R. Parodi, Estudios sistematicos sobre las Gramineae-Paniceae argen-
tinas y uruguayas, Darwiniana 15:65-111. 1969.

Plants annual or perennial, caespitose, rhizomatous, or decumbent and rooting at the
base; inflorescence an open or contracted panicle, sometimes with rather simple
branches and the spikelets unilaterally disposed along them. Disarticulation below the
spikelets. Spikelets more or less flattened on the first glume side and convex on the
second glume side, sometimes biconvex or even somewhat laterally compressed; first
glume usually much reduced, rarely as much as three-fourths as long as the spikelet,
mostly 1-3-nerved, membranaceous; second glume and lower (sterile) lemma subequal,
ca. as long as the spikelet, membranaceous, 3-11-nerved; sterile lemma often containing
an abortive or well-developed palea, and rarely a staminate flower; upper (fertile) floret
stiff or rigid, awnless, the lemma usually smooth and shining, its margins inrolled over
the edges of a flat or somewhat convex palea of similar length and texture; lodicules 2,
truncate; anthers usually 3; ovary with 2 separate style branches, these naked near the
base; stigmas plumose; caryopsis elliptical or obovate, dorsally flattened, with a large
embryo.

Panicum is an enormous genus, primarily distributed in warm cli-
mates of both eastern and western hemispheres. Early authors used
the name in a very inclusive sense, involving most of the species of the
subfamily, but a general tendency has been to remove groups of
species as segregate genera. Related or segregate genera in our flora
include Brachiaria, Digitaria, Echinochloa, Homolepis, Hymen-
achne, Ichnanthus, Isachne, Lasiacis, Leptocoryphium, Oplismenus,
Paspalum, Pseudechinolaena. The genus Panicum is generally rec-
ognized by the spikelets, which are borne in panicles and are awnless,
dorsally compressed, and with a short first glume and subequal second
glume and sterile lemma that conceal the rigid floret. A recent pro-

BURGER: FLORA COSTARICENSIS 351

posal has been made by Gould to remove the subgenus Dichanthelium
as a genus; however, these plants lose their distinctiveness in the
tropics, and I have continued to include them in Panicum. (Pani-
coideae: Paniceae.)

KEY TO SPECIES OF Panicum

la. Spikelets more than 3 mm. long 2

Ib. Spikelets less than 3 mm. long 11

2a. Fertile lemma rugose P. maximum

2b. Fertile lemma smooth 3

3a. Spikelets (at least those in axillary inflorescences) pubescent 4

3b. Spikelets all glabrous (see also P. cordovense) 5

4a. Sheaths, blades, and internodes densely papillose-hispid; spikelets acumi-
nate, all pubescent P. rudgei

4b. Sheaths, blades, and internodes sparsely pubescent; spikelets blunt, only

those in axillary inflorescences pubescent P. cordovense

5a. Leaf sheaths and blades densely papillose-pubescent 6

5b. Leaf sheaths and blades glabrous or only slightly pubescent on collar and edges 7

6a. Spikelets 3.5 mm. or less long, usually reddish toward base P. ghiesbreghtii

6b. Spikelets 4.5-5 mm. long, stramineous or marked with purple . P. parcum

7a. Spikelets glutinous, often with adhering particles P. glutinosum

7b. Spikelets not glutinous 8

8a. Plants with slender rhizomes; panicles 10-15 cm. long; lower floret
staminate P. aquaticum

8b. Plants not rhizomatous (submerged nodes sometimes rooting); panicles large,
35 cm. or more long 9

9a. Panicle branches simple, conspicuously whorled; spikelets blunt; sterile lemma

inflated by large palea P. mertensil

9b. Panicle branches rebranched, not conspicuously whorled; spikelets acute or acumi-
nate 10

lOa. Leaf blades elliptical, glabrous, 50 cm. or more long, up to 6 cm. wide; first

glume more than half as long as spikelet P. grande

lOb. Leaf blades linear, less than 2 cm. wide; first glume very short; dewlaps deep
purple P. elephantipes

lla. Glumes and sterile lemma pubescent 12

lib. Glumes and sterile lemma glabrous 20

12a. Leaf blades ovate, less than 4.5 x longer than wide 13

12b. Leaf blades narrowly ovate to linear, at least 5 x longer than wide 14

13a. Panicle very diffuse, spikelets diverging on slender pedicels; spikelets 1.3 mm. or
less long, without glands on sterile lemma P. trichoides

13b. Panicle slender, of up to 15 short, drooping, 1-sided spikelike racemes; spikelets
subsessile along their lower sides, at least 1.8 mm. long, usually bearing 2 circular,

eyelike glands on sterile lemma P. pulchellum

1 4 a. First glume at least half as long as spikelet 15

14b. First glume one-third to one-fourth as long as spikelet 17

15a. Fertile lemma rugose, becoming brown when mature P. sellourii

352 FIELDIANA: BOTANY

15b. Fertile lemma smooth, stramineous 16

16a. Plants bearing exserted terminal panicles only, the spikelets on spreading
pedicels, sparsely hairy; first glume acuminate, ca. half as long as

spikelets P. haenkeanum

16b. Plants bearing exserted primary panicles and small, few-flowered partly in-
cluded secondary ones, on later leafy branches; spikelets densely pilose; first

glume obtuse, ca. three-fourths as long as spikelet P. pantrichum

17a. Leaf blades and sheaths nearly glabrous, except for prominent cilia along the basal

margins of the blades P. sphaerocarpon

17b. Leaf blades and sheaths pilose or velvety 18

18a. Uppermost leaf blades 1-3 cm. long, less than 5 mm. wide; panicles less than

10 cm. long 19

18b. Uppermost leaf blades 5-15 cm. long, 10-15 mm. wide P. viscidellum

19a. Plants branching mostly from the base, forming soft cushions or mounds of foliage;
leaf blades and sheaths softly and densely pilose, with hairs up to 5 mm. long

P. laxiflorum
19b. Plants branching from culm nodes, with axillary tufts of branches; pubescence

mostly of short hairs 1-2 mm. long P. olivaceum

20a. Fertile lemma pubescent 21

20b. Fertile lemma glabrous 23

21a. Fertile lemma conspicuously woolly at apex and base; spikelets 1.0-1.3 mm. long;

first glume usually absent; panicle dense P. discrepans

21b. Fertile lemma with scattered appressed hairs; spikelets at least 1.5 mm. long; first

glume present 22

22a. Panicles 2-6 cm. long, the few branches up to 1.5 cm. long, densely flowered to

their bases P. amndinariae

22b. Panicles 12-17 cm. long, open, branches up to 10 cm. long, the lower half

naked, spikelets borne toward tips of branches only P. schiffneri

23a. Low, mat-forming plants, less than 10 cm. tall P. ciliatum, var. pubescens

23b. Plants taller, not forming mats or mounds 24

24a. Inflorescence a short linear cluster of a few spikelets; plants slender, wiry;

leaf blades involute, 1-2 mm. wide P. stenodes

24b. Inflorescence a many-flowered panicle; plants various, not wiry, usually with

flat blades 25

25a. Spikelets borne in 1-sided racemes along lower sides of primary or secondary

panicle branches, short-pedicellate and crowded 26

25b. Spikelets not arranged in 1-sided racemes, randomly disposed in open or crowded

panicles 33

26a. Leaf blades ovate, less than 6 x longer than wide 27

26b. Leaf blades narrowly ovate or linear, more than 10 x longer than wide 29

27a. Spikelets 1.0-2.5 mm. long 28

27b. Spikelets 2.5-3.0 mm. long, densely crowded, falcate P. frondescens

28a. Lower floret producing a naked caryopsis P. irregulare

28b. Lower floret sterile P. polygonatum

29a. Leaf blades 2.5-3 cm. wide; plants aquatic P. stagnatile

29b. Leaf blades mostly 1.5 cm. or less wide; mostly plants of wet ground but not truly
aquatic 30

BURGER: FLORA COSTARICENSIS 363

30a. Leaf blades narrowed to base, not cordate P. laxum

30b. Leaf blades broad or cordate at base 31

31a. Panicles rather open, not more than twice longer than wide, the branches up to 11
cm. long, not bearing long hairs P. boliviense

31b. Panicles slender, branches not more than 5 cm. long, often bearing long hairs;

nodes often bearded 32

32a. Panicles 25-30 cm. long P. pilosum var. lancifolium

32b. Panicles usually less than 15 cm. long P. pilosum var. pilosum

33a. Spikelets 2.2 mm. or more long 34

33b. Spikelets 2.0 mm. or less long 37

34a. First glume ca. one-fifth as long as spikelet P. parviglume

34b. First glume half or more as long as spikelet 35

35a. Leaf blades elliptic, ca. 10 x longer than wide, up to 6 cm. wide; sheaths glabrous;
plants aquatic P. grande

35b. Leaf blades linear, more than 15 x longer than wide, rarely more than 15 mm.

wide; sheaths papillose-hispid; plants of open dry areas 36

36a. Palea of sterile floret nearly as long as lemma P. cayennense

36b. Palea of sterile floret one-third as long as lemma P. hirticaulum

37a. First glume half as long as spikelet or shorter 38

37b. First glume at least two-thirds as long as spikelet 39

38a. First glume rudimentary, ca. 0.4 mm. long; ligule a minute membrane

P. trichanthum

38b. First glume ca. 1 mm. long; ligule a dense row of bristles up to 3.5 mm.
long P. hirsutum

39a. Spikelets 1.7-2.0 mm. long; leaf blades 4-11 mm. wide 40

39b. Spikelets 1.2-1.6 mm. long; leaf blades 2-3 mm. wide P. parvifolium

40a. Leaf blades glabrous or with few elongate hairs on cordate base; Spikelets

1.7-2.0 mm. long P. helobium

40b. Leaf blades pubescent on both surfaces; spikelets ca. 2 mm. long

P. errabundum

Panicum aquaticum Poir., Lam. Encycl. Suppl. 4:281. 1816. Figure
129.

Perennial; bases rhizomatous, the rhizomes often vertical; culms erect to decumbent,
45-130 cm. long; internodes 1.5-4.0 mm. thick, hollow, glabrous; nodes glabrous; leaf
sheaths ca. as long as the internodes, glabrous; collar and throat sometimes sparsely
pilose; ligule a short, long-ciliate membrane, in total 0.6-1.7 mm. long; leaf blades 7-27
cm. long, 5-7 mm. wide, linear, rather abruptly pointed, usually glabrous, rarely
papillose-pilose near the base above. Peduncles included or exserted up to 5 cm.; panicles
terminal, broadly ovoid, 10-18 cm. long, 7-11 cm. wide, the longest branch 6-11 cm. long;
branches ascending, naked near the base, the spikelets usually appressed along the
scabrous branches. Spikelets ovate, acuminate, (3.0) 3.3-3.7 mm. long, glabrous; first
glume 1.1-1.5 mm. long, acute, wider than long; second glume 3.3-3.6 mm. long, 9-11-
nerved; lower (sterile) lemma 3.0-3.5 mm. long, 9-11-nerved, enclosing a well-developed,
keeled palea and sometimes a staminate flower with 3 orange anthers 1.1-1.3 mm. long;
palea usually as long as or longer than the lemma; upper (fertile) floret 2.3-3.0 mm. long,
ovate 2.0-2.5:1, the lemma smooth, shining, rigid, minutely cuspidate; palea similar, flat;

FIG. 129. Panicum species. P. aquaticum: A, branch of inflorescence; B, base of culm;
P. arundinariae: C, panicle; D, spikelet; E, fertile floret.

354

BURGER: FLORA COSTARICENSIS 355

anthers 1.6 mm. long; caryopsis ca. 1.7 mm. long, elliptical 2:1. Chromosome number
n = 36 from a Costa Rican specimen.

Wet pastures, ditches, sandbars in rivers; scattered in a few
localities on the Pacific slope; elevations from 50-1,700 m. Known from
Viente Siete; along the road to Hda. Inocentes; Capellades. Appar-
ently blooming yearlong. Mexico to Costa Rica, southward to
Paraguay. West Indies.

Past descriptions do not mention the presence of rhizomes, but all of
our specimens have them. One specimen from the marsh along the
railroad at the Radiografica Transmitter is very tall, up to 2 m. high
and has hispid foliage. It is otherwise similar to the other specimens
and has the same chromosome number.

Panicum arundinariae Trin. ex Fourn., Mex. PI. 2:25. 1881. P.
mrgultorum Hack., Oesterr. Bot. Z. 51:369. 1901. Figure 129.

Caespitose perennial; culm bases often decumbent and rooting; culms mostly 50-80 cm.
long, scrambling in brush or hanging over embankments, branching freely; internodes
1.0-1.5 mm. thick, hollow, thick-walled, glabrous; nodes bearded; prophylla hirsute,
10-12 mm. long; sheaths overlapping or shorter than the internodes, minutely ciliate on
the margin, the surface glabrous except for the bearded auricles and collar; ligule a
minutely ciliolate membrane, 0.3-0.8 mm. long; leaf blades flat, 4-11 cm. long, 4-9 mm.
wide, ovate 10-13:1, the base rounded; surfaces nearly glabrous or sparsely appressed-
pilose, especially toward the tip. Peduncles slender, exserted 4-17 cm.; panicles terminal
on leafy branches, 2-6 cm. long, small and rather simple, made up of 3-5 short branches
0.5-1.5 cm. long which are densely flowered to their bases. Spikelets elliptical-obovate,
1.7-1.9 mm. long, glabrous, dorsally compressed but slightly biconvex, blunt; first glume
a nerveless translucent scale, 0.5-0.6 mm. long; second glume and lower (sterile) lemma
very similar, equal, 5-nerved; upper (fertile) floret 1.5-1.6 mm. long, blunt, broadly
elliptical, less than twice as long as wide; lemma finely striate, stramineous, shining,
with scattered fine pilose hairs; palea similar, slightly convex; lodicules 2, truncate;
anthers 3, orange, 0.7 mm. long; styles 2, separate; caryopsis elliptical 1.5:1, 1.1 mm.
long, yellowish, with a red dot over the embryo. Chromosome number n = 18 from Costa
Rican specimens.

Scattered in the Meseta Central, San Ramon area, and the Cartago
Valley, at elevations of 1,000-1,800 m. In shrubbery, often on brushy
roadbanks. June to February. Southern Mexico to Panama.

Panicum boliviense Hack., Fedde Repert. Sp. Nov. 11:19. 1912.

Duration indefinite, probably perennial; culms 60-125 cm. long, the bases often long-
decumbent and rooting at the nodes, branching from the rooted nodes and middle nodes
of erect portions; prophylla ca. 5 cm. long; culm internodes 1.5-2.0 mm. thick, hollow,
glabrous; nodes glabrous or slightly bearded; leaf sheaths shorter than or equal to the
internodes; overlapping margin pilose-ciliate; collar pilose; surface glabrous or
papillose-pilose toward the apex; ligule a minutely ciliolate membrane, 0.2-0.5 mm. long;
leaf blades glabrous, or pilose just above the ligule, more or less cordate at the base,
with a very short pseudopetiole; length usually 15-17 (32) cm., width 11-15 mm., the

356 FIELDIANA: BOTANY

length 11-14 x the width. Inflorescence terminal on leafy branches; peduncle included in
the uppermost sheath or exserted up to 10 cm.; panicles open, elliptical, 18-32 cm. long,
3-5 x as long as wide, the longest branch 6-14 cm. long; spikelets densely clustered and
short-pedicellate on the lower sides of the triquetrous primary or secondary branches.
Spikelets 1.3-1.8 mm. long, ovate, rather blunt, biconvex in lateral view, distended by
the enlarged palea of the sterile lemma and often gaping; first glume 0.7-1.0 mm. long,
broadly ovate, usually 3-nerved, acute; second glume 1.3-1.7 mm. long, 5-nerved, con-
vex; lower (sterile) lemma 3-nerved, 1.2-1.6 mm. long, enclosing an enlarged palea
nearly as long; upper (fertile) floret elliptical or ovate, 1.1-1.6 mm. long, acute,
stramineous; palea similar, flat; lodicules 2, truncate; anthers usually 2, purple, 0.5-0.6
mm. long. Chromosome number n = 20 from a number of Costa Rican specimens.

Wet forested areas, mostly near the Pacific Coast, around the Bay of
Nicoya; Cariblanco; Osa Peninsula; Buenos Aires; elevations mostly
sea level to 400 m. June to August. Southern Mexico to Panama, south
to Argentina; Cuba.

Panicum boliviense is very similar to P. laxum in spikelet structure
and size and shares the same chromosome number. It differs from P.
laxum primarily in size and vigor, in the wider and more cordate-
based leaf blades, and the larger and more branched inflorescence. The
two appear to be very closely related, with P. boliviense perhaps
representing a large extreme of P. laxum.

Panicum cayennense Lam., Tabl. Encycl. 1:173. 1791.

Caespitose annual; culms erect or spreading, 18-40 cm. tall, in small clumps, branching
from the base and middle nodes; internodes 1-2 mm. thick, hollow, papillose-hispid to
nearly glabrous; leaf sheaths mostly overlapping, papillose-hispid; ligule a short mem-
brane, ca. 0.3 mm. long, bearing a row of stiff hairs, in total 0.8-1.2 mm. long; leaf blades
linear, 9-18 cm. long, 5-8 mm. wide, more or less papillose-pilose on the surface. Pedun-
cles mostly included in the upper sheaths; panicles several, terminal and from the upper
leaf axils, commonly becoming tangled into an elongated compound inflorescence; indi-
vidual panicles 5-16 cm. long, 4-8 cm. wide, ovoid; branches divaricate; pulvini pubes-
cent, branches scabrous; pedicels divaricate, the terminal ones elongated, stiff. Spikelets
obovate 1.6-1.75:1, short-cuspidate, biconvex, 2.1-2.3 mm. long; first glume 1.3-1.6 mm.
long, broadly ovate, 5-nerved; a stout rachilla internode ca. 0.4 mm. long between the
first and second glumes; second glume 1.8-2.0 mm. long, 7-nerved; lower (sterile) lemma
1.8-2.0 mm. long, 5-nerved, enclosing a well-developed palea ca. 1.5 mm. long, some-
times with abortive anthers; upper (fertile) lemma 1.4-1.5 mm. long, broadly elliptical
1.4-1.5:1, rigid, shining, stramineous; palea similar, convex; lodicules 2, truncate; an-
thers 3, deep purple, 0.7-0.9 mm. long; styles 2, separate; stigmas purple.

This species has been collected repeatedly on the savannas around
Buenos Aires; Boruca, Hda. Argentina; elevations 380-450 m. Feb-
ruary to July. Southern Mexico to northern South America; Cuba.

Panicum ciliatum Ell., Bot. S.C. & Ga. 1:126. 1816, var. pubescens
(Vasey) Freckmann, comb. nov. P. laxiftorum Lam., var. pubescens

BURGER: FLORA COSTARICENSIS 357

Vasey, Contr. U.S. Natl. Herb. 3:30. 1892. P. strigosum Muhl. in Ell.,
Bot. S.C. & Ga. 1:126. 1816.

Caespitose perennial, forming dense rosettes or circular mats; plants 6-15 cm. tall;
culms branching from the base or lowermost node; internodes slender, less than 0.5 mm.
thick, hollow, thin- walled, glabrous; nodes appressed-pilose; foliage leaves 2-3 per culm;
leaf sheaths overlapping, mostly glabrous except for the finely pilose overlapping mar-
gin; ligule a minute ciliolate membrane, 0.1-0.2 mm. long; leaf blades flat, ovate 6-7.5:1,
rounded to the base, glabrous or sparsely pilose on the surface, strongly pectinate-ciliate
on the margins nearly to the tip with hairs up to 3 mm. long. Inflorescence terminal;
peduncle exserted 2-5 cm.; panicles pyramidal, 2-4 cm. long, 1-3 cm. wide, the rachis and
branches conspicuously soft-pilose, the hairs up to 2 mm. long; pedicels elongate,
spreading. Spikelets 1.3-1.5 mm. long, obovate 1.7:1, glabrous, obtuse; first glume
broadly ovate, ca. as wide as long, acute, 1-nerved, 0.6-0.7 mm. long; second glume and
lower (sterile) lemma subequal, 1.2-1.3 mm. long, 5-nerved; sterile lemma with a hyaline
palea 0.3-0.5 mm. long; upper (fertile) floret ca. 1.0 mm. long, elliptical, the lemma
smooth and shining, rigid; palea similar, flat; anthers 3, purple, ca. 0.3 mm. long.

There are no recent collections of this species from Costa Rica. A
single old collection by Oton Jimenez is in US. The locality is indicated
as "de Candelaria a San Cristobal." Since this is primarily a species of
low coastal savannas, the locality is somewhat suspect. Southern
Mexico, Belize, Guatemala, Nicaragua; Colombia; West Indies; south-
eastern United States.

This taxon belongs to the informal group Laxiflora of Hitchcock and
Chase, included in the subgenus Dichanthelium. Its closest relative in
our flora is P. laxiflorum.

Panicum cordovense Fourn., Mex. PI. 2:26. 1881. Figure 130.

Duration indefinite, probably perennial; plants creeping or scrambling in brush; bases
of culms long-decumbent and rooting; total length up to 2 m. , the ascending portions
40-120 cm. long, branching freely, the branches divaricate; internodes 1-2 mm. thick,
hollow, glabrous; nodes glabrous or hispid, dark; leaf sheaths shorter than the inter-
nodes, glabrous, papillose, or papillose-hispid; margins finely ciliate; ligule an erose
membrane, 0.2-0.4 mm. long; leaf blades 5.5-12 cm. long, 8-12 mm. wide, flat, narrowly
ovate 7-11:1, slightly oblique at the subcordate base; surfaces glabrous or sparsely
papillose-hispid; pseudopetioles very short, less than 1 mm. long. Terminal inflores-
cences large and open, 13-30 cm. long, 13-26 cm. wide, pyramidal, few-flowered;
branches solitary or paired; pulvini bearded. Spikelets of terminal panicles solitary or
paired, on unequal pedicels, appressed along the primary or secondary panicle branches,
glabrous, ovate 2.4-2.6:1, blunt-tipped, strongly nerved, 3.1-3.6 mm. long; first glume
2.2-2.6 mm. long, ovate 1.8:1, blunt-tipped, 3-nerved; second glume 2.9-3.2 mm. long,
5-7-nerved, slightly shorter than the spikelet; lower (sterile) lemma 2.8-3.2 mm. long,
7-nerved, lacking palea and flower; upper (fertile) floret 2.4-3.1 mm. long, obovate 2.2-
2.3:1, the lemma stramineous, smooth, shining, rigid, apiculate; palea similar, flat;
lodicules 2, truncate; anthers 3, 1.1-1.7 mm. long, orange; styles 2, separate; stigmas
purple. The spikelets of the terminal panicles seem to set seed rarely, and the one
caryopsis seen was small (1.2 mm. long). Axillary panicles small, few-flowered, the
spikelets crowded, some hidden in the sheaths; spikelets of the axillary panicles finely

Jf/t

FIG. 130. Panicum cordovense. A, panicle; B, spikelet from a terminal panicle; C,
spikelet from an axillary panicle; D, fertile floret.

358

BURGER: FLORA COSTARICENSIS 359

pilose, 3.5-3.8 mm. long, slightly wider than those of the terminal panicles, ovate 1.9-
2.1:1; fertile floret obovate, 2.8-3.0 mm. long; anthers small, 0.3-0.4 mm. long, remaining
trapped within the floret; caryopsis broadly elliptical 1.5:1, tan. Chromosome number n
= 27 from a Costa Rican specimen.

Moist forested areas, brushy roadsides, trails; mostly on the vol-
canoes of the Cordillera Central; San Ramon area; moist lower canyons
of the Talamanca Range; Finca Las Cruces, San Vito. Blooming mostly
from June to October. Southern Mexico to Brazil and Bolivia.

This species is peculiar in having both glabrous chasmogamous
spikelets in the terminal inflorescences and pubescent cleistogamous
ones in the later axillary inflorescences. Panicum pantrichum is simi-
lar. Although this dimorphism is somewhat similar to that which oc-
curs in the subgenus Dichanthelium, the similarity is probably due to
convergence, since the two groups are entirely different in vegetative
habit and chromosome number.

Panicum discrepans Doell in Mart., Fl. Bras. 2:2:252. 1877. Figure
131.

Perennial; culms 25-40 cm. long, decumbent, unbranched; internodes 1.0-1.5 mm.
thick, solid, glabrous; nodes dark, contracted, glabrous; foliage at the base of the culms
densely and conspicuously pilose; leaf sheaths shorter than the internodes, all except the
lowermost glabrous except for the ciliate margins; ligule a dense row of stiff white hairs,
2.0-2.5 mm. long, conspicuous; leaf blades 1.5-3.5 mm. long, 2-3 mm. wide, glabrous,
more or less inrolled. Peduncle exserted up to 4 cm.; panicles terminal on the culms, in
our specimen 2-3 cm. long, contracted, the branches ascending, to 1.5 cm. long; spikelets
dark, densely crowded along the branches, short-pedicellate. Spikelets 1.1-1.2 mm. long,
ovate 2.5:1, glabrous externally, plano-convex; first glume absent in ours, said by Hitch-
cock to be up to half as long as the spikelet in some; second glume and lower (sterile)
lemma equal, as long as the spikelet, nerves 3, nearly parallel, purple; the internerves
purple-dotted; upper (fertile) floret ca. 1.0 mm. long, ovate 2:1, the lemma strongly
convex, densely woolly at base and apex; palea equal, flat; lodicules 2, truncate; anthers
3, purple, 0.3-0.4 mm. long.

The only known Central American specimen of P. discrepans is the
following: Prov. Puntarenas: Muy comiin en los bordes de una charca
estacional. Tallos postrados. Mezclado con Cyperus haspan. Cerca del
cruce a Buenos Aires de Osa. Bermudez & Sanchez 329, 23 May 1976.
Brazil, Cuba.

Panicum elephantipes Nees, Agrost. Bras. 165. 1829.

Duration indefinite, probably perennial; culms up to 160 cm. long, the basal portions of
the stems submerged and rooting profusely from the nodes; branching not seen; inter-
nodes ca. 1 cm. thick, hollow, thin-walled, glabrous; nodes contracted, purple, glabrous;
leaf sheaths mostly overlapping, glabrous, with hyaline margins; auricles ciliate; dewlap
conspicuous, deep purple; ligule a dense row of white hairs, 2-3 mm. long; leaf blades
30-54 cm. long, 11-20 mm. wide, with a broad, subcordate base, glabrous or with a few

FIG. 131. Panicum discrepans. A, blooming plant; B, two views of a spikelet; C,
fertile floret, pubescent at base and tip.

360

BURGER: FLORA COSTARICENSIS 361

hairs on the upper surface behind the ligule. Peduncle included in the uppermost sheath;
panicles terminal, solitary, up to 30 cm. long and half as wide, ovoid, rather dense, the
numerous branches ascending, scabrous; spikelets mostly paired and unequally pedicel-
late, appressed along the branches. Spikelets ovate 4:1, acuminate, 3.8-4.2 mm. long,
glabrous; first glume triangular 2:1, hyaline, faintly nerved, 1.0-1.2 mm. long; second
glume and lower (sterile) lemma equal, as long as the spikelet, 5-7-nerved; upper (fertile)
floret ca. 3.5 mm. long, ovate 4:1, acuminate; lemma firm but not indurate, shining, the
edges thin and scarcely inrolled; palea similar, flat; lodicules 2, bifid; anthers 3, orange,
1.6-1.8 mm. long; styles 2, separate, naked below, the stigmas purple or brown, ex-
serted; caryopsis not seen.

The following is the only collection from Costa Rica: Prov. Limon,
sandbar, Barro de Colorado, elevation 1 m., 14 December 1974, Pohl &
Lucas 13026. El Salvador, Honduras, Guatemala, Belize; West Indies;
tropical South America to Argentina.

Panic urn errabundum Hitchc., Contr. U.S. Natl. Herb. 22:494.
1922.

Duration indefinite, probably perennial; culms long-decumbent and rooting and
branching at the prostrate nodes, the total length up to 140 cm.; internodes glabrous,
purple-spotted, 1.0-1.5 mm. thick, hollow; nodes purple, not prominent; sheaths shorter
than the internodes, spreading-pilose; ligule a minute membrane, ca. 0.2 mm. long; leaf
blades flat, the base cordate, 4-8 cm. long, 4-8 mm. wide, softly pilose above and below.
Inflorescences terminal on erect portions of culms; panicles very open, broadly pyrami-
dal, up to 10 cm. long and 12 cm. wide; peduncle, branches, and pedicels glabrous,
purplish; branches solitary or paired, strongly divergent; pedicels divergent, 1-3 times
as long as the spikelets, flexuous. Spikelets ovate 2:1, strongly convex or biconvex,
purple, glabrous, 1.9-2.1 mm. long; first glume broadly ovate, acute, 3-nerved, ca. 1.5
mm. long; second glume as long as the spikelet, 5-nerved; lower (sterile) lemma 4-
nerved, bulging, inflated by the enlarged palea that is ca. as long as the lemma, char-
taceous, with inflexed margins; upper (fertile) lemma stramineous, shining, faintly
striate, ca. 1.7 mm. long, elliptical 2:1; anthers 3, purple, ca. 1 mm. long; style branches
2, separate.

The following Costa Rican specimen is the only recorded North
American collection: Prov. Puntarenas, Canas Gordas, elevation 1,160
m., dense undergrowth in a marsh, old crater, 26 September 1968, P.
& D. 11159. This species was described by Hitchcock from Parika,
British Guyana. This species belongs to the group Parvifolia. See
further discussion under P. helobium. The specific epithet, unex-
plained by Hitchcock, means "wandering" and refers apparently to the
decumbent habit of the plants.

Panicum frondescens Mey., Prim. Fl. Esseq. 56. 1818. Figure 132.

Duration indefinite, probably perennial; culms long-decumbent and rooting at the
decumbent nodes; erect branches from the rooted nodes 10-60 cm. long, sparsely
branched from the lower and middle nodes; internodes 1-2 mm. thick, hollow, glabrous
or with a woolly line down one side; nodes dark, not prominent, mostly glabrous; leaf

FIG. 132. Panicum frondescens. A, panicle; B, panicle branch with spikelets; C,
stoloniferous base of plant; D, spikelet; E, fertile floret.

362

BURGER: FLORA COSTARICENSIS 363

sheaths shorter than the internodes, pilose-ciliate on the overlapping margin; apex cilio-
late, auriculate; collar with a pilose-ciliolate external ligule; internal ligule a short mem-
brane, ca. 0.2 mm. long, continuous with the margin of the auricles; leaf blades flat,
ovate 4-6:1, 2.5-9.5 cm. long, 7-17 mm. wide, rounded at the base to a short
pseudopetiole ca. 1 mm. long; surfaces glabrous to sparsely appressed papillose-pilose.
Peduncle puberulent or pilose; rachis puberulent, especially around the nodes; panicles
terminal on leafy branches, dense, spirelike, the length 4-6 x the diameter, composed of
numerous ascending or drooping 1-sided racemes, the lowermost ones remote, the up-
permost densely crowded. Spikelets densely crowded along the lower sides of the
branches, short-pedicellate in pairs that alternate along the lower 2 sides of the triquet-
rous rachis. Spikelets 2.5-2.7 (3.1) mm. long, falcate, biconvex, somewhat laterally com-
pressed; first glume broadly ovate, acute, 1.0-1.1 mm. long, 3-nerved; second glume 2.3
(2.8) mm. long, 5-nerved, strongly convex; lower (sterile) lemma 2.5 (2.8) mm. long,
slightly longer than the second glume, 5-nerved, strongly convex, saccate just above the
base; palea membranaceous, 1.4-1.5 mm. long; upper (fertile) floret 1.3-1.5 mm. long, the
lemma smooth, shining, rigid, ovate, acute, dorsally compressed; palea similar, flat;
anthers 3, 0.5-0.6 mm. long; styles 2, separate; caryopsis ca. 0.8 mm. long, elliptical,
amber.

This species is found occasionally in rain forests, cacao groves, or
shallow standing water at elevations below 100 m. Limon, Zent, La
Bomba, Cahuita, Siquirres, Guapiles, Dos Bocas, Rincon de Osa,
Puerto Cortes, Palmar. Southern Mexico to Honduras and Costa Rica;
Caribbean Islands; South America to northern Argentina.

The spikelets of P. frondescens resemble those of species of Sac-
ciolepis in being biconvex and possessing a palea in the sterile lemma;
however, there is no similarity in the general structure of the plants.
The closest relatives of this species appear to be the members of the
Panicum laxum alliance, which resemble it in general plant structure
and the possession of an enlarged palea in the sterile lemma.

Panicum ghiesbreghtii Fourn., Hex. PL 2:29. 1881.

Duration indefinite, probably annual; plants caespitose; culms 35-110 cm. long, de-
cumbent to ascending, branching from the base and middle nodes; internodes 1.0-2.5
mm. thick, hollow, papillose-pilose; nodes bearded; leaf sheaths mostly shorter than the
internodes, papillose-pilose; ligule a short membrane, 0.3-0.5 mm. long, bearing a dense
row of straight white cilia, in total 1-2 mm. long; leaf blades linear 27-40:1, 11-30 cm.
long, 4-8 mm. wide, flat, papillose-pilose; midrib conspicuous, white. Peduncles sparsely
papillose-pilose; panicles terminal and axillary, open, ovoid-pyramidal 2-3:1; spikelets on
divergent pedicels. Spikelets biconvex, 3.2-3.7 mm. long, ovate, acuminate 2.3:1; first
glume broadly ovate, 1.8-2.3 mm. long, 5-nerved; second glume and lower (sterile)
lemma separated from the first glume by a thick rachilla internode ca. 0.5 mm. long;
second glume 2.6-3.1 mm. long, 7-nerved; lower lemma 2.8-3.5 mm. long, 9-nerved;
upper (fertile) lemma ovate ca. 2:1, 2.2-2.4 mm. long, shining, rigid, stramineous; palea
similar, flat; anthers 3, purple, ca. 1.0 mm. long.

Coastal low savannas, from Hacienda la Taboga to the Nicaraguan
border, at elevations below 200 m.; western portions of the Meseta

364 FIELDIANA: BOTANY

Central, where probably introduced. June to February. Southern
Mexico to Panama and Colombia; West Indies.

This species is closely related to P. hirticaulum, P. parcum, and P.
cayennense. Although Hitchcock and Chase assumed that it is a per-
ennial, it is impossible to be certain of this from herbarium specimens.

Panicum glutinosum Swartz, Prodr. Veg. Ind. Occ. 24. 1788.

Caespitose perennial; culms 55-160 cm. long, unbranched, the bases sometimes de-
cumbent and rooting; plants sprawling in brush; internodes 2-4 mm. thick, hollow, gla-
brous; nodes glabrous; leaf sheaths longer or shorter than the internodes, glabrous;
sheath auricles and dewlaps pilose; ligule a minute membranaceous rim, 0.1-0.2 mm.
long; leaf blades 11-44 cm. long, 8-28 mm. wide, mostly glabrous except for prominent
papillose-based cilia on the lower margins, rarely sparsely papillose-hispid above.
Inflorescences solitary, terminal; peduncle exserted up to 17 cm.; panicle open, broadly
ovoid, 12-35 cm. long, 7-17 cm. wide, the longest branch up to 17 cm. long; lower
branches verticillate; pulvini pilose; spikelets borne on elongate spreading pedicels,
mostly toward the outer half of the branches; pedicels 2-many x as long as their
spikelets. Spikelets 3.0-3.5 mm. long, plump, obovate 2:1, glabrous, the bracts usually
glutinous and becoming covered with attached particles, rarely trapping insects; first
glume nearly as long as the spikelet, 2.8-3. 1 mm. long, 5-nerved, ovate, covering most of
the sterile lemma; second glume 2.5-3.0 mm. long, very broad, the margins enwrapping
the edges of the sterile lemma; nerves 7; lower (sterile) floret 2.6-3.2 mm. long, 5-nerved;
sometimes enclosing a narrow, tongue-shaped nerveless palea 2.0-2.4 mm. long; upper
(fertile) floret 2.8-3.1 mm. long, obovate, acute; lemma smooth, shining, rigid, stramine-
ous; palea equal; anthers 3, purple, 1.0-1.5 mm. long; flowers apparently mostly cleis-
togamous, the anthers remaining trapped within the lemma, along with a developing
caryopsis. Chromosome number n = 20 from Costa Rican and Venezuelan specimens.

Brushy areas at intermediate altitudes from 700-1,800 m. elevation;
central and southern Costa Rica; San Ramon area; Tejar, Agua
Caliente, Bajo Pacuare, San Cristobal Norte, Helechales del General,
Canas Gordas. Apparently blooming yearlong. Mexico to Bolivia and
Paraguay; West Indies.

The unique feature of this species is the viscid character of the outer
bracts of the spikelets, which causes them to adhere to passing ani-
mals. The species has no obviously close relatives in our flora.

Panicum grande Hitchcock & Chase, Contr. U.S. Natl. Herb.
17:529. 1915. Figure 133.

Duration perennial; plants coarse, 2-4 m. tall, erect from decumbent or stoloniferous
bases; culms mostly unbranched; lower nodes often producing masses of roots where
submerged in water; internodes 1-1.5 cm. thick, hollow, glabrous; nodes appressed-silky;
sheaths mostly longer than the internodes, glabrous, the margins hyaline; ligule a thick,
minutely ciliolate membrane, 1.0-2.5 mm. long; dewlap sometimes slightly pubescent,
dark colored; leaf blades large, flat, usually 35-75 cm. long, 3-5 cm. wide, elliptical
19-15:1, tapering to the narrow base, the apex not acuminate; surfaces glabrous; margins
strongly scabrous. Inflorescences terminal on leafy culms; peduncle glabrous, exserted;

FIG. 133. Panicum grande. A, panicle; B, leaf blade; C, two views of a spikelet.

365

366 FIELDIANA: BOTANY

panicle large, open-pyramidal, 55-70 cm. long, 25-40 cm. wide, the branches whorled,
spreading or ascending, the secondary and tertiary branches and spikelets more or less
appressed along the primary branches; pedicels appressed, mostly shorter than the
spikelets. Spikelets ovate 3.1-3.4:1, glabrous, 2.5-2.9 mm. long, rarely longer in terminal
spikelets; first glume ovate, acute, 3-nerved, 1.6-2.0 mm. long, ca. two-thirds as long as
the spikelet; second glume and lower (sterile) lemma subequal, exceeding the fertile
floret, 2.0-2.5 mm. long, 5-nerved; upper (fertile) floret 1.5-1.8 mm. long; lemma ellipti-
cal, 2.0-2.4:1, stramineous, shining; palea similar; lodicules 2, truncate; anthers 3, pur-
ple, 0.7-1.1 mm. long; styles 2, separate; caryopsis 0.9-1.1 mm. long, oblong-elliptical,
plump, gray, the lower portion suffused with purple. Chromosome number n = 10 from
Costa Rican specimens.

Forming large colonies mostly in coastal marshes, usually in stand-
ing water or on mud; Lago de Arenal, Matapalo, Tarcoles, Golfito,
Pigres, along the canal between Parismina and Moin; San Isidro,
Chitaria, Guapiles. September to December. Guatemala to Panama;
northern South America to Brazil.

This is one of the largest and most conspicuous of the herbaceous
grasses.

Panicum haenkeanum Presl, Rel. Haenk. 1:304. 1830. P. cos-
taricense Hack., Oesterr. Bot. Z. 51:428. 1901.

Duration indefinite; plants sprawling or trailing, scrambling into brush, rooting from
the lower nodes; culms to 2 m. long, branching from the base and middle nodes; inter-
nodes elongated, ca. 1 mm. thick, hollow, sparsely pilose; nodes not prominent, glabrous;
leaf sheaths much shorter than the internodes, sparsely pilose; collar densely bearded;
ligule a short membrane, 0.3-0.5 mm. long; leaf blades flat, ovate ca. 10:1. Peduncles
short-exserted; panicles terminal on leafy culms, ovoid, rather delicate, 7-16 cm. long;
spikelets widely spreading on delicate, flexuous, elongated pedicels. Spikelets elliptical
2.5-3.0:1, acute, 2.4-2.6 mm. long; first glume broadly ovate, acuminate, 3-nerved, the
lower margins overlapping; second glume and lower (sterile) lemma subequal, 5-nerved,
2.2-2.5 mm. long, very sparsely pilose with fine hairs; upper (fertile) lemma 1.7 mm.
long, elliptical 2:1, stramineous, shining; palea similar, flat; anthers 3, tan, 0.9-1.0 mm.
long. Chromosome number n = 10 from a Costa Rican specimen.

Rare or overlooked; gallery forests along streams in savannas; Las
Animas, Liberia; General Valley; Boruca. Elevations 200-300 m. Oc-
tober to February. Mexico; Costa Rica and Panama.

Panicum helobium Henrard, Meded. Rijks-Herb. Leiden 40:52.
1921. The name has usually been credited to Mez ap. Ekman, Ark.
Bot. II, (4):23, pi. 1, fig. 6. 1912. This is, however, a nomen nudum.
Henrard, although citing Mez, gives a full Latin description.

Duration indefinite; culms long-decumbent, creeping and rooting at the nodes, the
decumbent portions branching freely; erect culms unbranched, 10-70 cm. tall; prophylla
prominent, broad, up to 5 mm. long; culms glabrous, hollow, ca. 1 mm. thick; nodes dark,
not prominent; leaf sheaths mostly shorter than the internodes; glabrous; ligule a brown-

BURGER: FLORA COSTARICENSIS 367

ish membrane, 0.3-0.7 mm. long; blades flat, cordate-based, 2-6 cm. long, 4-11 mm. wide,
glabrous or with a few slender elongate hairs on the rounded basal margins. Peduncle
exserted up to 10 cm.; panicles solitary, terminal, broadly ovoid, 5-10 cm. long, 5-9 cm.
wide, many-flowered; peduncle, rachis, and pedicels glabrous; pedicels elongate, flexu-
ous. Spikelets glabrous, turgid, ovoid to obovoid, usually gaping because of the enlarged
palea of the sterile lemma, 1.7-2.0 mm. long; first glume ovate, ca. three-fourths as long
as the spikelet, 3- or rarely 4-nerved; second glume and sterile lemma as long as the
spikelet, both 5-nerved, or the midnerve frequently suppressed in the sterile lemma;
palea of the sterile lemma well developed, ca. as long as the fertile floret and distending
the lemma; fertile lemma 1.3-1.7 mm. long, stramineous, faintly striate; palea similar;
anthers 3, ca. 1 mm. long.

A Costa Rican specimen of this species in US is Standley & Valeria
41575. Prov. San Jose, vicinity of Santa Maria de Dota, altitude 1,500-
1,800 m., swampy woods, ascending, 26 December 1926-3 January
1927. The Parvifolia group is a complex of interrelated forms, difficult
to distinguish with existing literature. Several chromosome numbers
are involved. I have referred Costa Rican material to P. parvifolium,
P. errabundum, and P. helobium. A tentative treatment of this group
is to be found in J. R. Swallen, Notes on grasses. Phytologia 14
(2):65-76. 1966.

Panic- um hirsutum Swartz, Fl. Ind. Occ. 1:173. 1797.

Duration indefinite, probably perennial; caespitose in large clumps, 1-2 m. tall; culms
simple or branching from middle nodes; prophylla prominent, up to 15 cm. long; inter-
nodes up to 1 cm. thick, hollow, glabrous or papillose-hispid just below the appressed-
pilose contracted nodes; leaf sheaths mostly overlapping, sparsely papillose-hispid with
thick, glassy hairs; dewlap and collar hispid-bearded; ligule a short ciliate membrane, up
to 2 mm. long; leaf blades flat, up to 70 cm. long and 25 mm. wide, mostly glabrous, but
with a dense patch of long hispid hairs just behind the membranaceous ligule and
obscuring it; margins strongly scabrous. Inflorescences terminal on the main culm or a
leafy branch; peduncles stout, exserted up to 22 cm.; panicles large, densely flowered,
ellipsoidal, 30-50 cm. long, up to 15 cm. wide; branches ascending, naked only near their
bases; pedicels short, the lateral ones 0.5-1.5 mm. long, appressed along the panicle
branches; spikelets very numerous, densely covering the branches. Spikelets 1.8-2.1
mm. long, glabrous, ovate 2.4-2.7:1, tapering to a rather abrupt point; first glume
broadly ovate, acute, 3-nerved, 0.9-1.2 mm. long; second glume and lower (sterile)
lemma about equal, as long as the spikelet, exceeding the fertile floret; second glume
7-nerved; sterile lemma 7-9-nerved, enclosing a well-developed palea 1.2-1.5 mm. long;
fertile floret 1.3-1.4 mm. long, elliptical 2:1; lemma rigid, shining, the nerves usually
visible; palea ca. as long as the lemma, of similar texture; lodicules 2, truncate; anthers 3,
purple, ca. 0.7 mm. long; styles 2, separate; stigmas purple; caryopsis whitish, elliptical,
ca. 1 mm. long.

Apparently rare, along watercourses on the Caribbean Coastal
Plain. Zent Farm, Rio Bananito, confluence of Rio Puerto Viejo and
Rio Sarapiqui. February to September. Southern Mexico to Brazil,
Ecuador, and Trinidad and the West Indies.

368 FIELDIANA: BOTANY

Panicum hirticaulum Presl, Rel. Haenk. 1:308. 1830. P. pam-
pinosum Hitchc. & Chase, Contr. U.S. Natl. Herb. 15:55. 1910; Fair-
brothers, Amer. J. Bot. 40:710. 1953.

Caespitose annual in small clumps; culms 25-80 cm. long, erect or the lower nodes
decumbent and rooting, branching freely from lower and middle nodes; prophylla 3-5 cm.
long; internodes 1.0-2.5 mm. thick, hollow, papillose-hispid to glabrous; nodes
appressed-pilose, not prominent; leaf sheaths mostly longer than the internodes, densely
to sparsely papillose-hispid; ligule a minute membrane, densely ciliate with long hairs,
the total length 1.5-2.5 mm.; leaf blades flat, 7-27 cm. long, 6-15 mm. wide, papillose-
pilose to nearly glabrous. Peduncles papillose-pilose; panicles terminal on the main culms
or on leafy branches, open, ovoid, 13-35 cm. long, 2-4 x longer than wide; longest
branches up to 13 cm., straight, unbranched and naked below, the spikelets on second-
ary or tertiary branches appressed to the primary ones on their outer two-thirds.
Spikelets glabrous, reddish, 2.4-2.5 mm. long, ovate 3:1, acute; first glume 1.2-1.5 mm.
long, 3-5-nerved, ovate 3:1, acute; second glume 2.1-2.2 mm. long, 7-nerved; lower
(sterile) lemma 2.2-2.4 mm. long, 9-nerved, enclosing a small membranaceous nerveless
palea 0.3-0.8 mm. long; upper (fertile) lemma 1.5-1.8 mm. long, elliptical 2:1, smooth and
shining, stramineous; palea similar, flat; anthers 3, orange or reddish brown, 0.9-1.0
mm. long; caryopsis broadly elliptical, white, 1.3-1.4 mm. long.

Bluffs at Playas del Coco; San Luis de Turrubares; Atenas. July to
October. Southwestern United States to Panama; western South
America to Argentina. Size ranges for spikelets are based on Central
American material. Plants from more northerly regions appear to have
larger spikelets.

Panicum irregulare Swallen, J. Wash. Acad. Sci. 30:216. 1940.
Figure 134.

Duration indefinite; culms extensively creeping and rooting at the lower nodes; flow-
ering branches arising from the rooted nodes, up to 50 cm. long, not observed to branch;
attitude not known; culms 1.0-1.5 mm. thick, hollow, glabrous; sheaths mostly shorter
than the internodes, glabrous, auriculate, with a few hairs on the auricles; ligules not
seen; leaf blades borne on short, thickened, pubescent pseudopetioles ca. 1 mm. long;
blades flat, lanceolate, the base somewhat asymmetric, 4.5-7.0 cm. long, 9-15 mm. wide.
Inflorescences terminal on the erect branches; peduncle slender, exserted 5-15 cm.;
panicle very open, cylindrical, 16-24 cm. long, composed of about 15 slender drooping
racemes borne singly or in pairs, remote along the slender rachis; individual racemes 1-2
cm. long. Spikelets paired, unequally pedicellate along the lower sides of the rachis,
biconvex, 1.7-2.2 mm. long; disarticulation below the glumes, but the upper floret also
freely disarticulating; length 1.7-2.2 mm.; first glume ca. 1 mm. long, ovate, acute,
3-nerved; second glume ca. 2 mm. long, boat-shaped, 5-nerved, acute; lower lemma
membranaceous, 2.2 mm. long, ovate, acute, boat-shaped, 5-nerved, its palea ca. 1.4
mm. long, flat or concave, membranaceous, scabrid on the keels; lower flower perfect;
anthers 3, tan, 1.1-1.2 mm. long; caryopsis developing, free from the lemma and palea,
0.8 mm. long; upper lemma smooth and shining, dorsally compressed, ovate, acute, ca.
1.4 mm. long, coriaceous, its thickened margins embracing a palea of similar texture.

This peculiar species is known only from the type and one other
specimen, probably from the same locality. Type: Stony river bank,

FIG. 134. Panicum irregulare. A, growth habit; B, inflorescence; C, spikelet, lateral
view; D, spikelet, dorsal view; E, lower floret; F, upper floret.

369

370 FIELDIANA: BOTANY

vicinity of El General, Prov. San Jose; altitude 760 m. Skutch
February 1939.

In the following respects, this species resembles Pseudechinolaena
polystachya, which grows in the same area: creeping habit, nature of
inflorescence, paired spikelets which are biconvex, presence of a palea
and stamens in the lower floret, oblique-based lanceolate blades. It
differs in the much smaller spikelets which lack the stipitate bristles of
Pseudechinolaena. In view of its rarity, it may represent a hybrid
between this genus and a species of Panicum.

Panicum laxiflorum Lam., Encycl. Method. Bot. 4:748. 1798. P.
xalapense H.B.K., Nov. Gen. & Sp. 1:103. 1816.

Caespitose perennial; plants 10-25 cm. tall, forming dense but soft clumps of many
culms; branching freely from the lower and middle nodes; internodes ca. 1 mm. thick,
hollow, pilose; nodes retrorsely pilose; leaf sheaths mostly overlapping, densely pilose
with spreading or retrorse fine hairs up to 4 mm. long; ligule a sparse to dense row of fine
white hairs, 0.2-0.3 mm. long; leaf blades soft, flat, rounded to the base, 3-8 cm. long, 3-7
mm. wide, densely pilose on both surfaces and papillose-ciliate on the margins; blades
mostly of the same length and rather densely aggregated, the clumps very leafy, only
the primary panicles protruding above the general level. Peduncle of the primary panicle
4-5 cm. long; primary panicles 3-7 cm. long, up to 5 cm. wide, pyramidal, few-flowered,
the branches solitary or paired; spikelets borne on diverging pedicels 1-several times as
long as the spikelet; rachis and branches softly pilose. Axillary secondary panicles small,
few-flowered, partially hidden in the leaf sheaths. Spikelets 2.0-2.2 mm. long, finely
pubescent, obovate 1.7-1.8:1; first glume 0.7-1.0 mm. long, 1-2-nerved, ovate 4:3, acute;
second glume 1.8-2.1 mm. long, 5-7-nerved; lower (sterile) lemma 1.9-2.0 mm. long,
7-nerved, containing a hyaline palea 0.7-1.2 mm. long; upper (fertile) floret 1.7-1.9 mm.
long, elliptic 1.5-1.7:1, stramineous, smooth and shining; palea similar, slightly convex;
lodicules 2, truncate; anthers 3, purple, 0.4 mm. long; caryopsis obovate 1.2:1, 1.1 mm.
long. Chromosome number n = 9 from a Costa Rican specimen.

Occasional, open areas in forests, natural meadows, and road em-
bankments; Canton de Dota and lower slopes of the Talamanca Range,
1,400-2,600 m. elevation. Probably blooming yearlong, the primary
panicles probably produced at the beginning of the rainy season.

This species belongs to the informal group Laxiflora of the subgenus
Dichanthelium. In the temperate zone, members of this subgenus
produce winter rosettes of short, broad leaves. These are apparently
not produced in our species. A number of species have been described
which are here included in P. laxiflorum.

Panicum laxum Swartz, Prodr. Veg. Ind. Occ. 23. 1788. Figure
136.

Duration indefinite, probably perennial; culms 15-90 cm. long, rarely up to 120 cm.,
the bases often decumbent and rooting at the nodes, branching from the rooted portion
or the middle nodes of erect culms; internodes 1.0-1.5 mm. thick, hollow, glabrous; nodes

BURGER: FLORA COSTARICENSIS 371

glabrous or rarely retrorsely pilose; prophylla ca. 2 cm. long, ciliate on the keels; leaf
sheaths shorter than the internodes, the overlapping margin ciliate; surface glabrous or
papillose-pilose toward the apex; ligule a thin ciliolate membrane, 0.3-0.6 mm. long; leaf
blades flat, 6-15 (23) cm. long, 4-12 mm. wide, rather thin, rapidly folding or rolling when
the plants are uprooted; dewlap sometimes pilose; upper surface sometimes pilose above
the ligule. Inflorescences terminal on leafy culms; panicles usually 5-15 (33) cm. long,
open, cylindrical or ellipsoidal, with numerous straight primary branches, densely
covered to their bases with spikelets; spikelets short-pedicellate, borne on the lower
sides of the triquetrous rachis, in pairs or small groups; larger panicles sometimes with
evident secpndary branches. Spikelets 1.4-1.8 mm. long, ovoid ca. 2:1, rather blunt,
biconvex in lateral view, distended by the enlarged palea of the sterile lemma and often
gaping almost to the base; first glume broadly ovate, acute, 3-nerved, 0.7-1.0 mm. long;
second glume 1.3-1.8 mm. long, 5-nerved; lower (sterile) lemma similar but 3-nerved,
1.2-1.7 mm. long, with a membranaceous palea 1.3-1.6 mm. long; upper (fertile) floret
ovate, 1.2-1.4 mm. long, stramineous; lodicules 2, truncate; anthers 3, yellow or
splotched with purple, 0.8 mm. long; styles 2, separate; caryopsis 0.8 mm. long, ellipti-
cal, tan. Chromosome number n = 20 from numerous Costa Rican specimens.

Common in wet open or partially shaded sites; widespread from sea
level to 1,200 m. elevation, rarely higher. Blooming April to October,
occasionally during the rest of the year. Southern Mexico to Paraguay;
West Indies.

Panicum laxum is a member of the intricate Laxa group. The
species of this assemblage are poorly defined and much in need of
careful biosystematic study. Panicum boliviense may be only a large
form of P. laxum. Panicum polygonatum is also closely related, but
has more pointed spikelets lacking a palea in the sterile lemma.

Panicum maximum Jacq. , Coll. Bot. 1:76. 1786. Figure 135.

Caespitose perennial in large clumps; plants 1-2.5 m. tall; culms erect, arising from
hard scaly bases, simple or sparsely branched from the middle nodes; internodes 3-8 mm.
thick, cylindrical, hollow, glabrous or papillose-pilose below the nodes; nodes contracted,
appressed-pilose or hispid; sheaths loose, glabrous or more or less papillose or
papillose-hispid, especially on the margin and toward the apex; collar and dewlap
bearded; ligule a short, thick, ciliolate membrane, 1-2 mm. long, with a dense tuft of long
white hairs just above it on the upper surface of the leaf blades; blades flat, up to 65 cm.
long and 25 mm. wide, mostly glabrous except just behind the ligule; margins with white
sclerenchyma bands, coarsely scabrous. Inflorescences terminal on leafy culms; panicle
ovoid, 15-65 cm. long; lower branches verticillate, pilose at the base, scabrous, naked
near the bases, the longest up to 40 cm. long, ascending; spikelets short-pedicellate in
small clusters on secondary branchlets, more or less appressed along the primary
branches. Spikelets 3.3-3.6 mm. long, elliptic-obovate ca. 3:1, biconvex, glabrous; first
glume rounded, 3-nerved, 1.0-1.2 mm. long; second glume 3.0-3.1 mm. long, 5-nerved;
lower (sterile) lemma similar, ca. 3.2 mm. long, 5-nerved, with a thin, membranaceous
palea as long or slightly longer; anthers 3, 1.5-1.8 mm. long; upper (fertile) lemma
obovate 2.5:1, acute, rigid, stramineous, rugose; palea similar, rugose; lodicules 2, trun-
cate; anthers 3, orange, 1.2-1.8 mm. long; styles 2, naked for the lower half; stigmas
purple. Chromosome number n = 18 from a Costa Rican specimen.

FIG. 135. Panicum maximum. Panicle, plant base, two views of a spikelet, fertile
floret.

372

FIG. 136. Panicum species. P. laxum: A, blooming culm; B, spikelet, lateral view; C,
lower (sterile) floret, showing palea; P. polygonatum: D, three views of a spikelet.

373

374 FIELDIANA: BOTANY

Cultivated widely as a forage grass at low elevations, especially near
the coasts, and escaping freely to roadsides; mostly below 500 m., but
occasionally to 1,100 m. in the Meseta Central. May to November.
Native to Africa, but now widely cultivated in tropical and warm
temperate countries. The first herbarium collection from Costa Rica
dates to 1890. The species is highly apomictic. Local names: Guinea;
Pasto Guinea.

Panicum mertensii Roth in Roem. & Schult., Syst. Veg. 2:458.
1817. Panicum megiston Schult., Mant. 2:248. 1824. Figure 137.

Robust erect perennial from a knotty crown; culms up to 3 m. long, unbranched;
internodes 4-8 mm. thick, hollow but containing loose masses or diaphragms of aeren-
chyma, glabrous; leaf sheaths mostly shorter than the internodes, papillose or
papillose-hispid, apex auriculate; ligule a thick, erose-ciliolate membrane, 2-3 mm. long;
leaf blades 30-60 cm. long, 14-25 mm. wide, widest at the middle, glabrous, dark green,
the midrib white. Peduncles included or exserted up to 5 cm.; panicles terminal on the
culms, open, ovoid, 40-50 cm. long, 17-30 cm. wide; longest branch up to 16 cm. long;
branches borne in remote verticels, numerous, straight and stiff, bearing appressed
solitary or paired spikelets along the outer half; frequently one member of the spikelet
pair reduced or abortive. Spikelets 3.5-4.0 mm. long, obovate, strongly biconvex, gla-
brous; first glume 1.4-1.7 mm. long, broadly cordate, wider than long, 3-4-nerved; sec-
ond glume 3.2-3.8 mm. long, 9-nerved; lower (sterile) lemma 3.2-3.7 mm. long, 9-nerved,
containing a broad, firm, strongly keeled palea ca. 2.8 mm. long, sometimes with 3
abortive anthers ca. 0.2 mm. long; upper (fertile) floret 2.7-3.0 mm. long, ovate 2:1,
acute; lemma smooth, shining, rigid, stramineous; palea similar, convex; anthers 3,
purple, 1.4 mm. long; caryopsis ca. 1.6 mm. long, elliptical. Chromosome numbern = 20
from a Costa Rican specimen.

Rare; shallow water; shady areas at elevations below 100 m.;
Hacienda La Taboga, Finca La Taboga, Los Chiles. August to
January. Mexico and Guatemala to northern Costa Rica; Panama
Canal Zone; Cuba; Trinidad to Paraguay.

This species is tall and conspicuous. Most specimens are only flow-
ering tops and do not include basal portions. Amer. Gr. Natl. Herb. 76
has a large, hard, crownlike base, the culms bearing prop roots from
their lower nodes.

Panicum olivaceum Hitchc. & Chase, Contr. U.S. Natl. Herb.
15:225. 1910.

Caespitose perennial in small clumps; winter rosettes not seen; plants 15-42 cm. tall,
the culms erect to sprawling, branching freely from most nodes, producing axillary tufts
of foliage and small axillary panicles; internodes 1-2 mm. thick, hollow, densely velvety;
nodes densely bearded; sheaths shorter or longer than the internodes, densely soft-
pubescent; ligule a dense row of white hairs, 2.0-3.5 mm. long, rarely 0.5 mm. long on
smaller leaves; leaf blades 2-7 cm. long, 3-9 mm. wide, velvety pubescent on both
surfaces, ovate 6-8:1, cordate-based. Peduncle of primary panicle exserted 3-11 cm.;
primary panicle pyramidal, 3-7 cm. long, 2-6 cm. wide, many-flowered; spikelets more or

FIG. 137. Panicum mertensii. A, panicle; B, spikelet; C, fertile floret.

375

376 FIELDIANA: BOTANY

less appressed along the primary or secondary branches; rachis and peduncle softly
pilose; pedicels 1-several times as long as the spikelets. Secondary panicles borne at the
tips of the axillary branches, much smaller than the primary panicle, usually few-
flowered and with the peduncle included in the uppermost leaf sheath. Spikelets finely
pubescent, obovate 2.1-1.3:1, biconvex, usually purple, 1.6-2.0 mm. long; first glume
0.7-0.8 mm. long, broadly deltoid 1:1, the nerves obscure; second glume 1.7-1.9 mm.
long, 9-nerved, usually slightly shorter than the fertile lemma; lower (sterile) lemma
1.7-1.8 mm. long, 7-nerved, enclosing a hyaline palea 0.6-0.8 mm. long; upper (fertile)
floret elliptical ca. 1.5:1, 1.4-1.6 mm. long, rigid, shining, stramineous; palea similar,
slightly convex; anthers 3, purple, 0.7-1.0 mm. long; styles 2, separate; stigmas purple;
caryopsis elliptical 1.4:1, white, bearing a red mark near the base on the side opposite
the embryo.

Open roadsides and grasslands at intermediate elevations, between
1,000 and 2,200 m.; occasional. Rincon de la Vieja, San Ramon area,
Volcan Poas, Volcan Barba, mountains south of the Meseta Central,
lower portions of the Cordillera de Talamanca. Apparently blooming
yearlong, but the primary panicles produced mostly from June to Au-
gust.

This species belongs to the subgenus Dichanthelium, informal group
Lanuginosa of Hitchcock & Chase. In our flora, it is most closely
similar to P. viscidellum, from which it differs in its much smaller size
and in chromosome number. Southern Mexico to Venezuela.

Panicum pantrichum Hack., Verh. Zool. Bot. Ges. Wien 1915:72
(March). P. chiriquiense Hitchc. & Chase, Contr. U.S. Natl. Herb.
17:527. 1915 (July). Figure 138.

Duration indefinite, probably perennial; plants extensively creeping and forming flat
mats, branching freely from the rooted portions; ascending portions of culms 6-25 cm.
long, unbranched; prophylla 6-12 mm. long; internodes ca. 1 mm. thick, hollow, softly
pilose; leaf sheaths shorter than the internodes, papillose-pilose or papillose-hispid;
ligule an erose membrane, 0.2-0.3 mm. long; leaf blades 3.5-8 cm. long, 7-10 mm. wide,
asymmetrically ovate 5-8:1, flat, velvety-pilose. Peduncles mostly included or short-
exserted; panicles terminal on ascending leafy branches, 2-10 cm. long, 1-8 cm. wide, the
larger ones open, pyramidal, the few spikelets appressed along the primary or secondary
branches; small panicles partly included in the uppermost sheath, consisting of small
clusters of spikelets. Spikelets of both large and small panicles similar, ovate 2:1,
pointed, 2.2-2.8 (3) mm. long, the glumes and sterile lemma finely pilose; first glume
1.6-2.3 mm. long, ovate 1.7-1.8:1, 3-nerved; second glume 2.2-2.7 mm. long, 5-7-nerved;
lower (sterile) lemma 2.0-2.5 mm. long, 5-6-nerved, the midnerve often suppressed;
upper (fertile) floret 1.9-2.2 mm. long, elliptic-obovate 1.7:1, the lemma rigid, shining,
stramineous, the back flattened; tip rounded, not apiculate; palea similar, flat; anthers 3,
whitish, 0.3 mm. long, remaining trapped within the floret, which is apparently clei-
stogamous; styles 2, separate; caryopsis broadly elliptical, 0.9-1.4 mm. long, tan to
reddish, with a reddish linear mark opposite the embryo. Chromosome numbers n = 30
from a Costa Rican specimen and n = 26 from a Honduran collection.

Rare; creeping in shade of forests or brush; 1,100-1,700 m. elevation.

FIG. 138. Panicum species. P. pantrichum: A, blooming plant; B, spikelet; P.
pulchellum: C, blooming culm; D, spikelet, showing glands on sterile lemma.

377

378 FIELDIANA: BOTANY

San Ignacio, Frailes, Canas Gordas, 10 km. N of San Ramon. June to
October. Honduras and central Costa Rica and Panama to Brazil and
Bolivia.

This species is related to P. cordovense, but differs in size of plant
parts and spikelets, as well as in the velvety foliage. The spikelets
appear to be all of one type, whereas those of P. cordovense are gla-
brous in terminal panicles and pubescent in axillary ones. Spikelets of
P. pantrichum examined appear to be entirely cleistogamous, the
small anthers remaining attached to the stigmas on developed
caryopses.

Panicum parcum Hitchc. & Chase, Contr. U.S. Natl. Herb. 15:70.
1910.

Duration annual; plants caespitose; culms 50-125 cm. long, erect, usually unbranched;
internodes 2-3 mm. thick, hollow, sparsely papillose-pilose; nodes dark, contracted,
mostly glabrous; leaf sheaths shorter than the internodes, papillose-hispid; ligule a short
membrane 0.2-0.5 mm. long, crowned with a dense row of cilia, in total 1.2-1.3 mm. long;
leaf blades 11-35 cm. long, 6-10 mm. wide, more or less papillose-pilose to nearly gla-
brous, the tip rather abrupt. Peduncles included or exserted up to 9 cm.; panicles
terminal, ovoid ca. 2:1, 20-35 cm. long, ca. 12 cm. wide, rather open and few-flowered;
branches solitary, 9-18 cm. long; pulvini glabrous. Spikelets solitary on the tips of elon-
gated, stiff pedicels, often purple-marked, 4.7-5.1 mm. long, ovate ca. 3:1, acuminate;
first glume 3.1-3.7 mm. long, 5-7-nerved, ovate, acuminate; second glume 3.9-4.7 mm.
long, 9-nerved, ovate, acuminate, longer than the lower (sterile) lemma; lower lemma
3.8-4.2 mm. long, 9-nerved, with a narrow, hyaline palea 1.5-1.7 mm. long; upper (fer-
tile) floret 2.8-3.2 mm. long; lemma ovate 2:1, rigid, strongly convex, smooth and shin-
ing, stramineous, with a large basal scar; palea similar, flat; anthers 3, 1.2-1.4 mm. long,
deep purple; styles 2, separate; caryopsis elliptical, white. The spikelets have a promi-
nent, thick rachilla internode, 0.5-0.8 mm. long, between the first and second glumes.

Rare in Costa Rica; known only from the following two specimens:
Prov. Guanacaste, Playas del Coco, bluffs, 14 November 1968, P. & D.
11437; 10 km. by road W of Liberia, savannas, 19 December 1974, Pohl
& Lucas 13068. Western Central Mexico to Honduras, Nicaragua and
northwestern Guanacaste. August to December.

The spikelets in the specimens I have seen are somewhat smaller
than the range usually assigned to them, but the plants are otherwise
typical. Panicum parcum was assigned to the informal group Capil-
laria by Hitchcock and Chase. This group was differentiated from the
group Diffusa on the basis of annual vs. perennial duration. Spikelets
and general habit in the two groups are so similar that it is dubious
whether they can be maintained. Related species in the Costa Rican
flora include P. ghiesbreghtii and P. hirticaulum.

Panicum parvifolium Lam., Tabl. Encycl. 1:173. 1791. Figure 139.

FIG. 139. Panicum species. P. parvifolium: A, blooming plant; B, two views of a
spikelet; P. stenodes: C, blooming culm; D, group of spikelets.

379

380 FIELDIANA: BOTANY

Duration indefinite, probably perennial; culms up to 60 cm. long, the lower parts
decumbent and rooting; branching freely from the decumbent portions; internodes less
than 1 mm. thick, hollow, glabrous; nodes purple, slightly bearded; sheaths shorter than
the internodes, glabrous or more or less appressed-pilose; ligule a thin membrane, ca.
0.2 mm. long; leaf blades flat, often ascending, glabrous or appressed-pilose. Inflores-
cences terminal on leafy ascending portions of the culms, exserted; panicles broadly
pyramidal, very open; 4-7 cm. long, 4-9 cm. wide; branches solitary, spreading; pedicels
divaricate, flexuous, 1-3 x as long as the spikelets. Spikelets ovoid-elliptical, plump, less
than twice as long as wide, often biconvex, glabrous, 1.4-1.6 mm. long; first glume
broadly ovate, often blunt, 3-nerved, 0.9-1.0 mm. long; second glume as long as the
spikelet, 5-nerved; lower (sterile) lemma as long as the spikelet, 5-nerved, distended by
a well-developed palea of nearly equal length; 3 anthers sometimes present; upper (fer-
tile) floret 1.1-1.5 mm. long, broadly elliptical 7:4, rigid, shining, finely striate, the palea
of nearly equal length; anthers 3, purple, 0.9-1.1 mm. long; styles 2, separate; stigmas
dark. Chromosome number n = 18 from a Costa Rican specimen.

Margins of ponds and streams, often forming large colonies; common
around the lagunas near Buenos Aires and near San Isidro de el Gen-
eral and Rivas; Guayabo (Guanacaste). August to January. British
Honduras to northern South America, southward to Argentina; West
Indies; also reported from tropical Africa.

Panicum parvifolium is a common member of the group Parvifolia,
composed of slender, hydrophytic species having small spikelets. The
plants show much variation, and the group is in need of biosystematic
study. See further discussion under P. helobium.

Panicum parviglume Hack., Oesterr. Bot. Z. 51:429. 1901.

Perennial, from a hard crown; culms 1 m. or more tall; lower nodes decumbent and
rooting; branching from the base; internodes 1.5 mm. thick, solid, sparsely papillose-
hispid; nodes contracted, appressed-pilose; leaf sheaths longer or shorter than the inter-
nodes, sparsely papillose-hispid; collar hispid-bearded; overlapping margin densely
ciliate; ligule a densely ciliolate membrane, 0.7-1.0 mm. long; leaf blades flat, 8-20 cm.
long, 15-25 mm. wide, ovate 5-8:1, rather abruptly rounded to the asymmetric base;
midrib white, prominent beneath; margins strongly scabrous, with conspicuous white
marginal sclerenchyma bands; surfaces sparsely papillose-hispid, especially toward the
tip. Inflorescences terminal on leafy culms; panicle ca. 20 cm. long, 10 cm. wide, nar-
rowly pyramidal; rachis, branches, and pedicels scabrous; spikelets more or less ap-
pressed along primary and secondary branches, their pedicels 1-2 x as long as the
spikelets, and with a few fine hairs at the apex. Spikelets elliptical ca. 2:1, 2.2-2.5 mm.
long, strongly dorsally flattened, barely acute at the apex, glabrous; first glume a small
triangular or cufflike nerveless scale, 0.3-0.5 mm. long; second glume and lower (sterile)
lemma subequal, as long as the spikelet, 5-nerved; upper (fertile) floret somewhat
shorter, ca. 2 mm. long, broadly ovate 1.5:1, blunt, flattened, stramineous, longitudi-
nally striate; palea similar to the lemma and slightly convex; lodicules 2, truncate;
anthers 3, yellow, 1.0 mm. long; styles 2, separate. Chromosome number n = 18 from a
Costa Rican specimen.

Rare, at scattered localities in the Meseta Central; Guadalupe,
Alajuelita, San Miguel; elevation ca. 1,200 m. October to February.

BURGER: FLORA COSTARICENSIS 381

This species grows in brush. It was not collected in Costa Rica after
1912 until our recent collection. Southern Mexico, Guatemala, El Sal-
vador, Costa Rica.

Panicum pilosum Swartz, Prodr. Veg. Ind. Occ. 22. 1788, var.
pilosum. Figure 140.

Duration indefinite, probably perennial; plants 15-50 cm. tall, the bases sprawling or
stoloniferous, rooting at the decumbent nodes; erect branches arising from rooted nodes;
prophylla conspicuous, up to 2 cm. long; culm internodes 1-2 mm. thick, hollow, glabrous
or papillose-pilose below the nodes; nodes usually densely bearded with spreading fine
hairs; leaf sheaths mostly longer than the internodes, often divaricate from the internode
and inrolled, appearing somewhat like elongated pseudopetioles, surface nearly glabrous
to densely papillose-pilose; ligule absent or represented by a minute ciliolate ridge; collar
densely pilose; leaf blades 5-20 cm. long, 7-20 mm. wide, narrowly ovate, the length
mostly less than 10 x the width, acuminate, cordate at the base and with a short, broad
pseudopetiole; surfaces glabrous to softly pilose. Peduncle exserted 2-15 cm.; inflores-
cence terminal on erect portions of culms, 6-18 cm. long, narrowly cylindrical, open,
composed of 7-27 (50) drooping spikelike racemes, these mostly 1.5-2 (6) cm. long.
Spikelets solitary, paired, or in trios, the groups alternating on both sides of the midrib
of the lower side of the primary panicle branches; pedicels very short; margins of the
rachis bearing prominent, papillose-based cilia, 1-3 mm. long. Spikelets 1.4-1.6 mm.
long, ovate 2.0-2.5:1, acute, biconvex; first glume 0.6-0.8 mm. long, broadly ovate, acute,
1-3-nerved; second glume and lower (sterile) lemma about equal, as long as the spikelet;
second glume 5-nerved; sterile lemma 3-nerved, enclosing a well-developed palea 1.0-1.2
mm. long; upper (fertile) lemma elliptical, 1.2-1.3 mm. long, shining, stramineous,
strongly convex; palea similar, flat; anthers 3, purplish, 0.5-0.6 mm. long; styles 2,
separate; stigmas dark; caryopsis elliptical, 1.6:1, 0.8 mm. long, amber. Chromosome
number n = 10 from Costa Rican and Venezuelan specimens.

Panicum pilosum is a common weedy species in wet sites, mostly at
low elevations; sea level to 800 m., rarely up to 1,200 m. Rain forest
margins and clearings, wet pastures and roadsides, coconut groves and
beach margins, mostly near the coasts. May to December, possibly
yearlong. Southern Mexico to Argentina; Caribbean Islands.

Var. pilosum is very similar to var. lancifolium, which has the same
chromosome number and probably represents a large extreme of the
species.

Panicum pilosum, var. lancifolium (Griseb. ex Hitchc.) Pohl,
comb. nov. P. distichum Lam., y lancifolium Griseb., Fl. Brit. W.
Ind. 548. 1864. P. distichum, var. lancifolium Griseb. ex Hitchc.,
Man. Gr. W. Indies 267. 1936. P. milleflorum Hitchc. & Chase, Contr.
U.S. Natl. Herb. 17:494. 1915.

Var. lancifolium is similar to var. pilosum in aspect, inflorescence structure, spikelet
size, 3-nerved lower lemma, enlarged palea, and chromosome number. It differs mostly
in characters related to plant size and vigor, but there is considerable overlap in most of
the measurements. Culms 90-150 cm. long, including the long-decumbent basal portions;

FIG. 140. Panicum pilosum var. pilosum. A, panicle; B, portion of a panicle branch
bearing spikelets; C, two views of a spikelet.

382

BURGER: FLORA COSTARICENSIS 383

internodes glabrous, 3-4 mm. thick, hollow; nodes bearded or glabrous; leaf blades 15-28
cm. long, 7-18 mm. wide, glabrous or sparsely pilose; ligule absent. Inflorescence 26-35
cm. long, of 40-80 short ascending or spreading 1-sided spikelike racemes, mostly 1-5 (11)
cm. long, the lower ones sometimes with secondary branches. Spikelets as in var.
pilosum. Chromosome number n = 10 from a Costa Rican specimen.

Moist forests; Finca la Taboga, Puerto Viejo. August to December.
Previously known only from the Canal Zone.

Hitchcock and Chase, in describing P. milleflorum, indicated that it
was the same as Grisebach's P. distichum y lancifolium. Panicum
milleflorum does not merit separate status as a species, being only a
vigorous extreme of P. pilosum. Since Grisebach's name has priority
at the varietal level, it must be used.

Panicum polygonatum Schrad. in Schult., Mant. 2:256. 1824. Fig-
ure 136.

Duration indefinite, probably perennial; culms 25-110 cm. long, the bases long-
decumbent and rooting at the nodes; branching freely from the rooted nodes and some-
times from the middle nodes of erect culms; internodes 1.5-2.5 mm. thick, hollow, gla-
brous or rarely pilose; nodes not prominent, usually retrorsely bearded; leaf sheaths
shorter than the internodes, the overlapping edge ciliate, the surface glabrous, occasion-
ally with scattered pilose hairs toward the apex; collar often pilose; ligule a minutely
ciliolate membrane, 0.2-0.3 mm. long; leaf blades 5-25 cm. long, 8-15 mm. wide, the base
cordate, length 5-9 x the width; pseudopetiole short, ca. 1 mm. long; surfaces glabrous
or with a few pilose hairs on the upper surface above the ligule. Inflorescences terminal
on leafy culms; panicles open, narrowly pyramidal, 10-25 cm. long, 3-11 cm. wide, the
branches spreading or ascending, the lowermost remote, 3-11 cm. long, the upper
branches shorter and closer; spikelets short-pedicellate in pairs or small groups along the
lower sides of the triquetrous primary or secondary branches. Spikelets 1.3-1.9 mm.
long, ovate 3.1-3.4:1, acute; plano-convex; first glume 0.5-1.0 mm. long, 1-3-nerved,
ovate, acute; second glume 1.3-1.7 mm. long, 5-nerved, acute; lower (sterile) lemma
1.2-1.5 mm. long, narrower than the glume, 3-nerved; upper (fertile) lemma 1.0-1.2 mm.
long, elliptical 2-3:1, acute, stramineous; palea similar, flat; lodicules 2, truncate; anthers
3, purple, 0.4-0.5 mm. long; styles 2, separate; stigmas purple; caryopsis ca. 0.8 mm.
long, plump, tan. Chromosome number n = 20 from a number of Costa Rican specimens.

Wet ditches, pond margins, along trails in wet forests; wet sites,
mostly near both coasts; usually found from sea level to 300 m. eleva-
tion, but occasionally to 1,300 m. June to August, occasionally during
the remainder of the year. Southern Mexico to Paraguay.

Panicum polygonatum is a member of the group Laxa, related to P.
laxum and P. boliviense, but differing from both in the pointed
spikelets and the lack of a palea in the sterile lemma. A single Costa
Rican specimen, P. & D. 10679, from Laguna de Arenal, has conspicu-
ously pubescent foliage and panicle branches bearing papillose-based
cilia. It is otherwise similar to other Costa Rican specimens.

384 FIELDIANA: BOTANY

Panicum pulchellum Raddi, Agrost. Bras. 42. 1823. Figure 138.

Duration indefinite, probably perennial; plants extensively creeping and rooting at the
prostrate nodes, branching freely; erect portions of the culms 10-30 cm. long; prophylla
prominently flanged, 5-15 mm. long; culm internodes less than 0.5 mm. thick, hollow,
pilose or glabrous; nodes densely pilose-bearded; leaf sheaths shorter than the inter-
nodes, more or less pilose to nearly glabrous; margins ciliate; collar bearded; ligule a
minute membrane, 0.3-0.4 mm. long, ciliate or ciliolate; leaf blades flat, thin, obliquely
cordate-ovate 3-4:1, 1.8-5.0 cm. long, 4-17 mm. wide; surfaces pilose to glabrous, often
with purplish coloration. Peduncles included or exserted to 13 cm.; panicles solitary,
terminal on erect portions of the culms, 4-16 cm. long, 2-4 cm. wide, of 6-25 ascending or
drooping 1-sided spikelike racemes borne racemosely solitary or in pairs along the
rachis; spikelets solitary or paired, short-pedicellate in 2 rows along the lower sides of
the rachis. Spikelets finely pubescent, biconvex, acute, 2.0-2.3 mm. long; first glume
0.9-1.2 mm. long, acute, 3-nerved, ovate 2:1; second glume 2.0-2.1 mm. long, 5-nerved;
an evident internode between the first and second glumes; lower (sterile) lemma 1.9-2.0
mm. long, 5-nerved, with a well developed palea 1.3-1.6 mm. long, rarely with 3 anthers
0.8 mm. long; back of the sterile lemma usually bearing 2 circular flattened, eyelike
glands above the middle, between the midrib and the first pair of lateral nerves; these
may be absent, or 1-3 may occasionally be present; upper (fertile); floret 1.1-1.4 mm.
long, ovate, the lemma smooth and shining, rigid; palea similar; anthers 3, yellow,
0.6-0.7 mm. long; styles 2, separate; stigmas purple; caryopsis elliptical 2:1, 1 mm. long,
white. Chromosome number n = 10 from Costa Rican and Venezuelan specimens.

Occasional in moist forests, along trails, on forested roadsides, or in
brush. Mostly on the Pacific slope, from San Mateo and San Ramon to
Turrialba and southward to Canas Gordas; Meseta Central; La Virgen.
Elevations from near sea level to 1,400 m. November to June. South-
ern Mexico to Bolivia and Brazil; West Indies.

Panicum rudgei Roem. & Schult., Syst. Veg. 2:444. 1817. Figure
141.

Caespitose perennial in dense clumps; culms 75-125 cm. long, erect, spreading, or
scrambling in brush, branching freely from the upper nodes; internodes 1.5-3.0 mm.
thick, hollow, more or less densely pilose; nodes densely pilose; sheaths densely pilose,
longer or shorter than the internodes; ligule a short membranaceous rim, densely ciliate
with stiff hairs, in total 1.5-2.0 mm. long; leaf blades rather stiff, pilose, 20-40 cm. long,
caudate-acuminate, 8-14 mm. wide. Panicles terminal and axillary from the upper nodes,
forming an elongated compound mass, 30-40 cm. long, half or a third as wide; pedicels,
especially the terminal ones, much longer than the spikelets. Spikelets ovate, acuminate,
3.0-3.4 mm. long, biconvex, the bracts gaping and exposing the fertile floret, hirsute
toward the apex; first glume ovate, acuminate, 2.7-2.9 mm. long, 3-5-nerved; second
glume 2.7-2.9 mm. long, 5-7-nerved; lower (sterile) lemma ca. 2.5 mm. long, 7-9-nerved,
enclosing a palea of equal length and 3 stamens, the anthers deep purple, ca. 0.6 mm.
long; upper (fertile) lemma 1.7-1.9 mm. long, rigid, elliptical 1.6-1.7:1, shining,
stramineous; palea similar, flat; lodicules 2, truncate; anthers 3, deep purple, 0.8-0.9
mm. long. The spikelets are unusual in having definite thick internodes, up to 0.5 mm.
long between the glumes and between the florets. Chromosome number n = 9 from a
Costa Rican specimen.

This species is common on the savannas around Buenos Aires and

FIG. 141. Panicum rudgei. A, culm with several panicles; B, C, two views of a
spikelet; D, fertile floret.

386 FIELDIANA: BOTANY

occurs on the Boruca Savannas as well. Elevations 300-780 m. De-
cember to April. Southern Mexico and Guatemala to Panama, Bolivia
and Brazil.

Panic-urn schiffneri Hack., Ergebn. Bot. Exped. Akad. Wiss.
Suedbras. 11. 1906.

Caespitose perennial, scrambling in brush, branching freely; internodes 1.5-3.0 mm.
thick, solid or hollow with a small lumen, puberulent; leaf sheaths shorter than the
internodes, the margin ciliate, the surface puberulent or glabrous; collar bearded; ligule
a ciliolate membrane, ca. 0.5 mm. long; leaf blades flat, 12-15 cm. long, 13-20 mm. wide,
ovate 7-10:1, the surfaces mostly glabrous; base of blades more or less asymmetric,
rounded. Peduncles exserted 10-20 cm.; panicles 12-17 cm. long, terminal on leafy culms,
very open, 12-16 cm. wide, the longest branch up to 10 cm. long; lower branches solitary
and distant, naked below, the spikelets crowded on the outer third; upper branches
much shorter; rachis and branches pilose; pedicels short. Spikelets 1.5-1.7 mm. long,
elliptical-obovate 1.75-2.0:1, glabrous; first glume a minute nerveless cufflike scale,
0.2-0.4 mm. long; second glume and lower (sterile) lemma equal, as long as the spikelet,
5-nerved; lower floret lacking a palea; upper (fertile) floret broadly elliptical 3:2, blunt,
rigid, somewhat flattened; lemma stramineous, finely striate, bearing scattered fine
appressed hairs; palea similar; lodicules 2, truncate; anthers 3, orange, ca. 0.5 mm. long;
styles 2, separate; stigmas purple; caryopsis 1.0 mm. long, oblong 1.5-2.0:1, tan.

Rare in Costa Rica; known only by the following specimens: Prov.
Alajuela, San Miguel de San Ramon, 21 August 1934. Brenes 19260.
F.; Prov. San Jose, San Francisco de Guadalupe, 0. Jimenez s.n. Nov.
1910 US (specimen determined by Chase, but material very in-
adequate). Southern Mexico to Venezuela and Brazil; West Indies.

Panicum sellowii Nees, Agrost. Bras. 153. 1829.

Caespitose perennial from a hard, knotty crown; lower parts of the stems decumbent,
rooting at the nodes; culms 100-150 cm. long, weak and scrambling in brush, branching
freely, the branches divaricate; internodes 1-2 mm. thick, hollow, glabrous or finely
pilose; nodes glabrous to pilose; leaf sheaths shorter than the internodes, or the upper
ones overlapping, softly pilose to glabrous, the margin densely pilose-ciliate; ligule a
minute membrane, 0.2-0.3 mm. long; collar and auricles pilose; leaf blades ovate 4-8:1,
cordate-based, asymmetric, 6-12 cm. long, 7-18 mm. wide, nearly glabrous to velvety-
pilose. Peduncles included or short-exserted; panicles terminal on leafy branches, 10-28
cm. long, 4-16 cm. wide, ellipsoidal, very open; branches solitary or paired, straight,
ascending or reflexed, the longest ones 5-14 cm. long, nearly simple, spikelet-bearing on
the outer half, the spikelets mostly solitary, closely appressed to the branches. Spikelets
obovate 2:1, acute, 2.0-2.3 mm. long, usually finely pubescent; first glume ovate 2:1,
acute, usually 1-nerved, 1.2-1.5 mm. long; second glume shorter than the fertile floret,
5-nerved, 1.8-2.0 mm. long; lower (sterile) lemma 5-nerved, 1.9-2.2 mm. long, containing
a narrow, tongue-shaped hyaline palea 1.0-1.2 mm. long; upper (fertile) floret 1.6-1.9
mm. long, obovate 1.5-2.0:1, acute, the lemma strongly convex, reddish brown, minutely
roughened; palea similar, slightly convex; anthers 3, purple, 1.1 mm. long; styles 2,
separate; stigmas purple; caryopsis elliptical 3:2, ca. 1.2 mm. long, white. Chromosome
number n = 27 from a Costa Rican specimen.

BURGER: FLORA COSTARICENSIS 387

Brushy road embankments, bromeliad hedges, forest margins; ele-
vations 600-1,700 m.; occasional; Grecia, Turrialba, Agua Caliente,
Frailes, Rivas, Puriscal. July to November. Southern Mexico to
Paraguay and Argentina; West Indies.

Panicum sphaerocarpon Ell., Bot. S.C. & Ga. 125. 1821.

Caespitose perennial in erect or sprawling tufts, lacking well-developed basal rosettes;
culms 15-45 cm. long; internodes 1.0-1.5 mm. thick, hollow, glabrous, branching
from the base and middle nodes; nodes glabrous or upwardly bearded; leaf sheaths
longer or shorter than the internodes, glabrous except for fine pilose ciliation on the
overlapping margin; ligule a sparse row of hairs, 0.3-0.7 mm. long; lower leaf blades
shorter and broader than the uppermost ones; blades flat, cordate-based, firm-textured,
glabrous except for a few stiff, pustulose-based elongated cilia on the rounded basal
margins of the blades; lower leaf blades 3.0-6.5 cm. long, 8-11 mm. wide, 3-6 x longer
than wide; upper blades 3-4 cm. long, 5-8 mm. wide, 4-6 x longer than wide. Peduncles
of primary panicles 4-13 cm. long; primary panicles 4-7 cm. long, 3-4 cm. wide, ovoid or
pyramidal, the spikelets borne on diverging pedicels; secondary panicles smaller, on
shorter branches, their bases often included. Spikelets obovate ca. 1.8:1, brownish or
purple, finely puberulent, 1.5-2.0 mm. long; first glume blunt, 0.4-0.7 mm. long, broader
than long, usually 1-nerved; second glume 1.5-1.8 mm. long, 5-7-nerved; lower (sterile)
lemma 1.5-1.7 mm. long, 5-7-nerved, enclosing a hyaline palea 0.7-0.9 mm. long; upper
(fertile) floret 1.4-1.5 mm. long, broadly elliptical 1.5:1, ca. 1.5 mm. long, smooth and
shining, stramineous; palea similar, slightly convex; lodicules 2, truncate; anthers 3,
purple, 0.4 mm. long; styles 2, separate; stigmas purple; caryopsis broadly elliptical, 1
mm. long, whitish, with a red spot at the base opposite the embryo. Chromosome
number n = 9 from a Costa Rican specimen.

Occasional; pastures and road embankments; middle elevations,
mostly in the mountains south of San Jose; elevations 1,200-2,700 m.;
Aserri, Tarbaca, Copey, Volcan Barba. Probably blooming yearlong.
Eastern and southeastern United States, eastern Mexico to northern
Panama; Venezuela, Cuba.

This species belongs to the subgenus Dichanthelium, a group
largely confined to temperate North America. The plants have two
blooming periods, the secondary or axillary panicles produced later
than the primary ones, and tending to have highly cleistogamous
spikelets. In the tropical climates, the plants tend to lack the conspicu-
ous basal rosettes of short, broad leaves that they exhibit in climates
with a cold winter. Related species in our flora are P. laxiftorum, P.
vistidellum, and P. olivaceum.

Panicum stagnatile Hitchc. & Chase, Contr. U.S. Natl. Herb.
17:528. 1915.

This species has not as yet been collected in Costa Rica, but may be
looked for in coastal swamps.

388 FIELDIANA: BOTANY

Panicum stenodes Griseb., Fl. Brit. W. Ind. 547. 1864. Figure 139.

Short, densely tufted erect perennial, 15-40 cm. tall; culms unbranched, internodes
less than 1 mm. thick, glabrous, hollow; nodes glabrous, inconspicuous; leaf sheaths
short, glabrous to softly and densely pilose; ligule a minute membrane, 0.1-0.2 mm. long;
leaf blades 2 or 3, flat or involute, 1-8 cm. long, 1.0-1.5 mm. wide, nearly glabrous to
papillose-pilose. Peduncles included in the uppermost sheaths; panicles 1-5, exserted
from the terminal sheath, 1-2 cm. long, each a slender racemose cluster of a few ap-
pressed spikelets. Spikelets obovate 2:1, glabrous, 1.5-2.1 mm. long; first glume trian-
gular 1:1, 0.9-1.2 mm. long, usually 3-nerved; second glume 1.4-1.8 mm. long, 5-
(9-)nerved; lower (sterile) floret 1.3-1.8 mm. long, 5-7-nerved, with a hyaline palea ca.
0.5-0.8 mm. long; upper (fertile) floret 1.2-1.7 mm. long, ovate 3:2, stramineous, rigid;
palea equal, flat; anthers 2-3, deep purple, 0.4-0.6 mm. long; styles 2, separate; stigmas
purple; caryopsis deep purple, elliptical, 0.8 mm. long. Chromosome numbers = 10 from
a Costa Rican specimen.

The delicate, wiry little plants may easily be overlooked. This
species has been collected repeatedly on the savannas near Buenos
Aires around the ponds. We have a recent collection from the road to
Hacienda Las Animas, 2 km. E of the CIA. Dry savannas, elevations
from 200-380 m. Probably blooming yearlong, but the inflorescences
are very inconspicuous.

The group Tenera of Hitchcock and Chase, to which this species
belongs, is in need of revision. The exact number of species is debat-
able. Specimens from Buenos Aires have been variously determined
by Hitchcock and Chase as P. stenodes and P. stenodoides Hubb.,
although all material that I have seen is very similar. Panicum
tenerum, which is considerably larger and has more pointed spikelets,
has chromosome number n = 20. It has not yet been collected from
Costa Rica.

Panicum trichanthum Nees, Agrost. Bras. 210. 1829. Figure 142.

Duration indefinite; plants scrambling in brush; culms up to 150 cm. long, branching
freely, the lower portions prostrate and rooting at the nodes; internodes smooth and
glabrous, hollow, 1.5-2.5 mm. thick; nodes glabrous, dark; prophylla up to 3 cm. long;
leaf sheaths shorter than the internodes, glabrous except for the ciliate overlapping
margin; ligule a minute membrane, 0.2-0.3 mm. long; leaf blades often with a short
pseudopetiole up to 2 mm. long; blades cordate, narrowly ovate 4.5-8:1, 5.5-13 cm. long,
8-23 mm. wide, pilose on the collar, mostly glabrous but occasionally finely pilose on the
surfaces. Peduncles included or short-exserted; panicles terminal on leafy branches,
open, dome-shaped, 17-27 cm. long, rather delicate, the spikelets borne on elongated
flexuous pedicels. Spikelets obovate 2:1, biconvex, 1.2-1.6 mm. long; bracts covered with
minute vesicles; first glume 0.2-0.4 mm. long, membranaceous, nerveless; second glume
and lower (sterile) lemma about equal, as long as the spikelet; second glume 5-nerved;
sterile lemma 3-5-nerved, with a narrow, tongue-shaped palea 0.7-0.8 mm. long; upper
(fertile) floret ca. 1.1 mm. long, broadly ovate ca. 2:1, tan; palea similar to the lemma,
convex; anthers 3, tan, 0.5-0.8 mm. long; caryopsis broadly oblong 4:3, ca. 0.8 mm. long,
tan, opalescent. Chromosome number n = 18 from a Costa Rican specimen.

FIG. 142. Panicum species. P. trichoides: A, blooming plant; B, two views of a
spikelet; P. trichanthum: C, two views of a spikelet.

390 FIELDIANA: BOTANY

The plants clamber in brush or in marsh vegetation; occasional;
Finca la Taboga, Lagunas de San Bernardo, Villa Neilly, Santa Rosa
(Limon), Limon, Cahuita, Zhorquin. Near sea level to 550 m. eleva-
tion, mostly near the coasts. Central Mexico to Paraguay; West Indies.

This species is similar to P. trichoides in spikelet structure, but
differs in size, leaf proportions, pubescence, and chromosome num-
bers.

Panicum trichoides Swartz, Prodr. Veg. Ind. Occ. 24. 1788. Figure
142.

Sprawling annual, the culms long-decumbent and rooting at the nodes, forming large
patches; erect portions of the culms 10-80 cm. long; branching freely from both decum-
bent and erect portions; internodes 1-2 mm. thick, hollow, pilose; nodes prominent,
covered by the bases of the sheaths; prophylla 1.5-2.5 cm. long; leaf sheaths much
shorter than the internodes, copiously papillose-pilose; ligule a short minutely ciliolate
membrane, 0.2-0.3 mm. long; leaf blades thin and flat, obliquely cordate-ovate 3-5:1,
3.5-7 cm. long, 5-19 mm. wide, more or less papillose-pilose, the lower margins
papillose-ciliate. Inflorescences numerous, terminal on leafy branches; peduncles in-
cluded or exserted up to 18 cm.; panicles broadly dome-shaped, 4-18 cm. long, 3-11 cm.
wide, the longest branch 2-10 cm. long; panicles delicate, lacy, the small spikelets borne
on thin, threadlike pedicels much longer than the spikelets. Spikelets obovate 2:1,
1.2-1.3 mm. long, tapering to a slender base, plano-convex, rather thick; bracts finely
pilose; first glume narrowly ovate, 0.6-0.7 mm. long, 1-3-nerved; an evident internode,
ca. 0.2 mm. long between the first glume and the second; second glume slightly shorter
than the spikelet, 1.1-1.2 mm. long, 3-5-nerved; lower (sterile) lemma 1.1-1.2 mm. long,
3-5-nerved, enclosing a tongue-shaped hyaline palea 0.4-0.6 mm. long; upper (fertile)
floret 0.9-1.0 mm. long, ovate 2:1, the lemma minutely roughened, tan, strongly convex;
palea similar, flat; anthers 3, white, 0.4-0.5 mm. long; caryopsis obovate 2:1, 0.7-0.8 mm.
long, opalescent, white. Chromosome number n = 9 from a Costa Rican specimen.

Panicum trichoides is a common weed in wet, shaded sites at low
elevations, from sea level to 600 m. elevation, rarely to 1,000 m.,
mostly near the coasts. Blooming mostly from June to October, but to
some extent throughout the year. Mexico to Peru and Brazil; West
Indies; Tropical Asia.

This species is apparently most closely related to P. trichanthum.

Panicum viscidellum Scribn., U.S.D.A. Div. Agrost. Circ. 19:2.
1900. Figure 143.

Perennial; culms 35-110 cm. long, the bases decumbent or rooting; culms erect or
spreading, branching from the basal and middle nodes, sometimes producing dense tufts
of small branchlets; internodes 1.5-2.0 mm. thick, hollow, papillose-pilose; nodes densely
bearded with retrorse or spreading hairs; leaf sheaths shorter than the internodes,
pilose; ligule a dense row of short white hairs, 0.5-1.0 mm. long, with much longer hairs
on the upper leaf surface behind the ligule; leaf blades flat, soft, cordate-based, 5-12 cm.
long, 8-20 mm. wide, more or less pilose on both surfaces. Peduncles exserted up to 22
cm., terminal on the main culms or on leafy branches; primary panicles 5-11 cm. long, 3-9

ye*

FIG. 143. Panicum viscidellum. A, blooming culm; B, base of plant; C, two views of a
spikelet.

391

392 FIELDIANA: BOTANY

cm. wide, dome-shaped, rather dense; branches 1-several per node of the rachis;
spikelets appressed along the primary or secondary branches; lateral pedicels ca. as long
as the spikelets, the terminal ones much longer. Spikelets obovate 2:1, slightly acute,
1.8-2.0 mm. long, finely pubescent; first glume 0.4-0.7 mm. long, obscurely nerved, ovate
2:1, acute; second glume 1.6-1.9 mm. long, 7-nerved; lower (sterile) lemma 1.6-1.9 mm.
long, 7-nerved, enclosing a hyaline palea 0.7-1.1 mm. long; upper (fertile) floret 1.6-1.9
mm. long, elliptical 3:2, the lemma smooth and shining, rigid, apiculate; palea similar,
flat; lodicules 2, truncate; anthers 3, 0.9 mm. long, purple; styles 2, separate; stigmas
purple; caryopsis broadly elliptical 4:3, 1 mm. long, whitish, with a purplish stain near
the base and a red spot near the base on the side opposite the embryo. Chromosome
number n = 18 from Costa Rican specimens.

Roadsides, river banks, in brush or oak forests; occasional on the
Pacific slope, between 700 and 1,600 m. elevation; Volcan Rincon de la
Vieja, Zapote (Prov. Alajuela); San Ramon area, Tarbaca, Tejar,
lower slopes of the Cordillera de Talamanca. Probably blooming year-
long, but primary panicles produced from June to January. Southern
Mexico to Colombia.

This species seems to belong to the subgenus Dichanthelium on the
basis of its general morphology. Like other tropical species of this
subgenus, it fails to make basal rosettes. Swallen (Fieldiana Bot.
24:268. 1955) lists P. reflexopilum Steud., Syn. PI. Glum. 1:84. 1854. as
a synonym of P. viscidellum. As this name far antedates P. viscidel-
lum, it would have to be used if it could be firmly identified. No type
material attributed to this name is in the U.S. National Herbarium,
and the notes of Mrs. Chase indicate that she was unable to locate a
type in Europe (personal communication from T. R. Soderstrom). The
description seems to be applicable to P. viscidellum, but in the
absence of a type, it seems inadvisable to change the name.

EXCLUDED SPECIES

Panicum altum Hitchc. & Chase, Contr. U.S. Natl. Herb. 17:488.
1915.

This sea coast species was reported from Buenos Aires (Tonduz
3619). The specimen is immature and not identifiable. However, P.
altum grows on coastal sand dunes, an entirely different habitat from
the savannas of Buenos Aires.

PARATHERIA Grisebach

Panicle very slender, few-flowered; branches few, simple, strictly erect, deciduous at
maturity, each bearing near its base a solitary appressed subsessile spikelet, the branch
extending beyond the spikelet as a flattened bristle, tapering to a hispid apex; base of the
branch forming an elongated sharp-pointed callus below the point of attachment of the

BURGER: FLORA COSTARICENSIS 393

permanently attached spikelet. Spikelets dorsally compressed, narrowly ovate, acumi-
nate, remaining attached to the simple panicle branch and deciduous with it; glumes
equal, blunt, much shorter than the spikelet; lower (sterile) lemma and upper floret
about equal; sterile lemma membranaceous; upper (fertile) lemma stiff, acuminate, its
margins thin, flat, covering the edges of the palea of similar texture. Lower leaf sheaths
often swollen at the base and concealing a solitary cleistogene borne in the axil of an
elongated membranaceous prophyllum.

Paratheria is an anomalous panicoid genus, peculiar in its manner of
disarticulation and spicate inflorescence. Authors of treatments of Af-
rican grasses have placed the genus close to Pennisetum or Setaria
because of the sterile, bristle-like branches. The spikelet morphology
and cleistogamous habit appear most similar to the tropical American
genus Reimarochloa. The distribution pattern of Paratheria is difficult
to interpret, our species occurring in Cuba, Brazil, and tropical Africa,
with another species described from Sierra Leone. (Panicoideae:
Paniceae.)

Paratheria prostrataGriseb., Cat. PL Cub. 236. 1866. Figure 143a.

Duration indefinite; plants caespitose; culms prostrate or ascending, up to 60 cm. long,
branching from the base and lower nodes; internodes hollow, glabrous; nodes densely
upwardly bearded; prophylla membranaceous, 10-20 mm. long; leaves numerous; leaf
sheaths keeled, the lowermost ones densely hirsute, the upper mostly glabrous except
near the base; ligule a dense row of white cilia, 0.5-0.7 mm. long; dewlap hirsute; leaf
blades flat, 1-3 cm. long, 2-3 mm. wide, the midrib keeled beneath; lower blades hirsute,
the upper ones glabrous. Inflorescences terminal on the main culms or on leafy branches;
lower leaf sheaths often swollen and concealing solitary cleistogamous fruitful spikelets
(cleistogenes); peduncle and lower spikelets of terminal inflorescences included in the
uppermost sheath. Inflorescence a spikelike panicle, 6-9 cm. long; branches solitary,
simple, 1.5-3 cm. long, flattened or angular, strongly scabrous on the angles, tapering to
an acute apex; solitary spikelet attached to the branch near the base on a short pedicel
0.5-1.0 mm. long; branches deciduous from the rachis, the portion below the attachment
of the spikelet forming a stiff, acuminate callus. Spikelets narrowly ovate 7-9:1, acumi-
nate, dorsally compressed, 6-9.5 mm. long, glabrous except for a few hairs at the very
base; glumes equal, membranaceous, blunt, nerveless, 0.5-0.7 mm. long, or absent from
the cleistogenes; lower (sterile) lemma and upper (fertile) floret equally long; sterile
lemma lacking a palea, ca. 10-nerved, with 3 closely spaced nerves near each margin;
fertile floret with a stiff, smooth, 7-nerved lemma, its margins flat, covering the edges of
a palea of similar texture; lodicules 2, truncate; anthers apparently 2, 2-4 mm. long in
exserted spikelets, much smaller in the cleistogenes, mostly included, tangled with the
stigmas; caryopsis obovate 8:3, blunt, 4.0-4.2 mm. long, tan; style base persistent; em-
bryo conspicuous, ca. 2 mm. long; a red-brown spot at the base of the caryopsis opposite
the embryo.

This species was not previously reported from North or Central
America. A recent specimen from Buenos Aires, cited below, is the
first collection from Central America. Cuba, Dominican Republic;
Brazil, Guyana, Colombia; tropical West Africa; Madagascar. Costa
Rica: Prov. Puntarenas, Buenos Aires, Osa, elevation 385 m., ere-

FIG. 143a. Paratheria prostrata. Plant, inflorescence, and spikelets.

394

BURGER: FLORA COSTARICENSIS 395

ciendo en la orilla de una charca estacional, J. G. Laurito 2642, 5
September 1977 (CR, ISC, F).

PARIANA Aublet

REFERENCES: J. R. Swallen, Eight new species ofPariana. J. Wash.
Acad. Sci. 30:71-78. 1940. T. G. Tutin, A revision of the genus Pariana
(Gramineae). J. Linn. Soc. Bot. 50:337-362. 1936.

Perennial herbaceous grasses; caespitose, or rhizomatous but clump-forming; leaf
blades mostly broad, borne on short pseud opetioles. Inflorescences mostly arising di-
rectly from the soil on bladeless peduncles, rarely terminal on leafy culms; inflorescence
a club-shaped rame of several to many internodes. Pedicellate staminate spikelets borne
in verticels of 4-6 at each node of the rachis, the pedicels flattened, coriaceous, and often
fused in pairs by their lateral margins; staminate spikelets composed of a pair of flat
1-3-nerved glumes standing exterior to a dorsally compressed awnless floret; stamens
2-many; a single sessile pistillate spikelet concealed within each verticel of staminate
spikelets, its glumes herbaceous, equal, 1-nerved, covering the floret; lemma and palea
indurate; stigmas 2, barely emerging from the whorl of staminate spikelets.

Pariana is a small genus of herbaceous grasses of wet rain forests
from Brazil, Bolivia, and Peru to Costa Rica. Although they are
related to the bamboos, they do not form woody perennial culms.
Because of their very shaded habitats and inconspicuous basal inflores-
cences, they are probably overlooked by plant collectors. (Bam-
busoideae: Parianeae.)

Pariana parvispica Pohl, Iowa State J. Res. 47:73. 1972. Figure
144.

Perennial; rhizomatous, but the culms arising in clumps of few to many from one
crown; sterile culms unbranched, arching, 35-50 cm. tall, 1-2 mm. thick, hollow; glabrous
except for a single line of puberulence directly below the opening of the next sheath
above; nodes densely puberulent with spreading trichomes; lower internodes 6-11 cm.
long, bearing bladeless sheaths or small leaf blades, the sheath about one-third as long as
the internode; foliage leaves grouped near the tips of the culms; crowded, with overlap-
ping sheaths, the upper internodes 1-2 cm. long, the blades forming a flat spray,
simulating a palm leaf; leaves bearing blades usually 6-13 per culm, their sheaths over-
lapping, glabrous as a whole, but more or less puberulent along the margins near the
apex; ligule minute, 0.2-0.3 mm. long, membranaceous, minutely ciliolate, blades of
upper leaves 9-13 cm. long, 2-3 cm. wide, glabrous; pseudopetiole 1-2 mm. long, puberu-
lent on its upper surface; auricles prominent, bearing abundant stiff dark bristles 6-12
mm. long, inflorescences normally absent from leaf-bearing stems, but present on
Davidse 1410, which bears basal aphyllous inflorescences and some apical ones on leafy
culms. Inflorescence a thick, club-shaped spicate structure (rame), usually arising di-
rectly from the soil, the peduncle bearing 2-3 bladeless sheaths, the uppermost sub-
tending the inflorescence. Rame composed of several cylindrical segments ca. 9 mm.
long; each internode bearing at its base a whorl of 3 erect flattened, cartilaginous
pedicels, puberulent on their outer faces; pedicels overlapping and forming a continuous
sheath around the thin, flattened rachis, nearly as long as the internode; 2 of the pedicels

FIG. 144. Pariana parvispica. A, habit of plant, with basal inflorescence; B, a rame; C,
single segment of a rame, with staminate spikelets at the apex; D, pistillate spikelet.

396

BURGER: FLORA COSTARICENSIS 397

bearing paired staminate spikelets at their apex, the third with a single staminate
spikelet. Each of the 2 sets of paired spikelets has only 3 glumes, 2 being placed at the
free margins of the flat pedicel, the third between the 2 spikelets. Solitary spikelet
similar to the paired ones, but with 2 equal glumes. Staminate spikelets consisting of the
blunt, oblong, stiff, ciliate glumes, ca. 1 mm. long, standing external to a single floret;
staminate floret dorsally compressed, awnless, oblong, ca. 1.5 mm. long, lemma puber-
ulent, cartilaginous, very broad, facing outward, its margins inrolled around the edges of
the palea; palea smooth, stiffish, 2-nerved, its margins inrolled; flower with 2 broadly
spatulate lodicules, thickened above, ca. 1 mm. long; stamens 2, on thick, fleshy, short
filaments; anthers slightly exserted through the tip of the floret at anthesis; pollen
normal. Pistillate spikelet single at each node, completely concealed by the whorl of
flattened pedicels, only the stigmas visible externally, ca. 8 mm. long, dorsally com-
pressed, oval in cross section; glumes oblong, herbaceous, 1-nerved, enveloping the
floret, glabrous except for the ciliolate margins; lemma and palea coriaceous, equal,
tapering to a narrow herbaceous point; lemma very broad, its margins covering the
edges of the palea, glabrous; lodicules 3, flat, vasculated, ca. 1-1.5 mm. long, bearing at
their tips microhairs with 1, 2, or 3 cells; ovary slender, bottle-shaped, tapering into a
stiff style; stigmas 2, short, rather sparsely hairy, extruded through the herbaceous
tips of the lemma and palea and emerging from the whorl of pedicels at their apices. The
terminal segment of the rame tapers to a point. It consists of 3 sterile flattened overlap-
ping pedicels enveloping a single pistillate spikelet terminal on the end of the rachis.
Chromosome number n = 11, from microsporocytes of Pohl & Davidse 11646.

Rain forests, lowland Atlantic slope areas. Blooming occurs appar-
ently only during the short-day season, probably from December to
February.

This is the most northerly species of the genus Pariana. It differs
from all of the species of the genus described by Tutin and those
described by Swallen in the small size of the inflorescences and various
combinations of stamen number, pedicel length and union, and spikelet
features. It is difficult to assign P. parvispica to any of the sections
proposed by Tutin. At the type locality, the plants are abundant over a
considerable area of undisturbed rain forest and along the margins of
clearings. We have been able to cultivate the plants in the greenhouse,
and the chromosome count was obtained from such cultivated plants.
This is the species reported by Standley, Flora of Costa Rica 85 (1937)
as P. zingiberina Doell, a South American species, on the basis of
sterile material.

PASPALIDIUM Stapf

Rather succulent marsh or aquatic grasses, the culm bases often decumbent and
rooting; inflorescences terminal or axillary from upper nodes; inflorescence a slender
panicle composed of sessile one-sided racemes, borne singly or in pairs at the nodes of a
triquetrous rachis; racemes slender, erect, bearing solitary spikelets in 2 rows along the
lower sides of a triquetrous rachis that terminates in a reduced spikelet or a flattened,
naked point. Spikelets dorsally compressed, ovate, acute, awnless, placed with the first

398 FIELDIANA: BOTANY

glume outward, the second glume turned toward the midrib of the rachis; first glume
short, usually blunt; second glume nearly as long as the fertile lemma, which is exposed
at the tip; lower (sterile) lemma flat, as long as the spikelet, containing a palea of equal
length and usually a staminate flower with 3 anthers; upper (fertile) floret slightly
shorter than the lower floret, its lemma elliptical, acute, rugulose, with a prominent
areole above the base; margins inflexed over the keels of a similar palea.

A small genus of about 12 species in warm climates, mostly in the
Old World. The genus is most closely related to Brachiaria and
Urochloa. (Panicoideae: Paniceae.)

Paspalidium geminatum (Forsk.) Stapf, Fl. Trop. Africa 9:583.
1920. Panicum geminatum Forsk., Fl. Aegypt.-Arab. 18. 1775. Fig-
ure 145.

Duration indefinite; culms 40-140 cm. long, erect, the bases often long decumbent and
rooting; culms unbranched or rarely branched from the middle nodes; internodes gla-
brous, 3-5 mm. thick, hollow, thick-walled, the wall containing numerous radial cham-
bers separated by thin partitions, each filled with loose stellate parenchyma; nodes
glabrous, often contracted; leaf sheaths mostly overlapping, glabrous; ligule a short
membrane, densely ciliate, in total 0.7-2.7 mm. long; blades flat or somewhat inrolled,
6-20 cm. long, 5-8 mm. wide, glabrous or minutely scaberulous above. Peduncle short,
included; inflorescences terminal and sometimes axillary from the uppermost sheath;
panicles 10-30 cm. long, very slender, the racemes appressed to the triquetrous rachis;
lower racemes distant, up to 5 cm. long, the middle and upper ones progressively shorter
and closer, sometimes paired and subopposite, the shortest upper ones less than 1 cm.
long; rachis of racemes triquetrous, the angles minutely hirsute or scabrous, spikelet-
bearing to the base; spikelets very short-pedicellate, in 2 rows alternating along the
2 lower sides of the rachis. Spikelets disarticulating below the glumes, dorsally com-
pressed, elliptical 1.5:1, acute, mostly 2.0-2.5 mm. long, rarely longer; first glume
orbicular, 0.7-0.9 mm. long, thin, faintly 3-5-nerved or apparently nerveless; second
glume shorter than the spikelet, 1.7-2.3 mm. long, 5-7-nerved, blunt, sometimes with
cross-nerves near the apex; lower lemma 5-nerved, as long as the spikelet, with a palea
of equal length and usually a staminate flower, the anthers ca. 1.2 mm. long, orange;
upper floret rigid, the lemma 2.2-2.3 mm. long, elliptical 3:2-2:1, strongly rugulose;
nerves 5, faint; palea of equal length and similar texture; anthers 3, 1.2-1.5 mm. long,
orange; style branches separate, naked at the base; stigmas purple. Chromosome
number n = 27 from one Costa Rican specimen.

Coastal marshes; Taboga, Hacienda Palo Verde, Boca de Barranca;
Rio Banano (Limon); elevations near sea level. August to February.
Florida and Texas to Brazil and Peru; tropical Africa and Asia.

Specimens with larger spikelets have been assigned to var.
paludivagum (Hitchc. & Chase) Gould, Southw. Naturalist 15:391.
1971, based on Panicum paludivagum H. & C., Contr. U.S. Natl.
Herb. 15:32. 1910. Several of our specimens have spikelets approach-
ing the size range of this entity. Chromosome numbers ranging from n
= 9 to n = 27 have been reported for this species, and it is evident that
the group is complex and perhaps not yet well understood.

FIG. 145. Paspalidium geminatum var. geminatum: A, rooting base of culm and
inflorescence; B, two views of a spikelet; var. paltidivagum: C, two views of a spikelet;
D, fertile floret.

400 FIELDIANA: BOTANY

PASPALUM Linnaeus

REFERENCES: D. J. Banks, Taxonomy of Paspalum setaceum
(Gramineae). Sida 2:269-284. 1966. Agnes Chase, The North American
species of Paspalum. Contr. U.S. Natl. Herb. 28:1-310 + XVII. 1929.

Caespitose, rhizomatous, of stoloniferous annual and perennial grasses of extremely
diverse size and habit. Inflorescence of 1 or more one-sided racemes, the spikelets
short-pedicellate, borne in rows on the lower side of the rachis; spikelets mostly paired,
the pairs alternating on opposite sides of the midrib, and the racemes hence 4-rowed, or
solitary by absence or abortion of one member of each pair, and the racemes hence
2-rowed. Intermediate conditions also occur, resulting in racemes in part 3-rowed.
Rachis triquetrous, or flattened and sometimes winged, the midrib often prominent.
Spikelets oriented with the first glume away from the midrib of the rachis and the second
glume and the upper (fertile) lemma toward it. Spikelets more or less plano-convex,
ovate, elliptical, or obovate in outline, blunt or acute; first glume present on some or all
of the spikelets in some species, but absent in most; second glume and lower (sterile)
lemma membranaceous, usually equal and as long as the spikelet, covering and conceal-
ing the upper (fertile) floret; second glume covering all or most of the convex back of the
fertile lemma, entirely absent in a few species; sterile lemma flat, covering the palea of
the fertile floret, occasionally with a rudimentary or well-developed membranaceous
palea and rarely with a staminate flower; fertile floret usually nearly as long as the
spikelet; lemma stiff or rigid, its margins thick and more or less inrolled over the edges of
a palea of equal length and similar texture; lodicules 2, truncate; anthers usually 3; styles
2, separate, naked below; stigmas plumose; caryopsis elliptical or obovate, strongly
dorsally flattened. The basic chromosome number in the genus is x = 10.

Paspalum is a very large genus of grasses of warm climates, its
center of diversity being in the American tropics. Relatively few
species occur in the temperate zone. Estimates of the number of
species range from 200 to 400. The ecological diversity of the genus is
extreme. Some species are xeromorphic plants of dry savannas, while
others occur in fresh water and salt marshes or as floating aquatics.
The Central American species are all confined to low and moderate
elevations, rarely above 2,000 m. Some species, as P. notatum and P.
dilatatum, have forage value or are used for erosion control. Pas-
palum conjugatum is a common weed and is regarded as a poor forage
species. Paspalum paniculatum, P. candidum, and P. plicatulum are
also common and weedy. The genus is related to Panicum, differing in
its racemose rather than paniculate inflorescences. It is also similar to
Paspalidium and Urochloa, which differ in having transversely corru-
gated fertile lemmas, and to Axonopus and Brachiaria, which have
the back of the fertile lemma turned away from the midrib of the
rachis. Polyploidy and meiotic irregularities occur frequently.
(Panicoideae: Paniceae.)

BURGER: FLORA COSTARICENSIS 401

KEY TO SPECIES OF Paspalum

la. Spikelets (at least one of some pairs) possessing visible first glume 2

Ib. Spikelets lacking first glume and sometimes lacking both glumes 8

2a. Culms bearing single inflorescence on terminal peduncle, lacking axillary

inflorescences 3

2b. Culms bearing axillary as well as terminal inflorescences, sometimes several

peduncles arising from terminal sheath 5

3a. Tall, stout perennial, culms up to 3 m. tall; inflorescence a panicle of many racemes;

spikelets over 3.5 mm. long P. fasciculatum

3b. Plants less than 1 m. tall, slender; inflorescence of 2-7 racemes 4

4a. Spikelets paired, racemes 4-rowed P. botterii

4b. Spikelets solitary, racemes 2-rowed 46

5a. Racemes one on each peduncle; sterile lemma usually with well-developed palea

(see also P. setaceum) 6

5b. Racemes several to many on each peduncle P. setaceum

6a. Spikelets 2 mm. or less long 7

6b. Spikelets 2.5 mm. or more long P. pilosum

7a. Both spikelets of each pair with first glumes; spikelets 1.5-1.7 mm. long; racemes

up to 3 cm. long P. decumbens

7b. Lower spikelet of each pair with first glume, upper spikelet lacking one; spikelets

1.7-2.0 mm. long; racemes 3-5 cm. long P. nutans

8a. Second glume absent, spikelet consisting only of lower (sterile) lemma and

fertile floret; back of fertile lemma completely exposed 9

8b. Second glume present, covering all or most of back of fertile lemma ... 11
9a. Racemes falling from central axis of inflorescence entire, with spikelets attached;

spikelets whitish or green 10

9b. Racemes persistent on plant, only spikelets falling; sterile lemma of spikelets yel-
low or purple P. pulchellum

lOa. Sheaths strongly scabrous; spikelets up to 2 mm. long P. scabrum

lOb. Sheaths not scabrous; spikelets over 2 mm. long P. candidum

lla. Rachis of individual racemes broad and thin, 2-8 mm. wide 12

lib. Rachis of individual racemes less than 2 mm. wide 14

12a. Low, stoloniferous plants of wet sites; foliage glabrous . . . P. acuminatum

12b. Erect caespitose plants of dry savannas; foliage pubescent 13

13a. Spikelets 4.5-6.7 mm. long, cordate at base; second glume strongly pectinate-

ciliate, broadly winged; rachis 2.0-2.5 mm. wide P. pectinatum

13b. Spikelets 3.0-3.2 mm. long, not cordate-based or winged; rachis 5-8 mm. wide

P. stellatum

14a. Mature fertile lemma stramineous 19

14b. Mature fertile lemma reddish, chestnut-colored, or brown 15

15a. Plants low, stoloniferous; spikelets 1.2 mm. or less long P. orbiculatum

15b. Plants erect or sprawling, not stoloniferous; spikelets at least 1.5 mm. long . 16
16a. Culms tall, stout, 80-250 cm. long; racemes 4-18 cm. long; spikelets 2.6-3.2

mm. long, puberulent, apex with fringe of short hairs P. virgatum

16b. Culms slender, 20-150 cm. long; racemes 3-6 (11) cm. long; spikelets 1.8-2.8
mm. long, glabrous or appressed-pubescent, not fringed at apex 17

402 FIELDIANA: BOTANY

17a. Central part of sterile lemma with transverse wrinkles; anthers over 1 mm. long

P. plicatulum

17b. Central part of the sterile lemma flat, not wrinkled; anthers less than 1 mm.
long 18

18a. Spikelets appressed-pubescent, nearly circular in outline, length less than 1.3
x width; spikelets usually paired, raceme 4-rowed P. convexum

18b. Spikelets glabrous, obovate, length 1.3-1.5 x width; spikelets solitary,
racemes 2-rowed P. centrale

19a. Spikelets densely silky with long white hairs up to 6 mm. long borne on second
glume; inflorescences large, fan-shaped, of numerous racemes

P. saccharoides

19b. Spikelets glabrous or pubescent, sometimes ciliate, but not concealed with long,

white hairs; inflorescences various 20

20a. Racemes falling from common rachis as units, with spikelets attached to

flattened rachis; creeping or floating aquatic P. repens

2Gb. Racemes persistent on common rachis, spikelets falling from axis; plants of
wet or dry habitats 21

21a. Spikelets 2 mm. or less long 22

21b. Spikelets more than 2 mm. long 33

22a. Spikelets 0.6-0.7 mm. long P. parviflorum

22b. Spikelets at least 1 mm. long 23

23a. Raceme solitary on each peduncle P. nutans

23b. Racemes 2 or more on each peduncle (rarely 1 in depauperate individuals) ... 24

24a. Racemes numerous (7-70), forming a panicle 25

24b. Racemes usually 2-5, rarely solitary or as many as 8 26

25a. Spikelets blunt or barely acute, length 1.4 x width or less; rachis of racemes 0.5
mm. or less wide; racemes 18-70 per panicle P. paniculatum

25b. Spikelets acute, length 1.5 x width or more; rachis of racemes 0.6-0.8 mm. wide;

racemes 30 or fewer P. microstachyum

26a. Plants strongly stoloniferous; racemes 2, conjugate, very slender; spikelets

solitary, second glume silky-ciliate, especially toward apex P. conjugaium

26b. Plants not stoloniferous; racemes 1-several; spikelets glabrous or pubescent

but not silky-ciliate 27

27a. Plants with solitary terminal inflorescences and lacking axillary inflorescences 28

27b. Plants with terminal and axillary inflorescences from terminal sheaths and some-
times from lower sheaths P. setaceum

28a. Spikelets solitary, racemes 2-rowed 29

28b. Spikelets paired, racemes 4-rowed 31

29a. Spikelets bearing minute globular hairs; plants caespitose annuals P. multicaule

29b. Spikelets glabrous; plants caespitose or rhizomatous perennials 30

30a. Plants rhizomatous, forming open patches on wet mud 45

30b. Plants densely caespitose, forming flat mats on soil P. pumilum

3 la. Spikelets bearing minute glandular hairs; racemes paired (rarely 3) conjugate

P. clavuliferum

31b. Spikelets glabrous; racemes 1-6 32

32a. Racemes 4-6; spikelets 1.5-1.8 mm. long P. squamulatum

BURGER: FLORA COSTARICENSIS 403

32b. Racemes 1-3; spikelets 1.0-1.1 mm. long; fertile lemma finely tuberculate

P. pictum

33a. Spikelets silky-ciliate 34

33b. Spikelets glabrous or pubescent, but not conspicuously ciliate 36

34a. Spikelets broadly ovate, length ca. 1.5 x width P. dilatatum

34b. Spikelets ovate, acute, length at least 2.3 x width 35

35a. Spikelets mostly paired, racemes 4-rowed; leaf blades ovate, cordate-based, 6-12 x

longer than wide; racemes 1-5 P. humboldtianum

35b. Spikelets solitary, racemes 2-rowed; leaf blades linear, usually 20-50 x longer than

wide; racemes 8-33 P. fasciculatum

36a. Spikelets 4.3-5.0 mm. long, acute, narrowly elliptical, at least 2.6 x longer
than wide; rare; savannas of General Valley P. lineare

36b. Spikelets less than 4 mm. long, variously shaped 37

37a. Racemes usually 2, conjugate, sometimes a third below 38

37b. Racemes 5 or more, borne along common rachis 42

38a. Plants extensively stoloniferous, growing in wet areas 39

38b. Plants erect or sprawling, but not stoloniferous; plants of various habitats 40

39a. Spikelets glabrous; plants of sea beaches P. vaginatum

39b. Spikelets with pubescent sterile lemmas; moist areas in interior . . P. distichum

40a. Plants arising from thick, woody, scaly rhizomes; spikelets at least 3.5 mm.
long P. notatum

40b. Plants lacking rhizomes; spikelets less than 3 mm. long 41

41a. Spikelets nearly circular, blunt; bracts tan, mottled, or streaked with brown

P. serpentinum

41b. Spikelets ovate, acute; bracts uniformly green or tan P. minus

42a. Spikelets glabrous, solitary, racemes 2-rowed P. reclinatum

42b. Spikelets pubescent or glabrous, paired, racemes 4-rowed 43

43a. Racemes 5-8 in each inflorescence 47

43b. Racemes 15-150 in each inflorescence 44

44a. Culms erect, unbranched; basal leaf sheaths strongly keeled, closely overlap-
ping, forming flat fans; spikelets obovate, ca. 1.5 x longer than wide, purple,

glabrous or nearly so P. turriforme

44b. Culms becoming branched; basal sheaths not strongly keeled; spikelets obo-
vate, ca. 2 x longer than wide, mottled brown and tan, puberulent

P. corypheum
45a. Anthers pink, ca. 0.6 mm. long, sterile; endemic to Las Play it as del Rio

Bebedero P. jimenezii

45b. Anthers purple, 0.8-0.9 mm. long, producing pollen P. standleyi

46a. Plants stoloniferous; spikelets acute, 2.7-3.2 mm. long P. distichum

46b. Plants caespitose; spikelets blunt, less than 2 mm. long P. pumilum

47a. Leaf blades ovate, widest near middle, 5-8 x longer than wide, 1-2.5 cm. broad;

racemes 4-7 cm. long, rachis green; spikelets minutely appressed-pubescent

P. cosiaricense
47b. Leaf blades linear, 1 cm. or less wide; racemes 3-5 cm. long, rachis deep purple;

spikelets glabrous or nearly so, purple P. tonduzii

404 FIELDIANA: BOTANY

Paspalum acuminatum Raddi, Agrost. Bras. 25. 1823. Figure 146.

Duration indefinite, probably perennial; culms long decumbent and rooting from the
lower nodes, often trailing in water; erect portions 35-65 cm. long; culms branching
freely from the decumbent portions; internodes 1.0-1.5 mm. thick, solid, glabrous; nodes
glabrous, not prominent; leaf sheaths shorter or longer than the internodes, glabrous;
ligule a thin membrane, 1-2 mm. long, decurrent on the sheath margins; leaf blades 3-13
cm. long, 4-12 mm. wide, glabrous, ovate, rounded abruptly to the base. Inflorescences
terminal on leafy erect branches, occasionally axillary; peduncles included or exserted to
5 cm.; racemes 1-5 on a short rachis; individual racemes 2.5-5.0 cm. long, borne on a
short peduncle 1-2 mm. long; rachis flat, foliaceous, 2.5-3.0 mm. wide, scabrous on the
margins, bearing a single protruding spikelet on the tip; spikelets alternating in 2 rows;
pedicels short, angular. Spikelets strongly dorsally flattened, ovate 2.5:1, 3.2-4.0 mm.
long, short-acuminate; first glume absent; second glume and lower (sterile) lemma equal,
as long as the spikelet, thin and membranaceous, glabrous, 5-nerved, the lateral nerves
paired and close to the margins; upper (fertile) floret 0.4-0.8 mm. shorter than the outer
bracts, 2.4-3.0 mm. long, obovate 1.7-2.1:1, blunt, strongly dorsally flattened, stramine-
ous, finely roughened, bearing a group of minute cilia at the apex; palea similar and of
equal length, flat; lodicules 2, truncate; anthers 3, purple, 1.0-1.2 mm. long; styles 2,
separate; stigmas purple. Chromosome number n = 20 from two Costa Rican specimens
(reported originally as P. serratum).

Province of Cartago, near Paraiso and Peralta; margins of shallow
ponds; elevations 700-1,100 m. October to March. Louisiana and Texas
to Argentina.

This species and P. serratum H. & C. are very similar and differ
mostly in vegetative vigor. I believe that all of our Central American
specimens represent one species. We have abundant material from
Honduras which matches the Costa Rican specimens in all respects but
general vegetative size and vigor.

Paspalum botterii (Fourn.) Chase, J. Wash. Acad. Sci. 13:436.
1923. Dimorphostachys botterii Fourn., Mex. PI. 2:14. 1881. Figure
147.

Caespitose perennial from a knotty crown; plants 40-110 cm. tall; culms simple or
sparingly branched; internodes 1-3 mm. thick, hollow, glabrous; nodes glabrous or
appressed-bearded, dark; leaf sheaths mostly overlapping, keeled, sparsely to densely
papillose-hispid, collar bearded, overlapping margin ciliate; ligule a thin brown mem-
brane, 1.0-1.5 mm. long; a row of stiff elongate hairs just behind the ligule; larger leaf
blades 17-44 cm. long, 12-24 mm. wide, ovate 9-23:1, the base of the blade usually
cordate, sometimes the lower blades tapering to the base; blades flat, lax, more or less
papillose-pilose on both surfaces; midrib broad, white, keeled beneath. Inflorescences
terminal on leafy culms, 10-32 cm. long; panicle of 3-7 slender racemes borne racemosely
along an angled central rachis; individual racemes ascending, 5-20 cm. long; rachis of
racemes ca. 1.0 mm. wide, flat, the midrib not conspicuous, the margins raised, some-
times ciliate; spikelets paired on each side of the midrib, crowded. Spikelets brownish,
puberulent, 2.2-2.5 mm. long, obovate 1.4-1.6:1, blunt, dimorphic; first glume usually
absent in the terminal spikelet of each pair, present or absent in the lower spikelet; first
glume, when present, narrowly triangular, acute, 1-nerved, up to 1.6 mm. long; second

FIG. 146. Paspalum species. P. candidum: A, inflorescence; B, two views of a
spikelet; P. acuminatum: C, raceme apex with spikelets; P. repens: D, raceme apex
with spikelets; P. reclinatum: E, raceme apex with spikelets.

405

FIG. 147. Paspalum botterii. Inflorescence, spikelets, fertile floret.

406

BURGER: FLORA COSTARICENSIS 407

glume 3-5-nerved, slightly shorter than the fertile floret, which is exposed at the tip;
lower (sterile) lemma as long as the spikelet, 3-5-nerved; upper (fertile) floret 2.2-2.4
mm. long, elliptic-obovate; lemma whitish, finely striate, convex; palea similar, flat;
anthers 3, purple, 0.7-1.0 mm. long; styles 2, separate; caryopsis (one individual) 1.2
mm. long, elliptical 1.2:1, tan. Chromosome number n = 40 from Costa Rican specimens.

Dry savannas, roadsides, forest margins, beaches; occasional in
northern Guanacaste, mostly near the Pacific Coast; sea level to 250 m.
elevation; Playas del Coco, Playa Tamarindo, Puerto Castillo,
Hacienda Palo Verde, Bagaces, Finca la Pacifica. Blooming June to
December. Central Mexico and Guatemala to northwestern Costa
Rica.

This species is similar to P. costaricense, from which it differs in the
longer and narrower leaf blades, pubescent sheaths, the presence of a
first glume, and in chromosome number. The species is named for
Matteo Botteri.

Paspalum candidum (Humb. & Bonpl.) Kunth, Mem. Mus. Hist.
Nat. 2:68. 1815. Reimaria Candida Humb. & Bonpl. in Fliigge,
Monogr. Paspalum 214. 1810. Figure 146.

Sprawling or decumbent annual, the lower portions of the culms prostrate and rooting;
upper portions erect or scrambling or leaning in brush; culms branching freely, espe-
cially from decumbent nodes; internodes 1-2 mm. thick, hollow, thin-walled, glabrous;
nodes dark, often prominent, rarely slightly pubescent; leaf sheaths glabrous or the
overlapping margin finely ciliate; ligule a ciliolate, sometimes puberulent membrane,
1-2.8 mm. long; leaf blades flat, thin, 4-10 cm. long, 8-21 mm. wide, broad-based, ovate
3-5:1, tapering abruptly to an acute apex, glabrous to finely pilose on one or both
surfaces. Peduncles terminal on leafy branches, included or exserted up to 5 cm.; rachis
7-11 cm. long, flattened or triquetrous, glabrous or puberulent, bearing 6-23 ascending
or drooping racemes, these 1-3 cm. long, falling as units from the rachis; racemes pilose
at the base; rachis of racemes flattened, membranaceous, ca. 2 mm. wide, bearing
spikelets from the base but extending beyond the terminal spikelet as a flat point;
spikelets solitary, in 2 rows or occasionally 1 row, on very short pilose pedicels on the
lower (abaxial) surface of the rachis and partially concealed by it. Spikelets whitish or
rarely purplish, ovate-elliptical 1.8-2.1:1, blunt, 2.1-2.4 (2.7) mm. long; first and second
glumes absent; lower (sterile) lemma flat, membranaceous, faintly 3-nerved; as long as
the spikelet; upper (fertile) floret 2.0-2.3 (2.6) mm. long, the lemma smooth and shining,
firm but not rigid; palea similar and of equal length, flat; lodicules 2, truncate; anthers 3,
1.1-1.5 mm. long, yellow, sometimes suffused with purple near the base; styles 2, sepa-
rate; stigmas dark. Chromosome number n = 30 from Central American specimens.

Wet open or partially shaded areas; pastures, road ditches,
cornfields, river banks; elevations 1,200-2,300 m.; common in the
Meseta Central and occasional elsewhere at intermediate elevations in
the mountains, Monteverde, Poas, Irazu, Cordillera de Talamanca.
August to February. Southern Mexico to Chile.

Paspalum candidum is the most common Costa Rican member of

408 FIELDIANA: BOTANY

the informal group Dissecta of Chase, which also includes, in our flora,
P. scabrum, P. prostratum, P. reclinatum, and P. acuminatum. This
group of species are mostly plants of wet habitats, having broad,
foliaceous raceme rachises. Although all of our Central American
chromosome counts for P. candidum indicate n = 30, counts from
Venezuela of plants that are very similar morphologically indicate a
diploid strain with n = 10 exists there.

Paspalum centrale Chase, J. Wash. Acad. Sci. 17:145. 1927. Figure
148.

Plants caespitose, annual in cultivation, 30-85 cm. tall; culms erect or the bases
decumbent, branching from the lower and middle nodes; prophylla 4-6 cm. long; inter-
nodes 1.0-2.5 mm. thick, hollow, thick-walled, glabrous; nodes glabrous; leaf sheaths
keeled, loose, usually longer than the internodes, sparsely to densely papillose-pilose;
ligule a thin brown membrane, 3-4 mm. long; leaf blades linear, 9-24 cm. long, 3-11 mm.
wide, sparsely to densely papillose-pilose; midrib keeled beneath; base slightly wider
than the apex of the sheath; uppermost leaf blade reduced or obsolete. Peduncles ex-
serted up to 5 (12) cm.; inflorescences terminal on leafy branches, 4-12 cm. long, the
common rachis flattened and channeled, glabrous, 1.5-8 cm. long; racemes 1-9, solitary,
racemose along the central rachis; individual racemes 2-6 (9) cm. long, with a tuft of
elongate hairs at the base; rachis 1.0-1.3 mm. wide, zigzag, with a prominent midrib;
spikelets usually solitary, in 2 rows, occasionally some of them paired and the raceme 3-
or 4-rowed. Spikelets 2.0-2.5 mm. long, obovate 1.3-1.5:1, blunt, glabrous, grayish-
green; first glume absent; second glume and lower (sterile) lemma equal, as long as the
spikelet, thin, 4- or 5-nerved, the lateral nerves close to the margin, the sterile lemma
smooth, not wrinkled as in P. plicatulum; upper (fertile) floret very slightly shorter than
the spikelet, chestnut brown, plano-convex; lemma finely striate, the nerves evident;
palea similar, flat; lodicules 2, truncate; anthers 3, yellow or purple-tipped, 0.8-0.9 mm.
long; styles 2, separate; stigmas purple; caryopsis broadly elliptic, ca. 1.8 mm. long,
dark-streaked, with a purplish spot opposite the embryo. Chromosome number n = 30
from Costa Rican and Salvadorean specimens.

Dry pastures, savannas, dry lake bed; sea level to 500 m. elevation;
occasional in northwestern Guanacaste; Hacienda Murcielago, Finca
La Cuera, Finca La Pacifica, Viente Siete, Puntarenas, Atenas.
Blooming from July to October. Coastal El Salvador to Panama.

This species is very similar to P. plicatulum, differing mostly in the
broader rachis of the racemes, narrower spikelets, smooth sterile
lemma, and annual habit.

Paspalum clavuliferum Wright, Anales Acad. Ci. Med. Habana
8:203. 1871. Paspalum pittieri Hack, in Beal, Gr. N. Amer. 2:88. 1896.
Figure 149.

Small caespitose annual in small tufts; plants 10-30 cm. tall, erect; culms branching
from the base and middle nodes; internodes slender, less than 1 mm. thick, hollow,
glabrous; nodes glabrous; prophylla 13-18 mm. long; foliage mostly crowded on the lower

FIG. 148. Paspalum centrale. Inflorescence, spikelets.
409

FIG. 149. Paspalum species. P. clavuliferum: A, blooming plant; B, two views of a
spikelet; P. multicaule: C, portion of a raceme; D, two views of a spikelet; P.
parviflorum: E, inflorescence; F, two views of a spikelet.

410

BURGER: FLORA COSTARICENSIS 411

half of the culms; leaf sheaths more or less papillose-pilose, especially on the margins;
ligule a thin, brown membrane, 0.7-1.0 mm. long; leaf blades flat, 3-9 cm. long, 1.5-3.0
mm. wide, the midrib prominent beneath; surfaces papillose-pilose, prominently ciliate;
uppermost sheath bearing a reduced or abortive blade. Peduncles terminal and axillary
from the upper sheaths, the terminal one very slender, exserted 10-13 cm. beyond the
uppermost developed leaf blade, bearing a bladeless sheath; inflorescence a solitary
raceme or a conjugate pair at the summit of the peduncle, occasionally a third raceme
below them; individual racemes 1-4 cm. long, arcuate, the rachis triquetrous, 0.4-0.5
mm. wide; spikelets paired, 4-rowed, the pedicels less than 0.5 mm. long, puberulent.
Spikelets 1.2-1.4 mm. long, obovate 3:2, blunt; first glume absent; second glume and
lower (sterile) lemma equal, as long as the spikelet, hyaline, 3-nerved; second glume
usually more or less pubescent with minute, capitellate hairs; sterile lemma usually
glabrous or with a few capitellate hairs on the margins; both bracts sometimes with
minute brownish splotches; rarely the spikelets may be entirely glabrous; upper (fertile)
floret about as long as the spikelet, obovate, the lemma and palea stiff, finely striate;
anthers 3, tan, 0.2-0.3 mm. long; caryopsis obovate 4:3, blunt, 0.8 mm. long, tan.
Chromosome number n = 10 from a Costa Rican specimen.

Occasional on dry tuff outcrops, savannas, and sea cliffs, mostly in
northern Guanacaste, rare elsewhere. Hacienda Murcielago, Las
Animas, Playas del Coco, Piedades de San Ramon. August to De-
cember. Southern Mexico to Honduras; Costa Rica to northern South
America to Brazil; West Indies.

Plants in the same collection may have densely pubescent or gla-
brous spikelets. The presence of trapped anthers in spikelets contain-
ing mature caryopses suggests that this species is highly cleistogam-
ous, which may account for the presence of glabrous and pubescent
strains in close proximity.

Paspalum conjugatum Bergius, Acta Helv. Phys.-Math. 7:129.
1762. Figure 150.

Strongly stoloniferous perennial; flowering culms arising from the rooted stolons,
20-100 .cm. long, simple or branching from the lower nodes; internodes 1-3 mm. thick;
glabrous, shrunken in drying; nodes mostly glabrous or rarely appressed-bearded; leaf
sheaths more or less compressed, usually glabrous except for the finely ciliate overlap-
ping margin; sometimes both margins hyaline and glabrous; ligule a hyaline membrane,
0.3-1.5 mm. long; leaf blades 7-20 cm. long, 7-14 mm. wide, the upper surface sparsely to
densely pilose; collar minutely bearded; blades of stolons ovate, blunt, 2-4 cm. long, 5-8
mm. wide. Peduncles terminal on leafy culms, included or exserted up to 7 cm.; inflores-
cence of 2 conjugate slender divergent or reflexed racemes, rarely a third raceme borne
below them on vigorous plants; individual racemes 6-16 cm. long; spikelets solitary, in 2
rows, closely placed; rachis 0.7-0.9 mm. wide, the tip often bearing several minute
abortive spikelets; pedicels 0.3-0.4 mm. long. Spikelets strongly flattened, 1.3-1.9 mm.
long, elliptic-ovate 1.2-1.4:1, scarcely pointed; first glume absent; second glume and
lower (sterile) lemma equal, as long as the spikelet, hyaline, both with 2 marginal
nerves, lacking midribs; second glume finely ciliate with hairs up to 1 mm. long; lower
lemma similar but not ciliate; upper (fertile) floret ca. as long as the spikelet, whitish,

FIG. 150. Paspalum conjugatum. Blooming plant with a stolon, two views of a
spikelet, fertile floret.

412

BURGER: FLORA COSTARICENSIS 413

firm but not rigid, the lemma slightly convex, the palea flat; anthers 3, yellow, some-
times purple-splotched, ca. 0.6 mm. long; styles 2, separate; stigmas dark; caryopsis
1.0-1.1 mm. long, elliptical 1.3:1, tan, the persistent styles reflexed along the sides of the
caryopsis. Chromosome number 2n = 40 from Costa Rican specimens.

A common weed in moist pastures, road ditches, marshes, beaches,
cafetales, etc. On both Pacific and Caribbean slopes, from sea level to
1,200 m. elevation. Blooming yearlong. Southern United States to
Argentina; naturalized in the tropics of the Old World.

This species is weedy and aggressive in wet pastures. It is almost
universally regarded with disfavor and said to be rejected by livestock
and to increase under grazing conditions. Common name Turvurd or
Turbard. Our slides showed no pairing in meiosis, and it may be that
the species, which is highly uniform in aspect, is completely apomictic.
Several minor variants have been described, but my measurements
show complete intergradation in spikelet and leaf blade size. Such
variation as occurs appears to be related to fertility and moisture
supply.

Some authors have ascribed the name of this species to Swartz, on
the basis that the original publication by Bergius was a phrase name.
However, Bergius gives the name as "PASPALUM (conjugatum)
spicis conjugatis." His usage differs from that of Linnaeus, who placed
the "trivial" name in the page margin, whereas Bergius placed it after
the generic name but in parentheses. His intent seems clear, and there
is no reason to reject his authorship. The identity of the plate accom-
panying the description is conclusive.

Paspalum convexum Humb. & Bonpl. in Fliigge, Monogr. Pas-
palum 175. 1810. Figure 151.

Caespitose annual, the culms prostrate to ascending, 10-60 cm. long, the plants often
mat-forming; culms branching freely from base and lower nodes, the branches some-
times fascicled; culms 1.0-1.5 mm. thick, the internodes usually shrunken in drying,
glabrous; nodes glabrous; leaf sheaths loose, keeled, glabrous to densely papillose-pilose;
ligule a thin brown membrane, 1-2 mm. long; leaf blades flat, rounded to the base, the
midrib prominent beneath, usually 5-18 cm. long, 5-9 mm. wide, from densely papillose-
pilose to nearly glabrous; uppermost blade usually very reduced. Peduncles included or
exserted up to 7 cm.; inflorescences terminal on the main culm or on leafy branches, 4-8
cm. long, composed of 1-5 solitary racemes borne along a central rachis; individual
racemes 3-5 cm. long; rachis ca. 1 mm. wide, with a tuft of long white hairs at its base;
spikelets crowded, usually paired on each side of the midrib, in occasional individuals one
spikelet of the pair abortive and the raceme thus appearing 2-rowed. Spikelets 1.8-2.5
mm. long, obovate to subcircular 1.3-1.0:1, strongly plano-convex, the depth nearly
equal to the width; first glume absent (present in one abnormal individual); second glume
nearly as long as the spikelet, 5-7-nerved; lower (sterile) lemma as long as the spikelet,
5-nerved, both bracts very thin and membranaceous, bearing scattered fine appressed

FIG. 151. Paspalum convexum. A, blooming plant; B, portion of a raceme; C, two
views of a spikelet.

414

BURGER: FLORA COSTARICENSIS

415

hairs; occasional individuals have a rigid, convex, shiny brown sterile lemma, similar to
the fertile lemma; upper (fertile) floret nearly as long as the spikelet, the lemma very
strongly convex, shiny, striate, chestnut brown; palea similar, flat; lodicules 2, truncate;
anthers 3, purple, 0.8-1.1 mm. long. Chromosome numbers n = 10, 16, 20, 24 from
Central American and Venezuelan specimens.

This species is a weedy, sprawling annual of disturbed sites, road-
sides, ditches, savannas, sea cliffs; common at lower elevations in
northwestern Guanacaste and in the lower General Valley; occasional
in the western portions of the Meseta Central. Elevations sea level to
600 m., rarely to 1,400 m. Blooming mostly July to January. Northern
Mexico to Brazil; West Indies.

This species shows considerable variation in size, pubescence, and
inflorescence and spikelet characteristics. It also has meiotic and
chromosomal abnormalities. Paspalum convexum was assigned to the
informal group Plicatula by Chase, along with P. plicatulum and
P. centrale.

Paspalum corypheum Trin., Gram. Pan. 114. 1826. Figure 152.

Caespitose perennial from hard knotty crowns; culms 65-400 cm. long, erect or
scrambling in brush, branching freely when older; internodes 2-4 mm. thick, hollow,
glabrous or appressed-pilose, especially below the nodes; nodes densely bearded with
appressed or spreading hairs; leaf sheaths keeled, mostly overlapping, the lower ones
pustulose-hispid, the upper ones less pubescent; overlapping margin ciliate; collar con-
spicuously bearded; ligule a firm brown membrane, 1.0-4.5 mm. long; leaf blades flat,
usually 30-50 cm. long, 10-13 mm. wide, tapered to a narrow or cordate base; a dense tuft
of long, glassy hairs just behind the ligule, surfaces glabrous or puberulent, midrib
conspicuous, white, edges strongly scabrous, sometimes papillose-ciliate; uppermost
sheath bladeless or with a short abortive blade. Peduncles terminal on leafy branches,

FIG. 152. Paspalum corypheum. Portion of inflorescence, two views of a spikelet,
fertile floret.

416 FIELDIANA: BOTANY

exserted up to 18 cm.; inflorescence 8-24 cm. long, of 15-44 racemes borne singly or
whorled along a scabrous-angled central rachis; individual racemes 5-13 cm. long, the
rachis ca. 0.5 mm. wide, bearing a tuft of stiff white elongate hairs at its base, sometimes
a few scattered hairs along its length; spikelets paired, in 2 rows on each side of the
midrib. Spikelets 2.0-2.5 mm. long, obovate ca. 2:1, acute; first glume absent; second
glume nearly as long as the spikelet, 3-nerved, brownish and speckled with fine
papillose-based hairs; lower (sterile) lemma similar, 3-nerved, as long as the spikelet,
glabrous or sparsely hairy; upper (fertile) lemma nearly as long as the spikelet, whitish,
finely striate; palea similar, flat; lodicules 2, truncate; anthers 3, deep purple, 1.2-1.4
mm. long; styles 2, separate; stigmas deep purple. Chromosome number n = 30 from a
specimen from Honduras.

Dry, rocky Curatella-Byrsonima savannas, from the La Cruz area
to Canas; elevations 75-300 m. July to August. Belize and Honduras;
Costa Rica and Panama and northern South America to Brazil;
Trinidad.

Our specimens apparently represent this species in an early bloom-
ing stage, before branching has occurred. Chase indicates that the
plants may become much longer and more branched with age, and that
the panicle branches may droop. The spikelets of P. corypheum are
rather similar to those of P. botterii, but lack any evidence of the first
glumes present in the latter species.

Paspalum costaricense Mez, Fedde, Repert. Sp. Nov. 15:72. 1917.
Figure 153.

Caespitose perennial, the small clumps arising from a knotty crown; culms un-
branched, 30-75 cm. tall, 2-3 mm. thick, hollow, glabrous; nodes glabrous; leaf sheaths
overlapping, glabrous except for the finely ciliate overlapping margin; ligule a thin
brown membrane, 3-5 mm. long; leaf blades thin, flat, lax, ovate-obovate 5-8:1, usually
10-18 cm. long, 15-30 cm. wide, abruptly acuminate; midrib white, prominent; base
rounded; margins short-ciliate; surfaces usually glabrous, rarely with a few short hairs
near the margins; terminal sheath with a much reduced or abortive blade. Peduncles
solitary, terminal on leafy culms, exserted up to 9 cm. from the terminal sheath; inflores-
cence 6-13 cm. long, an open raceme of 5-7 solitary, ascending racemes borne singly
along a flattened rachis; individual racemes 4-7 cm. long, their rachis flattened, 0.6-1.0
mm. wide, with a low midrib; base of each raceme with a tuft of elongate glassy hairs;
spikelets paired, in 2 rows on each side of the midrib; pedicel of the terminal spikelet of
each pair 1.0-1.5 mm. long, that of the lower spikelet ca. half as long. Spikelets 2.4-2.8
mm. long, elliptical-obovate 1.7-2.0:1, barely acute; first glume absent; second glume and
lower (sterile) lemma equal, as long as the spikelet, very finely appressed-pubescent to
nearly glabrous, thin, 3-5-nerved, brownish or purple-splotched; upper (fertile) floret
elliptic-obovate, 2.2-2.5 mm. long, stramineous, finely striate; lemma convex; palea
similar, flat; anthers 3, 0.9-1.0 mm. long, dark; styles 2, separate; stigmas dark; cary-
opsis elliptic 1.4:1, tan, 1.9 mm. long; embryo large, a brownish stripe at the base of the
caryopsis opposite the embryo. Chromosome number n = 30 from a Costa Rican
specimen.

Moist, partially shaded sites; roadsides, brush, banana fields.

FIG. 153. Paspalum costaricense. A, plant base; B, culm and inflorescence; C, two
views of a spikelet.

417

418 FIELDIANA: BOTANY

Meseta Central, 1,100-1,700 m. elevation; San Jose area, Aserri, Tar-
baca, Copey. The type specimen was collected near the San Jose Rail-
road Station. Apparently blooming yearlong, but most specimens have
been collected from June to August. Guatemala, Honduras, El Sal-
vador, Costa Rica.

The very broad, lax leaf blades of this species are distinctive.

Paspalum decumbens Swartz, Prodr. Veg. Ind. Occ. 22. 1788.

Duration indefinite, probably perennial; plants decumbent, forming mats, rooting
from the nodes of prostrate portions; erect leafy branches 15-40 cm. long; prophylla 10-20
mm. long; internodes 1.0-1.5 mm. thick, hollow, glabrous; nodes often ciliate; leaf
sheaths keeled, finely ciliate on the overlapping margin, the surface glabrous or softly
pilose; ligule a thin brown membrane, 0.3-0.5 mm. long, sometimes forming an auricle;
leaf blades ovate 4.5-10:1, acuminate, 3-7 cm. long, 7-12 mm. wide, flat, the midrib
prominent beneath; base cordate, contracted into a short pseudopetiole; margins ciliate,
surfaces more or less pilose. Peduncles 1-6 from the uppermost sheath, very slender,
exserted up to 7 cm., more or less pilose, especially toward the apex; inflorescence a
solitary arcuate raceme, 7-30 mm. long; rachis ca. 0.5 mm. wide, its margins slightly
raised and incurved, sometimes bearing scattered elongate hairs; pedicels scabrous, the
members of each pair equal, forked from the base; spikelets paired, in 4 rows, crowded.
Spikelets 1.5-1.7 mm. long, glabrous, broadly obovate 1.2-1.4:1, strongly plano-convex;
first glume a broad, truncate nerveless scale, 0.2-0.4 mm. long; second glume broadly
ovate, blunt, 1.1-1.2 mm. long, 3- or rarely 5-nerved, the lateral nerves not close to the
margins; lower (sterile) lemma as long as the spikelet, 3-nerved, the lateral nerves
marginal; lemma enclosing a well-developed, 2-nerved flat palea 1.1-1.4 mm. long; fertile
lemma 1.4-1.5 mm. long, the upper half of the back exposed; surface striate, whitish;
palea similar, flat; lodicules 2, truncate; anthers 3, 0.6-0.8 mm. long, usually white; styles
2, separate; caryopsis suborbicular, ca. 0.9 mm. long, plano-convex, tan. Chromosome
number n = 10 from Costa Rican specimens.

Moist forests and forest margins, brush, riverbanks, roadsides and
ditches, road embankments; sea level to 1,200 m. elevation; common in
moist areas on both Pacific and Caribbean slopes; absent from drier
parts of Guanacaste. Blooming yearlong. Guatemala to Brazil and
Bolivia; West Indies.

This rather weedy species is highly unusual in its genus by possess-
ing not only first glumes but a well-developed palea in the sterile
lemma. This species is most closely related in our flora to P. nutans, a
tetraploid with longer racemes and larger spikelets.

Paspalum dilatatum Poir., Lam. Encycl. 5:35. 1804.

Caespitose perennial; culms arising from short, densely scaly rhizomes; plants up to
175 cm. tall, the culms ascending and arching, simple or rarely branched from lower
nodes; prophylla up to 15 cm. long, prominent; internodes oval, 2-4 mm. thick, hollow,
glabrous; nodes swollen, sparsely appressed-pubescent; leaf sheaths longer or shorter
than the internodes, loose, keeled, the lowermost ones more or less appressed-pilose
with weak hairs; upper sheaths glabrous; margin glabrous; ligule a firm brown mem-

BURGER: FLORA COSTARICENSIS 419

brane, 1-5 mm. long; leaf blades linear, up to 52 cm. long, tapering to a narrow base, up
to 10 mm. wide, glabrous except for a few long hairs on the basal margins; midrib keeled
below, white; blades flat, folded near the base. Peduncles slender, solitary, exserted up
to 30 cm.; inflorescence usually of 3-5 solitary racemes borne racemosely along a flat-
tened rachis up to 9 cm. long; individual racemes arcuate, drooping, 3-10 cm. long, with a
tuft of long silky hairs at the base; rachis 1.0-1.3 mm. wide; spikelets paired in 2 rows on
each side of the low midrib. Spikelets strongly dorsally flattened, ovate 1.5-1.6:1, acute,
3.1-3.7 mm. long; first glume absent; second glume and lower (sterile) lemma herba-
ceous, 5-7-nerved, both exceeding the upper (fertile) floret and flattened beyond its tip;
second glume slightly longer than the sterile lemma, bearing a prominent marginal
fringe of soft, fine hairs; sterile lemma similar but with fewer cilia; surfaces of both
bracts with scattered fine appressed hairs; upper (fertile) floret broadly ovate 1.2-1.3:1,
blunt, the lemma stramineous, finely striate, strongly flattened; palea similar, flat;
lodicules 2, truncate; anthers 3, 0.9-1.4 mm. long, deep purple; styles 2, separate; stig-
mas purple; caryopsis (one seen) 1.3 mm. long, elliptical, tan, with a longitudinal brown
mark opposite the embryo. Chromosome number 2n = 50 determined from Costa Rican
collections.

Roadsides, pastures, meadows; occasional on the volcanoes of the
Cordillera Central, 1,900-2,600 m. elevation; Vara Blanca, Volcan
Poas, Volcan Turrialba. Native to southern South America and prob-
ably introduced to Costa Rica as a forage plant; now widely distributed
as a wild and cultivated plant in the southern United States and in
many other warm temperate and tropical parts of the world. Meiosis in
our plants was irregular and the plants are apomictic.

Paspalum distichum L., Syst. Nat. ed. 10, 2:855. 1759. P. pas-
paloides (Michx.) Scribn., Mem. Torrey Bot. Club 5:29. 1894. Figure
154.

Extensively rhizomatous and stoloniferous perennial; erect portions of the culms 12-30
cm. long, simple; internodes up to 2 mm. thick, solid, glabrous; nodes appressed-
pubescent, somewhat swollen; leaf sheaths loose, keeled, glabrous to papillose-pilose,
especially at the nodes, throat, and collar; ligule a thin brown truncate membrane,
0.4-1.5 mm. long; leaf blades 2.5-10.0 cm. long, 3-6 mm. wide, usually glabrous except for
the papillose-ciliate lower margins, rarely finely pilose above, often folded. Peduncles
included or exserted up to 4 cm.; inflorescences terminal on the ascending or erect culms,
consisting usually of 2 racemes, the lower one sessile or subsessile, the upper one borne
on a rachis 5-10 mm. long; sometimes a third raceme borne below the terminal pair;
individual racemes 1-6 cm. long, the flattened rachis 1-2 mm. wide, with a prominent
midrib; a solitary spikelet borne at the tip of the rachis; spikelets solitary, in 2 rows.
Spikelets very short-pedicellate, 2.7-3.2 mm. long, obovate 1.9-2.4:1, strongly dorsally
flattened; first glume absent or, if present, deltoid to linear, 1-nerved, up to 1.9 mm.
long, highly variable in one inflorescence; second glume and lower (sterile) lemma equal,
as long as the spikelet, 3-5-nerved; glume glabrous, the lemma appressed-pubescent
with fine hairs; sterile lemma enclosing a rudimentary, usually bifurcate, membrana-
ceous palea, up to 1 mm. long; upper (fertile) floret ca. 2.7 mm. long, the lemma flat-
tened, whitish, finely striate, firm but not rigid; palea similar, flat; lodicules 2, truncate;
anthers 3, deep purple, 1.3-1.5 mm. long; styles 2, separate; stigmas deep purple.
Chromosome number n = 30 from Costa Rican specimens.

FIG. 154. Paspalum species. P. distichum: A, two views of a spikelet; P. vaginatum:
B, blooming culm; C, rhizomatous base; D, two views of a spikelet.

420

BURGER: FLORA COSTARICENSIS

421

Occasional, wet roadside ditches, wet pastures, margins of irrigation
ditches; mostly at intermediate elevations in the interior, from 1,000-
1,500 m. elevation. Monteverde, Birri, Meseta Central, Cartago, Juan
Vinas, Liverpool. June to November. Southern United States, north-
ward to New Jersey and Washington near the coasts, southward to
Argentina and Chile; West Indies; Eastern Hemisphere in warm
areas.

This species is confined mostly to the interior of Costa Rica, whereas
the very similar P. vaginatum occurs only on the coasts. Tetraploids
(n = 20) have been reported from other regions. Recent nomenclatural
arguments as to the identity of the Linnean type material have been
advanced by Fosberg (Rhodora 78:84. 1976) and Guedes (Taxon
25:512-513. 1976), who come to contradictory conclusions as to the
name of this taxon. I have followed Guedes, who uses the name in the
traditional sense.

Paspalum fasdculatum Willd. in Fliigge, Monogr. Paspalum 69.
1810. Figure 155.

Tall, coarse stoloniferous perennial, forming dense colonies; bases trailing and rooting
up to 5 m.; erect culms simple or sparingly branched, to 3 m. tall; internodes glabrous,
3-7 mm. thick, solid; nodes swollen, the sheath base covering the node glabrous to
copiously bearded; leaf sheaths shorter or longer than the internodes, glabrous or

FIG. 155. Paspalum fasdculatum. Inflorescence, two views of a spikelet, fertile
floret.

422 FIELDIANA: BOTANY

pustulose-hispid, especially near the base and apex; overlapping margin long-ciliate with
fine hairs; ligule a firm brown membrane, 0.3-0.7 mm. long, a row of stiff white hairs, 3-4
mm. long behind it; leaf blades flat, keeled beneath, 20-70 cm. long, 10-20 mm. wide;
surfaces glabrous to sparsely pilose, often with elongate hairs on the throat, collar, and
behind the ligule. Peduncles solitary, terminal on leafy culms; exserted up to 6 cm. from
the nearly bladeless uppermost sheath; inflorescence 8-18 cm. long, 7-15 cm. wide, a
rather dense fan-shaped panicle of 8-33 racemes borne racemosely along a short, angled
rachis 5-11 cm. long; racemes crowded, ascending or later drooping, 7-16 cm. long, the
lower ones longer than the upper; base of each raceme bearing a tuft of stiff white
elongate hairs; rachis flat, 0.8-1.4 mm. wide, with a low midrib; spikelets solitary, the
raceme 2-rowed. Spikelets 3.7-4.6 mm. long, ovate 2.3-2.7:1, acuminate, strongly dor-
sally flattened; first glume a minute nerveless scale or commonly absent; second glume
and lower (sterile) lemma equal, as long as the spikelet; second glume 3-5-nerved, the
margins bearing a fringe of fine silky hairs; sterile lemma similar, 3-7-nerved, the mar-
gins very sparsely ciliate; upper (fertile) floret 3.3-4.3 mm. long, ovate 2.4-3.1:1, acumi-
nate, strongly dorsally flattened, the lemma finely striate; palea similar, flat; lodicules 2,
truncate; anthers 3, orange, 2.2-2.8 mm. long; styles 2, separate; stigmas deep purple;
caryopsis elliptical 2:1, brownish, with a dark line two-thirds as long arising from the
base opposite the embryo. Chromosome number n = 10 from Costa Rican specimens.

Roadsides, marshes, open weedy sites, pastures, mostly in moist
areas; sea level to 600 m. elevation, rarely higher; near the Pacific and
Caribbean Coasts; San Jose area; Turrialba; Laguna de Arenal.
Blooming July to November. Southern Mexico to Argentina and
Ecuador. Common name: Gamalote.

Paspalum humboldtianum Flugge, Monogr. Paspalum 67. 1810.
Figure 156.

Rhizomatous perennial, forming tufts; culms 59-120 cm. long, erect to decumbent;
rhizomes abundant, scaly; culms branching mostly from the lower nodes; internodes
glabrous, hollow, 1.5-2.0 mm. thick; nodes not prominent, glabrous or appressed-
bearded; lower leaf sheaths overlapping, the upper shorter than the internodes; foliage
aggregated on the lower parts of the plants; overlapping margin of the sheaths ciliate,
the surfaces from nearly glabrous to papillose-hirsute or hispid, especially toward the
apex; ligule a thin brown membrane, 1.8-3.8 mm. long; leaf blades 7-14 cm. long, 8-17
mm. wide, flat, more or less appressed-pilose to nearly glabrous; sometimes papillose-
ciliate with long hairs; base of blade broad, subcordate; tip acuminate; uppermost leaf
blade much reduced. Inflorescences terminal on leafy culms; peduncle exserted 6-12 cm.;
panicle 5-11 cm. long, composed of 1-5 ascending racemes borne on a common rachis up
to 7 cm. long; rachis of individual racemes 4-7.5 cm. long, the rachis 1.0-1.5 mm. wide,
with a wide white midrib and flattened green margins; tip naked or bearing abortive
spikelets; spikelets overlapping, in 2 or 4 rows in the same raceme, one of each pair
longer-pedicellate than the other. Spikelets dorsally flattened, 3.0-3.7 mm. long, ovate
2.3-2.4:1, acute, prominently white-ciliate; first glume absent; second glume as long as
the spikelet, 3-nerved, the lateral nerves marginal, thickened, bearing a dense row of
radiating, pustulose-based white cilia 2-3 mm. long; surface glabrous or sometimes pu-
berulent; lower (sterile) lemma 3.0-3.5 mm. long, 3-nerved, narrower than the glume,
ovate 3:1, glabrous or scabrid toward the tip; upper (fertile) lemma 2.3-2.7 mm. long,
elliptic-obovate 2.3:1, whitish, smooth and shining, firm, not rigid; palea similar and of

FIG. 156. Paspalum humboldttanum. Inflorescence, two views of a spikelet, fertile
floret.

423

424 FIELDIANA: BOTANY

equal length; lodicules 2, truncate; anthers 3, purple, 1.5-2.2 mm. long; styles 2, sepa-
rate; stigmas purple.

Rare or overlooked; dry tuff savannas, steep dry road embank-
ments. Liberia, Nuestro Amo, San Rafael de Cartago, San Juan
Norte, Catarata Los Novios, Boruca savannas. August to November.
Mexico to Argentina.

Paspalum humboldtianum was included in the subgenus Ceresia by
Chase, along with P. pectinatum and P. stellatum in our flora. It
differs from the other species in its much narrower rachis. Chase
states that the rachis is 2-3 mm. wide, but our material never has a
rachis wider than 1.5 mm.

Paspalum jimenezii Chase, Contr. U.S. Natl. Herb. 28:159. 1929.
Figure 157.

Rhizomatous perennial; rhizomes extensive, mostly buried in mud; ascending portions
of the culms up to 20 cm. long, simple; branching abundant from the rhizomes; inter-
nodes up to 1 mm. thick, hollow, glabrous; nodes appressed-pilose; leaf sheaths keeled,
glabrous; overlapping margins of sheaths finely ciliate; ligule a thin membrane, 0.2-0.3
mm. long; leaf blades flat, mostly 4.5-8 cm. long, 4-6 mm. wide, glabrous, the midrib
prominent beneath, the tip acute, collar pilose-bearded. Peduncle included in the up-
permost sheath; inflorescences terminal on leafy culms, 2.5-3.0 cm. long, of 3-8 diverging
racemes borne on a short common rachis; individual racemes 2.0-2.5 cm. long; rachis 0.5
mm. wide, flat; pedicels 0.3-0.4 mm. long; spikelets borne in 2 rows. Spikelets 1.4-1.5
mm. long, ovate 5:3, acute; first glume absent; second glume and lower (sterile) lemma
equal, as long as the spikelet, glabrous, hyaline, each with 2 marginal nerves, the
midribs absent; upper (fertile) floret as long as the spikelet, the lemma faintly striate,
stiff but not rigid; palea equal, flat; anthers 3, pinkish, 0.6 mm. long; styles 2, separate;
stigmas purple.

Paspalum jimenezii is a sterile clone, reproducing only by rhizomes.
It occurs on the muddy banks of the tidal Rio Bebedero, at a locality
known as Las Playitas, on Hacienda Taboga, southwest of Canas. It
was first collected at this locality in 1913 by Jimenez, and we found it
there again in 1969. At that time, it formed a sizable population on the
banks of the river. Chromosome counts made from cytological fixations
showed that the chromosome number is 2n = 30, and that meiosis is
highly irregular. No viable pollen is formed, and both our collections
and the type specimen show collapsed, empty, and shrunken pollen
grains. No other specimens of P. jimenezii than the two cited below
are known. A third specimen from Panama in US, so named by Chase,
has normal fertile pollen and is probably of different origin. It is prob-
able that P. jimenezii is the result of a cross between the similar P.
standleyi (n = 20) and a diploid species, possibly P. orbiculatum. I
revisited the type locality in 1976, but was unable to find the original
colony. Extensive pasture improvement had been carried out at the

FIG. 157. Paspalum jimenezii. A, blooming plant with rhizomatous base; B, raceme
from rachis side; C, raceme from spikelet side; D, spikelet.

425

426 FIELDIANA: BOTANY

site, and it is possible that the clone had been destroyed. Its long
persistence at this site probably occurred because the plants were able
to cope with tidal mud deposition by their extensive production of
rhizomes. A further account of the cytology is in Pohl & Davidse
(1971).

Guanacaste: Las Playitas del Rio Bebedero, Hda. Taboga, 5 January
1913, 0. Jimenez 742 (holotype in US, duplicate in CR); same location:
16 January 1969, Pohl & Davidse 11660. Jimenez stated that Las
Playitas was at an altitude of 50 m. This is certainly an error, as the
Rio Bebedero is tidal at that point.

Paspalum lineare Trin. , Gram. Pan. 99. 1826.

Densely caespitose perennial in small hard clumps; bases of the culms covered with old
sheaths (basal foliage often burned off); culms slender, seldom branched, 1.0-1.5 mm.
thick, hollow, glabrous, 40-110 cm. tall; nodes densely upwardly bearded with appressed
white hairs; leaf sheaths pilose to glabrous, with a few elongate hairs around the throat;
basal leaf blades up to 60 cm. long, the culm blades much shorter, the uppermost one
much reduced; ligule a short firm membrane, 0.4-1.0 mm. long, decurrent on the sheath
margins; auricular hairs long, conspicuous, papillose-based; leaf blades 1.0-1.5 mm.
wide, laterally flattened, the upper surface reduced to a minute groove by the union of
the left and right sides of the blade. Peduncle exserted 10-15 cm. , glabrous except for the
bearded apex; racemes usually 2, 4-6 cm. long, ascending, the lower one sessile, the
upper one a rachis 4-10 mm. long; a tuft of long, silky hairs at the base of each raceme;
rachis of the racemes zigzag, 0.4-0.7 mm. wide, the basal 4-6 mm. naked; spikelets few,
rather distant, solitary in 2 rows; pedicels up to 2 mm. long. Spikelets 4.3-5.0 mm. long,
narrowly elliptical 2.6-2.9:1, acute; first glume absent; second glume and lower (sterile)
lemma equal, 5-nerved, firm, glabrous except for 2 tufts of minute hairs on the basal
margins of the glume; upper (fertile) floret rigid, stramineous, papillose-striate, 3.8-4.3
mm. long, elliptical 2.7-2.9:1, acute; palea similar, slightly concave; lodicules 2, truncate;
anthers not seen; styles 2, separate; stigmas purple; caryopsis elliptical 2.0-2.4:1, ca. 2.6
mm. long, tan, with a red line half its length opposite the embryo.

Rare, dry savannas. Two old specimens are known from Costa Rica.
They are: Savanes de Cabagra, March 1892, Tonduz 6548; Savanes de?
Tigre?, Tonduz 6544- Southern Mexico (Chiapas) and Belize to Argen-
tina; Cuba.

Paspalum microstachyum Presl, Rel. Haenk. 1:215. 1830. Figure
158.

Duration indefinite, said to be annual; plants caespitose, but the bases of the culms
sometimes decumbent and rooting; culms 15-85 cm. long, branching from the base and
lower nodes; prophylla2-6 cm. long; internodes 1-2.5 mm. thick, hollow, glabrous, green
or purple; nodes glabrous, dark, not prominent; leaf sheaths longer or shorter than the
internodes, glabrous to papillose-pilose; ligule a thin brown membrane, 0.5 mm. long,
sometimes with longer hairs behind it; leaf blades flat, ovate 5-10:1, acuminate, 4-23 cm.
long, 6-23 mm. wide, more or less papillose-pilose on the upper or both surfaces; bases of
upper and middle blades strongly cordate; lower blades tapering to a narrow base.

FIG. 158. Paspalum microstachyum. Inflorescence, two views of a spikelet, fertile
floret.

427

428

FIELDIANA: BOTANY

Inflorescences mostly terminal, sometimes a smaller secondary one axillary from the
uppermost sheath; panicle elongated, 8-14 cm. long, slender, of up to 30 solitary, paired,
or whorled spreading or drooping racemes borne along a slender angled rachis; indi-
vidual racemes 5-30 mm. long; central rachis and those of the racemes bearing scattered
elongate weak hairs, to 4 mm. long; pulvini with tufts of hairs; rachis of racemes flat,
0.6-0.8 mm. wide, bearing paired spikelets in 2 rows on each side of the midrib; pedicels
slender, the longer one of each pair 1.5-2.0 mm. long, the shorter about a third as long.
Spikelets 1.4-1.6 mm. long, elliptical-obovate 1.5-1.6:1, finely puberulent, the bracts
whitish or rusty-spotted, hyaline; first glume absent; second glume slightly shorter than
the spikelets, 3- or rarely 5-nerved; lower (sterile) lemma as long as the spikelet, 3-
nerved; upper (fertile) floret elliptic-obovate, whitish, striate, 1.4 mm. long; lemma
rather strongly convex; palea similar, flat; anthers 3, purple, 0.4 mm. long; caryopsis
elliptical 1.4:1, opalescent, ca. 1.0 mm. long. Chromosome number n = 10 from Costa
Rican and Venezuelan specimens.

Occasional, roadsides, cut-over rain forests, mostly at elevations
below 100 m.; northern Guanacaste to Puntarenas; Rio La Vieja,
Puerto Viejo, Hacienda de Zent, Atenas, Matina. Guatemala to Peru
and Brazil.

This rather weedy species appears to have no close relatives in our
flora.

Paspalum minus Fourn., Mex. PI. 2:6. 1881. Figure 159.

FIG. 159. Paspalum species. P. mimis (left): inflorescence, two views of a spikelet,
fertile floret; P. notatum (right): inflorescence, two views of a spikelet, fertile floret.

BURGER: FLORA COSTARICENSIS 429

Rhizomatous perennial, forming flat mats; rhizomes thick, woody, scaly; culms un-
branched, 27-53 cm. long, mostly lying on the ground; internodes 1-2 mm. thick, gla-
brous, often collapsed in dry specimens and possibly solid; nodes dark, shrunken,
glabrous; foliage yellowish green; leaf sheaths keeled, the lower ones longer than the
internodes, the foliage aggregated near the base; upper sheaths shorter than the inter-
nodes; sheaths glabrous except for papillose-based cilia on the overlapping margin,
especially near the apex; ligule a thin brownish membrane, 0.2-0.7 mm. long, backed by
a dense row of stiff erect hairs ca. twice as long; dewlap conspicuous, yellowish; leaf
blades as wide as the sheath apex, the lower ones 8-14 cm. long, 4-7 mm. wide, the
midrib conspicuous beneath; blade folded near the base; lower margins and occasionally
the upper surface bearing scattered elongate pustulose-based hairs up to 8 mm. long; tip
abrupt. Peduncles included in the uppermost bladeless sheath or exserted up to 3 cm.;
inflorescences terminal on the culms, solitary, consisting usually of a pair of conjugate
equal racemes, rarely a third one a short distance below; a pair of stiff deltoid bracts and
a tuft of silky hairs borne at the apex of the peduncle between the racemes; individual
racemes 4-7 cm. long; rachis 0.8-1.0 mm. wide, zigzag, usually bearing a solitary spikelet
at its tip; pedicels ca. 0.5 mm. long. Spikelets solitary in 2 rows, 2.4-2.5 mm. long,
ovate-obovate, blunt-pointed, glabrous, green; first glume absent; second glume and
lower (sterile) lemma equal, as long as the spikelet; second glume 3- or rarely 5-nerved;
sterile lemma usually 3-nerved; nerves marginal; upper (fertile) floret 2.1-2.2 mm. long,
elliptical or obovate, whitish, striate; lemma more convex than in P. notatum; palea
similar, flat; anthers 3, purple, 0.9-1.2 mm. long; caryopsis 1.4 mm. long, elliptical 1.4:1,
tan; styles reflexed along the upper edges of the caryopsis.

Open, often disturbed areas; savannas, roadsides, pastures; grassy
sea beaches; sea level to 750 m. elevation, rarely higher. Common in
Guanacaste, scattered elsewhere; San Jose, Turrialba, General Valley,
Puntarenas, Golfito, Barro de Colorado, Tortugero. June to January.
Southern Mexico to Peru and Paraguay; West Indies.

The plants may be often overlooked because of their mat-forming
habit. Our single chromosome count from Costa Rica (Pohl 12954) is n
= 25, an anomaly in a genus with a basic number of x = 10. Previous
counts for this species indicated n = 10 or 20. Paspalum minus is very
similar in spikelets and inflorescence to P. notatum, differing in
spikelet size and growth habit. Paspalum pumilum is also similar, but
has yet smaller spikelets and lacks the woody rhizomes common to
both of the above species.

Paspalum multicaule Poir., in Lam. Encycl. Suppl. 4:309. 1816.
Figure 149.

Caespitose annual in small tufts; plants (5) 12^40 cm. tall; culms branching from the
base or lower nodes; internodes glabrous, ca. 1 mm. thick, hollow, thick-walled;
prophylla up to 2 cm. long; nodes glabrous; foliage mostly on the lower half of the culms;
sheaths keeled, nearly glabrous to papillose-hispid, the margins softly ciliate; ligule a
thin brown membrane, 0.3-0.5 mm. long; leaf blades mostly 4-12 cm. long, 1.5-2.5 mm.
wide, conspicuously papillose-hispid on both surfaces with hairs up to 5 mm. long; sur-

430 FIELDIANA: BOTANY

face finely puberulent between the long hairs; midrib prominent beneath; margins of
blades becoming revolute; uppermost leaf sheath bladeless. Inflorescences terminal on
the main culm or on leafy branches; peduncle included or exserted from the bladeless
sheath up to 5 cm.; inflorescence usually a conjugate pair of spreading racemes, these 1-4
cm. long; rarely a third raceme is borne just below the pair; a pair of minute bracts occur
at the apex of the peduncle between the racemes; rachis of racemes silky at the base,
flattened, with a medial ridge, often zigzag, 0.5-0.7 mm. wide; spikelets in 2 rows;
pedicels less than 0.5 mm. long. Spikelets yellowish, nearly circular, 1.1-1.5 mm. long,
strongly plano-convex; first glume absent; second glume and lower (sterile) lemma equal,
as long as the spikelet; second glume 2- or rarely 3-nerved, hyaline, sparsely to densely
covered with globular hairs; lower (sterile) lemma 2-nerved, glabrous or with a few
marginal globular hairs; upper (fertile) floret about as long as the thin outer bracts;
lemma firm, finely striate, its margins sharply inflexed and forming a conspicuous rim
around the palea; anthers 3, purple, 0.3 mm. long; styles 2, separate, stigmas emerging
laterally from the spikelet; apex of the ovary and the mature caryopsis with a purple
splotch; caryopsis nearly circular, 0.8-1.0 mm. long, strongly plano-convex, whitish.
Chromosome number n = 10 from Costa Rican and Venezuelan specimens.

Dry rocky savannas, tuff outcrops; northern Guanacaste; Rincon de
la Vieja, Hacienda Murcielago, Liberia, Las Animas; Buenos Aires,
Boruca; Hacienda Argentina; 200-750 m. elevation. October to Feb-
ruary. Southern Mexico; Honduras; Costa Rica to northern South
America, Peru, Bolivia, and Brazil; West Indies.

This is one of a group of small annual species including P.
clavuliferum, P. pictum, and P. parviftorum.

Paspalum notatum Fliigge, Monogr. Paspalum 106. 1810. Figure
159.

Rhizomatous perennial, the rhizomes thick and woody, the short internodes densely
clothed with stramineous scales; culms simple, erect, 30-70 cm. tall; internodes 1-2 mm.
thick, hollow but often collapsed in drying, glabrous; nodes dark, contracted, glabrous;
foliage mostly near the bases of the culms, the upper portions with much reduced leaf
blades, the ultimate sheath usually bladeless; sheaths keeled, overlapping, glabrous or
bearing long, papillose-based cilia on the overlapping margin near the apex; dewlap
mostly yellowish, conspicuous; ligule a short membrane, 0.2-0.4 mm. long, a row of stiff
hairs just behind it are ca. twice as long; base of blade as wide as the sheath apex,
somewhat folded; lower leaf margins bearing papillose-based cilia to 4 mm. long; upper
surface of blades sometimes with a few elongate papillose hairs; lower blades 6-24 cm.
long, 6-10 mm. wide. Peduncles included or exserted 1.5-4.5 cm., bearing a tuft of glassy
hairs at the apex between the racemes; inflorescences terminal, solitary, usually com-
posed of a nearly conjugate pair of equal, diverging racemes, rarely a third present;
racemes 3-10 cm. long, naked for a short distance at the base, stiff; rachis flattened,
zigzag, 0.7-0.9 mm. wide; spikelets solitary, in 2 rows, closely placed; apex of rachis often
bearing a few reduced abortive spikelets. Spikelets greenish, shiny, 3.5-3.8 mm. long,
broadly ovate 1.4:1, barely pointed; first glume absent (a few spikelets bearing oblong
first glumes 2.5-3.0 mm. long on one specimen); second glume and lower (sterile) lemma
equal, as long as the spikelet, glabrous, 5-nerved, the lateral nerves paired near the

BURGER: FLORA COSTARICENSIS 431

margins; upper (fertile) floret 2.8-3.3 mm. long, ovate 1.3-1.4:1, whitish, striate; margins
of lemma sharply infolded, forming a flat rim around the equal palea; lodicules 2, trun-
cate; anthers 3, purple, 1.8-2.0 mm. long; styles 2, separate; stigmas purple, laterally
exserted; style branches finally reflexed along the upper edges of the caryopsis; caryop-
sis elliptical 4:3, tan, ca. 2 mm. long; an oblong brown mark present at the base opposite
the embryo. Chromosome number n = 20 from a Costa Rican specimen.

Open disturbed areas, roadsides, pastures, beaches; sea level to
1,500 m. elevation; occasional in Guanacaste and the Meseta Central;
Zarcero, Cartago, Limon. June to October. Eastern Mexico to Argen-
tina; West Indies; widely cultivated in Florida and in other warm
climates of the World.

Despite its apparent toughness, this species is cultivated as a forage
grass. Common name Jengibrillo. A cultivated type with diploid (n =
10) chromosome number is known as P. saurae (Par.) Parodi and prob-
ably does not occur in Costa Rica.

Paspalum nutans Lam., Tabl. Encycl. 1:175. 1791. Figure 160.

Duration indefinite, probably perennial; plants decumbent and mat-forming, the culms
rooting at the nodes, branching freely from the rooted nodes, the erect culms simple or
branched near the base, 25-55 cm. tall; internodes 1-2 mm. thick, hollow, glabrous; nodes
glabrous; leaf sheaths usually shorter than the internodes, glabrous except for the
densely ciliate overlapping margins; basal sheaths appressed-pilose; ligule a thin brown
membrane, 1.2-2.0 mm. long; leaf blades flat, ovate, acuminate, 9-13 cm. long, 7-14 mm.
wide, tapering to narrow base; more or less appressed-pilose above and below; midrib
white, carinate below; margins not ciliate. Peduncles 1-3 from the terminal sheath,
exserted up to 12 cm., glabrous; raceme solitary, arcuate, 3-5 cm. long, with a few
elongate hairs at its base; rachis ca. 0.5 mm. wide, its edges incurved; pedicels paired,
about equal. Spikelets mostly paired, in 2 rows on each side of the midrib of the rachis,
sometimes one of the pair abortive; spikelets 1.7-2.0 (2.2) mm. long, obovate 1.3-1.5:1,
blunt, strongly plano-convex; first glume usually absent, or if present, a minute ridge or
nerveless scale, up to 0.4 mm. long; second glume shorter than the spikelet, 1.6-2.0 mm.
long, 5-nerved, sometimes with a few short hairs on the margins; lower (sterile) lemma
as long as the spikelet, 5-nerved, glabrous, occasionally with a hyaline palea to 1.8 mm.
long; upper (fertile) lemma 1.8-2.0 mm. long, obovate-elliptical 1.3-1.4:1, whitish,
striate, blunt, strongly convex; palea similar, flat; lodicules 2, truncate; anthers 3, white
or purple-spotted, 0.7 mm. long; styles 2, separate; caryopsis 1.2-1.4 mm. long, broadly
elliptical 1.2-1.4:1, opalescent; a brown spot near the base opposite the embryo. Chromo-
some number n = 20 from Costa Rican and Venezuelan specimens.

Moist forests, along trails or roadsides; elevations 450-1,200 m.; oc-
casional; Barbacoas, Rivas, La Hondura, Canas Gordas, Aguas Zar-
cas. January to October; probably blooming yearlong. Guatemala and
Belize to northern South America and Brazil; West Indies.

This species is most closely related to P. decumbens, from which it
differs in larger spikelet size and in chromosome number.

FIG. 160. Paspalum nutans. Inflorescence, two views of a spikelet, fertile floret.

432

BURGER: FLORA COSTARICENSIS

433

FIG. 161. Paspalum orbiculatum. Inflorescence, two views of a spikelet, fertile floret.

Paspalum orbiculatum Poir., Lam. Encycl. 5:32. 1804. Figure 161.

Duration indefinite; possibly perennial; plants creeping extensively, the decumbent
stems branching freely and rooting at the nodes; prophylla 10-15 mm. long; erect flow-
ering culms 5-13 cm. tall; internodes less than 1 mm. thick, glabrous, hollow, the lumen
small; nodes glabrous or somewhat bearded; leaf sheaths flattened, mostly overlapping,
glabrous except for ciliation on the overlapping margin; collar and throat ciliate; ligule a
minute membrane, 0.1-0.2 mm. long; leaf blades flat, ovate 3-10:1, mostly glabrous, the
base of the blade usually truncate and contracted into a very short pseudopetiole.
Peduncles mostly included, the uppermost sheath bearing a rudimentary blade at the
apex, just below the racemes; inflorescence of 2-4 spreading racemes borne along a
short, flattened common rachis up to 6 mm. long; individual racemes 8-24 mm. long, the
rachis flattened, 0.5-0.7 mm. wide; pedicels minute, ca. 0.2 mm. long; spikelets in 2 rows.
Spikelets orbicular, rather flat, 0.9-1.2 mm. long, 0.8-1.0 mm. wide; first glume absent;
second glume and lower (sterile) lemma as long as the spikelet, hyaline, each bearing 2
faint nerves at the margins; midribs not present; bracts usually glabrous, tending to
disintegrate at maturity; upper (fertile) floret as long as the spikelet; lemma finely
striate, not very convex, becoming reddish at maturity, its margins flattened over the
edges of the slightly convex palea, forming a rim; anthers 3, purple, 0.3 mm. long; styles
2, separate; stigmas purple; caryopsis orbicular, 0.7-0.8 mm. long, rather flat. Chromo-
some number n = 10 from Costa Rican and Venezuelan specimens.

Creeping on wet roadsides or in water of ditches, mostly at low
altitudes near both coasts. July to December. Limon, Santa Rosa,

434 FIELDIANA: BOTANY

Puerto Viejo, Siquirres, Osa Peninsula. Two old specimens are known
from the San Jose area, but the elevation seems anomalous. Southern
Mexico to Panama, northern South America to Ecuador and Paraguay;
West Indies.

Paspalum paniculatum L., Syst. Nat. ed 10, 2:855. 1759. An exten-
sive synonymy is given by Chase. Figure 162.

Caespitose perennial in large clumps; plants erect; culms mostly 75-150 cm. tall,
branching from the lower and middle nodes; prophylla up to 8 cm. long; internodes
glabrous, 3-6 mm. thick, collapsed in drying; nodes prominent, sparsely to conspicuously
silky-bearded; leaf sheaths mostly overlapping; overlapping margin finely ciliate; lower
sheaths usually densely papillose-hispid, the upper more or less hispid to nearly gla-
brous; ligule a thin brown membrane, 0.5-1.0 mm. long; leaf blades flat, lax, mostly 17-35
cm. long, 13-24 mm. wide, the terminal one much smaller; base usually broad and
rounded to the sheath apex; midrib prominent, white, keeled beneath; surfaces more or
less papillose-pilose, sometimes densely so. Inflorescences terminal on leafy culms;
peduncle exserted up to 15 cm. , glabrous except near the bearded apex; panicles 6-25
cm. long, open-cylindrical; central rachis angled and grooved, glabrous; racemes usually
18-70, racemose along the rachis, some of them verticillate; bases or pulvini bearded
with tufts of long, silky hairs up to 4 mm. long; racemes spreading, often arcuate, the
lower ones 4-11 cm. long, the upper ones successively shorter; rachis of individual
racemes triquetrous, slender, 0.3-0.5 mm. wide, bearing scattered fine elongate hairs on
the margins. Spikelets paired on each side of the midrib, the terminal one on slender
pedicel ca. 1 mm. long, the other on a shorter pedicel; spikelets obovate 1.2-1.4:1, blunt,
1.2-1.5 mm. long, finely puberulent, brown or purple, often with dark splotches; first
glume absent; second glume and lower (sterile) lemma hyaline, equal, as long as the
spikelet, 3-nerved; upper (fertile) floret ca. as long as the spikelet, stramineous, finely
striate; lemma convex, the palea similar, flat; anthers 3, deep purple, 0.5-0.8 mm. long;
styles 2, separate; stigmas purple; caryopsis circular, ca. 0.8 mm. long, tan. Chromo-
some number n = 10 from Costa Rican and Venezuelan specimens.

Common in disturbed areas, mostly at low elevations near both
coasts, also in the Meseta Central, where it occurs to 1,500 m.; road-
sides, ditches, flood plains, marshes, often on forest margins or in
partial shade. Blooming yearlong, probably more abundantly during
the rainy season. Southern Mexico to Argentina; West Indies; intro-
duced in tropical climates of the Old World.

This species is quite weedy. It has no close relatives in the Costa
Rican flora, but may possibly be confused with P. corypheum.

Paspalum parviflorum Rohde, in Fliigge, Monogr. Paspalum 98.
1810. Figure 149.

Diminutive caespitose annual in small tufts; plants 5-14 cm. tall, erect; culms branch-
ing from the base and lower nodes; prophylla 7-12 mm. long; internodes glabrous, pur-
ple, less than 0.5 mm. thick, hollow, thick-walled; leaf sheaths more or less keeled,
overlapping, papillose-pilose with long hairs; ligule a minute membrane, 0.1-0.2 mm.
long; leaf blades flat or folded, 1-5 cm. long, mostly less than 1 mm. wide, the midrib

FIG. 162. Paspalum paniculatum. A, leafy culm; B, inflorescence; C, spikelet pair; D,
spikelet; E, plant base.

435

436 FIELDIANA: BOTANY

prominent beneath; surfaces and margins bearing elongated papillose-based hairs up to 5
mm. long. Peduncles mostly included in the uppermost sheath; inflorescence of 1-3
slender divergent racemes, each 1.0-1.5 cm. long, borne on a short rachis; rachis of
individual racemes narrow, 0.3-0.4 mm. wide, triquetrous, strongly zigzag, the spikelets
visible from both sides; spikelets borne in 2 rows, alternating and scarcely overlapping;
pedicels ca. 0.2 mm. long, ciliate near the apex. Spikelets elliptical-obovate 2-3:1, blunt,
0.6-0.7 mm. long; first glume absent; second glume and lower (sterile) lemma hyaline,
weakly 2-nerved near the margins, hyaline and easily disintegrating at maturity; mar-
gins of lower lemma and second glume bearing minute, peg-like hairs, presenting a
roughened or pebbly appearance under low magnification; upper (fertile) floret about as
long as the spikelet, stramineous; anthers 3, 0.3-0.5 mm. long, dark orange; styles 2;
stigmas purple.

Paspalum parviflorum was previously known from Panama, Ven-
ezuela, Surinam, Brazil, French Guiana, and Puerto Rico. The only
Costa Rican collection is the following: Guanacaste, 2 km. E of CIA on
road to Las Animas, elevation 200 m., dry tuff outcrop in open
Byrsonima-Curatella savanna, 4 December 1968, P. & D. 11531.
Chromosome number n = 10 from the above specimen. This diminu-
tive species is most closely related to P. multicaule, P. clavuliferum,
and P. pictum.

Paspalum pectinatum Nees in Trin., Gram. Icon. l:pl. 117. 1828.
Figure 163.

Densely caespitose perennial in hard tufts, the bases of the plants buried below soil
level and the foliage frequently burned off; culms erect; foliage mostly at the base of the
plants or on the lower half of the culms; culms unbranched, 30-100 cm. long; internodes
1.5-2.5 cm. thick, hollow, glabrous; nodes not prominent; basal sheaths disintegrating
into fibers; lower sheaths glabrous near the base and more or less hirsute toward the
apex; upper leaves reduced to bladeless sheaths; ligule a brown membrane, 0.5-1.0 mm.
long, with dense tufts of long hairs, up to 8 mm. long, behind it; leaf blades 11-65 cm.
long, 3-7 mm. wide, somewhat revolute, the midrib prominent below; surfaces densely
hirsute or velvety, the hairs 2-4 mm. long. Peduncles slender, exserted 3-15 cm. from
the uppermost bladeless sheath, the apex silky-bearded; inflorescences solitary, termi-
nal, 5-7 cm. long, consisting usually of a strict pair of conjugate racemes, sometimes with
a third raceme a short distance below; rachis flattened, 2.0-2.5 mm. wide, with a mem-
branaceous border and a prominent midrib; margins ciliolate or somewhat toothed; apex
of rachis protruding beyond the spikelets as a naked point; pedicels very short, 0.5 mm.
long or less; spikelets solitary, densely overlapping in 2 rows. Spikelets cordate-ovate
2.2-2.3:1, strongly dorsally flattened, papery, 4.5-6.7 mm. long; first glume absent; sec-
ond glume as long as the spikelet, acute, usually 3-nerved, with a wide papery wing;
lower (sterile) lemma much narrower than the second glume, ovate, acute, flattened,
3-nerved, the margins bearing a dense row of spreading, pustulose-based hairs up to 2
mm. long, their tips extending beyond the margins of the second glume; back of the
lemma with a few pustulose-based hairs; upper (fertile) lemma ovate 3:1, firm but not
rigid, strongly dorsally flattened, 3.5-4.5 mm. long, minutely ciliolate at the acute tip;
palea similar and of equal length; lodicules 2, truncate; anthers 3, ca. 2.2 mm. long; styles
2, divergent; stigmas purple. Chromosome number n = 10 from Nicaraguan and Sal-
vadorian specimens.

FIG. 163. Paspalum pectinatum. Inflorescence, two views of a spikelet, fertile floret.

437

438 FIELDIANA: BOTANY

Rare or overlooked; dry savannas near the CIA, from the La Cruz
area to Liberia, Buenos Aires, Savanas de Tigre, Guacimo, Paso Real,
Surubres; elevations 200-400 m. April to August. Southern Mexico to
Honduras, El Salvador, Nicaragua; Costa Rica and Panama to Colom-
bia and Brazil.

This species, P. stellatum, and P. humboldtianum are placed by
Chase in the subgenus Ceresia, characterized by flattened or winged
rachises and silky or strongly ciliate spikelets.

Paspalum pictum Ekman, Ark. Bot. 10:17:11, pi. 1, fig. 6. 1911. P.
maculatum Nash, N. Amer. Fl. 17:186. 1912.

Caespitose annual, in small tufts; plants 25-60 cm. tall, erect; culms branching from
the lower nodes; internodes ca. 1 mm. thick, hollow, glabrous; nodes glabrous; sheaths
longer or shorter than the internodes, keeled, glabrous, with thin hyaline margins; ligule
a thin brown membrane, 1.0-2.2 mm. long; leaf blades folded, the distinction between
sheath and blade obscure; lower blades up to 20 cm. long, 1.5-3.0 mm. wide, the upper
blades much reduced, the uppermost sheath often bladeless; lower margins of blades
with a few elongate, pustulose-based hairs, up to 5 mm. long. Peduncles glabrous,
exserted 5-10 cm. or some included in the sheaths; inflorescences terminal on the main
culm or on leafy branches; racemes 1-3, borne on a short common rachis 0.5-3.0 cm. long;
racemes diverging, the rachis narrow, flattened, 0.7 mm. wide, arcuate, 3-7 cm. long,
bearing a few elongate hairs at the base. Spikelets paired, crowded; pedicels glabrous,
ca. 0.6 mm. long. Spikelets obovate 5:4, blunt, 1.0-1.1 mm. long, strongly plano-convex;
first glume absent; second glume and lower (sterile) lemma hyaline, both slightly shorter
and narrower than the upper (fertile) floret, whose edges are exposed; second glume
with 0-3 nerves; sterile lemma 4-5-nerved, the lateral nerves paired near the margins;
both glume and sterile lemma purple-splotched near the apex and sometimes on the
back; fertile lemma strongly plano-convex, the surface conspicuously tuberculate except
near the apex; palea similar, flat; anthers 0.2-0.3 mm. long, purple; styles 2, separate;
caryopsis whitish, with a purple splotch at the apex between the 2 separate styles.

This species is known from Costa Rica only by a single collection,
Pittier 4474., which is the type of P. maculatum Nash. A fragment of
this collection is in US. It was collected on the Boruca savannas in
November 1891.

Paspalum pilosum Lam., Tabl. Encycl. 1:175. 1791. Figure 164.

Caespitose perennial; culms 50-130 cm. long, ascending or spreading, branching from
the base and middle nodes; internodes 1-3 mm. thick, hollow, glabrous to densely pilose;
nodes densely pilose-bearded to glabrous; leaf sheaths keeled, glabrous or papillose-
pilose, especially toward the summit; overlapping margin densely and finely ciliate;
collar sometimes bearded; ligule a thin brown membrane, 0.6-2.5 mm. long, a row or tuft
of elongate silky white hairs, up to 6 mm. long, behind it; leaf blades linear, up to 25 cm.
long, 5-10 mm. wide; midrib white, prominently keeled below; surfaces papillose-pilose
on both sides; margins ciliate. Peduncles 1-3 from the terminal sheath; sometimes one
additional from the sheath below, exserted 1-25 cm., glabrous or finely pilose, silky-
bearded at the apex; racemes solitary, slightly arched, 6-16 cm. long; rachis 1.0-1.5 mm.

FIG. 164. Paspalum pilosum. Inflorescence, spikelet pair, single spikelet, fertile
floret.

440 FIELDIANA: BOTANY

wide, its margins somewhat incurved, bearing scattered long weak hairs; spikelets
paired on each side of the prominent midrib; terminal spikelet of each pair on a hispid
pedicel ca. 1 mm. long, the other spikelet on a very short reflexed pedicel. Spikelets
glabrous, strongly plano-convex, obovate 1.8-1.9:1, 2.6-3.2 mm. long, dimorphic; termi-
nal spikelet of each pair with a very short, truncate membranaceous first glume or none;
lower spikelet of each pair usually with a narrow, acuminate, 1-nerved first glume up to 2
mm. long, rarely lacking a first glume; second glume slightly shorter than the spikelet,
2.4-3.0 mm. long, 5-nerved; lower (sterile) lemma as long as the spikelet, usually 5-
nerved, or the midnerve suppressed; apex blunt, forming a rim around the tip of the
fertile floret; lower lemma enclosing a 2-nerved membranaceous palea nearly as long,
usually bearing 3 well-developed anthers; upper (fertile) floret ovate, 2.5-2.8 mm. long,
the lemma strongly convex, conspicuously striate, whitish; palea similar, flat; lodicules 2,
truncate; anthers 3, deep purple, 1.0-1.2 mm. long; styles 2, separate; stigmas plumose,
deep purple. Chromosome number n = 40 from Costa Rican and Venezuelan specimens.

Widespread, mostly on the Pacific slope, at altitudes from 380-1,200
m.; common in scattered sites, on savannas, roadsides, pastures, and
disturbed areas; rather weedy. Blooming July to January. Hda.
Guachipelin to the Meseta Central; General Valley; Cariblanco;
Moravia de Chirripo. Belize to Panama and northern South America to
Bolivia and Brazil; Trinidad.

Paspalum plicatulum Michx., Fl. Bor. Amer. 1:45. 1803. Figure
165.

Common and weedy, sea level to 600 m. elevation, rarely up to 1,200
m.; open disturbed areas, roadsides, savannas, beaches, on both
Pacific and Caribbean slopes; often forming large colonies. Blooming
yearlong, but most abundantly from April to September. The various
members of the P. plicatulum complex range from the southeastern
United States to Argentina and the West Indies.

This species is a member of the informal group Plicatula of Chase.
The species all have deep brown fertile florets. Paspalum convexum,
P. boscianum, and P. centrale belong to this group. Their taxonomy is
intricate and is complicated by polyploidy and cytological ir-
regularities.

KEY TO VARIETIES OF Paspalum plicatulum

la. Foliage entirely glabrous var. glabrum

Ib. Leaf blades and sometimes sheaths bearing pubescence 2

2a. Sheaths and blades densely long-pilose var. villosissimum

2b. Sheaths glabrous; upper surfaces of leaf blades hairy near base var. plicatulum

Paspalum plicatulum var. plicatulum.

Caespitose perennial; plants 70-150 cm. tall, the culms erect to arching, branching
sparsely from the lower and middle nodes; internodes compressed, glabrous; nodes
glabrous; leaf sheaths keeled, mostly overlapping, glabrous or nearly so; ligule a thin

FIG. 165. Paspalum plicatulum. Inflorescence, two views of a spikelet with wrinkled
sterile lemma, fertile floret.

441

442 FIELDIANA: BOTANY

brown membrane, 1.0-3.5 mm. long; leaf blades flat, folded near the base, up to 43 cm.
long, 6-12 mm. wide, the lower surface glabrous, the upper surface sparsely to densely
long-pilose near the base; uppermost leaf blade very reduced or obsolete. Peduncles
included in the uppermost sheath or exserted up to 17 cm.; inflorescences terminal on the
main culm or leafy branches; panicles 6-22 cm. long, composed of 2-14 solitary racemes
borne along an angled and grooved central rachis; individual racemes with a tuft of long
hairs at the base; lowermost racemes 3-11 cm. long, the upper ones progressively
shorter; rachis 0.7-1.1 mm. wide, zigzag; spikelets normally paired and the raceme thus
4-rowed, sometimes one member of the pair abortive or lacking, and the raceme hence 2-
or 3-rowed. Spikelets usually 2.4-2.8 mm. long, elliptical-obovate 1.4-1.5:1, strongly
plano-convex, grayish, or brownish when fully mature; first glume absent; second glume
5-7-nerved, slightly shorter than the spikelet, usually appressed-pubescent, occasionally
glabrous; lower (sterile) lemma 5-nerved, glabrous, transversely wrinkled within the
margin; upper (fertile) floret nearly as long as the spikelet, rigid, longitudinally striate,
deep chestnut brown, strongly convex; palea similar, flat; lodicules 2, truncate; anthers
3, deep purple, 1.5-1.7 mm. long; styles 2, separate; stigmas purple. Chromosome
number of P. plicatulum var. plicatulum is n = 20 from numerous Central American
collections.

Paspalum plicatulum var. villosissimum Pilger, Bot. Jahrb. Syst.
30:131. 1901.

This variety differs from var. plicatulum in stature, being usually 55-100 cm. tall, and
in the usually densely pilose sheaths and blades. The leaf blades are narrower, usually
2-5 mm. wide and densely pilose. Inflorescence 7-12 cm. long, of 2-6 racemes, the lower-
most 3-7 cm. long, the upper shorter; rachis zigzag, 0.5-0.7 mm. wide. Spikelets 2.2-2.7
mm. long, obovate 1.4-1.7:1; first glume absent; second glume and lower (sterile) lemma
equal, as long as the spikelet, 5-nerved; glume appressed-pubescent, the lemma gla-
brous.

Dry Curatella-Byrsonima and Crescentia savannas at low eleva-
tions, northwestern Guanacaste from the La Cruz area to Liberia.
June to July. Most chromosome counts of this variety have indicated
that it is diploid, with n = 10; however several of our Costa Rican
accessions have had n — 20, with considerable meiotic irregularity.

Paspalum plicatulum var. glabrum Arech., Anales. Mus. Nac.
Montevideo 1:58. 1894.

No Costa Rican collections of this variety have been identified, but it
may occur. The plants, like those of var. villosissimum, are generally
smaller and more slender than those of var. plicatulum. Chromosome
number n = 10 from a Mexican collection.

Paspalum pulchellum Kunth, Mem. Mus. Hist. Nat. 2:67. 1815.
Figure 166.

Caespitose perennial in small clumps; plants 15-55 cm. tall, erect; culms unbranched,
slender; internodes less than 1 mm. thick, hollow, thin-walled, glabrous; nodes con-
tracted, upwardly bearded; bases of the sheaths also bearded; foliage mostly aggregated

FIG. 166. Paspalum pulchellum. A, plant habit; B, inflorescence; C, portion of a
raceme; D, spikelet, showing sterile lemma; E, spikelet, showing exposed back of fertile
lemma.

443

444 FIELDIANA: BOTANY

near the base of the plants, the upper parts of the culms nearly naked, with elongated
internodes and short or obsolete leaf blades; lower sheaths glabrous or more or less
appressed-silky; the knotty bases of the plants often densely silky; upper sheaths nearly
glabrous; ligule a minute membrane, 0.2-0.3 mm. long; leaf blades up to 20 cm. long, 1-2
mm. wide, usually folded or involute, usually copiously papillose-pubescent with
spreading hairs up to 4 mm. long. Peduncles included in the uppermost bladeless sheath
or exserted up to 10 cm.; inflorescences terminal on the culms, solitary, of 2-4 racemosely
arranged divergent racemes borne along a short flattened rachis ca. 5 mm. long; a tuft of
silky hairs at the base of each raceme; individual racemes 2-7 cm. long; rachis flat, zigzag,
up to 1 mm. wide, with 2 green lines flanking the white midrib; a solitary spikelet borne
on the tip; spikelets solitary, alternating in 2 rows; pedicels up to 0.5 mm. long, ciliate.
Spikelets 1.7-2.0 mm. long, obovate 1.1-1.6:1, rounded to a narrow tip; first and second
glumes absent; lower (sterile) lemma as long as the spikelet, usually pinkish to deep
purple, 3-nerved, the lateral nerves marginal, the edges inflexed over the margins of the
upper (fertile) floret; fertile lemma strongly convex, shining, as long as the sterile
lemma; palea similar, flat; lodicules 2, truncate; anthers 3, deep purple, 1.1-1.4 mm. long;
styles 2, separate; stigmas purple. Chromosome number n = 10 from a Venezuelan
specimen.

Occasional, dry Curatella-Byrsonima savannas, from Liberia to-
ward the Nicaraguan border; elevations 75-200 m. June to July.
Guatemala, Belize, eastern Honduras and Nicaragua; northern South
America from Venezuela to French Guiana and Brazil; West Indies.

The racemes of this species are often striking because of the contrast
between the purple sterile lemma and the shiny whitish fertile lemma.
In one population from Liberia, however, plants with purple and yel-
low spikelets occurred together.

Paspalum pumilum Nees, Agrost. Bras. 52. 1829. Figure 167.

Caespitose perennial in dense tufts; plants forming flat mats; culms 10-40 cm. long,
branching from the base only; prophylls in the basal rosette evident, up to 2.5 cm. long;
culm internodes 1.0-1.5 mm. thick, hollow, glabrous; nodes glabrous, not prominent;
foliage mostly clustered near the base, the culm blades few, the uppermost leaf reduced
or lacking a blade; sheaths and blades softly pubescent; ligule a thin membrane, 0.5-1.0
mm. long; leaf blades 5-10 cm. long, 3-7 mm. wide, flat, tapering rather abruptly to a
cuspidate tip. Peduncle included or exserted up to 6 cm.; inflorescence terminal, usually
of a nearly conjugate pair of racemes, sometimes a third one borne below them; racemes
divergent, often curved, 2.5-4.0 cm. long, slender, the spikelets solitary, borne in 2
rows. Spikelets ovate-elliptical, rounded at the tip or barely acute, glabrous, 1.5-1.8 mm.
long, 1.1-1.2 mm. wide; first glume usually absent, or present on a few spikelets, usually
a minute deltoid nerveless scale, up to 0.2 mm. long, rarely up to 1.2 mm. long; second
glume and lower (sterile) lemma equal, as long as the spikelet, 3-nerved, the lateral
nerves close to the margin; upper (fertile) floret slightly shorter; lemma stramineous, not
strongly convex; palea flat; lodicules 2, truncate; anthers 3, purple, 0.7 mm. long; styles
2, separate, naked below; stigmas purple.

This species is known in Costa Rica only by the following specimen:
Heredia, 3 km. S of crater of Volcan Barba, full sun in roadway,
prostrate in circular patches, chromosome number n = 10, P. & D.

BURGER: FLORA COSTARICENSIS

445

FIG. 167. Paspalum pumilum. Inflorescence, two views of a spikelet, fertile floret.

11777, 24 March 1969. West Indies and northern South America to
Uruguay and Chile.

Paspalum reclinatum Chase, J. Wash. Acad. Sci. 33:316-317. 1943.
Figure 146.

Duration indefinite; plants sprawling, the culms long-decumbent and rooting from the
lower nodes, branching freely from the rooted portions; ascending portions 30-45 cm.
long; prophylla up to 4 cm. long; internodes 1-2 mm. thick, hollow, glabrous; nodes
glabrous, dark; leaf sheaths mostly shorter than the internodes, glabrous or the margin
sparsely pilose; ligule a thin brown membrane, puberulent on the back, 0.7-2.0 mm. long;
leaf blades 5-14 cm. long, 4-9 mm. wide, glabrous or puberulent above the ligule, flat and
thin. Peduncle included in the uppermost sheath or short-exserted; panicles terminal on
ascending leafy branches, 5-10 cm. long, open-cylindrical, ca. 4 cm. wide, made up of 6-11
ascending or drooping racemes, each 1.5-2.5 cm. long; rachis of racemes slender and
pilose at the base, flattened and foliaceous, 1.0-1.2 mm. wide except at the base, tapering
to a narrow apex that bears a solitary spikelet at the tip; spikelets borne alternately in 2
rows on slender, short-puberulent pedicels, the 2 rows slightly wider than the rachis.
Spikelets 2.2-2.9 mm. long, ovate 2.0-2.3:1; first glume absent; second glume and lower
(sterile) lemma equal, glabrous, 3-nerved, white or purplish, thin, slightly exceeding the

446 FIELDIANA: BOTANY

upper (fertile) floret; fertile floret ovate 2:1, blunt, 2.0-2.5 mm. long, the lemma smooth
and shining, whitish, firm; palea of equal length and similar appearance, flat or slightly
concave; anthers 3, purple, 1.5 mm. long; styles 2, separate; caryopsis elliptical 2:1, tan.
Chromosome counts for all Costa Rican collections indicate n = 30.

Wet, seepy areas, mostly in moist canyons; elevation 1,500-2,100 m.
February to June. This species was described from South America,
and our Costa Rican collections are the first from Central America.
Alto Paloma, Quebrada Corralillo (Rancho Redondo), Rio Grande de
Orosi, at the power dam 8 km. S of Tapanti.

The specimen from Alto Paloma (P. & D. 11710) was originally
reported as P. prostratum Scribn. & Merr., but differs in pubescence
and chromosome number from that species.

Paspalum repens Berg., Acta. Helv. Phys.-Math. 7:129, pi. 7. 1762.
Figure 146.

Duration indefinite, probably perennial; culms up to 2 m. long, the lower parts creep-
ing or floating in water, rooting abundantly from the nodes; internodes up to 1 cm. thick,
hollow, thin-walled, glabrous; nodes glabrous, not prominent; leaf sheaths mostly over-
lapping, glabrous to papillose-pilose, often inflated; sheath auricles erect, pointed, 3-12
mm. long; dewlap and collar purple; ligule a ciliolate membrane, 2.5-3.5 mm. long; leaf
blades usually 20-40 cm. long, 12-14 mm. wide, softly pilose. Inflorescences terminal on
leafy branches; peduncles short, exserted 2-4 cm.; panicles densely ovoid, 10-16 cm.
long, 4-9 cm. wide, the numerous ascending or spreading racemes whorled or solitary,
dropping from the rachis when mature; longest racemes 4-7 cm. long; rachis of racemes
flattened, 1.5-1.8 mm. wide, foliaceous, extending beyond the ultimate spikelet as a
naked acuminate point; spikelets alternating in 2 rows on the lower side of each rachis,
the 2 rows as wide as the rachis. Spikelets 1.8-2.0 mm. long, ovate 2.3:1, acute; first
glume absent; second glume and lower (sterile) lemma hyaline, equal, as long as the
spikelet; second glume with 2 marginal nerves; lower lemma 2-3-nerved; upper (fertile)
floret shorter than the glume and lemma, ca. 1.8 mm. long, the lemma ca. 1.6 mm. long,
obovate 2.1:1, firm, not rigid, blunt; lodicules 2, truncate; anthers 3, purple, 0.9-1.2 mm.
long; styles 2, separate.

Occasional in swamps and ponds, sea level to 300 m. elevation;
Taboga, Lagunas de San Bernardo, Marais de Sierpe, Rio Colorado, 15
km. from Barro de Colorado. October to March. Southern Mexico to
northern South America, southward to northern Argentina; West In-
dies. Chase (1910) formerly included P. fluitans (Ell.) Kunth of the
United States under P. repens.

Paspalum saccharoides Nees in Trin., Gram. Icon. 1. pi. 107. 1828.
Figure 168.

Vigorous perennial; culms elongated, usually sprawling or drooping, hanging over
embankments or bluffs, the bases hard, with coarse, thick roots; lower portions of culms
rooting upon contact with the soil; internodes thick-walled, woody, 4-8 mm. thick, gla-
brous or appressed-pilose; nodes swollen; leaf sheaths overlapping, loose, glabrous, or
pilose at the base; margins ciliate with delicate silky hairs; ligule a minute membranous

BURGER: FLORA COSTARICENSIS

447

ridge, 0.2-0.3 mm. long, with a tuft of long, silky, erect hairs, up to 10 mm. long just
behind it; midculm blades 10-40 cm. long, 5-13 mm. wide, rather thick and somewhat
involute, pilose above and glabrous beneath; basal and uppermost leaf blades much
reduced. Inflorescences terminal on leafy culms; peduncles exserted up to 16 cm.; panicle
fan-shaped or pyriform, 12-30 cm. long, the numerous slender flexuous racemes fascicled
along a slender rachis up to 7 cm. long; axils and pulvini long-silky; racemes 9-25 cm.
long, densely silky with white hairs; rachis triquetrous, ca. 0.5 mm. wide, the angles
scabrous; spikelets solitary, in 2 rows on the lower 2 sides of the rachis; pedicels slender,
ca. 0.5 mm. long. Spikelets ovate 3-4:1, acute, 2.0-3.0 mm. long, with a slightly auricu-
late base; first glume absent; second glume as long as the spikelet, thin, with 2 marginal
nerves that are copiously ciliate with white, silky hairs 4-6 mm. long; midnerve rarely
present; lower (sterile) lemma slightly shorter than the glume, 1.8-2.4 mm. long, gla-
brous, 2-nerved, thin; upper (fertile) floret 1.6-1.8 mm. long, ovate ca. 3:1, acute, firm,
not rigid; palea similar to the lemma but slightly longer; anthers 3, yellow, 0.8-0.9 mm.
long; caryopsis 0.8 mm. long, obovate with a nearly truncate apex bearing the persistent
style base; embryo large, ca. one-third as long as the tan caryopsis.

Occasional, moist spots, mostly on the Caribbean slope at elevations
from sea level to 1,200 m., on bluffs, road embankments, above
streams; rare in the Meseta Central (Dos Rios) and absent from
Guanacaste; San Miguel (Alajuela); San Ramon to Naranjo, La Hon-

FIG. 168. Paspalum saccharoides. Inflorescence, two views of a spikelet, fertile floret.

448 FIELDIANA: BOTANY

dura, Cartago, Turrialba, Guapiles, San Vito, Limon. April to August.
Costa Rica to northern South America and the West Indies.

This species is striking because of the plumose panicle. The spikelets
are atypical for the genus Paspalum, being of delicate texture and
having a rather thin fertile lemma. The spikelets are somewhat similar
to those of some species of Digitaria, notably D. insularis; however,
the chromosome number of P. saccharoides is n = 10, from Costa
Rican specimens. The basic chromosome number of Digitaria is x = 9.
Paspalum saccharoides has no close relatives in the genus and may
deserve generic status of its own.

Paspalum scabrum Scribn., U.S.D.A. Div. Agrost. Bull. 4:36.
1897.

Duration indefinite, probably annual; culms to 110 cm. long, sprawling and rooting at
the lower nodes, branching freely from the decumbent portions; prophylla up to 8 cm.
long; culm internodes 2-3 mm. thick, hollow, retrorsely scabrous with short, sharp
points; leaf sheaths longer or slightly shorter than the internodes, strongly scabrous on
the ridges with minute, retrorse barbs; ligule a thin brown membrane, 2.0-2.5 mm. long;
leaf blades ovate 4-7:1, flat, 8-12 cm. long, 13-28 mm. wide, finely papillose-pilose on both
surfaces, the base rounded to a short pseudopetiole; midrib scabrous beneath. Inflores-
cences terminal on erect leafy branches; peduncle included in the uppermost sheath;
rachis grooved and angled, stiff-pubescent; panicles 10-20 cm. long, up to 5 cm. wide,
open-cylindrical, the racemes numerous, mostly whorled, 3-4 cm. long, falling as units
from the rachis at maturity; rachis of racemes flat, foliaceous, 2.0-2.5 mm. wide, the
midrib scabrous beneath; margins inflexed around the spikelets; tip extended beyond the
ultimate spikelet as a naked point 3-4 mm. long; spikelets rather distant, forming a single
row. Spikelets 1.7-2.0 mm. long, ovate 2:1, blunt, glabrous; first and second glumes
absent; lower (sterile) lemma and upper (fertile) floret equal, as long as the spikelet;
sterile lemma membranaceous, 3-nerved; fertile lemma smooth and shining, firm but not
rigid; palea similar and of equal length; lodicules 2, truncate; anthers 3, yellow to
purplish, 1.4-1.5 mm. long. Chromosome numbern = 10 from a Costa Rican specimen.

This species, although striking because of its very scabrous foliage,
is little known and apparently rare. It is known in Costa Rica from San
Pedro de San Ramon (Cuesta del Toro), between San Ramon and
Naranjo, and 10 km. E of San Mateo on the road to Atenas. The latter
specimen grew in a shaded moist gully at 880 m. elevation. December
to January. Guatemala and Nicaragua to Venezuela, Colombia, Ecua-
dor, and Bolivia. Paspalum scabrum is similar to P. candidum in
spikelet characters, but differs in foliage and in chromosome number.

Paspalum serpentinum Hochst. in Steud., Syn. PL Glum. 1:22.
1854. Figure 169.

Caespitose perennial in small tufts; culms erect, 60-100 cm. tall, unbranched; inter-
nodes up to 1.5 mm. thick, solid, glabrous; nodes glabrous, shrunken; foliage aggregated
near the base of the plants, the upper parts of the culms with elongated internodes and

FIG. 169. Paspalum serpentinum. A, inflorescence; B, growth habit; C, two views of a
spikelet, with mottled bracts.

449

450 FIELDIANA: BOTANY

nearly bladeless sheaths; lower leaf sheaths and blades densely grayish-pilose with
papillose-based hairs up to 3 mm. long; lower sheaths longer than the internodes, upper
ones shorter; ligule a thin membrane, 0.3-0.6 mm. long; lower leaf blades up to 30 cm.
long, 3-4 mm. wide, flat or involute. Peduncles slender, exserted up to 20 cm.; inflores-
cences terminal on the simple culms, consisting of a conjugate pair of diverging racemes;
apex of the peduncle with a tuft of silky hairs; individual racemes 3-7 cm. long, the rachis
narrow, zigzag, triquetrous, 0.5-0.7 mm. wide; pedicels 0.5-1.0 mm. long; spikelets
solitary in 2 rows, closely overlapping. Spikelets 2.5-2.8 mm. long, broadly elliptical
1.1-1.3:1, obtuse; first glume absent; second glume and lower (sterile) lemma equal, as
long as the spikelet, glabrous, mottled with reddish brown lines that radiate inward from
the margins of the bracts; lemma and glume 3-nerved, the lateral nerves very close to
the margins; upper (fertile) lemma strongly dorsally flattened, broadly elliptical,
whitish, finely striate; margins sharply inflexed, forming a flattened rim around the
palea; palea convex, but the margins sunken beneath the rim of the lemma; lodicules 2,
truncate; anthers 3, purple, 1.5 mm. long; styles 2, separate; stigmas purple; caryopsis
tan, broadly elliptical, 1.9 mm. long, with a red line ca. one-third as long at the base
opposite the embryo. Chromosome number n = 10 from a Nicaraguan specimen.

Dry savannas at low elevations. The only known Costa Rican speci-
men is the following: Guanacaste, 21 km. NW of Liberia, shallow dry
soil, elevation 75 m., Curatella-Byrsonima savanna, 31 July 1966,
Pohl & Calderon 10175. Belize, Honduras, Nicaragua, Panama; Trini-
dad and the Guianas.

Paspalum setaceum Michx., Fl. Bor. Amer. 1:43. 1803.

Perennial, in small tufts from short, knotty rhizomes; plants 35-65 cm. tall; culms
ascending, the internodes hollow, glabrous; nodes glabrous, dark; leaf sheaths shorter or
longer than the internodes, glabrous except for the finely ciliate overlapping margin;
dewlap and collar bearded; ligule a thin tan membrane, 0.3-0.5 mm. long, with a tuft of
white hairs behind it; leaf blades flat, usually 8-19 cm. long, 7-11 mm. wide, the length
8-18 x the width; surfaces glabrous, the margins prominently pustulose-ciliate with
hairs up to 4 mm. long. Peduncles terminal and axillary, 1-3 exserted up to 30 cm. from
the terminal sheath, usually 1 included or exserted from 1 to all of the lower culm
sheaths; inflorescence of 1 or 2 solitary racemes on a short rachis; individual racemes 4-8
cm. long, arcuate; rachis 0.7-0.8 mm. wide; spikelets paired, in 2 rows on each side of the
midrib. Spikelets 1.5-1.7 mm. long, elliptic-obovate 1.2-1.3:1, blunt or very slightly
pointed, strongly plano-convex; first glume absent; second glume and lower (sterile)
lemma equal, as long as the spikelet, brown-speckled, sparsely to densely puberulent
with capitellate hairs; second glume 3-nerved; sterile lemma 2-nerved, the midnerve
absent; upper (fertile) floret about as long as the spikelet, stramineous; lodicules 2,
truncate; anthers 3, brown, 0.5-0.7 mm. long; styles 2, separate; stigmas purple; caryop-
sis subcircular, 1.2 mm. long, tan-striate, opalescent, a brown spot opposite the embryo.
Chromosome number n = 10 from a Costa Rican specimen.

Sandy beaches of the Caribbean; Tortugero, Limon Airport, Rio
Banano, Cahuita; Puntarenas; usually rare. June to December.

This species belongs to a complex group of grasses which have been
variously treated as a number of species, or as varieties of a single one.
The most recent treatment, by D. J. Banks (Sida 2:4:269-284. 1966),

BURGER: FLORA COSTARICENSIS 451

places all of these plants in nine varieties under P. setaceum. None of
these varieties matches our plants very well. They come closest to P.
propinquum Nash, Bull. New York Bot. Gard. 1:291. 1899. The de-
scription given above is derived entirely from Costa Rican specimens,
which form a highly uniform group, quite unlike the temperate zone
representatives of the group. Several of our specimens have old an-
thers trapped in the mature fertile floret along with a well-developed
caryopsis. The plants are apparently largely cleistogamous, which may
account for the multiplicity of forms in the group.

Paspalum squamulatum Fourn., Mex. PI. 2:11. 1881. Figure 170.

Plants perennial, caespitose but the culms decumbent and rooting at the lower nodes,
branching freely from the rooted nodes; erect branches simple, 20-60 cm. long; prophylla
prominent, 2.0-4.5 cm. long; internodes glabrous, hollow, 1-2 mm. thick; nodes glabrous,
dark; leaf sheaths keeled, mostly longer than the internodes, glabrous except the finely
dilate overlapping margin; collar sometimes bearded; ligule a thin brown lacerate mem-
brane, 2.5-4.5 mm. long; leaf blades mostly 7-11 cm. long, 8-13 mm. wide, dark green,
flat, the midrib keeled beneath; base usually rounded; surfaces glabrous or more or less
pilose, especially the upper. Peduncle slender, solitary, included or exserted up to 14 cm.
from the terminal sheath. Inflorescence usually 4-8 cm. long, a raceme of usually 4-6
divergent racemes borne singly or paired along a flattened and channeled rachis; base of
each raceme with a tuft of long hairs; individual racemes 2-8 cm. long; rachis triquetrous,
0.5-0.7 mm. wide, zigzag; spikelets paired on each side of the midrib. Spikelets glabrous,
obovate 1.3-1.5:1, blunt, 1.5-1.8 mm. long, strongly plano-convex; first glume absent (a
minute rudiment present on one specimen); second glume 1.3-1.7 mm. long, 3- or rarely
5-nerved, slightly shorter than the fertile lemma, which is exposed at the tip; lower
(sterile) lemma as long as the spikelet, 3-nerved, lacking a palea; upper (fertile) floret
1.5-1.7 mm. long, obovate 1.2-1.3:1, 1.5-1.7 mm. long, whitish, striate, strongly convex;
palea similar, flat; lodicules 2, truncate; anthers 3, brown, 0.8-0.9 mm. long; styles 2,
separate; stigmas dark; caryopsis elliptic 1.2-1.3:1, strongly convex, whitish, opalescent.
Chromosome number n = 20 from Costa Rican specimens.

Moist open or partially shaded sites, volcanoes of the Cordillera
Central; Meseta Central; Canton de Dota; elevations 1,100-2,000 m.
Blooming June to February. Mexico to Costa Rica.

Spikelets and vegetative habit of this species are similar to P. nu-
tans, but the inflorescence is different.

Paspalum standleyi Chase, J. Wash. Acad. Sci. 17:146. 1927.

Rhizomatous perennial, forming mats; culms simple, erect, arising from the rooted
parts, 10-32 cm. tall; internodes up to 1 mm. thick, hollow, thick-walled, glabrous or the
lower ones pilose; nodes appressed-pilose; leaf sheaths mostly overlapping, glabrous or
pilose; nodes appressed-pilose; leaf sheaths mostly overlapping, glabrous or pilose, the
overlapping margin conspicuously pilose-ciliate; foliage mostly aggregated on the lower
portions of the culms, the upper blades much reduced or lacking; ligule a minute mem-
brane, ca. 0.2 mm. long; leaf blades linear, rather blunt-tipped, 2.5-7.0 cm. long, 2.5-5.0
mm. wide, glabrous or sparsely pubescent; pseudopetiole 1.0-1.5 mm. long, densely

FIG. 170. Paspalum squamulatum. Inflorescence, two views of a spikelet, fertile
floret.

452

BURGER: FLORA COSTARICENSIS 453

bearded below. Peduncles exserted 1.5-3.0 cm.; inflorescences terminal on leafy culms,
of 2-5 divergent racemes borne along a short, flattened rachis up to 10 mm. long; indi-
vidual racemes 1-3 cm. long; rachis flattened, zigzag, 0.5-0.6 mm. wide, naked or bearing
abortive spikelets for the basal 1 mm.; spikelets borne in 2 rows. Spikelets 1.4-1.5 mm.
long, ovate 1.6-1.9:1, acute, strongly flattened, glabrous; first glume absent; second
glume and lower (sterile) lemma equal, as long as the spikelet, each with 2 marginal
nerves and lacking midribs; bracts thin; upper (fertile) lemma slightly shorter than the
outer bracts, elliptical, firm but not rigid, finely striate; palea similar, flat; anthers 3,
purple, 0.8-0.9 mm. long; pollen normal; caryopses developing.

Gravelly river banks and sand bars. This species was previously
known only from the type, collected in Panama. I have recently found
it in abundance along the Rio Platano in Honduras. Our two Costa
Rican collections are cited below. Paspalum standleyi is probably
much more widespread in Costa Rica in suitable habitats.

Guanacaste, moist shady bank of Rio Corobici, Finca La Pacifica,
elevation 80 m., 3 December 1968, P. & D. 11516; Puntarenas, bank of
Rio Grande de Terraba, 11 km. SE of Rio Catarata, elevation 100 m.,
12 December 1968, P. & D. 11607.

Paspalum standleyi was placed by Chase in the group Parviflora,
consisting mostly of small annuals of dry savannas, whose chromosome
numbers, as far as known, are all n = 10. Our two collections of P.
standleyi are both n = 20, and the plants are rhizomatous perennials.
In inflorescence structure and spikelets, they are very similar to P.
jimenezii, a rare sterile triploid (2n = 30). It seems most probable that
these two are closely related, and that P. standleyi is a parent of P.
jimenezii.

Paspalum stellatum Humb. & Bonpl. in Fltigge, Monogr. Pas-
palum 62. 1810. Figure 171.

Caespitose perennial in dense tufts; culms 55-85 cm. long, erect, most of the foliage
near the base; upper leaf blades much reduced; internodes few, elongated, less than 1.5
mm. thick, hollow, glabrous or the upper internodes and peduncle with a few appressed
hairs; leaf sheaths nearly glabrous at the base, more or less pilose toward the apex,
shorter than the internodes; ligule a short membrane, 0.2-0.3 mm. long, with a dense
row of white hairs behind it; leaf blades up to 25 cm. long, 2-4 mm. wide, mostly involute;
lower surface sparsely hirsute, the upper surface densely hirsute with hairs up to 5 mm.
long. Peduncles slender, appressed-pilose, silky at the apex; inflorescences solitary,
terminal on the unbranched culms, 3.5-10 cm. long, composed of a single arched raceme
or rarely of 2 conjugate racemes; rachis broadly winged, 5-8 mm. wide, infolded about
the spikelets; midrib flanked by narrow conspicuous green stripes and purplish line on
each side; margins of rachis wide, thin and papery, russet or chestnut-colored; spikelets
densely crowded in 2 rows on the lower side of the rachis, but scarcely visible because of
the dense silky hairs of the bracts; pedicels very short, with a circle of diverging white
hairs at the tip. Spikelets angular-obovate ca. 2:1, strongly flattened, 3.0-3.2 mm. long;
callus densely bearded with erect silky hairs ca. half the length of the spikelet; first

FIG. 171. Paspalum stellatum. A, inflorescence; B, plant base; C, rachis of raceme; D,
spikelets and pedicels on the rachis; E, spikelet.

454

BURGER: FLORA COSTARICENSIS 455

glume absent; second glume as long as the spikelet, flat, membranaceous, lacking a
midrib, the 2 nerves marginal, thickened and corky on the upper half, densely ciliate
with spreading white hairs, those near the base shorter, those on the upper margins
pustulose-based, 3 mm. or more long; lower (sterile) lemma similar but narrower, mar-
ginally 2-nerved, 2.5-2.9 mm. long; upper (fertile) floret obovate 2.3:1, minutely stipi-
tate; lemma firm but not rigid, whitish; palea similar, of equal length; lodicules 2, trun-
cate; anthers 3, orange, 1.7-2.0 mm. long; styles 2, separate; stigmas brown; caryopsis
ca. 1.2 mm. long, obovate 1.6:1, tan.

Rare; Boruca savannas; elevation ca. 450 m. September to De-
cember. Southern Mexico to northern South America, southward to
Argentina; Hispaniola.

Paspalum tonduzii Mez, Fedde. Kept. Sp. Nov. 15:72. 1917.

Caespitose perennial; height unknown; culms erect or geniculate, unbranched; nodes
bearded; leaf sheaths longer than the internodes, keeled, papillose-pilose; ligule a very
short membrane; leaf blades flat, up to 30 cm. long and 10 mm. wide, papillose-pilose
above and below; midrib broad, whitish. Inflorescence solitary, terminal; peduncle in-
cluded; panicle 9-11 cm. long, of 7-8 ascending racemes; racemes 3-5 cm. long; rachis
deep purple, ca. 0.7 mm. wide; spikelets mostly paired, some of the lower ones abortive.
Spikelets 2.0-2.1 mm. long, obovate 1.7-1.9:1; bracts thin and delicate, mottled purple
and golden; first glume absent; second glume slightly shorter than the spikelet, 3-
nerved, occasionally finely puberulent near the apex; lower (sterile) lemma as long as the
spikelet, 3-nerved; upper (fertile) lemma stramineous, finely striate.

This species is known only from the type specimen, cited below. The
description was compiled from a type fragment and photograph in US
and from descriptions by Mez and Chase. HOLOTYPE: San Jose,
Plantations de maiz de Santa Maria de Copey, 1,800 m., February
1908, Tonduz 11767.

Paspalum turriforme Pohl, sp. nov. Figure 172.

Gramen altum, perenne, grex Virgata pertinens, a P. densum Poir. spiculis
acutioribus, longioribus (2.2-2.5 mm. vs. 1.7-1.9 mm.), angustioribus (1.4-1.5:1 vs. 1.0-
1.2:1), panicula longiore, racemis numerosis (ad 150) recedit, et a P. plenum Chase
spiculis glabris brevioribus (2.2-2.5 mm. vs. 2.5-3.0 mm.), latioribus (1.2-1.5 vs. 1.7-
2.3:1) abhorret.

Tall, vigorous caespitose perennial in dense clumps; plants up to 3 m. tall, erect; culms
unbranched; culm internodes up to 8 mm. thick, hollow, glabrous; nodes glabrous or
appressed-pilose; basal leaves numerous, the sheaths strongly keeled, glabrous to
sparsely hispid, closely distichously overlapping; culm sheaths keeled, overlapping,
glabrous except the papillose-ciliate overlapping margin; dewlap and collar densely
long-bearded with papillose-hispid hairs; ligule a firm tan lacerate membrane, 2-5 mm.
long; a dense tuft of stiff elongate hairs on the upper blade surface just behind the ligule;
leaf blades 40-95 cm. long, the base narrow, strongly keeled and channeled; blades
widest at the middle, flat, 12-17 mm. wide; margins strongly scabrous, cutting; tip
attenuate. Peduncles solitary, terminal, exserted up to 13 cm.; panicle dense, purple,
narrow, spirelike, 30-50 cm. long, of 40-150 closely placed ascending or drooping
racemes; common rachis strongly angled and grooved, scabrous; rachis of individual

FIG. 172. Paspalum turriforme. A, panicle; B, culm base, showing distichous leaf
sheaths; C, leaf sheath and blade; D, portion of a raceme; E, two views of a spikelet.

456

BURGER: FLORA COSTARICENSIS 457

racemes purple, 1.2-1.5 mm. wide, lower racemes 7-11 cm. long, the midrib prominent
on the naked side; base with a tuft of long, glassy hairs; margins with scattered long
hairs to 6 mm. long; spikelets very densely arranged in 4 rows, the total width of the
spikelets ca. twice the rachis width. Spikelets purple, 2.2-2.5 mm. long, obovate 1.4-
1.5:1, blunt; first glume absent; second glume and lower (sterile) lemma equal, as long as
the spikelet, 3-nerved, rather loose and somewhat wrinkled; upper (fertile) floret ca. as
long as the spikelet; lemma stramineous, rigid, striate, strongly dorsally flattened; palea
similar, flat; lodicules 2, truncate; anthers 3, purple, 1.5-1.6 mm. long; styles 2, separate;
stigmas deep purple.

HOLOTYPE: Costa Rica: Prov. Cartago, 0.5 km. E of Planta
Radiografica, along railroad, 2 km. W of Paraiso, elevation 1,300 m.,
open grass marsh, 6 February 1969, Pohl & Davidse 11699, ISC.
ISOTYPES: F, CR, US, K. TOPOTYPE: same location, 28 February
1969, P. & D. 11742. We collected this species in a marsh at the Planta
Radiografica near Paraiso. Previous collections were reported by
Chase from Nuestro Amo and Aguacaliente. February to May.
Guatemala, Honduras, Costa Rica.

This is the most striking of the Central American species of Pas-
palum because of its large size and very conspicuous inflorescences.
The leaf margins are extremely scabrous and readily cut human skin.
Our specimens are very consistent in appearance. The strongly keeled
and overlapping basal sheaths are very distinctive, but may not be
present on herbarium specimens. Chromosome number n = 20 from
Costa Rican and Honduran collections. (Originally reported as P.
plenum.) All meioses were very irregular, with univalents and multi-
valents present. It is very possible that this species, like many other in
Paspalum, is apomictic. Paspalum turriforme belongs to the informal
group Virgata of Chase.

Paspalum vaginatum Swartz, Prodr. Veg. Ind. Occ. 21. 1788. Fig-
ure 154.

Extensively rhizomatous and stoloniferous perennial; erect culm branches 2-50 cm.
long; prostrate parts of the plants freely branching; erect culms simple or sometimes
branching from the lower nodes and forming dense tufts; internodes 1-3 mm. thick,
hollow, glabrous; lower internodes short, the upper ones successively longer; nodes
glabrous, sometimes swollen, mostly concealed by the overlapping sheaths; leaves usu-
ally numerous; leaf sheaths loose, keeled, glabrous except for long silky hairs, up to 4
mm. long, on the short auricles; ligule a thin brown truncate membrane, 0.6-1.0 mm.
long, adnate to the short sheath auricles; leaf blades 2-14 cm. long, mostly 1-4 mm. wide,
conspicuously distichous, stiff, straight, ascending or spreading, involute, ridged and
scabrid above, glabrous except for a few long marginal cilia. Peduncle exserted up to 4
cm.; inflorescences terminal on erect portions of the culms, 2-8 cm. long, usually com-
posed of 2 conjugate diverging racemes, sometimes with 1-several more a short distance
below; terminal racemes equal, naked at the base for up to 1 cm.; each raceme 2-8 cm.
long, the spikelets borne in 2 rows, overlapping; rachis 1.0-1.5 mm. wide, flat, with a

458

FIELDIANA: BOTANY

prominent midrib, bearing a solitary spikelet on the tip. Spikelets 3.2-3.6 mm. long,
obovate 2.2-2.6:1, acute, glabrous; strongly dorsally flattened; first glume absent in our
material; second glume and lower (sterile) lemma equal, as long as the spikelet, mostly
5-nerved, or sometimes with the midnerve absent; lateral nerves paired, near the mar-
gins; sterile lemma lacking a palea; upper (fertile) lemma 2.5-3.2 mm. long, obovate,
acute, whitish, finely striate; palea similar, flat; lodicules 2, truncate; anthers 3, purple,
1.8-2.0 mm. long; styles 2, separate; stigmas dark; caryopses not seen; most spikelets
appear sterile.

Sandy or coral beaches of the ocean, salt marshes along the coast.
Moin, Limon, Uvita, Rio Banano, Cahuita, Playas del Coco, Coronado
(Pte). June to December; probably blooming yearlong. North Carolina
and southward; Baja California and southward on the Pacific Coast;
southward to Peru and Argentina; West Indies; worldwide in warm
coastal climates.

This species and P. distichum are rather similar and have often been
confused. Chase gives an extensive synonomy. Recent discussions of
the nomenclature of these species are reviewed under P. distichum. In
addition to the spikelet and inflorescence differences given in the key,
P. vaginatum often differs from P. distichum in its tendency to bear a
large number of closely overlapping leaves, and in the production of
dense tufts of culms. Our chromosome counts of Costa Rican P. dis-
tichum indicate n = 30. Literature accounts of the chromosome
number of P. vaginatum list n = 20.

Paspalum virgatum L., Syst. Nat. ed. 10, 2:855. 1759. Figure 173.

FIG. 173. Paspalum virgatum. Inflorescence, two views of a spikelet, fertile floret.

BURGER: FLORA COSTARICENSIS 459

Tall, vigorous caespitose perennial; plants 80-250 cm. tall, erect; culms unbranched;
internodes 3-8 mm. thick, hollow, glabrous; nodes shrunken, dark, glabrous; leaf sheaths
somewhat keeled, overlapping, glabrous, or the overlapping margin, collar, and dewlap
papillose-pilose; lower sheaths somewhat spongy, tessellate in drying; ligule a thin
brown membrane, 1-3 mm. long, with a tuft of long white hairs behind it; leaf blades
narrow-based, widest at the middle, flat; midrib wide, white, keeled beneath near the
base; surfaces glabrous or rarely puberulent. Peduncles solitary, terminal, included or
exserted up to 13 cm.; inflorescences 12-20 cm. long, of usually 8-13 ascending to droop-
ing racemes; individual racemes 6-18 cm. long, the rachis 1.0-1.5 mm. wide, bearing a
tuft of white hairs at its base; margins strongly scabrous and with scattered white hairs.
Spikelets paired, 2.6-3.2 mm. long, blunt, obovate 1.2-1.6:1, mucronate, strongly dor-
sally flattened; first glume absent; second glume and lower (sterile) lemma equal, as long
as the spikelet, 5-nerved, puberulent, the hairs longest at the summit; bracts purplish or
reddish brown; upper (fertile) lemma nearly as long as the spikelet, light reddish brown
or chestnut colored at maturity, striate; palea similar to the lemma, concave; lodicules 2,
truncate; anthers 3, purple, 1.3-1.7 mm. long; styles 2, separate; stigmas purple; caryop-
sis 2.0-2.4 mm. long, broadly elliptical, reddish tan, opalescent. Chromosome number
n = 20 from Costa Rican and Venezuelan specimens.

Moist pastures and roadsides, stream banks; occasional in
Guanacaste and the General Valley, San Vito, Rincon, San Jose area,
Rio Sixaola near Bambu. Elevations mostly from sea level to 500 m.
Blooming yearlong, but apparently most frequently during the rainy
season. Southern Texas to Brazil; West Indies.

The length of the spikelets in our specimens is in the upper end of
the range of sizes indicated by Chase, and some exceed it. The plants
are striking by their large size and vigor. The only closely related
species in our flora is P. turriforme, which does not have brown fertile
florets.

PENNISETUM L. Richard

REFERENCE: Agnes Chase, The North American species of Pen-
nisetum, Contr. U.S. Natl. Herb. 22:4:209-234 + X. 1921.

Perennial or annual caespitose, rhizomatous, or stoloniferous grasses; inflorescence a
spike of bristly fascicles (much reduced in P. clandestinum), these deciduous from the
rachis with the contained spikelets; spikelets 1-several per fascicle, usually sessile within
it, remaining attached and falling with the bristles; bristles (sterile branchlets) usually
numerous and conspicuous, antrorsely scabrous, often ciliate, mostly concealing the
spikelets. Spikelets dorsally compressed; first glume much shorter than the spikelet,
often obsolete, usually 1-nerved or nerveless; second glume usually shorter than the
spikelet, several-nerved; lower floret sometimes sterile and lacking a palea, or with a
well-developed palea and a staminate flower, the lemma usually 5-7-nerved; upper floret
perfect-flowered, the lemma 3-5-nerved; palea well developed; lodicules present or ab-
sent; anthers 3; ovary with a single style and 2 stigmas, or the styles separate.

Pennisetum clandestinum is exceptional in its reduced inflores-
cence, abortive glumes, numerous nerves of the lemmas, and growth

460 FIELDIANA: BOTANY

habit. It may merit being placed in a separate genus. Pennisetum is
closely related to Cenchrus, differing in the separate bristles of the
fascicle, which are antrorsely scabrous. In Cenchrus, the bristles are
more or less united into flat spines which are in almost all species
retrorsely barbed. The basic chromosome number in most species of
Cenchrus is x = 17, but various numbers excepting x = 17 have been
found in species of Pennisetum. Although it is difficult to assign a few
species of this complex definitely to one or the other of these genera,
the generic characters hold for the great bulk of the species.
(Panicoideae: Paniceae.)

KEY TO SPECIES OF Pennisetum

la. Low creeping plants; inflorescences reduced to 1-several spikelets, concealed within
sheaths, only their tips protruding, stigmas and stamens exserted; lemmas with
10-13 nerves P. clandestinum

Ib. Erect plants with exserted terminal inflorescences composed of numerous bristly
fascicles on elongated straight rachis; lemmas with 3-7 nerves 2

2a. Spikelet 1 per fascicle 3

2b. Spikelets several per fascicle 7

3a. Inflorescences solitary at tips of main culm or long leafy branches 4

3b. Inflorescences terminal and axillary, usually numerous on one culm and forming a

compound inflorescence 6

4a. Bristles of fascicle scabrous, not ciliate 5

4b. Bristles of fascicle densely silky-ciliate near their bases, adjacent bristles be-
coming matted together by hairs P. setosum

5a. Lower lemma empty, lacking palea or staminate flower; spikelets acuminate or
caudate; anthers purple, 1.2-1.5 mm. long; styles 2, separate ... P. tempisqiiense

5b. Lower lemma with palea of equal length and staminate flower; spikelets acute;
anthers orange, 3.0-3.6 mm. long; style single, bearing 2 stigmas P. complanatum
6a. Most bristles shorter than spikelet; lower floret sterile and lacking palea

P. distachyum

6b. Most bristles longer than spikelet; lower floret with well-developed palea and
usually a staminate flower P. bambusiforme

7a. Tall stout plants, culms up to 8 m. tall, 1.0-2.5 cm. thick; spikelets stalked within
fascicle P. purpureum

7b. Slender plants, culms less than 1.5 m. tall, 1-2 mm. thick; spikelets sessile in fasci-
cle 7

8a. Each fascicle with a single elongate inner bristle, 2-3 x as long as others;

spikelets 6-9 mm. long P. vulcanicum

8b. Inner bristle less than twice as long as others; spikelets 2-6 mm. long P. ciliare

Pennisetum bambusiforme (Fourn.) Hemsl. ex Jacks., Ind. Kew
2:458. 1895. Gymnothrix bambusiformis Fourn., Mex. PI. 2:48. 1881.
Figure 174.

Tall vigorous perennial; the culms arising in clumps from decumbent and sometimes
rooting bases, up to 1 cm. thick, hollow, glabrous; sheaths shorter than the internodes,

FIG. 174. Pennisetum species. P. bambusiforme: A, fascicle; P. complanatum: B,
fascicle; P. distachyum: C, fascicles; P. purpureum: D, fascicle; P. setosum: E, fascicle;
F, ciliate bristles; P. vulcanicum: G, fascicle.

461

462 FIELDIANA: BOTANY

glabrous or sometimes appressed-bearded just above the nodes and hirsute near the
apex, papillose-ciliate on the upper margins and auricles; ligule 1-4 mm. long, a short
membrane ciliate with a dense row of stiff erect hairs; larger leaf blades 20-32 cm. long,
20-40 mm. wide, more or less hirsute on both surfaces, flat, tapering to a petiole-like
base. Inflorescence large and compound, of numerous spikes exserted on peduncles of
varying lengths from the upper leaf sheaths, usually several from one axil, their sub-
tending leaf blades usually much reduced or obsolete. Individual spikes drooping, usu-
ally purplish, cylindrical, loose, bristly, 6-10 cm. long, 1-2 cm. thick, including the bris-
tles; individual fascicles borne on minute scabrous stipes; bristles numerous, scabrid,
unequal, mostly 6-12 mm. long, surrounding a single spikelet; the uppermost bristle
directly subtending the spikelet usually 16-18 mm. long, much longer than the others.
Rachis of the spikes flexuous, angular, scabrous. Spikelets ovate, acuminate, 3.9-5.2
mm. long, sessile in the fascicle and falling with it; first glume minute, obtuse, 1-nerved;
second glume broadly ovate, caudate, 1-nerved, 1-2 mm. long; lower lemma longer than
the upper, 4.0-5.2 mm. long, ovate, caudate, faintly 5-6-nerved, scabrid, enclosing a
2-nerved palea ca. two-thirds as long; 3 stamens usually present; upper floret perfect-
flowered, the lemma ovate, caudate, 3.0-4.2 mm. long, faintly 3-5-nerved, chartaceous,
scabrid, the palea shorter; lodicules 2, truncate; style branches 2, naked below; stigmas
brown; anthers 3, 1.5-2.0 mm. long. Chromosome number n = 18 from a Costa Rican
specimen.

Meseta Central and Cordillera de Talamanca; elevations from 950 to
2,600 m. This species is a conspicuous part of the vegetation of steep
slopes, where it arches over other plants, the large purplish compound
inflorescences drooping. Blooming July to March, possibly yearlong.
Southern Mexico to northern South America.

Pennisetum ciliare (L.) Link, Hort. Berol. 1:213. 1827. Cenchrus
ciliaris L., Mant. 302. 1771. Pennisetum cenchroides L. Rich, ex
Pers., Syn. PL 72. 1805.

Perennial from hard, knotty crowns, sometimes with short rhizomes; culms 25-100 cm.
long, erect, 1-2 mm. thick, solid or hollow, sometimes much branched from basal, lower,
and middle nodes and becoming bushy; leaf sheaths about equal to the internodes,
glabrous or sparsely pilose, keeled; ligule a densely ciliate membrane, 0.5-2.5 mm. long;
blades 3-24 cm. long, 2-9 mm. wide, scabrous, sometimes slightly pilose, tapering to a
caudate apex. Peduncle exserted; inflorescences terminal on leafy branches; inflores-
cence a densely cylindrical spike of bristly fascicles, 2-12 cm. long, 1-2.5 cm. wide; rachis
internodes 0.8-1.0 (2.0) mm. long; fascicles concealing the rachis, often purplish, 6-15
mm. long, including the bristles, 1.5-3.5 mm. wide; stipe of fascicles pilose, 0.5-1.5 mm.
long; bristles erect to spreading, flexuous, 4-10 mm. long, 0.2-0.6 mm. wide, conspicu-
ously ciliate, antrorsely scabrous, very slightly united at the base. Spikelets 2-4 per
fascicle, 2.0-6.0 mm. long, dorsally compressed; first glume 1.0-3.0 mm. long, 1-nerved,
thin and membranaceous; second glume 1.3-3.4 mm. long, 1-3-nerved; lower lemma
2.5-5.0 mm. long, 5-6-nerved, the palea 2.5-5.0 mm. long, enclosing a staminate flower;
upper lemma 2.2-5.4 mm. long, thin, 5-nerved.

This species has been cultivated in the grass garden of the IICA at
Turrialba, but has not as yet appeared in cultivation elsewhere in
Costa Rica. It has considerable forage potential and is much cultivated

BURGER: FLORA COSTARICENSIS 463

in warm climates. This species lies close to the indeterminate boundary
line between Pennisetum and Cenchrus. Because of the hard-based
perennial growth habit, lack of flattened, retrorsely-barbed spines, the
basic chromosome number of a: = 9, and the extensive occurrence of
apomixis, it seems more closely allied to Pennisetum than to Cen-
chrus. Native from Africa to India. Common name: Zacate buffel,
"Buffel grass."

Pennisetum clandestinum Hochst. ex Chiov. in Annuario Reale
1st. Bot. Roma 8:41, t. v., fig. 2. 1903. Figure 175.

Vigorous low creeping perennial; erect branches up to 45 cm. when not grazed, usually
15 cm. or less tall; rhizomes and stolons present; internodes very short and densely
clothed with overlapping sheaths; branching profuse, erect branches being produced at
most nodes; prophylla prominent, retrorsely scabrous on the keels; sheaths keeled,
glabrous or usually papillose-hirsute, especially on the upper margins; ligule a dense
ciliate rim, up to 2 mm. long; blades folded or flat, 3-9 cm. long, 2-5 mm. wide, the tip
blunt and sometimes slightly bifid; upper and lower surfaces glabrous or with scattered
long hairs. Inflorescence a short mostly concealed axillary spike, the 1-4 spikelets sessile
and solitary at the nodes of a short flattened rachis, only their tips exserted from the leaf
sheaths. Spikelets not disarticulating from the plant, each surrounded by a basal fascicle
of slender bristles of varying lengths, mostly less than half the length of the spikelet;
shape of spikelet narrowly lanceolate, tapering to a slender apex; first glume absent, the
second absent or reduced to a minute nerveless scale; lower and upper lemmas equal,
similar, 19-22 mm. long; lower lemma empty and without a palea, 10-13-nerved; upper
lemma 10-12-nerved, its palea 2-7-nerved, 16-17 mm. long; lodicules none; flower usually
hermaphrodite, protogynous, the short-plumose solitary style up to 3 cm. long, exserted
through the tip of the floret, stigmatic on its exposed parts; anthers 4-7 mm. long, at
anthesis exserted from the floret on stiff, erect, white filaments up to 3 cm. long, the
anthers dangling at their tips. Caryopses not seen.

This is one of the most abundant and widely distributed forage
grasses in upland pastures, from 1,500 to 2,500 m. elevation. It is
readily recognized by its creeping stems and light green color. Under
certain circumstances it becomes an invading weed on cultivated
ground. It is native to tropical Africa, but is cultivated in many parts of
the world. In the Americas, it occurs in California, Guatemala, Costa
Rica, and various South American countries.

Most reproduction in this species appears to be by the stolons, but
production of seed, which may be dispersed in the manure of grazing
animals, has been reported from South America. The erect stamens,
unique in this species, are often exserted during the mornings in very
humid weather. Unlike most other grasses, there is but a single
stigma. Both stamens and stigma are exserted from the tip of the
fertile floret, because of the lack of lodicules. Many florets with ex-
serted stigmas show anthers still concealed within the floret, and it is

FIG. 175. Pennisetum clandestinum. A, growth habit; B, fascicle with a spikelet; C,
emergent stamens.

464

BURGER: FLORA COSTARICENSIS 465

possible that they do not emerge. Common names are Kikuyo, Pasto
Kikuyo, Pasto africano.

Pennisetum complanatum (Nees) Hemsl. , Biol. Centr. Amer. Bot.
3:507. 1885. Gymnothrix complanata Nees, Bonplandia 3:83. 1855. G.
mexicana Fourn., Mex. PI. 2:48. 1881. G. grisebachiana Fourn., Mex.
PI. 2:48. 1881. Figure 174.

Perennial, rhizomatous, 75-200 cm. tall, or much shorter when grazed; culms branched
from the lower and middle nodes, often decumbent and rooting, 2-3 mm. thick, glabrous,
hollow, thick- walled; nodes glabrous or slightly appressed-hispid; sheaths longer than
the internodes, loose, somewhat compressed, glabrous or ciliate on the upper margins;
ligule 1.0-1.6 mm. long, a minute membrane crowned with a dense row of stiff white
hairs; blades 15-55 cm. long, flat or folded, 3-7 mm. wide, attenuate, scabrous, the upper
surface hirsute near the base. Peduncles exserted; inflorescence a dense cylindrical spike
of bristly fascicles, terminal on the main culm or on leafy branches, 8-17 cm. long, 7-10
mm. thick without the bristles, 10-25 mm. including them, tawny or purplish; spikelets
borne singly in the sessile fascicles on the angled scabrous rachis. Bristles of the fascicle
numerous, stiff, scabrous; outer bristles 1-5 mm. long, the inner 8-12, one single inner
bristle much longer, 10-19 mm. long; fascicle deciduous with the solitary contained
spikelet. Spikelets narrowly ovate, acute, dorsally compressed, 5-6 mm. long; first
glume rotund or ovate, nerveless or with a single weak nerve; second glume shorter than
the spikelet, 3.8-4.6 mm. long, 5-nerved, ovate, acute; lower lemma 4.4-5.7 mm. long,
ovate, 5-nerved, its palea equal; anthers 3, orange, 2.4-3.2 mm. long; upper floret 4.5-5.7
mm. long, chartaceous, the lemma ovate, acute, faintly 5-nerved, its palea equal to the
lemma; lodicules absent; anthers 3, orange, 3.0-3.6 mm. long; style single, dividing into 2
plumose short stigmas.

Known from Costa Rica only about the hot springs of Las Hornillas,
west face of Volcan Rincon de la Vieja, elevation 750 m. Southern
Mexico to El Salvador; Costa Rica and Panama.

Pennisetum distachyum Ruprecht, Bull. Acad. Roy. Sci. Bruxelles
9:2:242. 1842. Gymnothrix distachya (Rupr.) Fourn., Mex. PL 2:48.
1881. Figure 174.

Tall vigorous perennial; culms arching, 2.5-3 m. long, in clumps from hard, knotty
cormlike bases, the lower nodes rooting; internodes 3-6 mm. thick, glabrous; nodes
appressed-hispid; sheaths mostly shorter than the internodes, glabrous except for the
ciliate upper margins; ligule 1.5-3.5 mm. long, a short stiff membrane densely ciliate with
stiff erect white hairs; larger leaf blades 17-45 cm. long, 15-35 mm. wide, flat, tapering to
a narrow petiole-like base, glabrous to hirsute on both surfaces, the margins scabrous.
Inflorescence of numerous terminal and axillary spikes, these borne on slender pedun-
cles, usually several of unequal length from a single leaf axil; ultimate leaf blades of the
flowering branches much reduced. Individual spikes 3-10 cm. long, 7-10 mm. thick,
greenish or purplish; rachis slender, scabrous, flexuous, the minute scabrous stipes of
the fascicles persisting on the rachis after they disarticulate. Fascicles each with a single
spikelet, the bristles not conspicuous, mostly shorter than the spikelet except the in-
nermost, which may be up to 20 mm. long. Spikelets narrowly ovate, acute to acuminate,

466 FIELDIANA: BOTANY

dorsally compressed, 4.0-6.2 mm. long, remaining attached to the fascicle; first glume
minute, 0.5-1.2 mm. long, oblong-lanceolate, 1-nerved or nerveless; second glume ovate,
acute, faintly 3-nerved, 1.8-2.5 mm. long; lower lemma 4.8-5.4 mm. long, narrowly
ovate, acute or acuminate, scabrid toward the tip, faintly 5-nerved, the midnerve some-
times suppressed; no palea or flower present; upper lemma 3.8-5.4 mm. long, similar to
the lower, chartaceous, faintly 3-5-nerved, the margins thin and overlapping the edges
of the palea, which is 3.7-4.7 mm. long; lodicules 2, truncate; anthers 3, purple, 1.3-1.8
mm. long; styles naked at the base; stigmas 2, brown to purple. Chromosome number n
= 18 from a Costa Rican specimen.

Open, disturbed areas around San Jose, southern slopes of Volcan
Turrialba, San Ramon. February to November, probably yearlong.
Southern Mexico and Guatemala, Costa Rica.

The nomenclature of this species is confused and citations of authors
are often incorrect. Since P. distachyum was originally described by
Ruprecht in 1842, Fournier (1881) cannot be cited parenthetically.
Mrs. Chase believed the name should be applied to the species above,
having short bristles. Her usage is followed. The type specimen
(Galeotti 5680) was not seen by Chase, but was cited by Fournier,
when he transferred the species to the genus Gymnothrix in 1881.
Since descriptions are obscure and may refer to several species, de-
finite application of the name awaits the examination of the specimen.

Pennisetum purpureum Schum., Beskr. Guin. PL 64. 1827. Figure
174.

Tall stout perennial, forming large clumps; culms erect, to 8 m. tall, 1.0-2.5 cm. thick,
solid or hollow, the bases often decumbent and rooting; branching sparse, mostly from
the lower nodes; culms usually glabrous, glaucous, or sometimes pubescent near the
summit; nodes not prominent, glabrous or sometimes appressed-hispid; sheaths glabrous
or sometimes papillose-hirsute; ligule a minute membrane, bearing a dense row of long,
stiff white hairs, in total 1.5-3.5 mm. long; leaf blades up to 125 cm. long and 4 cm. wide,
glabrous to papillose-pubescent; midrib prominent beneath; margins strongly scabrous.
Inflorescence a dense cylindrical spike of bristly fascicles, up to 30 cm. long, 1-2 cm. thick
excluding the longer bristles; color golden yellow to purple; rachis cylindrical, densely
clothed with white hairs, bearing the stubs of the stipes of the fascicles. Fascicles
bearded at the base with short white hairs; bristles numerous, usually golden, scabrous,
of varying lengths up to 10-15 mm. long; innermost bristle thicker, up to 40 mm. long,
usually twice as long as the others; spikelets 1-5 per fascicle, the larger ones on minute
pedicels above the bristles, the smaller or abortive ones on longer pedicels to 2 mm.
Spikelets 4.5-7.0 mm. long, (except the abortive ones), dorsally compressed, narrowly
ovate, caudate; remaining attached and falling with the fascicle; first glume absent or a
minute rounded scale up to 0.7 mm. long; second glume ovate, 1-nerved, 1.5-2.6 mm.
long; lower lemma 4.0-5.2 mm. long, narrowly ovate, acuminate, 3-nerved, the nerves
scabrid; staminate flower of 3 stamens usually present; palea about equal to the lemma;
upper floret 4.6-7.0 mm. long, the lemma shiny, the 5-7 nerves scabrid; palea about equal
to the lemma; lodicules lacking; anthers 3, 2.7-3.6 mm. long; style 1, its upper part and
the 2 stigmas plumose.

BURGER: FLORA COSTARICENSIS 467

Cultivated as a forage grass at low and medium altitudes up to 1,800
m. and escaping on river banks and in open areas. Blooming July to
November, probably yearlong. Native to tropical Africa, but widely
cultivated in tropical regions of the world. Florida and the West In-
dies; Guatemala; Costa Rica, to Brazil. The earliest specimen from
Costa Rica was collected in 1924. An extensive synonymy is given by
Stapf and Hubbard in Fl. Trop. Africa 9:1017-1018 (1934). Common
names: Yerba elefante, Elefante, Gigante.

Pennisetum setosum (Swartz) L. Rich., in Pers. Syn. PL 1:72.
1805. Cenchrus setosus Swartz, Prodr. Veg. Ind. Occ. 26. 1788. Figure
174.

Vigorous perennial; culms 1-2 m. long, in clumps from hard, knotty cormose bases,
bases sometimes decumbent, arching, branching from middle and upper nodes, 3-5 mm.
thick, hollow, glabrous; leaf sheaths usually shorter than the internodes, glabrous or
pilose along the upper margins, one side with a vertical auricle; ligule a short stiff
membrane, densely ciliate with a row of long, stiff hairs, total length 1.5-2.7 mm.;
sometimes a row of minute bristles on the collar; leaf blades acuminate, the larger ones
15-55 cm. long, 4-18 mm. wide, mostly glabrous beneath, scabrid on margins and upper
surface, with long, papillose-based stiff hairs on upper surface near the base, sometimes
hirsute on both surfaces. Peduncles exserted on the main culm or on leafy branches,
glabrous; inflorescences purplish, arching, 10-25 cm. long, 6-10 mm. thick excluding the
bristles, 15-30 mm. including them; fascicles and bristles ascending in nature, often
reflexed in herbarium specimens; fascicles densely crowded, sessile on the thin cylindri-
cal, notched and grooved rachis; bristles of several unequal series, the outer ones very
short, thin and delicate, the inner flattened and rigid near the base, conspicuously ciliate
with delicate silky hairs about to the tip of the spikelet, the hairs of adjacent bristles
becoming interlaced and tangled; inner bristles 6-12 mm. long, except the innermost one
which is usually 16-22 mm. long, much exceeding the spikelet; fascicles with their in-
cluded spikelets freely deciduous from the rachis. Spikelets one per fascicle, ovate,
acute, 3.7-4.5 mm. long, sessile, remaining attached to the fascicle; first glume obsolete
or up to 1 mm. long, oblong, nerveless; second glume 3.7-4.5 mm. long, 5-7-nerved,
ovate, the tip 3-lobed; lower lemma 3.0-3.9 mm. long, ovate, 5-7-nerved, the tip lobed,
the palea shorter; anthers 3 or 0; upper floret readily deciduous from the spikelet,
perfect-flowered; lemma chartaceous, smooth and shining, ovate, acute, 2.2-3.0 mm.
long, its flat margins covering the edges of the palea; anthers 3, yellow, 1.7-2. 1 mm. long;
lodicules absent; styles 2, naked below; caryopsis elliptical, ca. 1.7 mm. long. Chromo-
some number 2n = 53 from a Costa Rican specimen.

Steep hillsides and road cuts, hilly savannas; western parts of the
Meseta Central, San Mateo, San Ramon, Nicoya Peninsula, Canas,
Boruca, Monteverde. Elevations 100-1,500 m. Blooming from late Oc-
tober to February. Southern Florida; southern Mexico to Brazil; West
Indies.

Many cytological abnormalities were observed, indicating possible
apomixis.

468 FIELDIANA: BOTANY

Pennisetum tempisquense Pohl, Fieldiana, Bot. 38:6. 1976. Figure
176.

Caespitose perennial; plants 39-100 cm. tall; culms erect, unbranched, densely clus-
tered, glabrous, glaucous, rather thin-walled, the interior filled with parenchyma; nodes
glabrous, constricted, dark; leaves ca. 7 per culm; sheaths mostly shorter than the
internodes, compressed and keeled, glabrous and glaucous, the margin thin and mem-
branaceous; ligule a short membrane, densely long-ciliate, 1.0-1.8 mm. long; leaf blades
flat or folded, keeled near the base, firm, scabrous-margined, the base narrower than the
summit of the sheath, glabrous and glaucous, 4.5-7.5 mm. wide, 8-22 cm. long, the
uppermost shorter. Peduncle exserted; inflorescence a solitary terminal spike of fasci-
cles, stiff and erect, whitish, 7-10 cm. long, 2.0-2.5 cm. thick, including the bristles;
rachis ca. 1 mm. thick, longitudinally striate, densely short-hispid; fascicles borne on
minute projections of the rachis, crowded, horizontally spreading, mostly 10-14 mm.
long; bristles ca. 20 per fascicle, whitish, of varying lengths, the outermost 3-4 mm. long,
the majority 8-10 mm. long, the innermost one longer and thicker, 12-17 mm. long, all
straight, upwardly scabrous, attached to a short, rounded common stipe ca. 0.2-0.3 mm.
long. Spikelet one per fascicle and sessile within it, narrowly ovate, acuminate, 5-6 mm.
long; first glume ovate, 1.0-1.5 mm. long, acute to rounded, scarcely nerved, mem-
branaceous; second glume, lower lemma, and upper lemma subequal, acuminate or awn-
tipped; second glume 5.0-5.5 mm. long, striate, 7-nerved; lower lemma 5.7-5.9 mm. long,
5-nerved, without a palea or flower; upper lemma 5.2-5.7 mm. long, faintly 5-nerved, the
palea about equal, 2-nerved, acuminate; anthers purple, 1.2-1.5 mm. long; ovary with 2
separate styles; stigmas purple; caryopsis oblong, tan, 2.1-2.2 mm. long.

Known only from the type specimen, collected on a black gumbo clay
flat, 8 km. N of Haciendo Palo Verde, Guanacaste, elevation 10 m.,
Pohl & Davidse 11725. The plants were past maturity when collected
in late February. Chromosome number n = 36, originally published as
P. nervosum in Pohl & Davidse, 1971.

This species differs from the widespread P. complanatum (Nees)
Hemsl. in its caespitose rather than rhizomatous character, in the
fewer, more slender whitish bristles, the acuminate spikelets with
sterile lower floret, and the separate styles. It differs from the South
American P. nervosum in its smaller size, solid culms, smaller inflores-
cences, fewer bristles, shorter spikelets with short first glume, and its
chromosome number (n = 36, that of P. nervosum being n = 18). It
appears similar to P. frutescens Leeke of southern South America,
from which it differs in its solid culms, longer bristles, smaller size,
lack of rhizomes, and different chromosome number. Pennisetum
frutescens has 2n = 63 (Nunez, 1952). The specific name is derived
from the Rio Tempisque, near the type locality.

Pennisetum vulcanicum Chase, J. Wash. Acad. Sci. 13:363. 1923.
Figure 174.

Perennial, 1.0-1.5 m. tall, erect, the culms somewhat branched, glabrous; sheaths
keeled, longer than the internodes, glabrous to papillose-pilose; leaf blades 20-45 cm.

FIG. 176. Pennisetum tempisquense. A, inflorescence; B, growth habit; C, fascicle, D,
pistil.

469

470 FIELDIANA: BOTANY

long, 5-8 mm. wide, attenuate, papillose-pilose above. Inflorescence 10-17 cm. long,
linear, cylindrical, 5-12 mm. thick, not including the bristles, up to 45 mm. including the
longer bristles; fascicles crowded, sessile; rachis visible; spikelets 3-5 per fascicle, ses-
sile; outer bristles short and fine, 3-4 mm. long; second series of bristles 10-12 mm. long,
scabrous; inner series much fewer, thick and stiff, prominently long-ciliate on their lower
halves; innermost bristle flattened, ca. twice as thick as the others and much longer, to
2-5 cm. long; stipe short, hairy. Spikelets 6-9 mm. long, dorsally compressed; first glume
ovate, apiculate, 1-nerved, 2.7 mm. long; second glume ovate, acute or blunt, 2-4-
nerved, 3.0-3.5 mm. long; lower lemma 5.2 mm. long, ovate, 5-nerved, its palea 4.5 mm.
long; anthers 3; upper lemma 5.7 mm. long, narrowly ovate, acuminate, 5-nerved, its
palea 4.5 mm. long; anthers 3, orange, 2.7-3.0 mm. long; styles 2, separate, long and
slender, naked below.

This species is rare and little known. One specimen named by Agnes
Chase (Gamier 822, from Managua, Nicaragua) had shriveled, non-
opening anthers and collapsed pollen. Southwestern Mexico,
Guatemala, El Salvador, Nicaragua. The only Costa Rican specimen
determined by Chase was from Nuestro Amo (0. Jimenez 522}. This
species is closely related to P. karwinskyi Schrad., which has been
transferred by DeLisle to Cenchrus as C. multiftorus Presl. By
growth habit and fascicle structure, it seems more closely related to
Pennisetum.

PENTARRAPHIS Humboldt, Bonpland, and Kunth

Tufted small annual or perennial grasses; spikelets borne in fascicles on a slender erect
flattened rachis and dropping from it whole; fascicle consisting of 1-2 spikelets, the lower
sometimes reduced to a group of 2-4 stiff bristles; spikelets 2-flowered; first glume
acicular, resembling the sterile bristles, the second subulate; lower floret perfect-
flowered, its lemma 3-lobed; marginal lobes awnlike, arising about the middle of the
length of the lemma; central lobe bifid, the 2 acuminate teeth arising at the base of the
awn; nerves 3, all near the center of the lemma; second floret similar to the first but
smaller, its flower abortive.

Species 3, in Mexico, Central America, and Colombia. The genus is
closely related to Bouteloua. (Choridoideae: Chlorideae.)

Pentarraphis annua Swallen, Ceiba 4:286. 1955. Figure 177.

Tufted annual; plants 10-25 cm. tall, the culms erect, in small tufts, branching from the
base and lower nodes, glabrous, hollow, ca. 0.3 mm. thick; nodes enlarged, glabrous;
prophylla 7-14 mm. long, exceeding the sheaths; sheaths glabrous, much shorter than
the internodes; ligule ca. 0.3 mm. long, a minute ciliate fringe; blades 1-4 cm. long, ca. 1
mm. wide, mostly involute, bearing a few scattered long hairs on the auricles and upper
surface. Inflorescences terminal and axillary, the axillary ones of 1-2 partly concealed
spikelets, the terminal inflorescence a slender spike, 2-3 cm. long, the rachis flattened,
scabrous, terminating in a forked bristle-like rudiment; spikelet fascicles less than 10;
fascicles consisting of a single fertile spikelet, subtended by several hispid bristles
(rudimentary sterile spikelets), ca. 2.5 mm. long, the whole disarticulating from the
rachis as a group with a bearded callus. Spikelets 8-9 mm. long, including the awns; first

FIG. 177. Pentarraphis annua. A, inflorescence; B, apex of rachis with two appen-
dages and a spikelet fascicle; C, spikelet fascicle; D, lemma.

471

472 FIELDIANA: BOTANY

glume bristle-like, similar to the sterile bristles, hispid on its upper half, 2.0-2.5 mm.
long; second glume subulate, 3.5-4.0 mm. long, tapering into a stiff scabrous awn; lower
floret perfect-flowered, its callus bearded; lemma 3.2-3.5 mm. long, strongly 3-lobed;
lateral nerves close to the midrib and extending into the acuminate teeth of the lemma;
awn arising between the teeth, 4-5 mm. long, stiff and scabrous; back of the lemma
bearing a transverse band of appressed-hispid hairs near the middle; margins of lemma
produced into 2 stiff acuminate awnlike lobes, 4-5 mm. long, attached ca. one-third below
the apex; palea 3.0-3.3 mm. long, bifid at the tip; anthers 3, purplish, 0.7-0.8 mm. long;
caryopsis narrowly elliptical, free, 1.3 mm. long, tan; second floret similar to the first but
smaller, its lemma 2.5-3.0 mm. long, glabrous, the flower apparently abortive.

Rare; Hacienda Las Animas, Guanacaste. Our only specimen was
collected from a dry tuff outcrop. December. Originally described from
Honduras; Panama and Colombia.

PEREILEMA Presl

Short-lived annual grasses, developing at the beginning of the dry season; plants
tufted, erect or the culms decumbent and rooting at the base, with erect flowering
branches arising from the rooting nodes. Inflorescence a dense, lobed cylindrical panicle.
Spikelets borne in dense fascicles crowded on the short erect branches; fascicles of
several functional spikelets, with an involucre of reduced sterile spikelets, mostly in the
form of short scabrid awns; spikelets 1-flowered; glumes equal, 1-nerved, awned from a
bifid apex; floret disarticulating from the persistent glumes; lemma terete, long-awned;
callus bearing straight erect hairs; palea about as long as the lemma.

The genus appears close to Muhlenbergia, differing in the fascicle of
sterile branchlets. (Chloridoideae: Sporoboleae.)

KEY TO SPECIES OF Pereilema

la. Upper leaf blades 5-8 mm. wide; awns straight; anthers 2, purple, 0.7-1.0 mm.

long P. beyrichianum

Ib. Upper leaf blades 2-3 mm. wide; awns flexuous; anthers 3, yellow, 0.5 mm. long

P. crinitum

Pereilema beyrichianum (Kunth) Hitchc., Contr. U.S. Natl. Herb.
24:385. 1927. Muhlenbergia beyrichiana Kunth, Enum. PL 1:200.
1833.

Tufted annual; culms sometimes decumbent and rooting from lower nodes, 40-80 cm.
long, mostly simple, 1-2 mm. thick, hollow, slightly scabrid-roughened, often reddish;
nodes glabrous, not prominent; prophylls prominent, 2-3 cm. long, 2-toothed; leaf
sheaths shorter than the internodes, minutely scabrid; ligule a thick brown membrane,
0.7-1.0 mm. long; leaf blades 10-20 cm. long, 5-8 mm. wide, scabrid; auricles prominent,
embracing the stem, ciliate. Peduncle mostly included, or exserted to 6 cm.; rachis of
panicle angular, upwardly ciliate-scabrous; panicle single, terminal on the culms or on
leafy branches arising from rooted lower nodes, 10-20 cm. long, 1-2 cm. wide, cylindrical,
lobulate near the base; branches solitary, short, 1-3 cm. long, erect and appressed to the
rachis, densely covered with fascicles of spikelets; fascicles dense. Functional spikelets
terete; glumes subequal, 0.7-1.0 mm. long, oblong to broadly ovate, bearing an awn 3-4

BURGER: FLORA COSTARICENSIS 473

mm. long; lemma 1.0-1.5 mm. long, 3-nerved, lanceolate, tapering into a straight awn up
to 2 cm. long; palea equal to lemma, tapering into a short awn tip; anthers 2, 0.7-1.0 mm.
long, purple; sheaths and awn often reddish; awns bearing chloridoid microhairs.
Chromosome number n = 40, from a Costa Rican specimen.

Occasional in the Meseta Central near San Jose; Guadalupe, Rio
Tiliri, Llano Grande, Puente Mulas; also near Santa Maria de Dota;
brushy slopes; elevations 800-1,800 m. Late November to February.
Guatemala and Costa Rica to northern South America.

Pereilema crinitum Presl, Rel. Haenk. 1:233. 1830. Figure 178.

Tufted annual, the culms sometimes decumbent and rooting at the lower nodes and
bearing upright flowering branches from the rooted nodes; prophylls prominent, 2-5 cm.
long, the keels bearing awns 2-4 mm. long at the tip; keels ciliate; culms 1 mm. thick,
hollow, glabrous; nodes glabrous; sheaths mostly overlapping, scabrid; ligule 0.3-0.5
mm. long, a minute lacerate membrane; leaf blades 5-15 cm. long, 2-3 mm. wide, gla-
brous, tapering to a narrow base; auricles prominent, embracing the stem, ciliate.
Peduncle ridged, angular, scabrid, included or exserted up to 5-10 cm.; panicles single,
terminal, narrowly cylindrical, lobulate below, 5-13 cm. long, 2-3 cm. wide, including the
awns; branches solitary, erect, ca. 1 cm. long, the lowermost often remote; spikelets
borne in densely crowded fascicles; sterile bristles ca. 3 mm. long. Glumes of functional
spikelets subequal, 1 mm. long, 1-nerved, oblong to ovate, bifid at the summit, with an
awn ca. 2 mm. long; lemma 1.5 mm. long, lanceolate, 3-nerved, the lateral nerves
marginal; callus hairs dense, erect, one-third to one-half as long as the lemma; lemma
scabrid, tapering into a reddish, undulate awn 2-3 cm. long; palea equal to lemma;
anthers 3, 0.5-0.7 mm. long, yellow. Chromosome number n = 10 from Costa Rican
material.

Scattered in the Meseta Central and a few other localities; Boruca,
San Isidro de El General, Valley of Rio Grande de Tarcoles; mostly on
steep exposed slopes, savannas, or road cuts; elevation 500-1,500 m.
Guatemala and Honduras; Costa Rica to Ecuador.

This species, like the preceding, develops very rapidly from seed at
the beginning of the dry season and soon goes to seed and dies.
November and December, rarely to February.

PHALARIS Linnaeus

Plants annual or perennial, caespitose or rhizomatous; inflorescence a dense cylindrical
or ovoid terminal panicle; spikelets laterally compressed, the glumes equal, keeled,
longer than and concealing the florets; florets 2 or 3, the lower 2 greatly reduced,
appearing as little scales attached to the base of the fertile floret and disarticulating with

it; fertile floret laterally compressed, rigid and shiny, awnless, glabrous or appressed-

hairy.

A genus of about 15 species of annual and perennial grasses, mostly
native to the North Temperate Zone, with a few in southern South
America. The genus belongs to the Pooid subfamily, and is probably

.725?

FIG. 178. Pereilema crinitum. A, inflorescence; B, fascicle of spikelets; C, glumes and
floret.

474

BURGER: FLORA COSTARICENSIS 475

most closely related to Hierochloe, from which it differs in its reduced
lower florets. (Pooideae: Phalarideae.)

KEY TO SPECIES OF Phalaris

la. Rhizomatous perennial; leaves longitudinally green and white striped; inflorescences
not produced under Costa Rican conditions P. arundinacea, f. picta

Ib. Caespitose annuals; leaves green; inflorescences produced 2

2a. Sterile lemmas 2, more than half as long as fertile floret P. canariensis

2b. Sterile lemma 1, less than half as long as fertile floret P. minor

Phalaris arundinacea L., Sp. PI. 55. 1753, f. picta (L.) Aschers.
and Graebn., Syn. Mitteleurop. Fl. 24. 1898.

This is a sterile form of the common reed canary grass of the north
temperate zone. It is widely culivated as an ornamental in cooler
climates. We have seen it cultivated in Los Yoses, but without
inflorescences.

Phalaris canariensis L., Sp. PI. 54. 1753. Figure 179.

Tufted annual; culms erect, 30-100 cm. tall; panicle ovoid, 1.5-4 cm. long, up to 2 cm.
wide, dense; spikelets broad, with a strongly winged keel; glumes 7-10 mm. long, with
alternating whitish and green longitudinal stripes; fertile floret acute, 4.8-6.8 mm. long,
densely appressed-pubescent; sterile florets 2, 2.5-4.5 mm. long, 1.4-1.7 mm. wide,
sparsely pubescent.

This species produces one of the types of "seeds" commonly fed to
caged birds. For this reason, the plants may appear on waste heaps
almost anywhere. Our single collection from Costa Rica was from a
gutter along Avenida Central near La Luz, San Jose.

Phalaris minor Retz., Fasc. Obs. Bot. 3:8. 1783.

Caespitose annual; culms 20-100 cm. tall; panicle ovate-oblong, 1-6 cm. long, 1-2 cm.
thick; glumes subequal, 4.0-6.5 mm. long, strongly keeled, and winged near the tip;
fertile lemma 2.7-4.0 mm. long, 1.2-1.8 mm. wide, ovate, with a beaklike apex, yellow to
gray-brown, shiny, appressed-pubescent; sterile floret one, usually 1.0-1.8 mm. long,
appressed to the fertile floret, rarely very reduced and only 0.2-0.3 mm. long.

A single specimen, probably of this species, was collected from a
corn field near Potrero Cerrado, Prov. of Cartago, at 2,300 m. eleva-
tion. The specimen lacks the basal portions and cannot be separated
with complete certainty from P. aquatica L., a bulbous-based or
rhizomatous perennial. Introduced from the Old World. Common
name: Pasto San Juan.

PHARUS Linnaeus

REFERENCE: A. Prodoehl, Oryzeae monographice describuntur, Bot.
Arch. l-J>harus X:247-252. 1922.

FIG. 179. Phalaris canariensis. A, blooming culm; B, spikelet; C, two lower sterile
lemmas and terminal fertile floret.

476

BURGER: FLORA COSTARICENSIS 477

Caespitose or trailing perennial herbs; leaf blades large, borne on conspicuous
pseudopetioles, lanceolate, elliptical, or obovate, inverted in position, the pseudopetiole
having a 180-degree twist; veins diverging from the midrib and running straight to the
margins of the blade; commisural veins conspicuous, the blades tessellate. Inflorescence
a solitary terminal panicle, the rachis usually terminating as a thin sterile bristle, rarely
tipped with a single spikelet. Spikelets unisexual, borne in pairs, the larger pistillate
member of each pair subsessile, the small pedicellate staminate spikelet appressed to it,
its pedicel arising at the base of the pistillate spikelet. Pistillate spikelets with 2 sub-
equal usually many -nerved glumes, shorter than the floret; floret 1, readily disarticulat-
ing above the glumes when mature; lemma cylindrical, straight or sigmoid, coriaceous,
the margins inrolled over an equal linear palea, lemma terminating in a short conical
beak; back of the lemma near the tip beset with uncinate hairs, these continuing to base
of the lemma in some species; nerves 7, not conspicuous except at the contracted base;
style 1, stigmas 3, hispid; caryopsis oblong, grooved on the palea side, ends blunt;
embryo small, basal. Staminate spikelets borne on slender rigid pedicels which are
shorter than the adjacent pistillate spikelet; glumes unequal, membranaceous, the first
usually very short, the second shorter than the floret; lemma usually 3-nerved;
membranaceous, laterally compressed, 3-5-nerved; palea slightly shorter, 2-nerved;
stamens 6.

The genus Pharus is confined to the tropics of the western hemi-
sphere. The plants are unique in their broad, "commelinaceous" leaf
blades, borne inverted and with strongly divergent veins. They may
not be recognized as grasses by the casual observer. The panicles are
rather fragile, readily breaking apart or separating from the plants.
The rachis, panicle branches, and pistillate florets bear uncinate
microhairs, those on the lemmas being conspicuous and serving to
cause the mature pistillate florets to adhere to passing animals. (Bam-
busoideae: Phareae.)

KEY TO SPECIES OF Pharus

la. Mature fruits (pistillate florets) at least 4 x as long as glumes, 20-23 mm. long,

sigmoid, strongly divergent from branches of inflorescence P. cornutiis

Ib. Mature fruits less than 3 x as long as glumes, 17 mm. or less long, straight or

sigmoid, appressed to branches 2

2a. Leaf blades narrowly lanceolate, 3 cm. or less wide, 5-10 x longer than wide;

culms long-decumbent, rooting at lower nodes P. parvifolius

2b. Leaf blades elliptical to obovate, larger ones more than 3 cm. wide, less than 5 x

longer than wide; plants caespitose 3

3a. Glumes of pistillate spikelets greenish or stramineous P. virescens

3b. Glumes of pistillate spikelets brown 4

4a. Pistillate floret uncinate-pubescent only on exposed portion above tips of

glumes P. latifolius

4b. Pistillate floret pubescent nearly to base 5

5a. Fruit strongly sigmoid P. mezii

5b. Fruit straight P. glaber

478 FIELDIANA: BOTANY

Pharus cornutus Hack., Oesterr. Bot. Z. 52:9:528. 1902. Figure
180.

Perennial, caespitose in small clumps; plants erect, 50-70 cm. tall; culms unbranched,
ca. 3 mm. thick, solid, glabrous; sheaths mostly longer than the internodes, overlapping,
glabrous or minutely puberulent; ligule a lacerate membrane, 1.5-2.0 mm. long; blades
flat, dark green, slightly roughened, broadly obovate, abruptly narrowed to an acumi-
nate tip, 6-14 cm. long, 3-8 cm. wide, borne on a puberulent pseudopetiole ca. 1 cm. long.
Peduncle exserted 6-15 cm.; peduncle, rachis, branches and spikelets all more or less
densely pubescent with uncinate hairs; inflorescence an open panicle, 15-20 cm. long and
about as wide; branches solitary, the spikelets borne in pairs on secondary or tertiary
branches; staminate spikelets appressed to the branches, the pistillate ones strongly
divergent. Pistillate spikelets with short glumes, ca. one-fourth as long as the floret; first
glume subulate, 2.7-4.5 mm. long, 3-nerved; second glume 4.5-5.5 mm. long, narrowly
triangular, 5-nerved; floret linear-cylindrical, sigmoid, firm, light-colored, heavily beset
with uncinate hairs above, less densely so to the base, 20-23 mm. long, 7-nerved, the
apical beak small, palea linear, as long as the lemma, firm, 2-nerved; stigmas 3. Stami-
nate spikelets borne on stiff erect pedicels, the tip of the spikelets reaching about to the
tips of the glumes of the paired pistillate spikelet; first glume subulate, 1.5-3.0 mm. long,
1-3-nerved; second glume ovate, 2.5-4.0 mm. long, 3-5-nerved; lemma thin, 3.0-5.0 mm.
long, 3-nerved; anthers 6, 1.4-1.7 mm. long, yellow.

Rare; lowland rainforests, 70-250 m. elevation. February to July.
Guapiles, La Selva, Finca Chirripo, Tsaki, Villa Quesada, Osa Penin-
sula. Endemic to Costa Rica.

Pharus glaber H.B.K., Nov. Gen. & Sp. 1:196. 1816. Figure 180.

Caespitose perennial; plants erect, 50-100 cm. tall, the culms unbranched, 3 mm.
thick, solid, glabrous; leaf sheaths overlapping, glabrous; ligule membranaceous, 1.0-1.5
mm. long; pseudopetioles 10-20 mm. long; leaf blades dark green, 11-22 cm. long, 3.5-4.5
cm. wide, elliptical to narrowly obovate, tapering rather abruptly to a short triangular
apex. Inflorescence solitary, terminal, 11-22 cm. long and about as wide, a very open
panicle, the primary branches solitary; spikelets appressed to the secondary branches of
the panicle; rachis and branches puberulent with uncinate hairs. Pistillate spikelets
8.2-12.0 mm. long; glumes lanceolate, brown, rather blunt, the first 4.2-5.8 mm. long,
3-nerved, the second 4.9-6.5 mm. long, 7-nerved; floret 8-12 mm. long, the lemma cylin-
drical with inrolled margins, obscurely 7-nerved, the back covered with uncinate hairs
nearly to the base; apex a straight conical glabrous beak 1.0-1.5 mm. long; palea equal to
the lemma. Staminate spikelets paired with the pistillate, on pedicels appressed to the
rachis and nearly as long as the pistillate spikelets, 2.5-2.7 mm. long, not disarticulating;
first glume 1.0-1.7 mm. long, lanceolate, 1-nerved; second glume 2.0-2.4 mm. long,
ovate, 3-nerved; lemma 2.5-2.7 mm. long, ovate, apiculate, faintly 3-nerved; palea ca.
one-fourth shorter than the lemma; stamens 6, the anthers 0.9-1.1 mm. long.

Rare; wet forests from 900-1,500 m. elevation; Sabalito, El Muneco,
Volcan Rincon de La Vieja. November to March. Mexico and the West
Indies to Colombia, Bolivia, and northern Argentina.

Pharus latifolius L., Syst. Nat. ed. 10, 2:1269. 1759. Figure 180.

Caespitose perennial, 30-100 cm. tall, forming open clumps, culms unbranched, gla-

FIG. 180. Pharus species. P. latifolius: A, blooming plant; B, branch of panicle with
two pistillate and a single staminate spikelet; P. glaber: C, two pistillate spikelets; P.
carmdus: D, paired pistillate and staminate spikelets.

479

480 FIELDIANA: BOTANY

brous, ca. 3 mm. thick, solid; nodes glabrous; sheaths rather loose, keeled, glabrous,
overlapping; ligule an erose brown membrane, 0.5-1.0 mm. long; blades borne on
pseudopetioles up to 7 cm. long; blades narrowly to broadly obovate, 15-30 cm. long, 3-8
cm. wide, 3 to 5 x longer than wide, tapering rather abruptly to an acuminate apex.
Inflorescence a solitary terminal panicle, up to 30 cm. long, broad, open, ca. as wide as
long; rachis, peduncle, and branches puberulent with uncinate microhairs. Pistillate
spikelets appressed to the branches, 10-17 mm. long; glumes brown, subequal, narrowly
ovate, acute, rounded on the back, obscurely 7-nerved, ca. three-fourths as long as the
floret; first glume 9-12 mm. long, the second 10-13 mm.; lemma stiff and cartilaginous,
slightly curved, oblong-linear, rounded on the back, the margins involute over the palea
and united just above the base; uncinate hairs abundant near the tip, extending down-
ward about to the apex of the glumes, rarely further; glabrous conical beak of the lemma
1.0-1.5 mm. long; palea membranaceous, linear, 2-nerved, about as long as the lemma;
lodicules not evident; style elongate, fleshy, the 3 stigmas slender, white; caryopsis
oblong, 9-10 mm. long, curved, rounded on the lemma side, grooved on the palea side.
Staminate spikelets brown, membranaceous, 2.8-4.0 mm. long; first glume 0.4-1.2 mm.
long, ovate, acute, 1-nerved; second glume 1.8-2.0 mm. long, ovate, 3-nerved; floret 1,
not disarticulating; lemma ovate, acute, 5-nerved, glabrous; palea equal to the lemma,
2-nerved; anthers 6, white, 1.4-1.7 mm. long. Chromosome number n = 12 from Costa
Rican specimens.

Common in rain forests of the Caribbean lowlands; Pacific lowlands
of southern Puntarenas Province; scattered elsewhere; sea level to 650
m. elevation. Blooming is apparently yearlong. Southern Mexico to
Peru and Brazil; West Indies.

Pharus mezii Prodoehl, Bot. Arch. 1:250. 1922.

Erect caespitose perennial; plants 50-100 cm. tall; culms unbranched, 1-2 mm. thick,
glabrous below, increasingly puberulent toward the inflorescence; leaves basal, the
sheaths glabrous; ligule ca. 1 mm. long, brown, membranaceous; leaf blades elliptical or
obovate, flat, 11-25 cm. long, 2.3-5.0 cm. wide, slightly scaberulous, conspicuously
cross-veined. Peduncle of isotype in US from base of the plant, without cauline leaves.
Inflorescence solitary, terminal, an open panicle, that of the isotype 13 cm. long, about as
wide, open pyramidal; branches solitary, spreading (note: this inflorescence may be
fragmentary). Spikelets paired, appressed along the branches. Pistillate spikelets 9-11
mm. long; first glume 5.5-6.0 mm. long, 6-9-nerved, lance-ovate, acute, brown; second
glume similar, 6.0-6.5 mm. long, 5-nerved; floret sigmoid, the lemma stiff, cylindrical,
9-11 mm. long, the margins incurved over the palea; nerves obscure, numerous; tip a
glabrous pointed beak 0.5-1.0 mm. long; dorsal surface of lemma covered with hooked
hairs at least half way to the base. Staminate spikelets on stiff slender pedicels ca.
two-thirds as long as the glumes of the associated pistillate spikelet, appressed to the
pistillate spikelet; first glume ca. 0.7 mm. long, second glume 1.7-1.9 mm. long, acute;
lemma 2.4-2.7 mm. long; anthers not seen.

The type number, Biolley s.n. (Museo Nacional de Costa Rica 17326)
was collected at Surubres, vertiente del Pacifico, altitude of 250 m., in
February 1909. Costa Rica to Colombia.

Pharus parvifolius Nash, Bull. Torrey Bot. Club 35:301. 1908. P.

BURGER: FLORA COSTARICENSIS 481

latifolius L., var. angustifolius (Nash) Prodoehl, Bot. Arch. 1:250.
1922.

Perennial; culms extensively trailing, branching freely from the nodes of the prostrate
portions, the erect branches up to 1 m. long, unbranched; culms 3-6 mm. thick, solid,
glabrous; nodes glabrous; sheaths glabrous, mostly overlapping; ligule a lacerate-
ciliolate membrane, 0.5-1.0 mm. long; blades borne on margined pseudopetioles 6-30
mm. long; blades dark green, glabrous, but roughened beneath by the conspicuous
commissural veins, 5-10 x longer than wide, 10-28 cm. long, 2.0-3.0 cm. wide, flat.
Peduncle exserted up to 15 cm.; inflorescence an open panicle, up to 30 cm. long;
branches mostly solitary; spikelets borne on second- or third-order branches, lying
parallel to the branches. Pistillate spikelets subsessile; glumes subequal, ca. 7 mm. long,
glabrous, lanceolate, 5-nerved; floret 12-15 mm. long, nearly straight, the lemma ter-
minating in a glabrous conical beak ca. 1 mm. long; back of lemma covered with abundant
uncinate hairs, less densely so nearly to the contracted base; nerves 7; margins incurved,
spread apart in fruit, exposing a firm glabrous linear palea of about the same length;
caryopsis free from the bracts, oblong, tan to brown, blunt at apex, tapering to a point at
the base, convex on the lemma side, shallowly grooved on the palea side, 9-11 mm. long.
Staminate spikelets borne on stiff erect pedicels appressed to the rachis and almost as
long as the glumes of the adjacent pistillate spikelet; staminate spikelets 3.0-3.7 mm.
long, narrowly ovate; first glume nerveless, deltoid to lanceolate, 0.7-1.4 mm. long, less
than half as long as the spikelet; second glume and lemma subequal, 3-nerved, 3.0-3.7
mm. long; palea equal to lemma, 2-nerved; stamens 6, the anthers 1.8-1.9 m. long, tan.
Chromosome number n = 12 from a Costa Rican specimen.

Rare; undisturbed moist forests, 500-1,200 m. This species is com-
mon in the forested canyon of the Rio Reventazon at the CATIE at
Turrialba. It has also been collected in the General Valley, at Finca
Las Cruces near San Vito de Java, and in a few localities on the
volcanoes of Guanacaste. It is abundant in moist forests above 1,100 m.
on Volcan Rincon de la Vieja on Hacienda Guachipelin, and on Volcan
Tenorio near Tierras Morenas. Blooming is apparently restricted to
the dry season. Southern Mexico to Panama; West Indies and northern
South America.

Pharus virescens Doell in Mart., Fl. Bras. 2:21. 1871.

Perennial; bases decumbent and rooting; erect portions of culms to 1 m. tall, un-
branched; culms solid, glabrous; sheaths overlapping, glabrous; ligule a ciliate mem-
brane, ca. 1 mm. long; pseudopetioles broadly margined, elongated, scarcely dif-
ferentiated from the sheath; blades large, light green, narrowly obovate, tapering rather
abruptly to an acuminate apex, length 25-33 cm., width 4-7 cm. Peduncle ridged and
grooved; panicles solitary, terminal, large and open, up to 30 cm. long and ca. as wide;
spikelets appressed to secondary or tertiary branches; rachis and branches scabrous and
beset with uncinate hairs; spikelets paired, or some of the pistillate ones solitary. Pistil-
late spikelets subsessile; glumes subequal, greenish or stramineous, not brown, nar-
rowly triangular, the tip rather blunt; first glume 10-11 mm. long, 5-nerved; second
glume similar, 10-12 mm. long; floret straight, cylindrical, flattened on the back, 13-15
mm. long, the terminal beak narrow, glabrous, 1.0-1.5 mm. long; back of lemma covered
with uncinate hairs two-thirds of way to the base, these especially numerous near the

482 FIELDIANA: BOTANY

margins; palea equal to the lemma, linear, 2-nerved. Staminate spikelets borne on slen-
der appressed pedicels from the base of the pistillate ones, the pedicel up to 10 mm. long;
spikelets laterally compressed, 2.5-4.2 mm. long; first glume ca. 1.2 mm. long, 1-nerved,
ovate, acute; second glume 2.5-4.2 mm. long, 3-nerved, narrowly ovate, acute; lemma
2.5-2.7 mm. long, narrowly ovate, 3-nerved, its palea equal; anthers 6, purple, 0.7-0.9
mm. long. One staminate spikelet with 2 florets and a total of 8 anthers was found.

Rare, lowland forests; apparently blooming from January to March.
El General, Shirores, Hamburg Finca. Guatemela to Peru and Brazil;
Hispaniola.

PHRAGMITES Adanson

REFERENCES: H. J. Conert, Die Systematik und Anatomic der
Arundineae, 1-208. Cramer. Weinheim. 1961. W. D. Clayton, The cor-
rect name of the common reed, Taxon 17:168-69. 1968. E. D. Voss,
Additional nomenclatural and other notes on Michigan monocots and
gymnosperms, Michigan Bot. 11:26-37. 1972.

Tall stout perennial reeds with plumy panicles; spikelets several-flowered; glumes
narrow, the first 3-nerved, the second 5-nerved, shorter than the florets; an evident
internode between the first and second glumes; disarticulation above the first floret and
at the base of the rachilla internode beneath each succeeding floret; rachilla internodes,
except the lowermost, covered with numerous long, silky hairs; lowermost floret persis-
tent with the glumes, its lemma 5-nerved, the flower staminate; other florets with
3-nerved lemmas and perfect flowers; lemmas slender, acuminate, glabrous; paleas much
shorter than the lemmas; uppermost florets shorter than the lower ones, so that the tips
of all lemmas are at approximately the same level.

Phragmites is a genus of about four species, widespread in the
temperate and warmer zones of the world. It is most closely related to
other large reeds such as Arundo, Gynerium, and Cortaderia. (Arun-
dinoideae: Arundineae.) The genus Phragmites is known from all the
continents except Antarctica. Authors recognize from one to several
species, which appear to be poorly defined.

Phragmites australis (Cav.) Trin. ex Steud., Nom. Bot. ed 2, 2:324.
1841. Arundo australis Cav., Ann. Hist. Nat. 1:100. 1799. Phragmites
communis Trin., Fund. Agrost. 134. 1820. Arundo phragmites L., Sp.
PL 81. 1753. Figure 181.

Plants forming large colonies; culms erect, unbranched except when injured, 2-8 m.
tall, up to 2 cm. thick, hollow, glabrous; rhizomes abundant, longitudinally ridged,
hollow, 1-2 cm. thick; leaves numerous, the sheaths usually overlapping, glabrous except
for auricular hairs 5-7 mm. long; blades glabrous, 30-50 cm. long, 15-25 mm. wide, flat;
peduncles mostly included; panicle solitary, rather dense, up to 45 cm. long, pyramidal,
drooping; lower branches numerous, whorled, naked at the base; spikelets very numer-
ous, compactly arranged on the outer portions of the branches, wedge-shaped, 11-15
mm. long; first glume 3.8-5.2 mm. long, 3-nerved, ovate, acute; second glume 5.5-6.5
mm. long, 5-nerved, ovate, acute; florets 3-5, the lowermost ones 9-10 mm. long, the

FIG. 181. Phragmites australis. A, panicle; B, leaf bases with auricular hairs; C,
rhizome; D, spikelet. Drawn from fertile material.

483

484 FIELDIANA: BOTANY

uppermost much shorter; lemmas lance-attenuate; paleas 2-3.5 mm. long; anthers 1.4-2
mm. long, yellow. Chromosome count 2n = 72 obtained from vegetative internodes of
the sterile strain from Trinidad.

This species is rare in Costa Rica and uncommon in Central America
in general. We have specimens from Trinidad, Laguna Bonilla, the
Limon area, and Finca Las Cruces near San Vito de Java. The colony
from Trinidad, on the south slope of Volcan Turrialba, fills a large
marsh. Although the plants are very tall, they never bloom in nature.
We have been able to induce the formation of sterile inflorescences in
the greenhouse at Iowa State in February 1973 and July 1975. No
fertile spikelets occurred in any of these inflorescences. Most spikelets
were minute rudiments, the largest about 5 mm. long. Another sterile
colony occurs on Finca Las Cruces. The other collections from Costa
Rica bear spikelets that are malformed or sterile in varying degrees,
and such sterility is extremely common in this species in Central
America. The description given above is taken from Central American
specimens, and may not apply closely to material from the temperate
zone. Various chromosome numbers have been reported for this
species.

PHYLLOSTACHYS Siebold & Zuccarini

REFERENCE: F. A. McClure, Bamboos of the genus Phyllostachys
under cultivation in the United States, U.S.D.A. Agriculture Hand-
book 114. pp. 1-69. 1957.

Bamboos of slender growth habit; rhizomes extensive; culm internodes hollow, D-
shaped in cross section, flattened above the insertion of the branch buds; primary
branches typically 2 at each node, unequal, sometimes a third smaller one present; culm
sheaths papery, the apex rounded to a narrow reduced blade; foliage leaf blades
pseudopetiolate, readily deciduous; leaf blades small, flat, tessellate. Inflorescence a
panicle whose branches bear clustered pseudospikelets (complex bracted structures that
resemble spikelets, but are internally branched into 1 or more true spikelets). Pseudo-
spikelets enveloped in conspicuous inflated sheaths that bear reduced blades and enclose
2-3 spikelets. Spikelets bearing 1-3 many-nerved empty bracts (glumes) at the base;
florets 1-3, the terminal one rudimentary; lemmas acuminate, many-nerved; palea about
equal to the lemma, 2-keeled, many-nerved; lodicules 3, flat, vasculated; stamens 3;
ovary with a single style and 3 stigmas.

Phyllostachys is a small Asiatic genus, important for several culti-
vated species, used for ornament, fishpoles, timber, paper, and edible
shoots. (Bambusoideae: Arundinariae.)

Phyllostachys aurea A. & C. Riviere, Bull. Soc. Natl. Acclim.
France, Ser. 3:716. 1878. P. bambusoides Sieb. & Zucc., var. aurea
(A. & C. Riv.) Makino. Figure 182.

Long-lived bamboo; rhizomatous; clumps dense to open; culms up to 10 m. tall, erect or

FIG. 182. Phylloatachya aurea. A, leafy branch; B, culm sheath; C, pseudospikelet.

485

486 FIELDIANA: BOTANY

slightly arching; internodes 1-4 cm. thick, hollow, glabrous, D-shaped in cross section;
nodes prominent; some culms, but not all, have a succession of several short internodes
near the base; culms branching freely from middle and upper nodes, with usually 2
unequal branches at each node, sometimes a third smaller one; branches slender but
stiff, rebranching; main culm sheaths up to 20 cm. long, the margins ciliate; apex
rounded, bearing a narrow linear reduced blade; foliage leaves borne on minor branch-
lets, usually 3-8 per branchlet; leaf sheaths ciliate on the margin; oral setae sometimes
present; ligule a short, thick ciliolate membrane, puberulent on the back, 0.7-0.8 mm.
long; external ligule a minute thick rim; leaf blades flat, tessellate, 4-10 cm. long, 5-16
mm. wide, ovate 5-6:1, abruptly acuminate, base rounded to a short flattened
pseudopetiole; margins scabrous; lower surface puberulent near the base, sometimes all
over the surface. Inflorescence a terminal panicle of clustered pseudospikelets, up to
35-50 cm. long, open, with rigid ascending or spreading branches; much smaller inflores-
cences occur on sheared specimens. Pseudospikelets numerous, ascending and overlap-
ping, often with small rigid bracts at their bases; spikelets concealed by inflated external
bracts, bearing reduced leaf blades, spikelets 1-several in each pseudospikelet. Spikelets
usually with a single acuminate, 9-11-nerved cylindrical glume, ca. as long as the
spikelet; some spikelets have 2 glumes; florets 1-2; rachilla internode supporting the
lowermost floret thickened to the apex, sometimes puberulent; disarticulation at the
base of the lowermost floret; florets cylindrical, acuminate, the lemma 9-11-nerved,
enwrapping the palea; rachilla internode prolonged 4-5 mm. beyond the ultimate floret
and bearing a rudiment at its apex; palea ca. as long as the lemma, several-nerved,
clasping the rachilla internode, the keels prolonged as 2 short awns; lodicules 3, flat,
vasculated; anthers 3, yellow, 12-13 mm. long; ovary bearing an elongated style with 3
short stigmas at its apex. Chromosome number n = 24 from a Costa Rican specimen.

This is the common yellow-stemmed bamboo, often used for sheared
hedges or allowed to grow naturally as a tall screen. It occurs com-
monly around San Jose and is occasionally found blooming. Flowering
plants have been seen in the Parque Bolivar, around the zoological
garden. A sheared hedge along Calle 33, S of La Luz bloomed in 1968,
without death of the plants. The individual inflorescences were small
and leafy. A tall clump along. Hwy. 204 N of the Colegio de Abogados
had culms 4-5 m. tall which were in flower in December 1968. These
culms were dying after flowering. Flowering habits of this species in
the western hemisphere are not well known, but our experience in
Costa Rica suggests that at least minimal blooming, without cane
death, may be fairly frequent. A large blooming panicle from Virginia,
collected by Dr. Allard, bears the notation that the plant had been
transplanted 15 years before and had remained vegetative for that
period. The species is native to China.

POA Linnaeus

Plants perennial or rarely annual, caespitose or rhizomatous; culms unbranched.
Inflorescence a terminal panicle, the branches usually clustered. Spikelets several-
flowered, laterally compressed, disarticulating above the glumes and between the
florets; glumes shorter than the florets, the first 1-nerved, the second usually 3-nerved;

BURGER: FLORA COSTARICENSIS 487

lemmas folded, 5-nerved, acute or blunt, awnless; midnerve, marginal and intermediate
nerves often pubescent; the blunt callus in some species bearing a tuft or web of crimped,
cottony hairs.

A large genus of temperate and arctic zones of the world, poorly
represented in the tropics. Many of the species are highly apomictic
and extremely variable. The genus is related to Festuca, from which it
differs in the rather blunt, awnless lemmas and in the leaf tips, which
are blunt and cupped like the prow of a boat. (Pooideae: Poeae.)

KEY TO SPECIES OF Poa

la. Plants rhizomatous; lemmas bearing elongated web of cottony hairs and also pubes-
cent on keel, marginal, and intermediate nerves; pastures on volcanoes

P. pratensis

Ib. Plants not rhizomatous; lemmas variously pubescent, with or without a web. . . 2

2a. Basal foliage stiff and erect, the elongated leaf blades folded, sharp-tipped;

glumes nearly as long as spikelet; lemmas densely scabrous with short, stiff

hairs; summit of Chirripo Grande P. chirripoensis

2b. Foliage soft, leaf blades flat; glumes shorter than lowermost lemma; lemmas not

densely scabrous; plants of middle altitudes 3

3a. Lemmas ciliate on keel, marginal, and intermediate nerves; no cottony web present;

low, spreading plants, 5-35 cm. tall P. annua

3b. Lemmas ciliate on keel, rarely also on marginal nerves; cottony web present at least

on lowermost lemma; plants usually erect, 20-100 cm. tall 4

4a. Ligules 4-10 mm. long; lower branches of panicles 3-7 per node . . P. trivialis
4b. Ligules less than 2 mm. long; lower panicle branches 1 or 2 per node

P. talamancae

Poa annua L., Sp. PL 68. 1753. Figure 183.

Duration annual or indefinite; plants 5-35 cm. tall, erect and tufted, or in wet habitats,
becoming long-decumbent and rooting at the nodes; branching from the base or from the
nodes of decumbent stems; prophylla prominent, up to 2.5 cm. long; culms soft, glabrous;
leaf sheaths mostly overlapping, glabrous; ligule a thin white membrane, 1-4 mm. long,
decurrent on the sheath margins; blades 0.5-11.0 cm. long, 1-4 mm. wide, soft, flat,
blunt-tipped, the uppermost much reduced. Plants of wet habitats have much larger
leaves than those of drier sites. Peduncle included or exserted up to 11 cm.; inflorescence
a solitary terminal panicle, 2-7 (11) cm. long, pyramidal, the branches solitary or paired,
the spikelets densely clustered near their tips. Spikelets laterally compressed, green or
purplish, 4.0-5.5 mm. long, disarticulating above the glumes and between the florets;
first glume ovate, acute, 1-nerved, 1.5-2.7 mm. long; second glume obovate, acute,
3-nerved, 2.2-3.3 mm. long, shorter than the lowermost floret; florets 2-6; lemmas 2.6-3.8
mm. long, ovate, rather blunt, often bronzy near the apex; nerves 5, all silky-pubescent,
the internerve area near the base also sometimes pubescent; palea slightly shorter than
its lemma, silky-ciliate on the keels; anthers 3, yellow, 0.9-1.2 mm. long. Chromosome
number n = 14 from Costa Rican specimens.

Open moist areas, ditches, pastures; Meseta Central, Poas, Irazii,
Cerro de la Muerte; elevations from 1,100 to 3,400 m. Apparently
blooming yearlong. Worldwide in cool climates; apparently introduced

488 FIELDIANA: BOTANY

in the New World. In North America, it extends southward to Volcan
Chiriqui in Panama.

Poa chirripoensis Pohl, Fieldiana, Bot. 38:10. 1976. Figure 184.

Perennial; densely caespitose; culms erect, unbranched, 37-58 cm. tall, hollow, gla-
brous, elliptical in cross section; nodes dark, not prominent; basal foliage abundant, the
blades stiff, erect, up to 30 cm. long, reaching about to midculm; sheaths keeled, slightly
scabrid, those of the 2-3 short culm leaves shorter than the internodes; ligule a thin
membrane, 2.0-4.5 mm. long, tapering abruptly to a point; leaf blades 2-3 mm. wide,
stiff, permanently folded, erect, tapering abruptly to a sharp rigid cusp, the surfaces
minutely roughened. Peduncle smooth, exserted 7-25 cm.; inflorescence a solitary termi-
nal panicle, open, pyramidal, 6-8 cm. long, 3-5 cm. wide; branches paired, spreading,
flexuous, bearing a few peglike hairs like those of the lemmas; pedicels thick, scabrous in
lines with similar hairs; spikelets clustered toward the outer ends of the branches.
Spikelets 3.7-4.4 mm. long, 1-2-flowered, the glumes keeled, 3.5-4.0 mm. long, nearly as
long as the florets; first glume triangular 5:1 as folded, the second slightly wider, both
3-nerved, tapering to acuminate tips, scabrous on the keels and nerves; lemmas ovate,
3.5-3.9 mm. long, 4:1-5:1 as folded, blunt-tipped, densely scabrous in lines with thick,
stiff, round-tipped hairs 0.05-0.10 mm. long; callus usually with a few short cobwebby
hairs; palea nearly as long as the lemma, scabrous on the keels with hairs similar to those
of the lemmas.

This species known only from the type specimen, Burger & Liesner
7448, collected from the rocky summit of Chirripo Grande at 3,820 m.
Poa chirripoensis is easily distinguished from others in Central
America by its dense cluster of stiff, erect, basal leaves, and by the
unique spicule-like hairs of the lemmas. It is not closely related to any
other North American species.

Poa pratensis L., Sp. PI. 67. 1753. Figure 183.

Vigorous perennial; plants erect, (10) 30-70 (110) cm. tall; rhizomes abundant, slender,
scaly, elongated; leafy innovations abundant at the bases of the clumps; culms un-
branched, glabrous, hollow, thin-walled, round in cross section, the nodes round; sheaths
shorter than the internodes, glabrous; blades up to 21 cm. long, the basal ones largest,
1-5 mm. wide, flat, dark green, glabrous; ligule a thin white membrane, 0.2-3.0 mm.
long. Peduncle slender, exserted up to 20 cm.; panicle solitary, terminal, 3-14 cm. long,
pyramidal, usually open, the branches mostly naked near the bases, the spikelets clus-
tered near the outer ends; lower branches usually 5 per node, several of them much
shorter than the others. Spikelets laterally compressed, 4.0-6.5 mm. long; the glumes
and lemmas keeled; disarticulation above the glumes and between the florets; first glume
2.0-3.0 mm. long, ovate, acute, 1-3-nerved; second glume ovate, acute, 3-nerved, 2.6-3.7
mm. long; florets 2-5; lemmas 3-4 mm. long, the uppermost ones shorter than the lower,
ovate or obovate, rather blunt, 5-nerved, often purple-marked near the tip, the margins
scarious; keel and marginal nerves silky-hairy; callus with a conspicuous web of cottony
hairs; palea slightly shorter than its lemma, scabrous on the keels; anthers 3, yellow,
1.3-1.7 mm. long.

Moist pastures at upper elevations, Irazii and Turrialba; Villa Mills;

FIG. 183. Poa species. P. talamancae: A, spikelet; B, floret; P. pratensis: C, spikelet;
D, floret; P. anmia: E, plant; F, spikelet; G, floret; P. trivialis: H, spikelet; I, floret.

489

FIG. 184. Poa chirripoensis. A, plant habit; B, spikelet; C, floret.

490

BURGER: FLORA COSTARICENSIS 491

elevations 2,600-3,100 m. Cosmopolitan in moist cool climates of the
world; introduced from Europe.

This is one of the most widely used pasture and lawn grasses in cool
climates. Along with many temperate-zone pasture grasses, it was
apparently introduced in the dairy areas of the volcanoes of the Meseta
Central. Most of these species are not well adapted and survive only
marginally. The earliest collection from Costa Rica was dated 1924.

Poa talamancae Pohl, Fieldiana, Bot. 38:8. 1976. Figures 183, 185.

Plants perennial, caespitose in dense tufts with abundant basal foliage; sheaths of
basal leaves keeled; blades flat, olivaceous, 3-14 cm. long, 2-4 mm. wide, their surfaces
minutely scaberulous, the margins scabrous, tip conspicuously cucullate; basal foliage
often floccose with fungus hyphae; culms erect or somewhat decumbent at the base,
slender, 20-60 cm. tall; internodes 3, ca. 1 mm. thick, hollow, glabrous, slightly scabrid,
with a light-colored band just below the prominent, purple nodes; culm leaves usually 3;
sheaths much shorter than the internodes, glabrous, slightly keeled and scabrid on the
keel; ligule a thin membrane, up to 2 mm. long; blades of culm leaves flat, 2-6 (14) cm.
long, 2-4 mm. wide, the uppermost usually short. Peduncle exserted up to 11 cm.;
inflorescence a solitary terminal panicle, 8-11 cm. long, up to 6 cm. wide, very open, the
solitary or paired slender flexuous branches up to 3 cm. long. Spikelets few, appressed
along the outer halves of the branches, 4.5-5.6 mm. long, laterally compressed, usually
purple; glumes shorter than the florets, the first ovate as folded, 1-nerved, 1.8-2.9 mm.
long; second glume oblong to obovate, 3-nerved, 2.3-3.4 mm. long, both glumes scabrous
on the keel; florets 2-3, the rachilla prolonged beyond the last one as a slender bristle
one-third to one-half as long as the floret, sometimes bearing a minute rudiment at its
tip; lemmas oblong-obovate in side view, 5-nerved, 3.1-4.1 mm. long; lower third to half
of the keel silky-ciliate, as also the basal portion of the marginal nerves; upper part of the
keel and surface of the lemma scabrid; at least the lowermost lemma bearing a scant
cottony web on the callus; palea about equal to the lemma, scabrous on the keels; anthers
3, yellow, 1.1-1.3 mm. long; caryopsis brown, narrowly ovoid, 2 mm. long.

Poa talamancae is not closely related to any other species of Poa
found in Costa Rica. It is probably to be assigned to the informal group
Palustres of Hitchcock. It appears most similar to P. orizabensis
Hitchc., Contr. U.S. Natl. Herb. 17:374. 1913, a Mexican species, from
which it differs in the abundant soft, flat, basal leaf blades, 3 stem
nodes, longer ligules, and larger spikelets with longer lemmas. The
specific name is derived from the Talamanca Range. This species is
endemic to The Cerro de la Muerte, and has been collected twice from
the area of Asuncion, on open, windswept paramos above 3,300 m.
elevation. Blooming dates February to July.

Poa trivialis L., Sp. PI. 67. 1753. Figure 183.

Caespitose perennial, the culm bases often decumbent; plants 20-100 cm. tall, the
foliage light green; culms unbranched, hollow, glabrous; nodes conspicuous, dark, con-

FIG. 185. Poa talamancae. A, plant habit; B, ligule; C, spikelet; D, two views of a
floret.

492

BURGER: FLORA COSTARICENSIS 493

tracted; sheaths usually scabrid but not visibly pubescent; ligule a thin white acute
membrane, 4-10 mm. long; blades 3-20 cm. long, flat, 1.5-6.0 mm. wide, scabrid.
Inflorescence a solitary terminal panicle, 3-25 cm. long, up to 15 cm. wide, pyramidal,
open or rather dense, the branches 3-7 at the lower nodes, the longer ones naked at the
base. Spikelets appressed to the branches, light green or purplish, 3-4 mm. long, later-
ally compressed, disarticulating above the glumes and between the florets; first glume
2-3 mm. long, lanceolate, acute, 1-nerved; second glume 2.5-3.5 mm. long, ovate, acute,
3-nerved; florets 2-4, the lemmas 2.5-3.5 mm. long, oblong-lanceolate in lateral view, the
margins infolded, the nerves conspicuous; keel short-ciliate at least on the lower half, the
lemma otherwise glabrous except for a cottony web attached to the callus; palea nearly
as long as the lemma, the keels scabrid; anthers 3, 1.5-2.0 mm. long.

Rare; moist pastures, 2,600-2,800 m. elevation; Irazii and Turrialba.
August and February. Widespread in temperate North America; in-
troduced from Europe and not previously reported from Central
America. This species, like P. pratensis and P. annua, was probably
introduced in pasture seed from Europe.

POLYPOGON Desfontaines

Caespitose perennial; inflorescence a terminal panicle; spikelets disarticulating with
the attached slender pedicels; glumes narrow, subequal, awned, 1-nerved; lemma much
shorter than the glumes, thin and membranaceous, awned, 5-nerved; rachilla not pro-
longed beyond the floret. (Pooideae: Agrostideae.)

Polypogon elongatus H.B.K., Nov. Gen. & Sp. 1:134. 1816. Figure
186.

Plants forming small clumps; culms erect, unbranched, 1-3 mm. thick, hollow, gla-
brous; nodes shrunken, dark; culm leaves 5-6, the sheaths longer or shorter than the
internodes, glabrous; ligule 4-8 mm. long, a whitish membrane, scaberulous on the back,
decurrent on the sheath margins; blades flat, thin, glabrous, scaberulous above, 15-30
cm. long, 4-15 mm. wide; peduncle glabrous, up to 30 cm. long; panicle solitary, 10-30 cm.
long, 1-7 cm. wide, rather dense but lax, the branches covered with spikelets to their
bases; rachis, branches, and pedicels scabrous; spikelets crowded along the branches,
laterally compressed, disarticulating at the base of the pedicel which ranges from short
to longer than the spikelet; glumes similar, the first a little longer than the second,
narrow, tapering to a short awn, 1-nerved, scabrid on the keel and surface; first glume
3-5 mm. long, the second 3-4.5 mm. long, including awns 1-2 mm. long; floret much
shorter than the glumes and concealed by them, usually not disarticulating separately;
lemma thin, membranaceous, glabrous, ovate, blunt, 5-nerved, the lateral nerves ex-
tending into blunt apical teeth; midnerve extending into a scabrid awn 1.2-2 mm. long,
arising from the cleft apex of the lemma; palea very thin, inconspicuous, nerveless,
0.4-0.5 mm. long; anthers 3, 0.5-0.7 mm. long, pale yellow. Chromosome number n = 28
from Costa Rican material. A South American count of n = 14 has also been reported.

Occasional at middle elevations around the Meseta Central and on
the Cordillera de Talamanca; moist roadsides and forests, 1,450-2,700
m. elevation. July to September; January. Mexico to Argentina.

c \

FIG. 186. Polypogon elongatus. A, panicle; B, spikelet; C, floret.

494

BURGER: FLORA COSTARICENSIS 495

POLYTRIAS Hackel

Low stoloniferous perennial; inflorescence a solitary terminal rame; spikelets paired or
in triads at each node of the thin, disarticulating rachis, one of each set pedicellate, and
one or two sessile; spikelets of each set equal and fertile, awned, dorsally compressed;
glumes equal, oblong, truncate, membranaceous; margins of first glume incurved over
the edges of the second; second glume oblong, truncate, keeled; sterile lemma absent;
fertile lemma minute, hyaline, bifid almost to the base, a twisted and geniculate brown
awn arising in the cleft; anthers 3; style branches naked below; palea lacking. One
species of the Asiatic tropics, naturalized in Africa and the western hemisphere.
(Panicoideae: Andropogoneae.)

Polytrias amaura (Biise ex Miquel) Kuntze, Rev. Gen. PL 2:788.
1891. Andropogon amaurus Biise ex Miquel, PL Jungh. 360. 1854.
Pogonatherum amaurum (Biise) Roberty, Monogr. Andropog. 393.
1960. Polytrias praemorsa (Nees) Hack, in DC, Monogr. Phan. 6:189.
1889. Pollinia praemorsa Nees in Hooker, J. Bot. Kew Misc. 2:98.
1850 (Nomen). P. praemorsa Nees ex Steud., Syn. PL Glum. 1:409.
1855. Figure 187.

Plants creeping by numerous stolons, the erect portions of the culms 10-15 cm. tall,
unbranched; culms 0.5-1.0 mm. thick, glabrous, hollow; nodes bearded; sheaths keeled,
ciliate on the margins, and sometimes slightly pubescent near the apex; ligule a minute
ciliate membrane, 0.2-0.5 mm. long; blades flat, 0.5-5 cm. long, ca. 2 mm. wide, loosely
hirsute on both surfaces. Peduncle 1-2 cm. long; inflorescence slender, rather dense, 2-3
cm. long, brownish silky; rachis internodes flat, 2-3 mm. long, brownish ciliate on the
edges and strongly bearded at the apex. Spikelets dorsally compressed, brownish silky,
ovate, 3-4 mm. long; the equal glumes completely covering and concealing the fertile
floret; fertile lemma thin, hyaline, 1 mm. long; awn exserted up to 4-7 mm., brown,
twisted and geniculate; anthers purple, 2.2-2.4 mm. long. Chromosome number n = 10
from Costa Rican material.

This delicate little creeping grass has been found in Costa Rica only
in the lawn behind the main building of the IICA at Turrialba, where it
forms the principal component of a lawn. The plants are recognizable
by the somewhat purplish cast which they lend to the turf. It was
blooming in late November. Previously, it has been known from Cen-
tral America only by a few collections from the Canal Zone. It is native
in southeastern Asia, Java, and the Philippines and has been reported
as an introduction from Camaroun, the Caribbean Islands, and Ven-
ezuela. Common name: "Java grass."

The name P. praemorsa has sometimes been used for this species.
Although the basionym, Pollinia praemorsa, was published four years
earlier than any other specific epithet, no description accompanied the
name, and none was published until 1855.

FIG. 187. Polytrias amaura. A, growth habit; B, a triad of spikelets.

496

BURGER: FLORA COSTARICENSIS 497

PSEUDECHINOLAENA Stapf

Creeping, broad-leaved grasses; inflorescence a terminal panicle of a few slender
racemes; spikelets paired, appressed along the lower sides of the slender rachis, or
frequently one of the pair abortive or missing; disarticulation below the glumes.
Spikelets laterally compressed, half-oval, the straight side nearest the rachis, the
glumes and tip of the sterile lemma appressed-hispid when young, at maturity beset with
thick columnar bristles which are retrorsely barbed at the tips; first glume acuminate,
from two-thirds to as long as the spikelet, 3-nerved, folded; second glume as long as the
spikelet, 5-nerved, strongly boat-shaped, bearing rows of pustulose-based apically
barbed bristles between the nerves; sterile lemma as long as the spikelet, broadly
oblong, rounded to a blunt flattened folded tip, chartaceous, faintly 5-nerved, but with a
large thin hyaline area occupying the lower back, about half the length of the lemma;
palea chartaceous, linear, its margins inrolled, ca. two-thirds as long as the lemma; a
staminate flower rarely present; fertile (second) floret ca. two-thirds as long as the
spikelet, its lemma narrowly ovate, acuminate, coriaceous, smooth and shining, its mar-
gins thick and overlapping the edges of the palea but not inrolled; palea of equal length
and similar texture.

One species in the tropics of both hemispheres. (Panicoideae:
Paniceae.)

Pseudechinolaena polystachya (H.B.K.) Stapf, in Prain, Fl. Trop.
Africa 9:495. 1919. Echinolaena polystachya H.B.K. Nov. Gen. & Sp.
1:119. 1816. Figure 188.

Duration indefinite; culms up to 1 m. long, the basal portions extensively creeping and
branching, rooting erect portions of culms unbranched; prophylla prominent, papillose-
hirsute on the keels; nodes hirsute; internodes more or less hirsute, especially toward
the apex; ligule a ciliate brownish membrane, 0.5-1.5 mm. long; sheaths usually much
shorter than the internodes, more or less hirsute, especially toward the apex; leaf blades
lanceolate, asymmetric, 1.5-7.5 cm. long, 5-16 mm. wide, appressed-hirsute on both
surfaces; peduncle included or exserted up to 15 cm., minutely pubescent to hirsute;
panicles 7-20 cm. long, the few racemose branches 3-6 cm. long, slender, the spikelets
appressed along their lower sides. Spikelets 3.2-4.0 (4.4) mm. long, strongly laterally
compressed; first glume 2.5-3.6 mm. long, ovate, acuminate, 3-nerved; second glume
3.2-4.0 mm. long, 5-nerved, keeled, boat-shaped; lower (sterile) lemma 3.0-3.7 mm. long;
fertile lemma 2.0-2.2 mm. long, narrowly ovate, acuminate, its palea similar; anthers 3,
1.2-1.5 mm. long, yellow. Chromosome number n = 18 from Costa Rican specimens.

Forest and brushy areas, in dense shade, frequently along trails;
mostly on the Pacific Slope, from southern Costa Rica to Turrialba and
the Meseta Central; Tilaran area; Guapiles and Guacimo; blooming
yearlong. Mexico to Brazil and Argentina; in the Old World from
Tropical Africa and Asia.

The spikelets of this forest grass exhibit a great change in appear-
ance during maturation. Young spikelets are appressed-hispid, but as
the fruit matures, the stiff, spinelike hairs are elevated on thick, hol-
low multicellular hairs. The points of the spines are directed down-

FIG. 188. Pseudechinolaena polystachya. A, panicle; B, immature spikelet with
spines appressed to the bracts; C, mature spikelet with spines elevated and reflexed.

498

BURGER: FLORA COSTARICENSIS 499

ward, and the whole spikelet acts like a small bur. Bor states that ripe
spikelets frequently become attached to the legs of cattle in India, and
we have often had them become attached to our clothing in Costa Rica.

RADDIA Bertolini

Caespitose perennial low grasses of rain forests; leaf blades short, distichous,
crowded, all in one plane. Spikelets unisexual, in the same or different inflorescences.
Pistillate spikelets: dorsally compressed, disarticulating above the equal glumes; floret
1, borne on a thick rachilla internode and falling attached to it. Staminate spikelets:
laterally compressed, lacking glumes; floret 1; stamens 3. Lodicules in both sexes 3, flat,
truncate.

This small genus is closely related to Cryptochloa, Lithachne, Dian-
drolyra, and Olyra. Generic limits in this group are not well known,
and new discoveries in the group are frequent. (Bambusoideae:
Olyreae.)

Raddia costaricensis Hitchc., Proc. Biol. Soc. Wash. 40:87. 1927.
Figure 189.

Caespitose perennial, forming dense clumps of numerous wiry slender culms, their
upper portions arching and spreading; culms up to 38 cm. long, the lower 2-3 internodes
much elongated, comprising three-fourths of the total length, naked or with short
bladeless sheaths; internodes slender, hollow, glabrous; nodes constricted; apex of the
internodes enlarged; foliage crowded at the apex of the culms, the 5-20 leaves forming
flat sprays, their sheaths closely overlapping, the upper half of each sheath densely
papillose-pilose with tan hairs; ligule a minute ciliolate membrane, ca. 0.5 mm. long;
pseudopetiole thick, pulvinar, 0.5-1.0 mm. long, papillose-pilose like the sheaths; blades
narrowly ovate, 5-7:1, 35-43 mm. long, 4.5-9 mm. wide, flat, or revolute in drying,
densely papillose-pilose beneath, with a few scattered hairs above; edges scabrous.
Peduncles included in the sheaths; inflorescences usually several, usually a many-
flowered one from the axil of one of the lower foliage leaves, and a small one at the apex
of the culm, the branches slender and delicate, usually curved. Spikelets unisexual, both
kinds borne in the same inflorescence. Pistillate spikelets: One to several, borne at the
apex of the inflorescence, dorsally compressed, outline ovate 4:1, the pedicels thick and
flattened; glumes 2, equal, exceeding the floret, 8-9 mm. long, whitish, membranaceous,
acuminate, the first 11-nerved, the second narrower, 9-nerved; floret solitary, dorsally
compressed, borne on the apex of a thickened rachilla intemode ca. 1 mm. long and
deciduous with it; lemma 5.5 mm. long, 5-nerved, the margin, lower back, and rachilla
heavily bearded with cottony hairs; palea equal in length, with 2 keel nerves, plus 2 faint
nerves between the keels and 2 faint marginal nerves; lodicules 3, flat, truncate; style 1;
stigmas 2, large, plumose, apically exserted; caryopsis not seen. Staminate spikelets:
Laterally compressed, narrowly ovate, 3.0-3.7 mm. long, contracted into a short callus
at the base; glumes absent; lemma thin, membranaceous, 3-nerved; palea equal, 2-
nerved; lodicules 3, flat, truncate; stamens 3, the anthers yellow, 1.7-1.8 mm. long.
Chromosome numbern = 11.

This species was first collected on the Rio Hondo near Madre de
Dios, by Pittier in 1896. It was not found again until 1966, when it was
relocated at the type locality by Dr. T. R. Soderstrom. We have col-

FIG. 189. Raddia costaricensis. A, plant base; B, leafy culm with inflorescences; C,
inflorescence with a terminal pistillate spikelet and staminate spikelets below it.

500

BURGER: FLORA COSTARICENSIS 501

lected it again in the same locality in 1969. The plants are rare and
scattered in dense rain forest.

This species has recently been transferred to a new genus, Arberella
Soderstrom & Calderon, and will be designated as Arberella costari-
censis (Hitchc.) Sods. & Cald., Brittonia 31:439. 1979.

RHIPIDOCLADUM McClure

REFERENCE: F. A. McClure, Genera of bamboos native to the New
World, (Gramineae: Bambusoideae), Smithsonian Contr. Bot. 9:101.
1973.

Caespitose bamboos; clumps of few to many stems; culms thornless, hollow, cylindri-
cal, in most species slender and graceful, arching and drooping, often forming foliage
curtains on canyon walls; branches numerous, the fan-shaped cluster originating from a
flattened triangular meristem just above the node; individual branches slender, un-
branched or with 1 or 2 solitary branchlets; foliage leaves borne on their distal parts.
Inflorescences in our species terminal on the branches, mostly 1-sided and slender, the
spikelets subsessile or sessile in 2 rows on the lower side of the rachis. Spikelets
several-flowered, laterally compressed, disarticulating above the glumes and lowermost
(sterile) lemma and between the florets; glumes 2 (3 in R. harmonicum'), unequal;
lowermost floret sterile or with a rudimentary flower; lemmas 5-7-nerved, acuminate or
short awned; palea 2-keeled and with several weak nerves on the lateral flanges;
lodicules 3; stamens 3; stigmas 2; caryopsis not seen; most spikelets appear sterile and
empty.

The species of Rhipidocladum in Costa Rica are usually recogniza-
ble by their very slender, gracefully arching (or trailing in R. maxonii)
growth habit and unarmed, hollow, cylindrical stems with elongated
internodes, usually less than 1 cm. thick. Rhipidocladum harmonicum
is exceptional in its more erect growth habit and thicker culms.
Blooming is infrequent, but sterile plants can be recognized by their
triangular, flattened branch meristems and by the midculm leaf
sheaths, which have deltoid, erect, reduced blades. Species 11, rang-
ing from Mexico to Brazil, Bolivia, Peru, and Ecuador, at low, frost-
free elevations. (Bambusoideae: Arthrostylideae.)

VEGETATIVE KEY TO SPECIES OF Rhipidocladum

la. Delicate sprawling or trailing plants; culms less than 3 mm. thick, usually less than 3
m. long; leaf blades 2-4 cm. long, 2.5-4 mm. wide R. maxonii

Ib. Erect or arching plants; culms 5-20 mm. thick, up to 20 m. long; leaf blades 6-12 cm.

long, 6-15 mm. wide 2

2a. Mature culms ca. 2 cm. thick R. harmonicum

2b. Mature culms less than 1 cm. thick 3

3a. Apex of leaf sheath prolonged into erect auricules that are adnate to ligule; auricular
bristles usually absent; larger leaf blades 9-17 mm. wide R. pittieri

502 FIELDIANA: BOTANY

3b. Apex of leaf sheath truncate at level of insertion of pseudopetiole, usually bearing
auricular bristles; leaf blades mostly 6-8 mm. wide R. raeemiflorum

Rhipidocladum harmonicum (Parodi) McClure, Smithsonian
Contr. Bot. 9:105. 1973. Arthrostylidium harmonicum Parodi, Physis
19:479. 1944.

Caespitose bamboo; clumps of few culms, 10-20 m. long, nearly erect or arching above;
rhizomes not seen; culms ca. 2 cm. thick, smooth and glabrous, cylindrical; internodes
green, thin-walled, hollow, 35 cm. long or more, often waterfilled when young; nodes not
prominent; midculm sheaths much shorter than the internodes, more or less appressed-
hispid on the surface, especially near the base and on the exposed edge; collar marked by
a partial row of hispid bumps; ligule a thick, minutely ciliolate membrane, ca. 1 mm.
long, slightly arched; sheath blade erect, as wide as the sheath apex at its base, up to 7
cm. long, half of the length being a narrow acuminate "tail"; margins of the blade
papillose-hispid in tufts. Foliage-bearing lateral branches of the culms numerous at each
middle and upper node, arising from the edges of a flattened triangular meristematic
plate in a fan-shaped group; individual branches slender, up to 40 cm. long, their proxi-
mal nodes bearing short bladeless sheaths, the foliage leaves 5-6, borne on the outer
two-thirds of the branch; sheath apex terminating in rounded auricles, bearing flattened
bristles up to 8 mm. long; ligule a thick, slightly ciliolate membrane, ca. 1 mm. long,
slightly arched; pseudopetioles 2-3 mm. long, glabrous or minutely puberulent; blades
flat, scaberulous, the midrib evident only near the base, 8-13 cm. long, 13-16 mm. wide,
ovate 6-8:1, the base rounded, asymmetric; surfaces glaucous, glabrous except for small
woolly tufts on the lower surface at the base. Inflorescence a simple terminal spike;
rachis flexuous, 4-6 cm. long; spikelets few (4-6), glabrous, 1.5-2 cm. long; sterile bracts
3-4, membranaceous, acute, glabrous, the first obsolete or scalelike; second acute, 3-
nerved, glabrous, 3.5-4 mm. long; third acute or slightly obtuse, 7-nerved, 6-8 mm. long;
fourth similar but larger, 7.5-9 mm. long; fertile lemmas 9-11-nerved, 11 mm. long, the
apex acute, awnless; palea slightly shorter than the lemma, 2-keeled, the keels ciliate;
lodicules lanceolate, acuminate; anthers 3, 6.0-6.5 mm. long. (Description of spikelets
from Parodi.)

Rare; Rio Conejo, Canas Gordas, and Bajo Pacuare. At the last site,
several clumps were seen near the road, about 3 km. E of the Rio
Pacuare. The young culms were strictly erect. Their internodes con-
tained water. Elevation 1,000-1,200 m. The identification of these
specimens is somewhat tentative, since they are the only North
American collections, and all are sterile. The Rio Pacuare specimen is
a good match for W. H. Camp E 1613 from Ecuador, in US.

Rhipidocladum maxonii (Hitchc.) McClure, Smithsonian Contr.
Bot. 9:105. 1973. Arthrostylidium maxonii Hitchc., Proc. Biol. Soc.
Wash. 40:80. 1927. Figure 190.

Delicate, vinelike bamboo, the culms 1-3 m. long, arching or trailing in brush;
rhizomes very short, scaly; culms arising separately or in small clumps, scaly at the base;
internodes elongated, 10-18 cm. long, naked, cylindrical, glabrous, hollow, 1.5-2.5 mm.
thick; nodes not prominent, glabrous or retrorsely appressed-pubescent; foliage leaves

FIG. 190. Rhipidocladum maxonii. A, culm base; B, branch complements and culm
internodes; C, inflorescence.

503

504 FIELDIANA: BOTANY

borne on primary branches that arise in a dense semi-verticel of 30 or more from a
flattened triangular appressed meristem that arises just above each node; branches very
slender, the lower internodes exposed, the foliage aggregated toward the tip; leaves
several per branch, their sheaths mostly overlapping; exposed sheath margin puberulent
in a line that extends down the internode below; auricular bristles slender, whitish, 6-8
mm. long; pseudopetiole ca. 1 mm. long, puberulent on one margin, the line of hairs
continuing along one margin of the leaf blade lower surface, the remainder of the under-
surface with only scattered elongated hairs; ligule minute, a ciliolate membrane 0.1-0.2
mm. long; leaf blades flat, light green, linear, 2-4 cm. long, 2.5-4.0 mm. wide, glabrous
above, scabrous on the margins. Inflorescences numerous, borne at the tips of the
primary branches, small, 8-10 mm. long, the few spikelets borne in 2 rows on one side of
the flattened rachis, crowded and standing out at right angles to the rachis; peduncles
included in the uppermost sheath or exserted 3-8 mm. Spikelets sessile or nearly so, 8-10
mm. long, laterally compressed; first glume 1.2-1.5 mm. long, ovate, 1-nerved; second
glume 2.0-2.7 mm. long, the two closely adjacent; a thick rachilla internode borne above
them; lowermost floret sterile, consisting of an empty lemma 3.5-4.2 mm. long, 4-5-
nerved, ovate 2:1, acute; disarticulation usually above the sterile lemma; upper florets,
with the exception of the reduced terminal one, with paleas, the palea ranging from
nearly as long as the lemma to much shorter; lemmas ovate, 5.0-6.4 mm. long, acute,
7-9-nerved, glabrous (except in the type number, which has pilose lemmas); palea 2-
keeled; anthers 3, yellow, 4.2 mm. long; ovary with a single short style and 2 stigmas;
fruit not seen; most florets appear empty.

Region south of Cartago. The type (Maxon & Harvey 8154) is from
Santa Clara de Cartago. Other flowering specimens are Standley
33543 from El Muneco and Standley 391 79 from La Estrella. The only
known flowering dates are 1923, 1924, 1955, and 1972. Our recent
collections from El Muneco and El Empalme area are vegetative. The
latter collection (Pohl & Lucas 13005) consists of small seedlings and
young plants, so that it may be inferred that the plants have flowered
recently. Because of their small size and habit of growing in brush, the
plants are quite inconspicuous. Wet forests and brushy slopes.
Endemic to Costa Rica.

This is one of the most easily recognized of the Costa Rican bam-
boos, because of its delicate, vinelike aspect and the peculiar pubes-
cence patterns of the sheaths, blades, and culm internodes.

Rhipidocladum pittieri (Hack.) McClure, Smithsonian Contr.
9:105. 1973. Arthrostylidium pittieri Hack., Oesterr. Bot. Z. 53:75.
1903. Figure 191.

Caespitose bamboos, in clumps of up to ca. 50 culms; rhizomes pachymorph, the
clumps dense; culms very slender, less than 1 cm. thick, up to 10 m. long, their lower
portions arching, the upper part long-drooping, the colonies forming graceful curtains of
foliage on canyon walls; internodes elongated, cylindrical, greenish, thin-walled, gla-
brous; culm sheaths purplish, glabrous except the felty exposed margin; ligule a stiff
membrane, ca. 0.5 mm. long, slightly arching, minutely ciliolate; blade erect, triangu-
lar, about as wide as the sheath apex, coarsely hispid on the lower margins and upper

FIG. 191. Rhipidocladum species. R. racemiflorum: A, branch complement of a
blooming plant; B, leaf blade; R. pittieri: C, leaf blade; D, spikelet.

505

506 FIELDIANA: BOTANY

surface near the base; leafy branches from all of the middle and upper culm nodes, borne
in dense fan-shaped clusters of up to 50, arising from a flattened, appressed triangular
meristematic plate just above the node; leafy branches very slender, mostly unbranched,
up to 60 cm. long, bearing several foliage leaves on the outer half; lower blades decidu-
ous, the sheaths persistent; sheaths glabrous, terminating in erect auricles that are
adnate to the ligule; ligule a membrane, 1.5-2.5 mm. long; pseudopetiole 1.5-4.0 mm.
long, puberulent; blades abscissing with the pseudopetiole; blades flat, 7-12 cm. long,
6-16 mm. wide, glabrous except for a dense tuft of woolly hairs on one side of the midrib
at the base of the abaxial surface; midrib not conspicuous except near the base of the
blade; margins scabrous; outline narrowly ovate, 7-10:1, acuminate. Inflorescences usu-
ally solitary and terminal on the branchlet, rarely several on one branch. Peduncle
included or exserted up to 1 cm. Inflorescence a slender, 1-sided raceme, 3-10 cm. long,
less than 1 cm. thick; spikelets subsessile in 2 rows, alternating on the lower side of the
rachis, their stiff, appressed pedicels 1-2 mm. long. Spikelets ca. 2 cm. long, laterally
compressed, stramineous or whitish, the bracts often green-spotted; first glume acicu-
lar, 2.5-4.5 mm. long, tapering into an awn tip; second glume 4.9-6.7 mm. long, ovate,
acuminate, 5-nerved; lowermost lemma empty, lacking palea and flower, 6.5-7.9 mm.
long, ovate 3:1, 7- or rarely 9-nerved, acuminate or awn-tipped, the awn up to 2 mm.
long; rachilla internode above the sterile lemma thick and stiff, up to 4 mm. long;
spikelets disarticulating above the lowermost lemma and between the remaining florets;
well-developed florets 1-3, the rachilla terminating in a reduced slender lemma; upper
lemmas 10-11 mm. long, ovate 3:1, tapering to an awn tip 1-2 mm. long; nerves usually 7;
upper margins of the lemmas short-ciliate; awn upwardly scabrous; palea about equal to
the lemma, ciliate near its tip; keels 2, the marginal flanges of the palea each having
several faint nerves as well; upper rachilla segments slender, ca. 4 mm. long; lodicules
flat, brownish; anthers 3, yellow, 3.5-6 mm. long; fruit not seen.

Costa Rican collections of this species are from the canyon of the Rio
Virilla, SW, N, and NE of San Jose. Type material (Tonduz 7198) was
marked "Rio Virilla, pres San Juan" (possibly Tibas). The plants are
abundant on the canyon walls at Puente de Mulas, near San Antonio,
where I first observed it in vegetative condition in 1968. Subsequent
observations indicated that the plants remained in vegetative condi-
tion until 1973. The specimens of the type number available to me are
small fragmentary flowering branchlets. The collection date was 1892.
No subsequent specimens were collected in either vegetative or flow-
ering condition until 1973. In that year, Roy Lent collected it in flow-
ering condition from the Rio Virilla between San Miguel Sur and
Paracito. I found the large stand in bloom at Puente de Mulas in June
1973. All plants were in the reproductive stage, and no new culms
were found. The spikelets were disarticulating very freely. No evi-
dence of stamens or mature fruit could be seen. I revisited the same
locality in December 1974, at which time all old plants were dead. A
very limited number of seedlings were found along the trail on the
south side of the Rio Virilla, above the powerhouse. They were usually
found growing in litter on the tops of flat boulders or in clefts between
the rocks. It seems evident from the nearly complete absence of sta-

BURGER: FLORA COSTARICENSIS 507

mens, the lack of developed caryopses, and the paucity of seedlings,
that most of the spikelets are sterile.

Rhipidocladum racemiflorum (Steud.) McClure, Smithsonian
Contr. Bot. 9:106. 1973. Arthrostylidium ? racemiflorum Steudel,
Syn. PL Glum. 1:336. 1854. Figure 191.

Slender bamboos; rhizomes pachymorph, the plants forming dense clumps; culms
numerous, 10-15 m. long, arching and trailing or ascending into trees, cylindrical, hol-
low, 5-10 mm. thick, glabrous; internodes elongated; nodes not enlarged; sheaths of main
culms mostly glabrous, or the exposed margin slightly felty; ligule a stiff membrane,
slightly arched, ca. 0.5 mm. long, minutely ciliolate; blades reduced, erect, ca. as wide at
the base as the sheath apex, triangular, acuminate, ca. 3-4 cm. long, the margins
coarsely hispid-ciliate near the base; upper surface somewhat coarsely pubescent near
the base; foliage-bearing branches numerous (60-80 per node), arising from the edges of
a flattened triangular meristem borne just above the node, forming a fan-shaped cluster;
lower sheaths of each branchlet bladeless, the several leaf blades borne on the outer
portion of the branch; primary branches sometimes bearing 1 or 2 solitary secondary
branches from their distal nodes; sheaths shorter than the internodes, mostly glabrous
except for the puberulent margins (more puberulent in juvenile plants); apex of sheaths
truncate, usually bearing auricular bristles up to 8 mm. long, these readily deciduous;
ligule minute, a thin membrane 0.2-0.5 mm. long; pseudopetioles 1.0-1.5 mm. long,
glabrous or puberulent; leaf blades flat, 6-8 cm. long, 5-9 mm. wide; midrib scarcely
visible except at the base; upper surface glabrous; lower surface with a tuft of woolly
hairs on one side of the midrib at the base, sometimes also with some appressed pubes-
cence on the lower surface. Peduncles included or exserted up to 8 mm.; inflorescences
numerous, solitary at the tips of primary branches or terminal on a secondary branchlet;
inflorescence a slender, one-sided raceme; rachis thin, slightly arching, 4-6 cm. long;
spikelets usually ca. 10, appressed to the lower side of the rachis in 2 rows, borne on
short appressed pedicels less than 1 mm. long, inserted 3-5 mm. apart. Spikelets 14-18
mm. long, laterally compressed, disarticulating above the sterile lemma and between the
larger florets; first glume 2.8-3.9 mm. long, acicular from a broadened base, 3-nerved;
second glume 4.4-5.3 mm. long, including the awn tip, triangular 2.5:1, 5-nerved; lower-
most lemma sterile, lacking a flower and a palea, ovate, 6.0-6.5 mm. long, 5-7-nerved,
the rachilla internode above it thick and stiff, 1 mm. long; well-developed florets usually
2, frequently a reduced sterile one above the second; disarticulation at the apex of the
rachilla internode above the sterile lemma and between the 2 florets; lemmas 8-10 mm.
long, ovate 3:1, 5-7-nerved, ciliate near the apex with short, stiff hairs; awn apical, 1-2
mm. long; palea as long as or longer than the lemma, somewhat bowed out above the
base, evidently 2-keeled, stiffly ciliolate on the upper portions of the keels and on the tip;
marginal flanges of the palea faintly nerved; stamens 3; anthers 5 mm. long, yellow;
well-developed ovaries or caryopses not seen.

This species is scattered at low altitudes in Guanacaste and the
Nicoya Peninsula and occurs in the western part of the Meseta Central
as well. A single specimen from the General Valley is the south-
ernmost record in Costa Rica. The plants are graceful and delicate, the
numerous culms often arching and trailing. They occur on savannas
and in open forest, often along streams and canyon walls. The species

508 FIELDIANA: BOTANY

is monocarpic, like R. pittieri, the plants dying after flowering.
Blooming is apparently fairly frequent. I have seen flowering or fruit-
ing specimens from Costa Rica dated 1926, 1939, 1941, and 1973. The
two collections from 1973 are my numbers 12962 and 12963, both from
the flanks of Volcan Tenorio. These two colonies were separated by ca.
5 km. The plants were in an advanced stage of "fruiting" when col-
lected in June 1973. The spikelets were freely disarticulating, although
most of the florets appeared to be empty, and no developed ovaries and
few anthers could be found. These colonies were not relocated, but I
found another colony of the same species (13060) along the Rio Tenorio
3 km. S of Rio Naranjo, in December 1974. In this colony, all mature
plants were dead and rapidly disintegrating. Numerous seedlings were
found about the dead plants. They ranged up to 50 cm. tall and were
beginning to produce short rhizomes. The leaf-bearing branches were
borne in small fascicles and lacked the well-developed flat triangular
meristematic plate that characterizes mature plants.

RHYNCHELYTRUM Nees

Caespitose perennial; inflorescence a panicle. Spikelets densely covered and concealed
with purplish or white silky hairs that are twice as long as the bracts; spikelets laterally
compressed, the outline pyriform; first glume linear, much shorter than the spikelet;
second glume and sterile lemma subequal, keeled, elevated on a short stipe above the
first glume; second glume 5-nerved, ovate, strongly keeled, tapering abruptly to a nar-
row apex, bearing a short straight awn from just below the tip; lower lemma very similar
to the second glume, but with a staminate flower, the erect palea nearly as long as the
lemma, ciliate at the tip; fertile floret a third shorter than the spikelet, laterally com-
pressed, boat-shaped, smooth and shining, chartaceous, obscurely nerved, the margins
thin, not inrolled; palea about equal to the lemma.

This common weedy grass is easily recognized by the extremely
silky-pink, purple, or silvery-white inflorescences. About 25 species of
this genus are native to Africa. (Panicoideae: Paniceae.)

Rhynchelytrum repens (Willd.) Hubbard, Kew Bull. (1934): 110.
1934. Tricholaena rosea Nees, "Cat. Sem. Hort. Vratisl. a. 1836"; Fl.
Afr. Austr. 1:17 1841. T. repens (Willd.) Hitchc., Man. Gr. W. Ind.
331. 1936. Rhynchelytrum roseum Stapf & Hubb. ex Bews, World's
Grasses 223. 1929. Figure 192.

Rather slender caespitose perennial; culms up to 1 m. tall, erect or the bases some-
times decumbent, branching from the base or from lower nodes, hollow, papillose-
hirsute; the nodes bearded; prophylla up to 3 cm. long, pubescent; sheaths shorter than
the internodes, papillose-hirsute, the upper ones glabrous or nearly so; ligule a circle of
stiff hairs, 0.8-1.2 mm. long; blades 6-17 cm. long, 2-5 mm. wide, more or less papillose-
hirsute; plants leafy below, the upper blades reduced and usually glabrous. Panicles
terminal on the culms, solitary, oval, pedicels very delicate and flexuous, long-hairy near

FIG. 192. Rhynchelytrum repens. Plant, panicle, spikelet, fertile floret.

509

510 FIELDIANA: BOTANY

the apex. Spikelets 3.5-4.5 mm. long, but appearing twice that because of the long
pubescence; first glume 1 mm. long, linear; second glume and lower lemma subequal,
3.5-4.0 mm. long, carinate; lower lemma concealing a staminate flower, the palea 3 mm.
long, closing off the cavity of the lemma, ciliate at the apex; fertile floret readily decidu-
ous, the lemma boat-shaped, 2.2-2.5 mm. long, awnless, the flower perfect; anthers 3,
2.1-2.3 mm. long, tan. Chromosome number n = 18 from Costa Rican material.

Common; open areas or partial shade, roadsides and cafetals, banana
plantations, from sea level to 1,700 m. Probably blooming yearlong.
This African species occurs in Florida and from Mexico to Brazil;
Caribbean Islands. We have no records from the Caribbean slope in
Costa Rica, but this species probably occurs there.

Common names: Zacate ilusidn, Zacate de seda, "Ruby grass,"
"Natal grass."

ROTTBOELLIA Linnaeus fil.
Nomen Conservandum

Tall caespitose plants; inflorescence a terminal or axillary pedunculate cylindrical
rame; spikelets and pedicels sunken into the thick, hollow rachis, which disarticulates
into single internodes at maturity. Each internode has a fleshy knoblike projection at the
base which fits into a cavity in the apex of the internode below. Spikelets paired on each
internode, the sessile spikelet of each pair perfect-flowered, its coriaceous, many-
nerved, convex, ovate first glume with an acute tip and a transverse notch near the base;
second glume coriaceous, many-nerved, deeply boat-shaped, closely lining the cavity of
the thick internode; sterile lemma flat, 3-nerved, membranaceous, its palea hyaline,
shorter than the lemma; floret perfect; anthers 3, yellow; styles naked below, stigmas
purple. Pedicellate spikelet shorter than the fertile one, its flat, coriaceous, many-
nerved pedicel united along one margin to the edge of the rachis internode, and together
with the first glume of the sessile spikelet, completely closing off the cavity of the rachis
internode. Pedicellate spikelet sterile, consisting of a flat, ovate, acute, many-nerved
first glume bifid at the tip, with infolded margins and a slightly smaller 3-nerved second
glume enclosing a small rudimentary floret.

Closely related to the similar genera Manisuris, Coelorachis, and
Hemarthria. A small genus of several species native to the tropics
of the Old World, one species introduced in tropical America.
(Panicoideae: Andropogoneae.)

Rottboellia exaltata L. f., Sup. PI. 114. 1781. Stegosia exaltata
(L.f.) Nash, N. Amer. Fl. 17:84. 1909. Figure 193.

Tall annual, the plants up to 2 m. tall, erect, freely branching, the bases of culms often
somewhat decumbent and with long, stiff prop roots; prophylla up to 8 cm. long, split
near the tips; internodes glabrous, pithy; nodes glabrous; leaf sheaths strongly bristly
with papillose-based stiff hairs; ligule a stiff membrane, ca. 1 mm. long; leaf blades
numerous, up to 40 cm. long and 20 mm. wide; midrib conspicuous, wide and white;
blades tapering to a narrow base, the upper surface hispid, the lower glabrous. Pedun-
cles terminal and axillary, slender, flattened, angular; rame cylindrical, 1-3 mm. thick,
7-15 cm. long, stiff; individual internodes 6.0-8.5 mm. long. Sessile spikelet 3.7-5.0 mm.

FIG. 193. Rottboellia exaltata. A, axillary inflorescence; B, portion of a rame, showing
spikelets sunken into the rachis; C, spikelet pair, showing disarticulation from a lower
internode.

511

512 FIELDIANA: BOTANY

long; pedicellate spikelet shorter than the sessile one and always sterile. Terminal por-
tion of the rame gradually reduced to a slender rachis bearing rudimentary spikelets.
Chromosome number n = 10 from Costa Rican material.

Occasional weed along streams and in pastures; mostly at low
elevations. Limon area, Siquirres, Turrialba, Quepos, Puntarenas,
Guanacaste. Blooming apparently yearlong. This Old World species
occurs in southern Florida and the West Indies. The Costa Rican
occurrences indicate rather recent introduction, but the plants are
spreading aggressively.

The stiff bristly hairs on the leaf sheaths are very irritating, since
they break off readily and penetrate the skin. Costa Rican farmers
indicate that livestock also reject the plants. Other chromosome num-
bers have been reported from Asia.

SACCHARUM Linnaeus

REFERENCE: E. Artschwager & E. W. Brandes, Sugarcane (Sac-
charum officinarum L.): Origin, Classification, Characteristics, and
Descriptions of Representative Clones, Agriculture Handbook No.
122. U.S. Dept. Agric. 307 pp. 1958.

Tall perennial grasses with thick, solid stems having many short internodes. Inflores-
cence a large terminal plumy panicle of numerous elongated rames, which disarticulate
at maturity into individual internodes, each bearing a spikelet pair, one spikelet of each
pair sessile and one borne on a short pedicel. Spikelets equal, bisexual, awnless, dorsally
compressed, somewhat boat-shaped; acute, callus of spikelets short, truncate, bearing
numerous silky hairs several times as long as the spikelets; first glume and second glume
subequal, longer than the internal spikelet parts and concealing them, chartaceous; first
glume flat on the back, usually 4-nerved and lacking a midrib; second glume boat-shaped,
3-5-nerved; lower (sterile) lemma slightly shorter than the first glume, flat on the back,
2-nerved, dilate on the upper margins, thinner than the glumes; upper (fertile) lemma
much smaller than the lower one, or absent, often reduced to a thin, subulate membrane,
ciliate at the tip; palea absent; lodicules 2, truncate, vasculated; stamens 3; stigmas 2, on
slender, naked style branches, usually exserted laterally from the spikelet.

A small genus of about six species of the Asiatic tropics, including
many hybrid, polyploid, or apomictic forms that are difficult to place;
plants wild or frequently cultivated for sugar production. The genus is
closely related to Erianthus, Miscanthus, Imperata, and Eriochrysis.
(Panicoideae: Andropogoneae.) Sugarcane, the only representative of
the genus in the Americas, is readily recognized by its large size, thick
solid culms with numerous nodes, and plumy panicles. It might possi-
bly be confused with Gynerium sagittatum (Cana brava), which is
found only in the wild, and has several-flowered unisexual spikelets
and nonsweet culms, bearing their leaves in fan-shaped clusters near
the apex. Common names: "Sugarcane," Cana de Azucar.

BURGER: FLORA COSTARICENSIS 513

Saccharum officinarum L., Sp. PI. 54. 1753. Figure 194.

Giant grasses, mature plants becoming several meters tall; caespitose (but planted
from buried culms that sprout at the nodes); culms many-noded, solid, usually un-
b ranched, sweet, of various colors, up to 5 cm. thick; lower leaf blades and sheaths often
disarticulating from mature culms; internodes usually glabrous and often strongly
bluish-glaucous; sheaths longer than the internodes, overlapping, glabrous or pubescent,
sometimes producing auricles at the apex; ligule a thick short membrane; blades rather
stiff and spreading, 1-2 m. long, narrow at the base and widest at the middle, glabrous or
the broad midrib pubescent; margins very scabrous. Peduncle stout, cylindrical, bearing
a solitary terminal panicle; inflorescence large, silky with white or pinkish hairs.
Spikelets mostly 3-4 mm. long, glabrous except for the long hairs on the short, blunt
callus; lower lemma flat, conforming to the first glume, and slightly shorter than it;
upper lemma 1.5-2.5 mm. long, thin and membranaceous, nerveless, ciliate at the tip,
sometimes absent; anthers ca. 2.0 mm. long. Numerous chromosome numbers have been
reported for cultivated strains of this species, but n = 20 or 40 are the most common.

Widely cultivated at lower elevations for sugar production. Rarely,
spontaneous individuals may be seen on field margins or roadsides, but
these are probably survivors of cultivation. Blooming is highly irregu-
lar, and the season for a particular stand may depend on day length,
altitude, rainfall, the genetic individuality of the clone, and other fac-
tors. Bloom is most frequent during the short days of the year. Native
to the Asiatic tropics.

SACCIOLEPIS Nash

Inflorescence a dense or spikelike panicle, rarely reduced to a spikelike raceme; inter-
nodes hollow; spikelets flattened on the first glume side or biconvex; second glume and
sterile lemma boat-shaped, equal, somewhat saccate near the base; first glume much
shorter than the spikelet, 3-5-nerved; second glume with 7-9 conspicuous nerves; sterile
lemma 5-7-nerved, with a short or well-developed palea and sometimes a staminate
flower, upper floret much shorter than the sterile lemma, lanceolate to ovate, dorsally
compressed, acute, chartaceous, smooth and shining, awnless; margins of lemma not
inrolled; palea similar to the lemma, both bracts very obscurely nerved.

The genus is closely related to Hymenachne, from which it differs in
having hollow internodes. About 40 species, in the tropics of the east-
ern hemisphere, with a few in the Americas. (Panicoideae: Paniceae.)

KEY TO SPECIES OF Sacciolepis

la. Delicate sprawling plants with thin culms; uppermost leaf blade usually 1-4 cm. long;

ligule minute, 0.1-0.3 mm. long; spikelets 2.5-2.8 mm. long S. indica

Ib. Erect tufted plants; culms thick, somewhat succulent; uppermost leaf blade 15-25

cm. long; ligule 1.0-2.5 mm. long; spikelets 2.0-2.2 mm. long S. myuros

Sacciolepis indica (L.) Chase, Proc. Biol. Soc. Wash. 21:8. 1908.
Aira indica L., Sp. PI. 63. 1753. (As A. spicata, corrected in Errata,
end Vol. II.) Figure 195.

Probably perennial; plants tufted or with decumbent or weakly rhizomatous culm

FIG. 194. Saccharum officinarum. Blooming plant, portion of a panicle consisting of
several rames, a sessile spikelet with a pedicel and rachis internode.

514

FIG. 195. Sacciolepis species. S. myuros: A, panicle; B, spikelet; S. indica: C,
spikelet.

515

516 FIELDIANA: BOTANY

bases; branching from the base of the plants only; culms 15-50 cm. long, very slender,
glabrous, the foliage mostly aggregated near the base; nodes glabrous; sheaths glabrous,
shorter than the internodes; ligule a minute membrane, 0.1-0.3 mm. long; blades 3-10
cm. long, 2-4 mm. wide, glabrous. Peduncle very slender, 10-23 cm. long, often making
up more than half of the height of the plant; panicles solitary, terminal, spikelike, 1.5-7.0
cm. long, usually less than 5 mm. thick, often purplish. Spikelets individually pedicellate
on the rachis, densely overlapping and concealing it, biconvex, 2.5-2.8 mm. long; first
glume 1.1-1.5 mm. long, ovate, boat-shaped, 5-nerved; second glume boat-shaped, nar-
rowed to a blunt apex, 7-nerved, 2.5-2.8 mm. long; sterile lemma similar but more
saccate at the base, 7-9-nerved, concealing a narrow stiff palea ca. 1 mm. long; fertile
floret 1.5 mm. long, narrowly ovate, acute, smooth and shining, nerves obscure; palea
ca. as long as the lemma; anthers 3, 0.6-0.9 mm. long, purple. Chromosome number n =
9 from Costa Rican specimens.

Wet pastures, lawns, ditches, riverbanks; mostly on the Caribbean
slope; Meseta Central; elevations from 50-1,700 m. June to February,
probably yearlong. Native to southeastern Asia and the Islands of the
South Pacific; introduced in Africa, southeastern United States, and
Central America.

Sacciolepis myuros (Lam.) Chase, Proc. Biol. Soc. Wash. 21:7.
1908. Panicum myuros Lam., Tabl. Encycl. 1:172. 1791. Figure 195.

Probably perennial; plants erect, tufted, 20-50 cm. tall; culms thick, somewhat succu-
lent, sometimes with prop roots from lower nodes; prophyllum thin, brownish, to 2.5 cm.
long; culms glabrous, hollow, thin-walled; nodes glabrous; sheaths overlapping, gla-
brous; ligule a thin brownish membrane, 1.0-2.5 mm. long; blades 15-25 cm. long, 2-5
mm. wide, glabrous beneath, sparsely and weakly pubescent above. Peduncles slender,
erect, glabrous, exserted up to 18 cm.; inflorescence a dense cylindrical spikelike panicle,
4-18 cm. long, 5-8 mm. thick, the branches few-flowered, erect and appressed to the
rachis, concealed by the densely overlapping spikelets. Spikelets biconvex, 2.0-2.2 mm.
long; first glume 0.9-1.2 mm. long, ovate, blunt, convex, 3-nerved; second glume and
sterile lemma similar, 2.0-2.2 mm. long, boat-shaped, the sterile lemma more saccate
near the base, both 7-nerved, softly ciliate on the upper third; sterile lemma with a stiff,
narrow palea ca. half as long as the lemma; fertile floret 1.0-1.2 mm. long, concealed by
the glumes and sterile lemma, dorsally compressed, smooth and shining; lemma nar-
rowly ovate, acute, the palea similar, both obscurely nerved; anthers 3, 0.5-0.7 mm.
long, purple. Chromosome number n = 18 from Costa Rican material.

Rare, streams and marshes in savannas, south of LaCruz,
Guanacaste. Elevations 200-250 m.; October to January. Southern
Mexico to Honduras; Costa Rica; Panama; Colombia to Guyana and
Brazil; Cuba.

SCHIZACHYRIUM Nees

REFERENCES: S. T. Blake, Taxonomic and nomenclatural studies in
the Gramineae, No. 1, Proc. Roy. Soc. Queensland 80:6:55-84. 1969. S.
T. Blake, Revision of the genera Cymbopogon and Schizachyrium
(Gramineae) in Australia, Contr. Queensland Herb. 17:1-70. 1974. S.

BURGER: FLORA COSTARICENSIS 517

Hatch, A biosystematic study of the Schizachyrium cirratum-S. san-
guineum complex, Unpubl. Ph.D. Diss., Texas A.&M. Univ. 112 pp.
1975. G. V. Nash, Schizachyrium, in N. Amer. Flora 17:2:100-109.
1912. G. Roberty, Monographic systematique des Andropogonees du
globe, Boissiera 9:1-455. 1960.

Perennial or annual grasses of small or moderate stature; inflorescences usually sev-
eral to many per culm, terminal and axillary; individual inflorescence a solitary rame on a
bracted peduncle; rame consisting of several-many pairs of spikelets, each pair borne at
the base of a disarticulating rachis internode and falling attached to it; rachis internodes
narrow at the base and thickened upward, the apex being obliquely cup-shaped and
hollow, often with pointed appendages on the edges; pedicels similar but thinner. One
spikelet of each pair sessile, perfect-flowered, and usually awned, the other spikelet
borne on a pedicel attached at the base of the internode and reduced, sterile, or rudimen-
tary, awned or awnless. Terminal segment of the rachis bearing a single sessile spikelet
and 2 pedicellate ones. Sessile spikelets: Glumes subequal, firm, as long as the spikelet
and completely concealing the inner parts, the awn protruding at the tip; first glume
dorsally flattened, slightly convex, the 2 principal nerves at the lateral folds of the
glume, sometimes prolonged into points at the apex; midrib absent, but weak nerves
sometimes present between the 2 main ones; margins of first glume sharply inflexed,
clasping the edges of the second glume; second glume keeled, boat-shaped, about as long
as the first; lower (sterile) lemma hyaline; upper (fertile) lemma hyaline, awned between
2 prominent acuminate lobes; awn exserted, geniculate.

The genus is related to Andropogon and is sometimes regarded as a
subgenus or section of it. It differs in having a single rame on each
peduncle. Other related genera, sometimes included with Schiz-
achyrium in Andropogon, are Bothriochloa, Diectomis, Euclasta,
Hyparrhenia, and Hypogynium. Blake indicates that Schizachyrium
includes 60-70 species, mostly from warm climates in both eastern and
western hemispheres. (Panicoideae: Andropogoneae.)

KEY TO SPECIES OF Schizachyrium

la. Rachis of rames straight, spikelets appressed to it; rachis glabrous or pubescent;

anthers 3 2

Ib. Rachis of rames strongly flexuous, spikelets standing out from it; rachis and pedicels

conspicuously silky-ciliate with long hairs; anther 1 S. microstachyum

2a. Leaf blades 3.5 cm. or less long, parallel-sided, rounded abruptly to a blunt tip;
dwarf annuals; sessile spikelets 2.0-3.5 mm. long; anthers less than 0.6 mm.

long S. brevifolium

2b. Leaf blades up to 20 cm. long, tapering, the tip acute or acuminate; tufted

perennials; sessile spikelets at least 4.5 mm. long; anthers over 1.5 mm. long . 3

3a. Leaf blades 1-3 mm. wide, acuminate; first glume of sessile spikelet flat on the back,

glabrous; pedicellate spikelet ca. as long and wide as sessile one 5. tenerum

3b. Leaf blades 3-5 mm. wide, acute; first glume of sessile spikelet convex, margins
inrolled; back glabrous or pubescent; pedicellate spikelet reduced, much shorter
than sessile one S. hirtiflorum

Schizachyrium brevifolium (Swartz) Nees ex Biise in Miq. PI.

518 FIELDIANA: BOTANY

Jungh. 359. 1854. Andropogon brevifolius Swartz, Prodr. Veg. Ind.
Occ. 26. 1788. An extensive synonymy is given by S. T. Blake. Figure
196.

Caespitose annual, the culms weak, becoming decumbent and rooting at the lower
nodes; branching abundant from the lower nodes; plants producing numerous axillary
inflorescences, 1-5 peduncles arising from most of the middle and upper nodes; culms
4-60 cm. long; internodes less than 1 mm. thick, hollow, oval in cross section, glabrous,
usually reddish; nodes glabrous; leaf sheaths keeled, longer or shorter than the inter-
nodes, glabrous, reddish; ligule a thin white membrane, 0.3-0.7 mm. long; leaf blades
oblong, 1.0-3.5 cm. long, 1-4 mm. wide, glabrous; base of blade rounded to a minute
pseudopetiole; apex rounded abruptly to a broad blunt tip; blades flat but keeled be-
neath, especially toward the apex. Inflorescences terminal on the main culms and from
numerous leaf axils, the peduncles included or exserted from the leaf sheaths, bearing
bladeless sheaths that subtend and usually include the base of the solitary rame; 1-5
peduncles arising from one leaf axil; rames 1.0-2.5 cm. long, consisting usually of 5-8
spikelet pairs; internodes narrow at the base, widened upward, very thin, the one side
convex, the other hollowed out; pedicels similar to the rachis internodes but narrower;
apex of each internode obliquely cup-shaped, with 2 points on the edges; base of the
sessile spikelet partially hidden by the cup-shaped rachis apex. Sessile spikelets 2.0-3.5
mm. long, narrowly ovate 4.5-6.0:1, acute, dorsally flattened; callus short-bearded with
straight erect white hairs; first glume as long as the spikelet, firm-textured, slightly
convex on the back, scabrous, with 2 lateral keels near the apex that are prolonged into
erect points; glume nerveless between the keels or with several weak nerves; second
glume slightly shorter, strongly keeled, 1-nerved, scabrous on the keel; lower (sterile)
lemma hyaline, nearly as long as the upper lemma; upper (fertile) lemma hyaline,
nerveless, bifid almost to the base, the awn inserted in the cleft; first segment of the awn
strongly twisted, brown, mostly included within the glumes, then geniculate, the upper
segment white, straight, the exserted portion 5-7 mm. long; lodicules 2, truncate; an-
thers 3, purple, 0.4-0.6 mm. long. Pedicellate spikelets much reduced, with a short
straight awn.

Most of our specimens have glabrous rachis internodes and pedicels,
and hence belong to var. brevifolium. Two specimens, one from
Hacienda Murcielago and another from the Liberia area, have ciliate
rachis internodes and pedicels. This variant has been described as var.
flaccidum (A. Rich.) Stapf, Fl. Trop. Africa 188. 1917 (Andropogon
flaccidus A. Rich., Tent. Fl. Abyss. 2:452. 1851).

Curatella-Byrsonima savannas, tuff outcrops, dry volcanic slopes,
steep road cuts. Common in Guanacaste, occasional in western parts of
the Meseta Central; Boruca savannas; elevations 100-1,150 m.; absent
from moister areas and from the Caribbean slope. Mexico to Brazil;
West Indies; widespread in the tropics of Africa and Asia and the
islands of the western Pacific. Germination of the seeds occurs during
the rainy season, but the plants remain vegetative until late October.
Blooming November to January.

Schizachyrium hirtiflorum Nees, Agrost. Bras. 334. 1829. An-

FIG. 196. Schizachyrium species. S. brevifolium: A, blooming culm; B, seedlings in
vegetative condition; S. microstachyum: C, compound inflorescence of several rames.

519

520 FIELDIANA: BOTANY

dropogon hirtiflorus (Nees) Kunth, Rev. Gram. liSuppl. XXXIX.
1830. S. semiberbe Nees, Agrost. Bras. 336. 1829. A. semiberbis
(Nees) Kunth, Rev. Gram. IrSuppl. XXXIX. 1830.

Caespitose perennial in small tufts; plants 90-150 cm. tall, erect; culms branching from
the middle and upper nodes; internodes elongated, glabrous, elliptical in cross section,
solid, 1.5-2.8 mm. thick; leaf sheaths keeled, shorter than the internodes, glabrous;
ligule a minutely erose membrane, 0.8-1.0 mm. long, leaf blades flat, up to 19 cm. long,
3-5 mm. wide, keeled beneath, scabrous above at the base, otherwise glabrous. Pedun-
cles several to many, terminal and axillary from the middle and upper nodes, mostly
included in bladeless sheaths; rames solitary on each peduncle, the base mostly included
in the terminal sheath, 3-13 cm. long, slender, straight; rachis internodes 6-8 mm. long,
convex on the back, thickened upward, the oblique basal callus upwardly bearded; apex
obliquely cup-shaped; pedicels similar to the rachis internodes but thinner, 5.0-6.5 mm.
long, ciliate along one margin; rachis internodes and pedicels glabrous or more or less
pubescent on the back. Sessile spikelets: 5.8-7.8 mm. long, including the basal callus of
the internode; outline ovate 6-10:1, acute; first glume as long as the spikelet, convex on
the back, the margins incurved; apex bifid; second glume about as long, keeled, 1-3-
nerved; lower (sterile) lemma 4-5 mm. long, hyaline, often purplish; upper (fertile)
lemma 4.0-4.5 mm. long, membranaceous, ciliate, very narrow, deeply divided into 2
acute lobes to the basal third; awn brown, tightly twisted below, geniculate, light-
colored and straight above the bend, exserted ca. 10 mm.; palea absent; anthers 3,
yellow, 1.5-2.0 mm. long; styles 2, separate; naked for the basal two-thirds; stigmas
purple. Pedicellate spikelets: 2.5-4.0 mm. long, with an awn 1.0-3.5 mm. long; first glume
flat, faintly nerved; second glume slightly shorter; florets usually lacking; one specimen
had a well-developed lower lemma and 3 stamens. Chromosome number n = 30 from the
single Costa Rican specimen.

Dry Curatella-Byrsonima savannas, coastal bluffs; from the
Nicaraguan border to Canas; sea level to 200 m. elevation; Boruca
savannas; dry hillsides, Canton de Dota, to 1,500 m. September to
January. Florida and southwestern United States to southern South
America.

A variety of chromosome numbers has been reported. Specimens
display a continuous spectrum of pubescence patterns on the first
glume of the sessile spikelet and the margins and surfaces of the rachis
internodes and pedicels. For this reason, I have united S. hirtiflorum
and S. semiberbe under the first name, which has page priority in
Nees. Hatch has proposed submerging the American plants under S.
sanguineum (Retz.) Alst., an Afro- Asian species originally described
from Madagascar, a procedure previously adopted by Roberty.

Schizachyrium microstachyum (Hamil.) Ros., Arr. & Izag., Bol.
Fac. Agron. Montevideo 103:35. 1968. Andropogon microstachyus
Hamil., Prodr. Fl. Ind. Occ. 8. 1825. Figure 196.

Caespitose perennial in small tufts; plants 90-150 cm. tall, erect; culms simple below,
becoming branched above into a compound inflorescence; internodes 2.0-3.5 mm. thick,

BURGER: FLORA COSTARICENSIS 521

glabrous, oval in cross section, the interior filled with white or pinkish pith; nodes
glabrous, not prominent; leaf sheaths keeled, glabrous or rarely obscurely puberulent,
the lower ones longer than the internodes, the upper shorter; h'gule a firm membrane,
0.7-2.0 mm. long, adnate to the sheath margins; leaf blades up to 40 cm. long, 3-8 mm.
wide, glabrous, flat but keeled beneath, occasionally with a few hairs at the throat.
Culms becoming much-branched above, forming an elongated ovoid compound inflores-
cence, composed of numerous solitary rames borne on spatheolate peduncles; compound
inflorescence 20-40 cm. long, 3-8 cm. wide, rather loose and feathery. Individual rames
on slender branches, the base of each invested by an involute or flattened sheath
(spatheole) which may conceal the lower spikelet pairs; spatheoles 15-35 mm. long;
rames 25-60 mm. long, with up to 8 spikelet pairs; peduncle usually very short; rachis
internodes 4-6 mm. long, widened upward, conspicuously ciliate on the edges, the cilia
longest toward the cup-shaped apex; pedicels similar but more slender, 3.6-5.5 mm.
long. Sessile spikelets: Callus blunt, minutely bearded, hidden by the hollow apex of the
rachis internode; spikelet 4.5-5.0 mm. long, narrowly ovate ca. 10:1, acute; glumes about
equal, as long as the spikelet, the first slightly convex on the back, with 2 submarginal
keels, the edges inflexed over the margins of the second glume, the apex slightly biden-
tate; second glume slightly shorter, 1-nerved, strongly keeled, the keel scabrous; lower
(sterile) lemma acute, hyaline, ciliolate on the margins, 3.2-3.8 mm. long; upper (fertile)
lemma hyaline, strongly 2-lobed to the insertion of the awn near the base, lobes acute,
ciliolate; awn dark brown and strongly twisted below, the exserted portion above the
bend straight or loosely twisted, ca. 10 mm. long; palea absent; lodicules 2, truncate;
anther 1, brown, ca. 1 mm. long; styles 2, separate; stigmas dark; caryopsis linear-
cylindrical, 2.5-2.8 mm. long, amber. Pedicellate spikelet: Abortive, usually 1-2 mm.
long, with a straight awn to 2 mm. long. Terminal sessile spikelet accompanied by 2
pedicellate spikelets. Chromosome number n = 10 from Costa Rican and Salvadorian
specimens.

Occasional; Curatella-Byrsonima savannas, steep road embank-
ments; regions of La Cruz and San Ramon; Nuestro Amo, Las Con-
cavas, Navarro, Turrialba, Siquirres. Elevations 250-1,100 m. August
to March. Schizachyrium microstachyum is a member of a species
complex that ranges from Mexico to Argentina. Our specimens belong
to ssp. elongatum (Hack.) Rosengurtt, loc. cit. which possesses an
elongate and rather loose inflorescence. In this subspecies, the
spatheoles may often be flattened rather than closely convolute.
Specimens with such flattened spatheoles may have a conspicuously
different appearance from those in which the spatheoles are rolled.

Central American plants have often been included in S. conden-
satum (H.B.K.) Nees, but are now assigned to S. microstachyum by
South American agrostologists.

Schizachyrium tenerum Nees, Agrost. Bras. 336. 1829. Andropo-
gon tener (Nees) Kunth, Rev. Gram. 565. 1832.

Perennial, in dense tufts; culms 40-110 cm. long, erect or reclining, branching from the
base or rather sparingly from middle nodes; internodes slender, 1.0-1.5 mm. thick,
hollow, glabrous; nodes glabrous, not prominent; lower leaf sheaths overlapping, the

522 FIELDIANA: BOTANY

upper ones shorter than the internodes, glabrous, slightly keeled; ligule a thin mem-
brane, 0.5-0.7 mm. long; leaf blades narrow, 1.0-2.5 mm. wide, flat, up to 25 cm. long,
keeled beneath, the uppermost one much reduced; midrib broad, whitish; upper surface
scabrous near the base and sometimes with a few elongated papillose-based hairs.
Peduncles exserted 3-5 cm. , slender; inflorescences terminal and axillary from the upper
leaf axils; rames slender, 3-10 cm. long, the spikelets appressed to the straight rachis;
internodes of the rachis 3.8-4.5 mm. long, thick, rounded on the back, hollow, the inner
surface grooved, membranaceous; apex strongly obliquely cup-shaped; base of internode
bearded; pedicels narrower, about as long as the internodes. Sessile spikelets: 4.5-5.0
mm. long, ovate 5-6:1, acute; first glume convex, firm and light-colored near the base,
greenish and striate above with ca. 7 weak nerves; apex bidentate; margins inflexed over
the edges of the second glume; second glume strongly keeled, scabrous on the keel,
faintly 3-nerved; lower (sterile) lemma 3.2-4.0 mm. long, flattened, membranaceous,
2-nerved near the margins, lacking a palea or a flower; upper (fertile) lemma 3.5-4.0 mm.
long, narrow, hyaline, divided to the middle into ciliate, acuminate lobes, the awn arising
between them; awn exserted ca. 10 mm., with a brown, strongly twisted first segment,
geniculate, the upper segment straight; palea absent; anthers 3, yellow, ca. 2 mm. long.
Pedicellate spikelets: Somewhat similar to the sessile ones and about as long, 4.7-5.2
mm. long, awnless or awn-tipped; first glume convex, ca. 7-nerved; second glume keeled,
ca. as long as the first; florets absent.

Known in Costa Rica only by the following specimens: Cartago, 5
km. E of Paraiso, elevation 1,130 m., savanna remnant, 1 November
1968, P. & D. 11394; Puntarenas, 5.3 km. N of Buenos Aires by road,
elevation 470 m., open savanna, 10 October 1968, P. & D. 11243.
Southeastern United States, Mexico and Guatemala, Panama to
Argentina; West Indies.

SECALE Linnaeus

Vigorous caespitose annual cereal grass; culms unbranched; inflorescence a solitary
erect terminal spike, the spikelets solitary, densely imbricated in 2 rows on opposite
sides of the persistent rachis. Spikelets 2-flowered; glumes narrow, much shorter than
the florets, awnless; lemmas strongly keeled, the tips long-awned, the midrib bearing a
row of short, rigid bristles; rachilla prolonged above the palea of the second floret as a
naked bristle; grains cylindrical, falling free from the florets when mature. (Pooideae:
Triticeae).

Secale cereale L., Sp. PL 84. 1753.

This European species is widely cultivated as a grain crop in cold
climates. It has been cultivated for forage on the volcanoes of the
Meseta Central, but is not common. It may persist in old fields after
cultivation at upper elevations. Common names centeno or "rye."

SETARIA Beauvois

REFERENCE: J. M. Rominger, 1962. Taxonomy of Setaria (Gra-
mineae) in North America. Illinois Biol. Monogr. 29: VIII + 132.

BURGER: FLORA COSTARICENSIS 523

Annual or perennial, caespitose or rhizomatous grasses; inflorescence a spikelike or
rarely open panicle; some or all of the spikelets subtended by one or more bristles (sterile
branches), these either antrorsely or retrorsely barbed. Spikelets disarticulating below
the glumes, dorsally compressed and flat on the first glume side, more or less convex on
the second glume side; first glume much shorter than the spikelet, usually deltoid and
1-3-nerved; second glume shorter than or subequal to the spikelet in length, 5-7-nerved;
lower (sterile) lemma about as long as the spikelet, 5-7-nerved, often with a well-
developed palea about equal to it in length, sometimes containing a staminate flower or a
caryopsis; glumes and lower lemma membranaceous, or rarely the lemma stiff; upper
(fertile) floret with a coriaceous or rigid, convex, often corrugated awnless lemma, its
margins covering the edges of a flat or concave palea of equal length and similar texture;
keels of the palea usually prominent, protruding as ridges; stamens 3; style branches
naked below; caryopsis elliptical, flattened, with a large embryo.

Setaria is a genus of ca. 125 species of grasses of temperate and
tropical regions of both eastern and western hemispheres. Some
species are important weeds of croplands; S. italica is a minor crop
plant ("millet"); several are used as ornamentals for their peculiar
plicate leaves. The common species are readily recognizable by their
bristly, cylindrical inflorescences and typically panicoid spikelets. The
genus is closely related to Pennisetum, from which it differs by the
disarticulation of the spikelets above the attachment of the bristles of
the fascicles. Some authors include in Setaria the species regarded by
Hitchcock as belonging to Panicum, subgenus Paurochaetium. These
species have a bristle subtending only the terminal spikelet of each
branch. Ixophorus, which occurs in Central America, also has a single
bristle accompanying each spikelet, but the spikelets at maturity have
an enlarged and protruding palea in the lower floret. (Panicoideae:
Paniceae.)

KEY TO SPECIES OF Setaria

la. Leaf blades elliptical, longitudinally corrugated, usually 3-10 cm. wide 2

Ib. Leaf blades linear or narrowly lanceolate, not corrugated, up to 3 cm. wide ... 3

2a. Lower panicle branches 6-25 cm. long, panicles rather open, green

S. paniculifera
2b. Panicle branches, except lowermost, usually less than 5 cm. long; panicle dense,

often purplish S. poiretiana

3a. Each spikelet or spikelet group subtended by 5-10 yellow bristles, edges of sheaths

thin, translucent, glabrous 4

3b. Each spikelet subtended by 0-3 greenish bristles; sheath edges ciliate 5

4a. Panicles 1-8 cm. long; plants usually less than 1 m. tall; anthers purple, 0.8 mm.

or less long; wild plants S. geniculata

4b. Panicles 8-25 cm. long; plants 1-2 m. tall; anthers tan, 1.4 mm. or more long;

cultivated crop plants S. anceps

5a. Spikelets disarticulating only below glumes; fertile lemma rugose; lower floret never
producing caryopsis 6

524 FIELDIANA: BOTANY

5b. Spikelets disarticulating below glumes or below fertile floret; fertile lemma smooth

and shining, not rugose; lower floret often producing a caryopsis S. magna

6a. Bristles bearing upwardly pointing (antrorse) barbs only 7

6b. Bristles bearing both antrorse and backwardly pointing (retrorse) barbs ... 8

7a. Rachis of panicle scabrous; sterile lemma lacking palea S. liebmannii

7b. Rachis of panicle bearing elongated fine hairs; sterile lemma enclosing palea of equal

length S. vulpiseta

8a. Spikelets 2.3-2.6 mm. long; sterile lemma enclosing palea of equal length; an-
trorse and retrorse barbs intermixed along length of bristles S. tenax

8b. Spikelets 1.4-1.8 mm. long; palea of sterile lemma absent or small; retrorse
barbs borne only on upper half of bristles 9

9a. Sterile lemma lacking palea; bristles bearing retrorse barbs on the upper half; pani-
cles up to 20 cm. long S. tenacissima

9b. Sterile lemma with palea ca. half as long; panicles usually 10 cm. or less long; bristles
bearing only few retrorse barbs at the very tip S. scandens

Setaria anceps Stapf ex Massey, Sudan Grasses 33. 1926.

Perennial from hard crowns; short rhizomes present; culms erect or the bases decum-
bent, up to 2 m. tall, with 5-10 nodes; internodes glabrous, compressed, hollow but
thick-walled; sheaths keeled, longer than the internodes, glabrous, their margins gla-
brous, thin and translucent; ligule a thin membrane, crowned by a dense row of white
hairs, in total 1.5-2.5 mm. long; dewlap conspicuous, colored; blades flat, glabrous, up to
45 cm. long and 13 mm. wide; base of blade scabrous-puberulent behind the ligule.
Inflorescence a solitary terminal panicle on a long-exserted glabrous peduncle; panicle
densely cylindrical, 8-25 cm. long, ca. 1 cm. thick, including the yellow bristles; spikelets
densely crowded in small fascicles, concealing the rachis; each spikelet or spikelet group
subtended by a cluster of 5-10 yellow, stiff, antrorsely scabrous bristles. Spikelets ovate
2.5:1, 2.4-2.8 mm. long; first glume 1.2-1.3 mm. long, narrowly ovate; second glume 1.5
mm. long, narrowly ovate, acute, 3-5-nerved; lower (sterile) lemma as long as the
spikelet, 5-nerved, thin, enclosing a palea of similar length and shape and a staminate
flower; anthers 3, tan, 1.6-1.7 mm. long; upper (fertile) floret ca. 2.3 mm. long; lemma
ovate, strongly rugose except at the mucronate tip; palea equal, with conspicuous keels;
anthers 3, 1.4-1.5 mm. long, tan; styles separate; stigmas purple.

This African species has been cultivated in the grass garden of the
CATIE at Turrialba and is now being cultivated in the Sarapiqui area.
I have seen fields near Cariblanco, La Virgen, and Aguas Zarcas. This
species belongs to the S. sphacelate, complex, which is a group dis-
playing much morphological and cytological diversity. Some of the
species are discussed by W. D. Clayton in Kew Bull. 20:262-264. 1966.

Setaria geniculata (Lam.) Beauv., Ess. Nouv. Agrost. 51, 178.
1812. Panicum geniculatum Lam., Encycl. 4:727. 1798. For an ex-
tended synonymy, see Hitchc., N. Amer. Fl. 17:320. 1931. Figure 197.

Perennial, caespitose from a hard, knotty crown or short rhizomes; culms 30-120 cm.
long, erect or sometimes decumbent and even rooting at lower nodes, branching from
lower and middle nodes; culms 2 mm. thick, hollow, glabrous; ligule a ring of stiff hairs,
less than 1 mm. long; blades flat, up to 25 cm. long, 2-10 mm. wide, glabrous or with a

FIG. 197. Setaria geniculata. A, panicle; B, rhizomatous base; C, spikelet with fascicle
of sterile branches.

526 FIELDIANA: BOTANY

few long hairs on the upper surface at the base. Peduncle glabrous, scabrid and grooved
at the tip, 5-32 cm. long; inflorescence a dense, spikelike panicle, 1-8 cm. long, up to 2.5
cm. thick, including the yellow or bronzy bristles; bristles clustered, 4-12 below each
spikelet, antrorsely scabrous, 2-15 mm. long; rachis minutely pubescent; spikelets soli-
tary or often 2 together on a short branchlet. Spikelets elliptical, 2.0-2.8 mm. long, color
greenish or often purple at the tip or overall; first glume deltoid, 0.8-1.0 mm. long,
3-4-nerved; second glume 1.1-1.4 mm. long, 5-nerved, much shorter than the fertile
lemma; lower (sterile) lemma about as long as the spikelet, usually herbaceous, 5-7-
nerved, sometimes grooved along the midrib and somewhat coriaceous and slightly
rugose, its palea about as long as the lemma; anthers 3, purple, 0.6-0.8 mm. long; upper
(fertile) floret rigid, ovate 2:1, the lemma strongly convex, strongly rugose, often purple
at the acute tip; palea equal, rugose, concave, the keels forming prominent ridges, the
marginal flanges wide, enwrapping the base of the caryopsis; anthers 3, purple; caryop-
sis elliptical 3:2, whitish, the embryo over half the length. Chromosome number n = 18
from Costa Rican specimens. Other chromosome counts of n = 36 are known from
elsewhere.

Widespread and common, from sea level to 1,800 m. elevation; road-
sides, lawns and pastures, grassy wet pond margins, savannas. Proba-
bly blooming yearlong, but with a flowering peak in the rainy season.
Widespread in the western hemisphere, from about 40 degrees N lat.
in the United States to Argentina.

This species displays a bewildering variety of aspects, depending
particularly on the length and color of the bristles and the color of the
spikelets. Rominger (1962) has discussed this variation and concluded
that no clearly separable entities are to be found in the complex.
Hitchcock (1931) gives a voluminous synonymy. The status of the name
is somewhat questionable, since Beauvois (1812) in describing the
genus Setaria, did not indicate that the species was based on Panicum
geniculatum of Lamarck. Later authors have made the assumption
that it was so based. If one rejects this assumption, then the name
should be cited as Setaria geniculata Beauv.

Setaria liebmannii Fourn., Mex. PI. 2:44. 1881.

Caespitose annual; culms 30-120 cm. long, erect or the bases decumbent and rooting
from the lower nodes, unbranched, or sometimes much branched from the lower nodes;
culms up to 3.5 mm. thick, hollow, thin-walled, glabrous; nodes sparsely appressed
bearded, or the upper glabrous; leaf sheaths glabrous except for the minutely bearded
overlapping margin; collar short-hispid; ligule a dense row of silky white hairs, 1.5-2.0
mm. long; leaf blades flat, lax, 5-25 cm. long, 4-24 mm. wide, scabrous on the surfaces;
margins with a cartilaginous white band. Peduncle exserted, glabrous, scabrous near the
apex; inflorescence solitary, terminal on the main culm or on leafy branches, cylindrical,
tapering to base and apex, 5-20 cm. long, 2-3.5 cm. wide, including the greenish yellow
bristles; with short, ascending branches up to 2 cm. long; rachis scabrous, somewhat
exposed between branches; spikelets racemose along the branches, up to about 10 per
branch, some of them abortive, each accompanied by a single antrorsely scabrous bris-
tle, these 7-17 mm. long. Spikelets ovate 5:3, glabrous, 2.3-2.7 mm. long; first glume
deltoid, 3-nerved, 0.8-1.0 mm. long; second glume ovate, 1.9-2.2 mm. long, with 5 main

BURGER: FLORA COSTARICENSIS 527

nerves and 2 inconspicuous lateral ones; lower (sterile) lemma as long as the spikelet,
2.3-2.7 mm. long, with 5 main nerves and 2 inconspicuous lateral ones; palea and flower
lacking; upper (fertile) floret 2.0-2.3 mm. long, ovate 5:3, lemma blunt-apiculate, rigid,
the middle third of the length strongly rugose with ca. 10 coarse transverse ridges; palea
rugose, as long as the lemma, with strongly ridged keels; lodicules 2, truncate; stamens
3, the anthers 1.2-1.3 mm. long, orange. Chromosome numbern = 9 from a Costa Rican
specimen.

Rare; low elevations, on sea cliffs and savannas; known from Playas
del Coco, Mata de Limon, and Finca la Pacifica. July and August.
Southern Arizona to Costa Rica, mostly on the Pacific slope.

Setaria magna Griseb., Fl. Brit. W. Ind. 554. 1864.

Tall, robust annual; culms up to 4 m. tall and 2 cm. thick, hollow, glabrous; leaf sheaths
shorter than the internodes, keeled, glabrous, the overlapping margin short-ciliate;
ligule an inverted V-shaped line, a short membrane bearing a dense row of stiff white
hairs, in total up to 3.5 mm. long; blades flat, scabrous, up to 50 cm. long and 35 mm.
wide. Peduncle exserted, scabrous; inflorescence dense, cylindrical, lobulate, 15-70 cm.
long, 3-5 cm. thick, including the bristles; rachis densely pilose; spikelets numerous,
borne on short overlapping lateral branches, each subtended by 1-3 antrorsely scabrous
bristles. Spikelets 2.0-2.3 mm. long, elliptical or obovate 2:1, disarticulating below the
glumes but also freely above the sterile lemma, the mature fertile floret dropping; first
glume broadly deltoid, 3-nerved, 0.8-1.0 mm. long; second glume slightly shorter than
the spikelet, 1.8-2.2 mm. long, 7-nerved; lower lemma as long as the spikelet, 5-7-
nerved, with a well-developed palea of equal length, frequently containing a flower and
developing a naked caryopsis; upper (fertile) floret elliptical 2:1, 1.8 mm. long, the lemma
smooth and shining, not rugose, minutely longitudinally striate, faintly 5-nerved, the
margins barely covering the edges of the flat palea; caryopsis rotund, 1 mm. long,
whitish; anthers 0.5 mm. long.

This very tall species is found mostly in salt marshes of the Atlantic
and Gulf Coasts of the United States and in the Greater Antilles. It has
also been collected in the Yucatan. The only Costa Rican collection is
Pittier 6825, collected in March 1892, which carries labels indicating
that it is from Boca Zacate or Punta Mala. These two localities are over
15 km. apart. It may be that this species was introduced by accident,
and it probably does not currently occur in Costa Rica.

Setaria paniculifera (Steud.) Fourn., Mex. PI. 2:42. 1881. Panicum
paniculiferum Steud., Syn. PI. Glum. 1:54. 1853.

Perennial in large clumps or colonies; culms 1-4 m. tall, unbranched, erect or the bases
decumbent; internodes compressed, up to 7 mm. thick, hollow, thick-walled, glabrous or
slightly appressed-hispid below the nodes; nodes glabrous or appressed-hispid; leaf
sheaths overlapping, keeled, more or less papillose-hispid, especially on the overlapping
margin; collar bearing an external ligule of stiff, glassy hispid hairs, up to 2 mm. long;
internal ligule a minute membrane tipped with a dense row of short hairs, up to 2 mm.
long, sometimes with longer hairs on the upper blade surface adjacent to it; leaf blades
strongly plicate, narrowly ovate, tapering to a petiole-like base and an acute tip; nerves
diverging from the midrib; length up to 60 cm.; width to 10 cm.; surfaces scaberulous and

528 FIELDIANA: BOTANY

with scattered glassy hispid hairs. Peduncle exserted, ridged, bearded at the apex;
inflorescence a large open terminal panicle with diverging or drooping branches; rachis
and branches angular, scabrous; length up to 60 cm.; lower branches 15-35 cm. long,
usually one to several long ones borne together with several short basal branches;
spikelets borne racemosely along the primary branches or along short secondary
branches; some of the spikelets, especially terminal ones, accompanied by slender, flexu-
ous, antrorsely scabrous sterile branches, these up to 18 mm. long; pedicels 0.2-2.0 mm.
long, appressed to the branches. Spikelets ovate 3.5:1, acuminate, glabrous, 3.2-3.8 mm.
long; first glume 1.8-2.0 mm. long, ovate, acute, 3(4)-nerved; second glume ovate, acute,
5-nerved, 2.4-2.7 mm. long, shorter than the fertile lemma; lower (sterile) floret with an
ovate, 5-nerved lemma 3.1-3.5 mm. long, equalling the fertile floret; palea absent or if
present, 1.2-2.6 mm. long; no flower present; upper (fertile) lemma ovate, 3:1, acumi-
nate, stiff, faintly 5-nerved, slightly rugulose on the back; palea equal to the lemma;
lodicules 2, truncate; anthers 3, yellow or orange, 1.0-1.5 mm. long; caryopsis elliptical
2.5:1, white, flattened. Chromosome number n = 17 from Costa Rican specimens.

Occasional; riverbanks, moist open areas, roadsides, forest margins;
from sea level to 800 m. elevation, on both Caribbean and Pacific
slopes. Probably blooming yearlong. Southern Mexico to Panama,
Colombia, and Venezuela; Caribbean Islands.

The plants are very conspicuous because of their large, corrugated
leaf blades. The only similar grass in Central America is S. poiretiana.

Setaria poiretiana (Schult.) Kunth, Rev. Gram. 47. 1829. Panicum
poiretianum Schult. in R. & S., Syst. Veg. Mant. 2:229. 1824. Figure
198.

Caespitose perennial; culms 1-3 m. tall, unbranched; internodes compressed, solid,
3.5-4.5 mm. thick, glabrous or hispid below the nodes; nodes appressed-hispid; sheaths
mostly overlapping, keeled, papillose-hispid with stiff, glassy hairs; collar hispid; ligule a
short thick membrane, crowned with a dense fringe of hispid hairs, in total 1.5-3.0 mm.
long; blades elliptical, up to 70 cm. long, 3-5 cm. wide at the middle, strongly plicate, the
nerves diverging from the midrib; base narrow, petiole-like, up to 10 cm. long; apex
long-caudate; surfaces sparsely hispid, scabrous near the tip. Peduncle exserted,
grooved, hispid-bearded at the apex; inflorescence a solitary, terminal, narrowly cylin-
drical panicle, tapering to a narrow apex, 35-70 cm. long, 7-15 cm. wide near the base;
rachis grooved, scabrous; branches mostly ascending or the lowermost drooping; lower
branches 5-8 cm. long, borne in remote partial verticels, spikelet-bearing to their bases;
rachis plainly exposed between adjacent verticels; upper branches shorter and more or
less overlapping and concealing the rachis; spikelets secund, very shortly pedicellate
along the primary branches or on short secondary branches; pedicels 0.2-0.5 mm. long;
some of the spikelets, especially the terminal ones, subtended by solitary slender, flexu-
ous bristles, these antrorsely scabrous and 10-15 mm. long. Spikelets 3.0-3.7 mm. long,
ovate 3:1; first glume ovate, blunt, 3-nerved, 1.7-1.8 mm. long; second glume ovate,
blunt, 5-8-nerved, 2.0-2.4 mm. long, reaching about to the middle of the fertile lemma;
lower (sterile) lemma 3.0-3.5 mm. long, slightly shorter than the tip of the fertile lemma,
membranaceous, 5-nerved; palea absent or oblong, up to 2.5 mm. long; upper (fertile)
floret ovate, acuminate, 2.9-3.5 mm. long; lemma stiff, very faintly rugulose, acuminate,
faintly 5-nerved, the palea as long and similar in texture; lodicules 2, truncate; anthers 3,
yellow to orange, 1.4-2.0 mm. long; caryopsis elliptical 2:1, 2 mm. long, brownish; em-
bryo ca. half the length.

FIG. 198. Setaria poiretiana. A, panicle; B, leafy culm with plicate leaf blades; C,
branchlet with spikelets and sterile branches (bristles).

530 FIELDIANA: BOTANY

This species is known from Central America only by the following
specimen: Cartago, 3 km. S of Tres Rios, along sewerage ditch in
cafetal, 1,300 m., Pohl 12782, 2 April 1972. Southern Mexico; northern
South America to Argentina; Caribbean Islands.

This species bears a strong resemblance to S. paniculifera, differing
in the much narrower panicle and more caudate leaves. Previous
descriptions indicate that the sterile lemma lacks a palea or has a
rudimentary one. Our specimen has a well-developed palea, but is
otherwise very similar to Pringle 3921 from Mexico cited by Rominger
as belonging to this species.

Setaria scandens Schrad., in Roem. & Schult., Syst. Veg. Mant.
2:279. 1824.

Caespitose annual; culms 20-80 cm. tall, erect, branching from the base and lower
nodes; prophylla prominent, 2-3 cm. long; internodes hollow, thin-walled, glabrous;
nodes glabrous or bearded below the edge of the sheath; leaf sheaths keeled, shorter
than the internodes, more or less papillose-pilose, especially along the margins; upper
sheaths mostly glabrous; ligule a dense row of hairs, 0.5-1.0 mm. long; blades flat, thin,
5-16 cm. long, 7-16 mm. wide, widest at the middle, tapering to a narrow base. Pedun-
cles slender, papillose-pilose or glabrous, up to 15 cm. long; inflorescence terminal on the
main culm or on leafy branches; panicles narrowly cylindrical, dense, 3-6 cm. long, less
than 1 cm. thick, including the bristles; rachis scabrous and with scattered long pilose
hairs that protrude between the spikelets; branches very short, few-flowered; 1-3 stiff,
undulate bristles borne below each spikelet; bristles 3-5 mm. long, strongly antrorsely
scabrous except at the tip, where a few retrorse barbs occur. Spikelets very strongly
plano-convex, the depth about equal to the width, 1.5-1.8 mm. long; first glume broadly
deltoid, faintly 3-nerved; second glume broadly ovate, 1.4-1.7 mm. long, 5-nerved,
shorter than the fertile lemma; lower (sterile) lemma 1.5-1.8 mm. long, equalling the
fertile floret, 5-nerved, its palea a narrow, nerveless scale one-third to one-half as long as
the lemma; upper (fertile) lemma 1.3-1.6 mm. long, rigid, strongly rugose except near
the tip, strongly boat-shaped, the depth equalling the width; palea equal to the lemma,
rigid, longitudinally striate; anthers tan, 0.5 mm. long.

Rare or overlooked; San Juan (Tibas), Las Juntas. August to
November. Southern Mexico to Panama; Caribbean Islands; South
America to Paraguay.

This species is similar in general aspect to the temperate zone S.
viridis (L.) Beauv., from which it differs in bristle number and the
retrorse terminal barbs.

Setaria tenacissima Schrad., in Roem. & Schult., Syst. Veg. Mant.
2:279. 1824. Figure 199.

Annual, caespitose, 1-2 m. tall, the culms unbranched or branching from lower nodes;
culms 2-3 mm. thick, hollow, glabrous; nodes glabrous; sheaths glabrous, keeled, rather
loose; ligule a dense ring of stiff white hairs, ca. 1 mm. long; blades flat, 10-22 cm. long,
4-13 mm. wide, pilose on both sides. Inflorescence solitary, terminal, the peduncle ex-

FIG. 199. Setaria species. S. tenax: A, panicle; B, spikelet; S. tenacissima: C, panicle;
D, two views of a spikelet; S. vulpiseta: E, panicle; F, spikelet.

531

532 FIELDIANA: BOTANY

serted, glabrous, grooved, scabrous at the apex; panicle cylindrical, rather stiff, 5-20 cm.
long, 1-3 cm. wide, including the stiff bristles; branches 3-5 mm. long, bearing several
spikelets; bristles 10-17 mm. long, stiff, the lower half upwardly barbed, the apical half
retrorsely barbed. Spikelets elliptical 5:3, strongly plano-convex, becoming purple when
mature, 1.4-1.6 mm. long; first glume broadly ovate, blunt, 3-nerved, ca. 0.7 mm. long;
second glume slightly shorter than the spikelet, 5-nerved, exposing the back of the
fertile lemma only at the tip; lower (sterile) lemma as long as the spikelet, 5-nerved,
lacking palea or flower; upper (fertile) floret slightly shorter than the sterile lemma;
lemma very strongly convex, its stramineous surface rugose with numerous fine trans-
verse ridges on the lower two-thirds; palea flat, similar in texture; anthers 3; caryopsis
elliptical 4:3, whitish, strongly plano-convex.

Rare or overlooked in Costa Rica; in brush. Blooming December to
February. Elevations 800-1,200 m. Canas Gordas, San Ramon,
La Guacima, Rio Tiliri. Guatemala to Brazil and Bolivia; Caribbean
Islands.

Setaria tenax (L. Rich.) Desv., Opusc. 78. 1831. Panicum tenax L.
Richard, Actes Soc. Hist. Nat. Paris 1:106. 1792. Figure 199.

Caespitose perennial, forming hard, knotty crowns; culms 50-200 cm. tall, erect,
branching from the base; internodes 2-3 mm. thick, hollow but thick-walled, glabrous;
nodes narrow, impressed; sheaths usually longer than the internodes, keeled toward the
apex, glabrous or pilose, the overlapping edge ciliate; collar appressed-hispid; ligule a
short membrane, long-ciliate with a dense row of stiff hairs, in total 0.7-3.0 mm. long;
blades flat, narrow at the base, up to 32 cm. long, 7-22 mm. wide, scabrous or pilose.
Peduncle sparsely pilose or glabrous, exserted; inflorescence solitary, terminal on the
culms, cylindrical, 5-20 cm. long, 2-3 cm. thick, including the flexuous bristles; rachis
densely pilose with spreading hairs; branches up to 6 mm. long, the spikelets densely
crowded, 5-10 per branch; bristles up to 15 mm. long, covered with intermixed retrorse
and antrorse barbs. Spikelets 2.3-2.6 mm. long, ovoid 3:2, very strongly convex on the
fertile lemma side, the sterile lemma side usually somewhat inflated as well; first glume
1.0-1.4 mm. long, broadly ovate, 3-5-nerved; second glume ca. half as long as the
spikelet, 1.5-1.8 mm. long, 7-9-nerved, ovate, blunt, exposing much of the back of the
fertile lemma; lower floret sterile, the lemma nearly as long as the spikelet, 2.1-2.4 mm.
long, ovate, nerves 5 or 5 plus 2 weak lateral ones; palea as long as the lemma; upper
(fertile) floret 2.2-2.4 mm. long, lemma elliptical 3:2, nerves 5, faint, tip mucronate;
lower two-thirds of lemma transversely rugose; palea equal to the lemma, rugose;
lodicules 2, truncate; anthers 3, dark, 0.6-1.2 mm. long; caryopsis rotund 7:6, white,
strongly plano-convex.

Occasional at altitudes up to 280 m. in Guanacaste; roadsides, river
banks, or in brush. July to August. Southern Mexico to Paraguay and
Argentina; West Indies.

Setaria vulpiseta (Lam.) Roem. & Schult., Syst. Veg. 2:495. 1817.
Panicum vulpisetum Lamarck, Encycl. Meth. 4:735. 1798. Figure 199.

Caespitose perennial, the culms arising from hard crowns, up to 2 m. tall, erect,
branching from the base; internodes compressed, up to 6 mm. thick, hollow but thick-
walled, glabrous or slightly appressed-pilose below the narrow, impressed nodes; leaf
sheaths keeled, mostly longer than the internodes, more or less appressed-pilose, espe-
cially the overlapping margin; collar bearing an external ligule, composed of a short

BURGER: FLORA COSTARICENSIS 533

membrane bearing a dense ring of stiff hairs, in total ca. 3 mm. long; internal ligule
similar; leaf blades thin, flat, very narrow at the base, widened at the middle, scabrous,
especially toward the tip, up to 60 cm. long and 35 mm. wide. Inflorescences solitary,
terminal, borne on exserted peduncles; larger panicles 25-33 cm. long, cylindrical, rachis
densely pilose with spreading hairs, somewhat open, 4-6 cm. thick, including the yel-
lowish bristles, the branches ascending, up to 2.5 cm. long, bearing small clusters of
spikelets on secondary branches; bristles 10-15 mm. long, antrorsely scabrous, the tip
truncate. Spikelets 2.4-2.6 mm. long, ovate 5:3; first glume ovate, broad, 1.0-1.5 mm.
long, 3-5-nerved; second glume 1.9-2.0 mm. long, usually 7-nerved; lower floret sterile,
the lemma as long as the spikelet, bluntly mucronate, 5-nerved, containing a palea of
equal length; upper (fertile) floret 2.2-2.3 mm. long, ovate 5:3, the lemma strongly
rugose on the lower two-thirds, bluntly mucronate; lodicules 2, truncate; anthers 3,
brown, 0.7-1.0 mm. long; style branches naked below.

Roadsides and brushy areas at low elevations; occasional in the
southern General Valley, Turrubares, Colonia Carmona, Siquirres.
August to February. Southern Mexico to Panama, Venezuela, Peru,
and Argentina; Caribbean Islands.

SORGHASTRUM Nash

Perennial or annual grasses; inflorescence a terminal panicle of short rames, each
consisting of 1-several internodes, each node bearing a sessile, perfect-flowered spikelet
accompanied by a slender hairy pedicel and a similar hairy rachis internode; pedicellate
spikelet almost always absent, rarely a minute rudiment present; disarticulation at the
base of each internode, the spikelet, internode, and pedicel falling as a unit. Spikelets
dorsally compressed, ovate; callus blunt, bearded; glumes equal, coriaceous, entirely
covering and concealing the delicate florets; lower (sterile) lemma hyaline, nerveless,
ciliate on the upper margins; upper (fertile) lemma similar, bifid at the tip, the awn
arising between the ciliate teeth, its base forming the broad white midrib of the lemma;
lodicules 2, truncate or forked at the apex; anthers 3; stigmas 2, laterally exserted from
the spikelets; awn exserted from the glumes, twisted and geniculate.

Sorghastrum is similar to Sorghum in possessing a panicle of short
rames bearing awned sessile spikelets, but differs in lacking staminate
pedicellate spikelets, the pedicels being naked at the tip or rarely with
a minute rudiment. About 20 species in warm climates of the Americas
and Africa. (Panicoideae: Andropogoneae.)

KEY TO SPECIES OF Sorghastrum

la. Awns very conspicuous, 2-4 cm. long; weak caespitose or sprawling annual

S. incompletum

Ib. Awns not conspicuous, less than 1 cm. long, usually exserted less than length of
spikelet; tall perennial in dense tufts S. setosum

Sorghastrum incompletum (Presl) Nash, N. Amer. Fl. 17:130.
1912. Andropogon incompletus Presl, Rel. Haenk. 1:342. 1830. Figure
200.

Tufted annual, 25-90 cm. tall, the plants erect, or sprawling and rooting at lower

FIG. 200. Sorghastrum species. S. incompletum: A, inflorescence; B, spikelets with
sterile pedicels and rachis internodes; S. setosum: C, rame with two spikelets.

534

BURGER: FLORA COSTARICENSIS 535

nodes, branching freely from the base and lower nodes; culm internodes glabrous, solid
and pithy or hollow; nodes contracted, slightly appressed-hispid; sheaths glabrous or
occasionally papillose-hispid; ligule a stiff brown membrane, 0.5-1.7 mm. long; leaf blades
up to 28 cm. long, 8 mm. wide, rounded abruptly to a narrow base. Peduncle included or
exserted up to 10 cm.; inflorescence solitary, terminal, cylindrical, loose to usually com-
pact, 5-15 cm. long, diameter 2-3 cm., the awns very conspicuous; branches thin and
delicate, flexuous, usually glabrous except at the base of the rames, which consist of 1-3
internodes, each bearing a sessile spikelet; internodes of the rachis and pedicels slender,
two-thirds as long as the spikelet, heavily bearded with stiff white hairs. Spikelets
dorsally compressed, ovate 4:1; callus blunt, bearded with white hairs; first glume flat on
the back, 5-7-nerved, more or less hispid, the margins narrowly incurved over the edges
of the second, tip narrowly truncate, ciliolate; second glume convex on the back, slightly
keeled, glabrous, 3-nerved, slightly longer than the first glume; lower (sterile) lemma
thin and membranaceous, nerveless, oblong, truncate, 2.5-3.0 mm. long, the upper
margins ciliate; upper (fertile) lemma membranaceous, very narrow, forming a narrow
margin along the sides of the flattened awn-base, the tip 2-lobed, ciliate; anthers 3,
1.0-1.3 mm. long, brown. Pedicellate spikelets are usually lacking, but rarely a minute
rudimentary one occurs. Chromosome number n = 10 from a Costa Rican specimen; n =
20 reported from Venezuela.

Open savannas at low elevations, 100-380 m. elevation. Liberia area,
Nicoya, Boruca. December to January. Mexico to Venezuela and
Colombia; Africa.

Sorghastrum setosum (Griseb.) Hitchc., Contr. U.S. Natl. Herb.
12:195. 1909. Andropogon setosus Griseb., Cat. PI. Cuba 235. 1866.
Figure 200.

Perennial; caespitose in large, dense clumps; culms 1-2 m. tall, unbranched, glabrous,
solid or with a small lumen, up to 3 mm. thick; nodes not prominent, appressed-bearded
with short erect white hairs; internodes elongated; sheaths glabrous; ligule a stiff brown
membrane, 1.5-3.5 mm. long, its margin adnate to the sheath apex; leaf blades up to 50
cm. long, 5-7 mm. wide, widest at the middle, tapering to a narrow base; uppermost
blades much reduced. Peduncle included in the uppermost sheath or exserted up to 15
cm., glabrous; inflorescence a solitary terminal panicle of rames, narrowly cylindrical,
loose or rather dense, 20-32 cm. long; branches thin and delicate, ascending. Rames of
2-6 internodes and spikelets; internodes and sterile pedicels ca. two-thirds as long as the
spikelets, heavily bearded with spreading stiff white hairs. Spikelets all alike, 3.5-5.6
mm. long, sessile, ovate 4-5:1, acute, the callus blunt, bearded; glumes golden brown,
the first sparsely to densely bearded with stiff, spreading white hairs, flat on the back,
7-9-nerved, its margins incurved and covering the edges of the second glume; second
glume as long as the first, convex, slightly keeled, glabrous, 5-nerved; lower (sterile)
lemma 3.0-4.2 mm. long, oblong, with a slightly bifid tip, hyaline, nerveless, its upper
margins ciliate; upper (fertile) lemma 2.7-4.0 mm. long, narrowly triangular, its upper
margins ciliate, bifid at the tip into 2 triangular lobes, the awn arising between them;
awn twisted and geniculate, exserted about the length of the spikelet, or very short and
not twisted; lodicules 2, truncate or slightly lobed at the tip; anthers 3, yellow, ca. 2.5
mm. long. Chromosome number n = 10 from the Costa Rican specimen.

Known in Costa Rica only by the following specimen: Guanacaste,
Hacienda Murcielago Road at CIA, elevation 300 m. Pohl & Erickson

536 FIELDIANA: BOTANY

12650, 26 July 1971. Open marshy areas. Southern Mexico to Hon-
duras, southern Nicaragua and northwestern Costa Rica; Venezuela to
Argentina; West Indies.

This species is similar to the common S. nutans (L.) Nash of tem-
perate North America, but differs in the smaller spikelets, weaker
awns, and apparently different chromosome number. Our specimen is
a close match for material distributed by the U.S. National Herbarium
as S. agrostoides (Speg.) Hitchc., Amer. Grasses Natl. Herb. 278.

SORGHUM Moench

REFERENCE: J. D. Snowden, The cultivated races of Sorghum, Ad-
lard. London. 274 pp. 1936.

Plants annual or perennial, caespitose or rhizomatous; inflorescence a much-branched
terminal panicle of short rames, these consisting of several internodes, each bearing a
pair consisting of a sessile, perfect-flowered, usually awned fertile spikelet, accompanied
by an awnless staminate or sterile pedicellate one; terminal segment of each rame
bearing a single sessile spikelet accompanied by 2 pedicellate ones; rachis disarticulating
at the base of each internode, the sessile and pedicellate spikelets falling as a unit with
the rachis internode and pedicel, or the pedicellate spikelet deciduous. Sessile spikelets:
Dorsally compressed; glumes stiff and rigid, ovate, entirely enclosing and concealing the
delicate florets (except in strains cultivated for grain); first glume flat or slightly convex,
many-nerved, its margins slightly inflexed over the edges of the second; second glume
similar, convex or keeled, several-nerved; lower (sterile) lemma thin, hyaline, nerveless,
ciliate, longer than the second; upper (fertile) lemma hyaline, nerveless, the apex
strongly 2-lobed, the awn arising between the ciliate lobes, not continued to the base of
the lemma; palea minute or lacking; lodicules 2, thick and fleshy, broadly truncate, the
apex ciliate; anthers 3; styles 2, the plumose stigmas laterally exserted from the
spikelets; caryopsis broadly elliptical or subspherical, in cultivated grain strains bursting
from the glumes. Pedicellate spikelets: Soft-textured; glumes ca. equal in length, the
first flat on the back with submarginal narrow keels, 5-7-nerved; second glume boat-
shaped, usually 5-nerved, its margins incurved, ciliate near the apex; sterile lemma
hyaline, faintly nerved or nerveless, the upper margins inflexed, ciliate; fertile lemma
shorter than the sterile one, ciliate, awnless; lodicules 2, broadly truncate, the apex
ciliate; flower staminate or absent; anthers 3; ovary absent; palea absent or minute.

Sorghum is native to the Old World, presumably originating in Af-
rica, but widely distributed in warm climates of the eastern hemi-
sphere. The genus has ca. 50 species, but numerous hybrid forms are
in cultivation. In the western hemisphere, the genus is represented by
numerous cultigens and several weedy rhizomatous perennials. The
genus is closely related to the American genus Sorghastrum, from
which it differs in having rames that possess well-developed, usually
staminate, pedicellate spikelets. (Panicoideae: Andropogoneae.)

KEY TO SPECIES OF Sorghum
la. Tall, slender, strongly rhizomatous perennial; caryopsis remaining concealed within

BURGER: FLORA COSTARICENSIS 537

glumes; occasional weed S. halepense

Ib. Coarse, maizelike plants; annuals; rhizomes absent; caryopsis large, subspherical in
some strains and bursting from glumes S. tricolor

Sorghum bicolor(L.) Moench, Meth. PL 1:207. 1794. Holcus bicolor
L., Mant. Alt. 301. 1771. Sorghum wtlgare Pers., Syn. PL 1:101. 1805.

This species is here construed to include all of the common cultivated annual sor-
ghums, with the exclusion of Sudan grass. The plants are so variable as to preclude
writing a botanical description to include all of them. Usually the plants have thick,
maizelike stems, and in vegetative condition, much resemble maize seedlings. The culms
are usually thick and maizelike, and the leaf blades are very wide and resemble those of
maize. Plant height is extremely variable, some dwarf grain strains being only 1 m. tall,
whereas tall forage strains may be as much as 5 m. tall. The inflorescences vary from
very dense in some grain strains to very loose and lax. Spikelet color varies from
stramineous to red, deep purple, or black. In some strains, the grains are small and
contained within the glumes, whereas in grain strains, the caryopses may burst the
glumes open. In general, the spikelets do not disarticulate spontaneously, remaining on
the inflorescence until threshed. Africa, but now cultivated in all warmer and drier parts
of the world. Chromosome number n = 10.

The following general groups of sorghums may be recognized, al-
though modern plant breeding has combined traits of many of these:

1. Grain sorghums. These have enlarged caryopses and are culti-
vated as a substitute for maize, especially in dry climates. Some
modern strains are dwarf and suited for mechanical harvesting of
the grain.

2. Sweet sorghums. The stems are juicy and sweet, and are fed to
livestock or are crushed for syrup. The grain is usually inferior.

3. Broomcorn. In this strain, the main axis of the panicle is very
short, and the lateral branches slender and elongated. The dried
panicles are used in the manufacture of brooms and brushes, and
plants are often seen growing around houses.

Sorghum halepense (L.) Pers. Syn. PL 1:101. 1805. Holcus
halepensis L., Sp. PL 2:1047. 1753. Figure 201.

Tall erect perennial; culms erect, arising from extensive scaly rhizomes; culms un-
branched, to 2 m. tall, glabrous, solid, the interior pithy; nodes constricted, appressed-
hispid; sheaths shorter than the internodes, glabrous or often pubescent on the collar;
ligule a stiff membrane, 3-6 mm. long, appressed-pubescent on the back and ciliate at the
apex; leaf blades flat, narrow at the base, widest at the middle, up to 66 cm. long and 3.5
cm. wide; midrib broad, white; edges of blades not scabrous. Peduncle exserted up to 20
cm., glabrous; inflorescence solitary, terminal, narrowly pyramidal, open, up to 40 cm.
long, usually ca. one-third as wide; branches whorled, ascending, up to 13 cm. long,
naked near the base, the pulvini pubescent; spikelets borne in short rames of 1-5 pairs,
mostly on second-order branches, appressed to the branches; internodes and pedicels ca.
one-half as long as the sessile spikelets, flattened and ciliate; disarticulation at the base
of each internode and at the apex of the pedicels, the summits of the internodes and
pedicels cup-shaped. Sessile spikelets: Ovate 2:1, 4-6 mm. long, acute, stramineous, more

FIG. 201. Sorghum halepense. Inflorescence, rhizomatous base, two views of a
spikelet pair, showing sessile and pedicellate spikelets.

BURGER: FLORA COSTARICENSIS 539

or less appressed-hispid; glumes stiff and rigid; first glume slightly convex, faintly 9-
nerved, the margins narrowly inflexed over the edges of the second; second glume
boat-shaped, faintly 5-7-nerved, its margins ciliate above; lower (sterile) lemma hyaline,
narrowly ovate, faintly nerved, 3.8-4.5 mm. long, its margins ciliate; upper (fertile)
lemma ovate, 2-lobed, ciliate, the awn absent or up to 1.5 cm. long, twisted and genicu-
late, arising between the lobes; palea absent or a minute nerveless ciliate scale; lodicules
2, truncate, ciliate; anthers 3, yellow, 2.0-2.6 mm. long; stigmas purple. Pedicellate
spikelets: 4.0-5.7 mm. long, texture herbaceous; first glume flattened, ovate 2.5:1, acute,
6-9-nerved; second glume boat-shaped, 5-7-nerved; lower lemma 3.8-4.5 mm. long, nar-
rowly ovate, hyaline, faintly nerved; upper (fertile) lemma 2.5-3.5 mm. long, awnless;
palea absent; anthers 3, yellow, 2.0-2.5 mm. long. Chromosome number n = 20.

Rare or occasional in Costa Rica; Nicoya, Siquirres, Limon, Las
Concavas, San Jose. May to November. Johnson grass, which is a bad
weed in warm temperate climates, seems to barely maintain itself in
Costa Rica. The earliest collection was an 1895 Pittier specimen from
Siquirres. In 1908, it occurred in the cemetery at Guadelupe and was
brought from there to an experimental field. It now occurs as a casual
weed on the campus of the university, but does not appear to be
particularly aggressive. This species originated in the Old World, pos-
sibly in the Mediterranean area, but is now widespread in warm cli-
mates of the world. Common names: Zacate de Johnson, "Johnson
grass."

Awns of the sessile spikelets are very easily deciduous, and many
spikelets of a panicle may lack them at maturity. In other plants, none
are apparently produced.

Sorghum sudanense (Piper) Stapf, commonly known as "Sudan
grass," is a caespitose annual closely resembling S. halepense. It lacks
rhizomes, and the rachis internodes and pedicels break irregularly,
leaving jagged ends, rather than disarticulating regularly as in S.
halepense. Sudan grass may at times occur as a cultivated crop,
although I have never seen it in Costa Rica.

SPARTINA Schreber

Perennial, usually rhizomatous grasses; culms unbranched; inflorescence of 1-many
1-sided spikes. Spikelets flat, strongly laterally compressed and keeled, subsessile,
densely imbricated in 2 rows along the lower sides of the triquetrous rachis; disarticula-
tion below the glumes; glumes strongly keeled, longer or shorter than the single floret;
first glume 1-nerved, the second 1-3-nerved; lemma awnless, firm, 1-3-nerved; palea
about equalling the lemma, 2-nerved.

Spartina is a genus of ca. 17 species of perennial grasses, most of
them being native to salt marshes or less commonly to interior grass-
lands. The genus has been variously placed and has no obvious close
relatives. (Chloridoideae: Chlorideae.)

540 FIELDIANA: BOTANY

Spartinaspartinae(Trin.) Hitchc., Contr. U.S. Natl. Herb. 17:329.
1913. Vilfa spartinae Trin., Mem. Acad. Imp. Sci. St.-Petersbourg,
Ser. 6, Sci. Math, Seconde Pt. Sci. Nat. 4:82. 1840. Figure 202.

Perennial, forming dense hard clumps; culms up to 200 cm. tall, erect; rhizomes
absent; culms glabrous, solid, the interior filled with pith; sheaths glabrous, mostly
overlapping; ligule an arc of hairs, 1-2 mm. long; blades 12-125 cm. long, 1.5-4 mm. wide,
firm, involute, strongly ridged and scabrous above, scabrous on the margins, glabrous
below; inflorescence 6-70 cm. long, a terminal raceme of 6-75 one-sided spikes; individual
spikes 0.5-7 cm. long, stiff and erect. Spikelets 10-60 per spike, 4-10 mm. long; first
glume 2-8 mm. long, 1-nerved; second glume 4-8 mm. long, apparently 1-nerved, nar-
rowly lanceolate, scabrous on the keel; lemmas narrowly ovate, blunt-tipped or apicu-
late, scabrid on the keel, 5-6 mm. long; palea ca. equal to the lemma; anthers 3, yellow or
purple, 3-5 mm. long. Chromosome number n = 20 from Costa Rican fixations.

Rare, coral beaches around Limon, Uvita, Piuta. The clumps are
very firmly attached to the rock. Our specimens were collected in
September, but the blooming season may be much longer. Florida to
Texas, Mexico, British Honduras, Costa Rica; Paraguay and Argen-
tina.

Other recent reports indicate that the chromosome number of n = 20
is correct, although earlier investigations listed a basic chromosome
number of x = 7 for this genus.

SPOROBOLUS R. Brown

REFERENCES: W. D. Clayton, Studies in the Gramineae: VI.
Sporoboleae. The Sporobolus indicus complex, Kew Bull. 19:287-295.
1965. P. Jovet & M. Guedes, Le Sporobolus indicus (L.) R. Br. var.
fertilis (Steud.) Jov. et Gued. naturalise en France, avec une revue du
groupe du Sporobolus indicus dans le monde, Bull. Centr. fitudes
Rech. Sci. 7(l):47-75. 1968; and Validation of names in Sporobolus,
Taxon 22:163. 1973.

Annual or perennial caespitose or rhizomatous grasses. Inflorescence a panicle.
Spikelets small, 1-flowered; glumes equal or unequal, usually shorter than the floret,
1-nerved or nerveless; disarticulation above the glumes, or more commonly the spikelet
remaining intact, the seed being extruded from the split ovary wall; lemma awnless,
1-nerved; palea ca. equal to the lemma or slightly longer, often splitting between the
nerves when mature; mature ovary usually swelling and becoming gelatinous when
wetted, splitting and extruding the adhesive seed.

A large genus of temperate zone and tropical grasses of both eastern
and western hemispheres. The spikelets in this genus are similar to
those of Muhlenbergia, differing in the faintly nerved lemmas and total
absence of awns, as well as in the free pericarp of the grain.
(Chloridoideae: Sporoboleae.)

FIG. 202. Spartina spartinae. A, inflorescence; B, spikelet; C, caespitose culm base.

541

542 FIELDIANA: BOTANY

KEY TO SPECIES OF Sporobolus

la. Strongly rhizomatous plants; foliage harsh and wiry; beaches along the Caribbean

near Limon S. virginicus

Ib. Caespitose plants without rhizomes; foliage various; not confined to sea beaches . 2
2a. Panicle pyramidal or open-cylindrical, not more than 3 x longer than wide;

branches spreading, whorled, naked at bases 3

2b. Panicle narrowly cylindrical or spikelike, more than 5 x longer than wide;

branches erect and appressed, spikelet-bearing to their bases 4

3a. Spikelets more than 3 mm. long, purple; panicle open-cylindrical S. cubensis

3b. Spikelets less than 2 mm. long, grayish; panicle pyramidal S. pyramidatus

4a. Leaf blades conspicuously papillose-ciliate 5

4b. Leaf blades not papillose-ciliate 6

5a. Spikelets chestnut-brown, less than 2 mm. long S. ciliatus

5b. Spikelets leaden-gray, 2.9 mm. or more long S. purpurascens

6a. Spikelets less than 2 mm. long; culm internodes hollow; nodes less than 0.5 mm.

high; inflorescence lax; plants of low elevations S. jacquemontii

6b. Spikelets over 2 mm. long; culm internodes solid; nodes 1-2 mm. high; inflores-
cence dense and strict; plants of middle elevations S. indicus

Sporobolus ciliatus Presl, Rel. Haenk. 1:242. 1830. Figure 203.

Caespitose in small tufts, 10-35 cm. tall; apparently annual; culms erect, branching
from the base and lower nodes, glabrous, sometimes glandular-spotted near the nodes;
prophylla up to 20 mm. long; nodes glabrous, contracted; foliage mostly near the base of
the plants, the upper internodes much longer than the lower; sheaths mostly ca. as long
as the internodes, papillose-ciliate on the margins; ligule a minute ciliate fringe, ca. 0.3
mm. long; blades firm, flat, cordate-based, 1.5-6.5 cm. long, 2.0-4.5 mm. wide, conspicu-
ously papillose-ciliate on the margins, often with scattered papillose-based hairs on the
surfaces; uppermost blade usually much reduced. Peduncle exserted up to 3 cm.;
inflorescences solitary, terminal on the main culms or on leafy basal branches; panicles
slender, 2-9 cm. long, ca. 5 mm. wide, the erect verticillate branches less than 1 cm.
long, densely flowered to the base. Spikelets reddish brown, biconvex, 1.8-2.0 mm. long,
V-shaped and gaping when mature; first glume narrowly lanceolate or deltoid, 0.6-0.7
mm. long, nerveless or 1-nerved; second glume ovate, 1.6-1.7 mm. long, 1-nerved;
lemma ovate, 1-nerved, 1.7-1.9 mm. long; palea ca. equal to the lemma but much
broader, splitting between the nerves when mature, the caryopsis discharged between
the split halves; anthers yellow, 0.6-0.7 mm. long; grain oval, 1.0-1.2 mm. long, the
ovary wall gelatinizing when wet and discharging the elliptical laterally flattened white
seed. Chromosome number n = 27 from Costa Rican material.

Rare, hilly savannas at Boruca; collected in 1893 and again in 1968.
August to November. Honduras to Panama and Brazil.

Sporobolus cubensis Hitchc., Contr. U.S. Natl. Herb. 12:237. 1909.
Figure 203.

Perennial, in dense tufts; plants 50-70 cm. tall, erect; foliage aggregated at the base of
the plants; basal sheaths short, heavily pilose on the margins; basal blades very elon-
gated, up to 60 cm. long, 3-4 mm. wide, glabrous except for a few long hairs on the lower
margins; upper surface prominently ridged; blades usually folded or involute; culm

FIG. 203. Sporobolus species. 5. ciliatus: A, panicle; B, spikelet; S. cubensis: C,
panicle; D, spikelet.

543

544 FIELDIANA: BOTANY

blades much reduced. Inflorescence a solitary terminal panicle, 8-15 cm. long, 2-4 cm.
wide, the branches whorled or solitary, perpendicular to the rachis; spikelets borne near
the tips of the spreading branches and appressed to them, short-pedicellate. Spikelets
purplish, 3.1-4.0 mm. long; first glume ovate, acute, 1.6-2.2 mm. long, obscurely nerved;
second glume 3.2-3.9 mm. long, ovate, acute, faintly 1-nerved; floret 2.8-4.0 mm. long,
the lemma ovate, acute, rounded on the back, faintly 1-nerved; palea equal to the lemma
or slightly longer, faintly 2-nerved, often splitting between the nerves at maturity;
anthers 3, purplish, 2.0-2.4 mm. long; caryopsis ca. two-thirds as long as the spikelet,
obovate, rounded at the apex; ovary wall gelatinizing when wet.

This species has been collected only once in Costa Rica, from the
savannas of Canas Gordas at 1,100 m. elevation. February. Cuba and
Puerto Rico; northern South America; Belize and northeastern
Nicaragua.

Sporobolus indicus (L.) R. Br., Prodr. Fl. Nov. Holl. VI:170. 1810.
Agrostis indica L., Sp. PI. 63. 1753. Sporobolus poiretii (R. & S.)
Hitchc., Bartonia 14:32. 1932. Figure 204.

Perennial, in dense clumps; plants 55-95 cm. tall, erect; culms unbranched, 1.0-3.5
mm. thick, glabrous; nodes prominent, 1-2 mm. long; internodes solid, pithy; sheaths
glabrous except for the ciliolate upper margin; ligule a minute ciliolate fringe, 0.1-0.3
mm. long; blades glabrous, flat, 13-35 cm. long, 3-5 mm. wide. Peduncle exserted 1-16
cm.; inflorescence solitary, terminal, a dense spikelike cylindrical panicle, 15-33 cm.
long, 0.5-3.0 cm. thick (mostly less than 1 cm.); branches 1-4 cm. long, erect and ap-
pressed, densely covered with overlapping short-pedicellate spikelets. Spikelets
grayish, laterally compressed, 2.1-2.7 mm. long, usually not disarticulating, the seed at
maturity extruded from the gelatinizing caryopsis and emerging from the floret at its
apex; glumes unequal, the first a rounded nerveless scale, 0.5-1.0 mm. long, erose at the
apex, the second ovate, acute or rounded and erose at the apex, 0.9-1.5 mm. long, faintly
one-nerved; floret longer than the glumes, the lemma ovate, acute, faintly 1-nerved,
2.1-2.5 mm. long, glabrous; palea similar but slightly shorter, faintly 2-nerved, 1.9-2.2
mm. long, glabrous; anthers 3, white, 0.5-1. Omm. long; seed quadrate, truncate, brown,
glistening. Inflorescences frequently become smutted when the seeds are extruded.
Chromosome number n = 18 from a Central American specimen.

Common in open areas, roadsides, and pastures; middle elevations,
300-1,900 m., most common above 1,000 m. June to December; proba-
bly blooming yearlong. Southeastern United States to Ecuador and
Paraguay; West Indies.

This species and S. jacquemontii are very similar, but occupy dis-
tinct ecological niches. The taxonomy of the group is confused, and it is
unlikely that a final disposition of its members could be made without
intensive biosystematic study. The papers cited above, by Clayton
(1965) and Jovet and Guedes (1968), offer an introduction to the com-
plexities. Common name: Pitilla.

Sporobolus jacquemontii Kunth, Rev. Gram. 2:427, t. 127. 1831.
Vilfa jacquemontii (Kunth) Trin., Mem. Acad. Imp. Sci. St.-

FIG. 204. Sporobolus indicus. Panicle, blooming plant, spikelet, floret.

645

546 FIELDIANA: BOTANY

Petersbourg, Ser. 6, Sci. Math., Seconde Pt. Sci Nat. 4:92. 1840.
Sporobolus indicus Am. Auth., non Agrostis indica L.

Perennial, caespitose, often in large circular clumps; plants 40-110 cm. tall, erect;
culms unbranched, glabrous, 1-2 mm. thick; internodes hollow; nodes glabrous,
shrunken, narrow, less than 0.5 mm. high; sheaths glabrous except for the minutely
ciliolate upper margins, shorter than the internodes; ligule a minutely ciliolate fringe,
0.2-0.3 mm. long; blades glabrous, 12-30 (60) cm. long, 2-5 mm. wide, usually involute,
ridged above, tapering to long, fine flexuous points. Peduncle exserted 6-16 cm.; panicle
solitary, terminal, 13-25 cm. long, narrowly cylindrical but open, 1-3 cm. wide, the
branches ascending or somewhat spreading, the lower ones often 3-5 cm. long. Spikelets
grayish, rather densely clustered along the primary or short secondary branches,
short-pedicellate, laterally compressed, 1.5-1.8 mm. long, usually not disarticulating,
the seed at maturity extruding from the gelatinizing caryopsis and emerging from the
floret at its apex; glumes subequal, usually less than half as long as the spikelet, obovate,
blunt, erose, the first nerveless, 0.4-0.8 mm. long, the second faintly 1-nerved, 0.7-1.0
mm. long; floret 1.5-1.7 mm. long, glabrous, the lemma acute, faintly 1-nerved; palea ca.
equal to the lemma; anthers 3, white, or purple-tinged, 0.9-1.1 mm. long; caryopsis ca.
one-third shorter than the floret; seed quadrate, truncate at the apex, brown and glis-
tening. The inflorescences may become smutted when the seeds are extruded. Chromo-
some number n = 12 from a Costa Rican specimen.

Common at low elevations in Costa Rica, mostly under 100 m.;
beaches, pastures, roadsides, and open areas generally. June to Feb-
ruary, probably blooming yearlong. Southeastern United States and
the West Indies; Mexico to northern South America.

This species is very similar to the upland S. indicus, but occupies a
different habitat. See discussion of the two under S. indicus. Common
name: Pitilla.

Sporobolus purpurascens (Swartz) Hamil. , Prodr. PL Ind. Occ. 5.
1825. Agrostis purpurascens Swartz, Prodr. Veg. Ind. Occ. 25. 1788.

Caespitose; possibly perennial; plants 11-32 cm. tall, erect; culms branching from the
base only, hollow, ca. 1 mm. thick, glabrous; foliage mostly basal, the culms with 1-3
leaves, the uppermost blade much reduced; sheaths glabrous except for the ciliate mar-
gins, longer than the internodes; ligule a row of stiff hairs, 0.7-0.8 mm. long; blades flat,
firm, 4-19 cm. long, 3-5 mm. wide, broad-based, the margins conspicuously papillose-
hispid, sometimes with scattered papillose hairs above. Inflorescence solitary, terminal,
a narrow, spikelike panicle, 6-12 cm. long, less than 5 mm. thick; branches verticillate,
erect, short, less than 1 cm. long, overlapping; spikelets short-pedicellate, densely
covering the branches to their bases. Spikelets leaden-gray to purplish, terete, 2.9-3.3
mm. long; first glume 1-2 mm. long, lanceolate, faintly 1-nerved; second glume 2.7-3.3
mm. long, 1-nerved, lanceolate; lemma ovate, 2.7-2.9 mm. long, 1-nerved, glabrous;
palea equal in length to the lemma but broader, splitting between the nerves when
mature; anthers 3, cream-colored to purplish, 1.1-1.4 mm. long. Caryopsis flattened,
narrowly elliptical, 1.6-1.8 mm. long; ovary wall gelatinizing when wet. Chromosome
number n = 30 from Costa Rican material.

Rare, open roadsides, 1,000-1,500 m.; Meseta Central and Canton

BURGER: FLORA COSTARICENSIS 547

de Dota. September to October. Mexico to Brazil and Bolivia; West
Indies.

Sporobolus pyramidatus (Lam.) Hitchc., U.S.D.A. Misc. Publ.
243:84. 1936. Agrostis pyramidata Lam., Tabl. Encycl. 1:161. 1791.
Sporobolus argutus (Nees) Kunth, Rev. Gram. Suppl. XVII. 1829.
Vilfa arguta Nees, Agrost. Bras. 395. 1829.

Plant perennial, caespitose, spreading; culms 15-60 cm. long, branching only from the
base, glabrous, hollow, 1.0-1.5 mm. thick; sheaths longer or shorter than the internodes,
glabrous except for the ciliate upper margins; ligule a dense row of stiff white hairs,
0.5-0.8 mm. long; foliage mostly near the bases of the culms; blades flat, whitened, 4-19
cm. long, 2-4 mm. wide, pustulose-hispid on the margins near the base, occasionally with
scattered pustulose-based hairs on the upper surface; margins strongly scabrous.
Inflorescences solitary, terminal; panicle 3-13 cm. long, pyramidal, ca. 3 x longer than
wide; branches whorled, stiffly spreading, glabrous, the lower third to half naked; up to
11 branches in the lowermost whorl; spikelets appressed along the outer portions of the
branches. Spikelets grayish or silvery, rather translucent, laterally compressed, 1.6-1.8
mm. long; first glume 0.6-0.7 mm. long, subulate, 1-nerved; second glume 1.6-1.8 mm.
long, 1-nerved, lanceolate; lemma 1.5-1.7 mm. long, lanceolate, 1-nerved, glabrous;
palea ca. equal to the lemma but broader, splitting when mature between the nerves, the
seed discharged between the split halves; anthers 2, tan, 1.2 mm. long; grain 1. 1-1.2 mm.
long, oval, flattened, the pericarp readily splitting and discharging the brown seed when
wet. Chromosome numbers n = 12, 18 from Costa Rican specimens.

This species was collected once in Costa Rica from a salina at sea
level along the Bay of Nicoya at Colorado. January. Southwestern
United States to Argentina; West Indies.

Sporobolus virginicus (L.) Kunth, Rev. Gram. 1:67. 1829. Agrostis
virginica L., Sp. PL 63. 1753. Figure 205.

Vigorous perennial, spreading by extensive stiff, scaly rhizomes; culms 5-50 (85) cm.
long, erect, freely branching, 1-2 mm. thick, hollow, glabrous; internodes of lower half of
culms short, concealed by the overlapping sheaths of the numerous leaves; sheaths
glabrous except for the pilose upper margins; ligule a minute densely ciliate membrane,
0.2-0.4 mm. long; auricular hairs conspicuous, up to 3 mm. long; blades harsh, mostly
involute, ridged above and sometimes with scattered papillose hairs on the upper sur-
face, 3-14 cm. long, 2-5 mm. wide. Peduncle included or exserted up to 5 cm.; inflores-
cence terminal, a densely cylindrical panicle, 2-9 cm. long, 3-10 mm. thick; branches
short, erect, densely flowered to their bases; spikelets appressed to the branches,
densely overlapping; pedicels from very short to ca. as long as the spikelets. Spikelets
grayish or stramineous, glossy, laterally compressed, 2.0-3.3 mm. long; first glume
1-nerved, lanceolate, acuminate, 1.7-2.4 mm. long; second glume 1-nerved, ovate,
acuminate, 2.0-3.1 mm. long; lemma ovate, 1.9-2.5 mm. long, 1-nerved; palea equal to
the lemma, often splitting between the nerves; anthers tan or purplish, 1.1-1.4 mm. long;
caryopsis 0.9-1.2 mm. long; ovary wall gelatinizing but thin.

Occasional on coral or sandy beaches, Isla Uvita, Moin. June to
September, possibly yearlong. Southeastern United States to Peru
and Brazil; West Indies; tropics of the Old World.

FIG. 205. Sp&robolus virginictis. Blooming culms with rhizomatous

548

BURGER: FLORA COSTARICENSIS 549

Length and width of the leaf blades vary greatly. The Costa Rican
specimens have larger blades than most. Seed set is apparently low.

STENOTAPHRUM Trinius

REFERENCE: J. D. Sauer, Revision of Stenotaphrum (Gramineae:
Paniceae) with attention to its historical geography, Brittonia 24:202-
222. 1972.

Stoloniferous grasses; leaf sheaths flattened and keeled; leaves often subopposite by
suppression of internodes; inflorescence a terminal or axillary flattened corky spike,
bearing spikelet groups alternately in 2 rows along one side of the rachis, usually sunken
into hollows of the rachis, which falls intact from the plant or tardily disarticulates into
individual segments; spikelets solitary, paired, or in 3's, subsessile or one sessile and one
on a thick angular pedicel which is continued beyond the spikelet as a stiff angular beak
or bears a third spikelet. Spikelets disarticulating from the rachis or remaining on it,
lanceolate or ovate, acute, awnless, placed with the first glume away from the rachis;
first glume a short usually nerveless scale; second glume membranaceous, strongly
gibbous, as long as the lemma of the lower floret, ovate, acute, 5-7-nerved; lower lemma
firm, flat on the back and with inflexed margins, 3-5-nerved, acute; palea stiff, with
inflexed edges, ca. as long as the lemma; floret sterile, staminate, or perfect; upper floret
with a stiff, acute, gibbous, faintly 5-nerved lemma, its thin margins overlapping the
edges of the palea but not inrolled; palea indurate; flower perfect.

Stenotaphrum is a small genus of grasses of the tropics of the Old
World. (Panicoideae: Paniceae.)

Stenotaphrum secundatum (Walt.) 0. Kuntze, Rev. Gen. PL 2:794.
1891. (Given as S. secundum, sphalm. for secundatum). Ischaemum
secundatum Walt., Fl. Carol. 249. 1788. Figure 206.

Duration indefinite, the plants creeping extensively by stiff stolons; culms flattened,
glabrous, solid, pithy; branching abundant; prophylla prominent, lanceolate, 10-25 mm.
long; nodes of stolons prominent, usually with 2 subopposite leaves and 2 erect branches
at each node; erect flowering culms usually 10-25 cm. tall, leafy; sheaths strongly flat-
tened and keeled, much shorter than the internodes, glabrous except for short cilia at
the throat; ligule a very short membrane, strongly dilate, ca. 0.5 mm. long; blades flat,
glabrous, 5-20 cm. long, 5-11 mm. wide, the midrib keeled near the base; apex of blades
blunt, rounded or emarginate. Inflorescences terminal and from upper leaf axils, the
rachis thick, flattened, falcate, 3-4 mm. wide, 5-10 cm. long. Spikelets 3.5-5.2 mm. long;
first glume blunt and rounded, or a truncate collar, nerveless or rarely 3-nerved, 0.5-1.6
mm. long; second glume and lower lemma equal and as long as the spikelet; lower floret
sterile, staminate, or perfect-flowered; second floret perfect-flowered; some clones en-
tirely sterile; anthers 3, tan or purple, 2.0-2.5 mm. long. Chromosome number n = 9
from Costa Rican material.

Inner margins of sea beaches, Pacific Coast; occasional in the inte-
rior at low elevations, probably in cultivation. Blooming June to De-
cember, probably yearlong. Worldwide in warm climates; sometimes
cultivated as a coarse lawn grass. A striped-leaf form is sometimes
cultivated for ornament.

FIG. 206. Stenotaphrum secundatum. Blooming plant with stoloniferous base, two
views of a spikelet, fertile floret.

550

BURGER: FLORA COSTARICENSIS 551

Other chromosome counts are given by Sauer (1972).
STIPA Linnaeus

Perennial grasses; inflorescence a terminal panicle; spikelets 1-flowered, disarticulat-
ing above the glumes; glumes equal, longer than the floret, several-nerved; lemma hard,
cylindrical, convolute, the margins overlapping and concealing the palea; callus hard,
sharp, bearded; awn stiff, geniculate, attached at the tip of the lemma, the basal segment
usually strongly flattened and tightly twisted.

A large genus of about 250 species, in temperate regions of the
entire world; mostly alpine in the tropics. The genus is readily recog-
nized by the hard, cylindrical floret with a strong awn and exceedingly
sharp callus. The floret functions as a ratchet-drill device to cause
self-planting of the seed. The awns are hygroscopic and wind tighter
when dried and unwind when moistened. The genus is closely related
to Oryzopsis, with which it forms spontaneous hybrids. The limits of
these two genera and the related genera Piptochaetium and Nassella
are obscure, and many species have been transferred from one to
another by authors. (Pooideae: Stipeae.)

KEY TO SPECIES OF Stipa

la. Lemma with crown of long hairs, 2-5 mm. long, at apex; awn firmly attached to

lemma 2

Ib. Lemma lacking crown of long hairs at apex; awn readily detachable from mature

lemma See: Nassella linearifolia

2a. Plants 20-35 cm. tall; panicle stiff, narrow, 3-10 cm. long; palea as long as

lemma S. hans-meyeri

2b. Plants 50-115 cm. tall; panicle lax, 15-35 cm. long; palea less than half as long as
lemma S. icku

Stipa ichu (Ruiz & Pav.) Kunth, Rev. Gram. 1:60. 1829. Jarava ichu
Ruiz & Pav., Fl. Peruv. Chil. 1:5, pi. 6. 1798. Figure 207.

Perennial, in dense, hard tufts; culms erect, 50-115 cm. tall, unbranched, ca. 2 mm.
thick, hollow, thick-walled, minutely scabrid; nodes glabrous, not prominent; most leaf
blades in an erect basal tuft, stiff; culm leaf sheaths ca. half the length of the internode,
glabrous except for dilation on the margins and a few auricular hairs at the apex; firm
sheath auricles present; ligules 0.5 mm. long, membranaceous; blades 25-70 cm. long,
1.5-2 mm. wide, involute, strongly ridged above, scabrid beneath; peduncle minutely
puberulent or scabrid, included or exserted up to 10 cm. Panicle solitary, terminal,
narrowly cylindrical, 15-35 cm. long, 2-3 cm. wide, lax, nodding, silvery and plumy at
maturity; branches and pedicels scabrous. Spikelets very numerous, compactly ar-
ranged; glumes silvery, thin, membranaceous, often purplish near the base, equal, nar-
rowly linear-lanceolate, tapering to an acuminate apex, 7.5-11 mm. long, faintly 3-
nerved; floret cylindrical, narrowly fusiform, 2.5-3.5 mm. long, including the rather
blunt callus; lemma tan, rather uniformly appressed-pubescent, the edges meeting;
palea oblong, 0.7-1.2 mm. long, 2-nerved, sometimes pubescent, awn twice-geniculate,
10-20 mm. long, the lower segment twisted; anthers 3, 1-1.2 mm. long; lemma tapering

FIG. 207. Stipa and Nassella species. S. ichu: A, glumes and floret; S. hans-meyeri:
B, glumes and floret; Nassella linearifolia: C, glumes and floret.

552

BURGER: FLORA COSTARICENSIS 553

at apex to a short neck, bearing a prominent tuft of straight spreading white hairs, 3-4.5
mm. long. Chromosome number 2n = 40 from Costa Rican material.

Occasional on open slopes; Irazu, 2,600-3,000 m.; inflorescences have
been seen from June to November. Mexico to Argentina. Chromosome
numbers of 2n = 40, 42, and 44 have been reported for this species.

Stipa hans-meyeri Pilger, Bot. Jahrb. 56, Beibl. 123:24. 1920.
Figure 207.

Densely tufted perennial, the foliage stiffly erect, rigid; plants 20-35 cm. tall; culms ca.
0.5 mm. thick, glabrous, shining, hollow, thick-walled; nodes glabrous; leaves 3-4 per
culm; sheaths mostly overlapping; ligules 3-4 mm. long, firm, erect, pointed, firmly
membranaceous; blades ca. 1 mm. wide, completely involute, glabrous below, the upper
surface ridged and scabrous, tip acerose. Peduncle minutely puberulent; panicle strict,
few-flowered, 3-10 cm. long, often with a membranaceous prophyll at the base. Spikelets
erect, terete, glumes equal, 7-9.5 mm. long, narrowly lanceolate, purplish at the base, 1-
or faintly 3-nerved; lemma 3.5 mm. long, including the rather short callus, narrowly
elliptical, the nerves obscure; margins barely meeting, callus short-bearded; body with a
line of pubescence along the margins and another along the midrib; apex with a conspicu-
ous tuft of spreading white hairs 2.4-4 mm. long; palea 3 mm. long, oblong, 2-nerved,
terminating in a short beak. Chromosome number n = 11 from a Costa Rican specimen.

This South American species is known from Central America only by
two collections from the paramos of Chirripo Grande and Cerro Buena
Vista, at altitudes above 3,400 m. Blooming dates November to April.
These high-altitude regions are known to support other South Ameri-
can species, which are probably migrants from South America during
the Pleistocene cooling of the tropics.

STREPTOCHAETA Schrader ex Nees

REFERENCES: V. M. Page, Leaf anatomy of Streptochaeta and the
relation of this genus to the bamboos, Bull. Torrey Bot. Club. 74:232-
239. 1947; and Morphology of the spikelet of Streptochaeta, Bull. Tor-
rey Bot. Club 78:22-37. 1951.

Erect perennial herbs from knotty crowns; culms mostly unbranched, sometimes de-
cumbent and rooting at the lower nodes, producing new plants from the rooted portions;
leaf blades ovate, borne on short pseudopetioles. Inflorescence a terminal spike of
pseudospikelets, these spirally arranged on the slender angular rachis and deciduous
from it as a group, entangled by the twisted and contorted awns. Pseudospikelets terete,
bearing ca. 11 spirally imbricated stiff bracts, the lowermost 4 or 5 much shorter than
the rest; longest (nominally sixth) bract tapering into an elongated, coiled and twisted
awn; facing this bract are two stiff acute lanceolate bracts, and within this group of
bracts a perfect flower with 3 stiff, elongated, erect, many-nerved lodicules; stamens 6,
united at the base of the filaments; styles 3.

The above structure is usually interpreted as a spikelet; however,
studies by Page (1951) strongly indicate that the "spikelet" is instead a

554 FIELDIANA: BOTANY

compound structure equivalent to the pseudospikelets of certain bam-
boos, to which group Streptochaeta is related. The number and char-
acters of the short basal bracts in our material are more variable than
those indicated by Page. (Bambusoideae: Streptochaeteae.)

Species three, from Mexico to South America. The genus is often
regarded as the most primitive of grasses, but bears many evidences of
complexity in vegetative and flowering structure.

KEY TO SPECIES OF Streptochaeta

la. Spike dense, many-flowered; rachis triquetrous, densely and coarsely papillose-
hirsute on angles; internodes between successive pseudospikelets 1-4 mm. long

S. sodiroana

Ib. Spike slender, few-flowered; rachis flattened, puberulent; internodes between suc-
cessive pseudospikelets 10-25 mm. long S. spicata

Streptochaeta sodiroana Hack., Oesterr. Bot. Z. 40:113. 1890.
Figure 208.

Perennial; culms in small clumps, sometimes decumbent and rooting at lower nodes,
usually unbranched, 2-3 mm. thick, pithy, with a small cavity, glabrous; lower inter-
nodes longer than the sheaths; upper internodes covered by sheaths; leaf sheaths gla-
brous except just above the appressed-hispid nodes, papillose-ciliate along the upper
margin and the edges of the pseudopetioles; ligule none; pseudopetioles flattened, ter-
minating at the base of the blade in a short, appressed-hispid pulvinus; blades elliptic-
ovate, somewhat asymmetric, abruptly acuminate at the apex, glabrous and smooth-
margined, conspicuously tessellate. Peduncle included or long-exserted, sparsely
puberulent near the base, becoming coarsely hirsute above, papillose-pubescent on the
angles of the rachis and the cupules of the spikelets; spike 15-27 cm. long, densely
cylindrical, ca. 1 cm. thick; pseudospikelets spirally arranged around the rachis, becom-
ing bound together by the intricately coiled and twisted awns and eventually shed as a
group. Pseudospikelets terete, 13-17 mm. long, excluding the awn; awned bract tapering
into a minutely hispid awn, the lower segment straight, 3-8 cm. long, the terminal
segment 3-4 cm. long overall, but much contorted, golden brown; the two bracts facing
the awned bract stiff, barely united at the base; lodicules 3, narrowly triangular, stiff,
erect, ca. 11 mm. long; anthers 6, 4-5 mm. long. Chromosome numbern = 11.

Occasional in undisturbed moist lowland forest, from sea level to 300
m. elevation; most common in the provinces of Puntarenas, from
Quepos to Golfito and near Rincon de Osa, near the coast; and Limon,
near Limon and Guapiles. One collection was secured from near Puerto
Viejo in the Province of Heredia, and another near Florencia in
Alajuela. Belize; Honduras; Costa Rica; Panama; Ecuador. Blooming
has been noted from October to ca. February 1, but old inflorescences
may be found on the plants at almost all seasons. Since the pseudo-
spikelets become completely entangled by their awns, they are often
not shed from the plant. The rachis or peduncle when old may bend
down, carrying the pseudospikelets to the soil, where they may germi-

BURGER: FLORA COSTARICENSIS 555

nate in a mass. Seedlings have been seen twice, in July and Sep-
tember. In addition, the rooting of old culms from their lower nodes
seems to be an effective means of reproduction.

Streptochaeta spicata Schrad. ex Nees, Agrost. Bras. 537. 1829.
Figure 208.

Perennial from a knotty crown; culms erect or sometimes decumbent at the base and
rooting from lower nodes, producing new plants; culms 25-90 cm. tall, rarely branching,
hollow, glabrous except for a puberulent line down one side; nodes mostly concealed by
the overlapping sheaths, appressed-pubescent; sheaths 2-4 cm. long, puberulent, mostly
overlapping; auricles truncate or erect, prominent, coarsely papillose-ciliate; ligule none;
blades slightly asymmetric, ovate, tapering to an acute apex, 8-15 cm. long, 2.5-4.5 cm.
wide, mostly glabrous but ciliolate near the tip, borne on a short, flattened pseudopetiole
which terminates in an appressed-hispid pulvinus at the base of the blade. Inflorescence
solitary, terminal; peduncle mostly included in the bladeless upper sheath; rachis 6-12
cm. long, flattened, puberulent; internodes 10-25 mm. long. Pseudospikelets few (3-9),
erect, appressed to the rachis, terete, disarticulating from the rachis but becoming
entangled by the much-contorted awns and usually remaining attached to the woolly tip
of the rachis; pseudospikelet with about 5 short, blunt, many-nerved outer bracts ca. 2-3
mm. long; sixth (awned) bract ca. 2 cm. long, tapering into a stiff slender awn, its basal
straight segment 2-3 cm. long, the upper twisted and contorted segment glabrous.
Chromosome number n = 11.

Moist forests; rare in Costa Rica and known only from the following
two collections. Guanacaste: Volcan Rincon de la Vieja, west side;
montane forest, 900 m., Hacienda Guachipelin, Pohl & Davidse 11672,
17 January 1969; Parque Nacional de Santa Rosa; moist forest in a
ravine, elevation 300 m., Pohl & Erickson 12631, 23 July 1971. South-
ern Mexico, Honduras, Nicaragua, Costa Rica, Panama; northern
South America from Trinidad to Ecuador and Paraguay.

STREPTOGYNA Beauvois

Perennial herbaceous grasses; leaf blades narrowed to a pseudopetiole; an external
membranaceous ciliate ligule present along the collar; inflorescence a slender unilateral
raceme of narrow erect spikelets; rachis triquetrous, grooved on two sides, the pedicels
of the spikelets alternately fitting into the grooves; third side of rachis convex. Glumes
unequal, much shorter than the florets; florets several; lemmas convolute, concealing the
palea, firm, awned; callus prominent, oblique; lodicules 3, plane, narrowly spatulate,
vasculated; stamens 2 or 3; ovary with style terminating in 3 greatly elongated stiff,
twisted stigmatic branches, which at maturity become entangled with those of other
spikelets, causing them to fall as a group. The leaf anatomy, lodicules, and the basic
chromosome number of x = 12 are all bambusoid.

Species two, one in the tropics of the Old World. (Bambusoideae:
Streptogyneae.)

Streptogyna americana Hubbard, Hook. Icon. Plant., Ser. 5, Vol.
6: Tab. 3572:5. 1956. Figure 209.

FIG. 208. Streptochaeta species. S. spicata: A, leaf and inflorescence; S. sodiroana: B,
leaf and inflorescence; C, pseudospikelet.

556

FIG. 209. Streptogyna americana. A, leaf base and external ligule; B, inflorescence; C,
group of florets entangled by the persistent stigmas.

557

558 FIELDIANA: BOTANY

Culms erect to arching, 50-150 cm. tall, unbranched, from short, knotty rhizomes;
leaves many, aggregated near the base, with overlapping sheaths; culms solid, pithy,
glabrous; nodes glabrous, not prominent; sheaths mostly overlapping, glabrous except
somewhat retrorsely hispid near the apex; ligule a short membrane, ciliate with a dense
fringe of stiff hairs, ca. 2 mm. long; a similar external ligule surrounds the collar at the
same level; leaf blades numerous, the larger ones 55-65 cm. long, 10-15 mm. wide, mostly
glabrous. Peduncle solid, glabrous except puberulent near the apex; inflorescence a
solitary terminal raceme, slender, 30-47 cm. long; lowermost spikelets sometimes abor-
tive. Spikelets on short erect pedicels, solitary, 3-5 cm. long, excluding the awns and
style branches; disarticulation above the glumes and between the florets; glumes stiff,
the first 3-5-nerved, lance-linear, 6-8 mm. long; the second 7-9-nerved, ovate, awn-
tipped, 12-15 mm. long; florets 3-5, the apical one rudimentary; lemmas firm, convolute,
15-25 mm. long, with a hard oblique callus 1-3 mm. long; rachilla internodes sigmoid,
slender, acuminate, 4-5 mm. long; lemma obscurely 7-9-nerved, glabrous, minutely
tuberculate, 15-25 mm. long, with an awn 20-25 mm. long; palea hidden within the
lemma, the awned tip emerging above the apex of the lemma; caryopsis linear-cylindric,
grooved on one side, ca. 12 mm. long.

Rare; lowland forest, Los Tejares, in the valley of the Rio Ceibo;
elevation ca. 200 m.; Finca los Helechales, 1,800 m. December to April.
Chiapas and Vera Cruz, Mexico, Belize, northeastern Nicaragua,
southern Costa Rica, Panama, Venezuela, Trinidad and Surinam to
Brazil.

This species was known as S. crinita Beauv. in earlier American
publications, but this name refers to a similar Old World species.

SWALLENOCHLOA McClure

REFERENCE: F. A. McClure, Genera of bamboos native to the New
World (Gramineae: Bambusoideae), Smithsonian Contr. Bot. 9:106-
113. 1973.

Plants densely caespitose; rhizomes pachymorph; culms not bearing thorns; inter-
nodes cylindrical or flattened on the branch-bearing side, usually with a small central
cavity formed by the breakdown of the central parenchyma; midculm branch comple-
ment usually of 3-5 primary branches, which may become rebranched; branches in-
travaginal, closely ascending; main culm sheaths with short, erect triangular blades;
ligule a short, stiff membrane; foliage blades on branches usually stiff, often tessellate.
Inflorescence a dense cylindrical terminal panicle. Spikelets disarticulating above the
reduced glumes; lower 2 florets sterile; terminal floret perfect; rachilla not prolonged
beyond the palea; lodicules 3, flat, vasculated, one smaller than the other pair; anthers 3;
stigmas 2. (Bambusoideae: Chusqueae.) Chromosome number n = 20.

Swallenochloa is closely related to Chusquea, differing mostly in the
slightly hollow internodes, in the intravaginal rather than extravaginal
branching, equal rather than unequal primary branching, and the
dense inflorescences. Most of the species are high-alpine, often above
timberline. The Costa Rican species share a basic chromosome number
of n = 20 with Chusquea species. Since this is an unusual number

BURGER: FLORA COSTARICENSIS 559

among the Bambusoideae, it suggests that these two genera are very
closely related.

KEY TO SPECIES OF Swallenochloa

la. Ligules 1-7 cm. long, acuminate; leaf blades lax, not strongly tessellate: panicles

25-50 cm. long S. longiligulata

Ib. Ligules up to 5 mm. long, truncate; leaf blades strongly tessellate; panicles less than

20 cm. long 2

2a. Leaf blades 1.5-11 cm. long, 4.5-12 mm. wide, yellowish green; ligules 0.5-1.0

mm. long; culms 1-3 m. tall; anthers 2.7-3.5 mm. long S. subtessellata

2b. Leaf blades 6-19 cm. long, 11-23 mm. wide, dark green; ligules 3-5 mm. long;
culms up to 10 m. long; anthers 3.6-4.5 mm. long S. vulcanalis

Swallenochloa longiligulata Sods. & Cald., Brittonia 30:305. 1978.
Figure 210.

Long-lived perennial bamboo; caespitose in dense clumps of up to 50 culms; culms
arching, 3-10 m. long, up to 3 cm. thick, branching from the middle and upper nodes,
cylindrical, soft, with an irregular central cavity, glabrous or with patches of
appressed-hispid hairs; nodes with a sheath girdle and nodal ridge, glabrous; culms
sheaths 17 cm. long (2 seen), appressed-hispid especially toward the apex; ligule thick,
stiff, hispid-ciliolate, up to 2 mm. long; culm blades deltoid, 5.5 cm. long, 1 cm. wide,
erect, as wide as the sheath apex, appressed-hispid above; foliage-bearing branches 5-10
per node, 70-90 cm. long, some of them rebranching; leaf sheaths on primary branches
overlapping, keeled, glabrous or ciliate on the margins, the lower ones often deciduous,
the middle ones with deciduous blades; sheath auricles united with the ligule, erect, stiff,
vasculated, the whole 1.5-7.0 cm. long, acuminate; external ligule stiff, ca. 0.5 mm. long;
leaf blades flat, ovate 9-22:1, acuminate, 12-28 cm. long, 8-23 mm. wide, dark green,
glabrous, not conspicuously tessellate, the midrib prominent beneath; margins white-
banded, scaberulous. Inflorescences numerous, terminal on leafy branches, the peduncle
mostly included in the uppermost sheath; rachis, branches, and pedicels scabrous or
appressed-pubescent; panicles very slender, 25-50 cm. long, ca. 1 cm. thick, loose, the
rachis visible; lower branches up to 11 cm. long, the upper ones much shorter, all strictly
ascending; pedicels erect, angular, mostly longer than the spikelets. Spikelets nearly
terete, falcate, stramineous or purplish, 6.0-7.7 mm. long, tapering to a point, disar-
ticulating above the glumes only; first glume 0.3-0.7 mm. long, blunt; second glume
similar, 0.9-1.2 mm. long, both nerveless; first sterile lemma 3.0 mm. long, 3-nerved,
acuminate; second sterile lemma 3.7-4.8 mm. long, 3-5-nerved, ovate, acuminate; fertile
lemma 5.7-6.4 mm. long, rounded on the back, 5-7-nerved, the margins enfolding the
palea; palea ca. as long as the lemma, broad, enwrapping the flower, 2-keeled, grooved
between the keels, the nerves projecting as rigid points; lodicules flat, vasculated, ciliate
toward the blunt apex; anthers 3, yellow, 3.&4.1 mm. long; caryopsis fusiform, 3.8-5.0
mm. long, brown; raphe dark, two-thirds as long as the grain, terminating in a depressed
chalaza; embryo small, basal. Chromosome number n = 20 from the type.

Cordillera de Talamanca, from 1,400 to 3,000 m. elevation; Volcan
Barba. The only recent bloom of this species occurred in 1972 and 1973.
The colony at Tres de Junio contained only a few blooming plants, but
the stand at Alto de Roble was almost entirely in bloom and dying in
1973. Recent examination of the area appears to indicate that the

FIG. 210. Swallenochloa longiligulata. A, seedlings; B, branch with persistent leaf
sheaths; C, culm with branch complement; D, inflorescence; E, group of spikelets.

560

BURGER: FLORA COSTARICENSIS 561

colony has now disappeared. This stand produced some well-filled
caryopses, and I collected a number of seedlings growing on moss
among the old dying plants. The seedlings have narrow, pubescent
leaves and lack the very elongated auricle-ligules of the adult form.
Most of the spikelets on the blooming plants appear to be sterile, and
very few caryopses were seen. The following specimens were collected
in flower. Prov. Heredia, Alto de Roble, Rio Las Vueltas: Lent 2626,
Burger & Gentry 9039, Pohl & Selva 12810; Prov. Alajuela, Alto
Paloma, 12 km. N of La Luisa, 1,950 m., Pohl & Davidse 11708. Prov.
San Jose, Tres de Junio, along CIA 5 km. SE of El Empalme, 2,000 m. ,
Pohl & Selva 12842, (Type).

Swallenochloa subtessellata (Hitchc.) McClure, Smithsonian
Contr. Bot. 9:113. 1973. Chusquea subtessellata Hitchc., Proc. Biol.
Soc. Wash. 40:81. 1927. Figure 211.

Caespitose in dense clumps; culms mostly 1.5-3 m. tall, erect, stiff; rhizomes short,
pachymorph; culms branching abundantly from the middle and upper nodes, the
branches strict and erect; internodes of culms 4-8 mm. thick, with a small irregular pith
cavity; surfaces glabrous, often with crustose wax deposits; nodes enlarged, with a
sheath girdle and a nodal ridge, the branch complement arising between them; main
culm sheaths deciduous, 12-13 cm. long (2 individuals), rounded to the apex; sheath
blades narrower than the sheath apex, 2.0-2.5 cm. long, 7-8 mm. wide, narrowly trian-
gular, acuminate; ligule 1.7 mm. long, thick, decurrent onto the sheath margin, minutely
ciliolate; back of sheath glabrous except for the ciliate margin; primary foliage-bearing
branches several per node, stiff and erect, rebranching; leaf sheaths keeled, overlapping,
persistent after the blades disarticulate but becoming loose, pectinate-ciliate on the
margins and collar, glabrous or appressed-pilose on the surfaces; ligule a thick, ciliolate
membrane, 0.5-1.0 mm. long; leaf blades yellowish green, stiff and leathery, ovate,
1.5-11 cm. long, 4.5-12 mm. wide, the base rounded to a short pseudopetiole ca. 2 mm.
long; apex abruptly acuminate into a rigid involute point; blades glabrous except for the
white-banded, strongly scabrous margins. Panicles terminal on the leafy branchlets;
peduncles mostly included in the terminal sheaths, puberulent; panicles densely cylindri-
cal, purple, 5-13 cm. long, 7-14 mm. thick; branches numerous, clustered, short, erect;
spikelets mostly on pedicels as long as themselves, overlapping and concealing the rachis
and branches. Spikelets 5.5-7.0 mm. long, purple; disarticulation above the glumes only;
glumes blunt, oval or circular, nerveless, the first 0.4-0.8 (1.2) mm. long, the second
0.6-1.8 mm. long; first sterile lemma 5.0-6.5 mm. long, rounded on the back, acute or
awn-tipped, 5-7-nerved, glabrous or the upper margins short-ciliate; second sterile
lemma similar, 5.0-7.0 mm. long; fertile floret 5.0-6.5 mm. long, the lemma glabrous,
5-7-nerved, acute or awn-tipped; palea slightly shorter, 2-4-nerved, broad, envelop-
ing the flower; lodicules 3, flat, vasculated; anthers 3, yellow, 2.7-3.5 mm. long; styles
2, naked below; caryopses not seen. Chromosome number n = 20 from Costa Rican
specimens.

Common on paramos along the CIA at elevations above 3,000 m.
Asuncion, Buena Vista, Las Vueltas, Cuerici, Chirripo, Irazii, Poas.
Inflorescences may be found on the plants at all seasons of the year.
Costa Rica; Volcan Chiriqui.

JE/I

FIG. 211. Swallenochloa subtessellata. A, base of plant with buds; B, culm sheath; C,
leafy branch; D, several inflorescences; E, spikelet.

BURGER: FLORA COSTARICENSIS 563

This species has been observed bearing inflorescences over a long
period of years. The amount of bloom varies greatly from year to year,
but it is always possible to find some plants with panicles. Flowering
does not seem to result in death of the old clones, as is common in the
related genus Chusquea. Despite the abundance of flowering, I have
not detected caryopses in herbarium specimens, and have never ob-
served seedlings in the field.

Swallenochloa vulcanalis Sods. & Cald., Brittonia 30:309. 1978.
Figure 212.

Caespitose bamboo in dense small clumps; culms erect when short, arching when tall,
up to 10 m. long, stiff; internodes cylindrical, up to 2.5 cm. thick, solid or with an
irregular lumen in the center; nodes glabrous; sheath girdle evident; culm sheaths gla-
brous, ca. 15 cm. long, rounded to a very reduced blade; ligule in the form of an inverted
V, a thick ciliolate membrane, ca. 1 mm. long (1 individual seen); primary branch bud
flanked with few buds of foliage-bearing branchlets, these up to ca. 10 per node, stiff,
usually with 3-4 leaf blades in addition to the deciduous lower leaves; fascicle of branch-
lets dense; subtended by basal bracts and prophylls; leaf sheaths glabrous except for the
ciliolate overlapping margin; ligule a stiff membrane, 3-5 mm. long, decurrent on the
sheath margins; leaf blades flat, rather stiff and leathery, olivaceous, ovate 6-9:1, 6-19
cm. long, 11-23 mm. wide, conspicuously tessellate; surfaces glabrous; margins with
white, scabrous, cartilaginous bands; base abruptly rounded to a pseudopetiole 1-3 mm.
long; apex caudate-acuminate. Inflorescence a dense cylindrical purple panicle, 9-19 cm.
long, 1-2 cm. thick; peduncle included in the uppermost blade-bearing sheath; rachis,
branches, and pedicels puberulent or scabrous; pedicels appressed, the lateral ones 2-3
mm. long. Spikelets purple, 6.2-10 mm. long; glumes broadly rounded, nerveless or the
second 1-nerved, the first 0.6-1.0 mm. long, the second 1.2-1.5 mm. long; disarticulation
above the glumes, the remainder of the spikelet falling as a unit; sterile lemmas 2,
rounded on the back, ciliolate near the keeled tip; first sterile lemma 3.7-6.3 mm. long,
ovate 2.3-3.5:1, the awn ca. 0.5 mm. long; nerves 4-5, the lateral ones closely paired;
second sterile lemma similar, 5.0-7.4 mm. long, ovate 3.2-3.7:1, the awn tip to 1 mm.
long; nerves 5, equally spaced; surfaces of sterile and fertile lemmas scabrid or finely
puberulent; fertile lemma 5.7-7.5 mm. long, ovate 2.1-2.5:1, 5-nerved, with a short
awn-tip, rounded on the back, keeled toward the ciliolate tip; palea 5.7-6.8 mm. long,
slightly shorter than the lemma, 4-nerved, bidentate at the tip; lodicules 3, obovate, flat,
vasculated only near the middle, ciliate with stiff elongate hairs on the upper third;
anthers 3, yellow, 3.6-4.5 mm. long; style short; stigmas 2; caryopsis not seen. Chromo-
some number n = 20 from a specimen from Turrialba (reported as C. lehmannii).

This species is common near the crater of Irazu and occurs at upper
elevations of Poas and Turrialba as well. It was first collected in flow-
ering condition at the crater of Irazu in 1900. We obtained a second
blooming collection on Volcan Turrialba in 1968. Since the Irazu Crater
is a much- visited site and this species still occurs there, it is likely that
blooming is rare. Elevations 2,300-3,300 m.

This species is recognizable in vegetative condition by the leathery,
strongly tessellate leaf blades. In appearance, it is intermediate be-

FIG. 212. Sivallenochloa vulcanalis. A, branch complement; B, culm sheath; C,
inflorescence; D, spikelet.

564

BURGER: FLORA COSTARICENSIS 565

tween Swallenochloa subtessellata and the common species of Chus-
quea.

THRASYA Humboldt, Bonpland, & Kunth

Perennial grasses; peduncles several from the uppermost sheath, elongated, bearing
at their summit a single, slender, usually arched raceme; rachis flattened, its mem-
branaceous margins partly enveloping the spikelets. Spikelets borne in a single row
along the midrib of the rachis, minutely pedicellate, in pairs, the members of each pair
placed longitudinally, with the first glumes and lower (sterile) lemmas facing each other
and the second glumes and fertile lemmas facing apart; disarticulation below the glumes;
spikelets more or less dorsally compressed; first glume short or obsolete; second glume
shorter or longer than the spikelet; sterile lemma ca. as long as the spikelet, stiff, deeply
grooved in the middle and often splitting longitudinally when mature, sometimes with a
staminate flower; palea well developed, also grooved; upper (fertile) floret coriaceous,
the lemma dorsally flattened, sometimes bearded at the apex, its margins inrolled over
the edges of a stiff, flat palea of equal length.

Thrasya is a genus of ca. 20 species, ranging from Mexico to tropical
South America and the West Indies. The species could be confused
with some of the species of Paspalum that have single racemes. They
differ in the placement of the spikelets in a single row, back to back in
pairs, whereas Paspalum species have spikelets all placed with the
backs of the fertile lemmas turned toward the midrib. (Panicoideae:
Paniceae.)

KEY TO SPECIES OF Thrasya

la. Racemes 2-6 cm. long 2

Ib. Racemes 10-30 cm. long 3

2a. Spikelets glabrous or rarely with a few minute marginal hairs; margins of rachis

not ciliate T. campylostachya

2b. Spikelets conspicuously bearded; margins of rachis conspicuously ciliate with

stiff, yellow, papillose-based hairs T. trinitensis

3a. Rachis ca. 2.5 mm. wide; spikelets 3.3-4.5 mm. long T. robusta

3b. Rachis 4-5 mm. wide; spikelets 4.5-5.5 mm. long T. petrosa

Thrasya campylostachya (Hack.) Chase, Proc. Biol. Soc. Wash.
24:115. 1911. Panicum campylostachyum Hack., Oesterr. Bot. Z.
51:367. 1901. Figure 213.

Caespitose perennial; culms 50-110 cm. long, decumbent, branching from lower and
middle nodes, the internodes 1.0-1.5 mm. thick, hollow, glabrous or pilose just below the
apex; nodes bearded; sheaths pilose; ligule a brown membrane, 0.7-1.5 mm. long; blades
keeled, flat, 6-17 cm. long, 3-7 mm. wide, pilose on both surfaces. Peduncles up to 5 from
the terminal sheath, exserted 10-15 cm.; inflorescence a solitary terminal raceme on each
peduncle, arcuate, 4-6 cm. long, the rachis slender, flattened, 1.5-2.0 mm. wide, bearing
a spikelet at its tip. Spikelets 2.2-2.8 mm. long, ovate or obovate 2:1, glabrous or with a
few hairs near the margins of the bracts; basal callus small, ca. 0.2 mm. long; first glume
broad, blunt, 0.4-1.2 mm. long; second glume 1.5-2.2 mm. long, ovate, 5-nerved, shorter

566

FIELDIANA: BOTANY

FIG. 213. Thrasya species. T. campylostachya: A, spike; T. petrosa: B, spike; C,
portion of rachis with a pair of spikelets; T. robusta: D, portion of rachis with spikelets.

than the fertile lemma; lower lemma 2.2-2.8 mm. long, only slightly grooved in the
middle, faintly 4-nerved, its palea stiff, equal to the lemma; lodicules 2, truncate; anthers
3, purple, 1.3-1.5 mm. long; upper floret ca. 2 mm. long, the lemma cartilaginous,
minutely papillose in lines, its edges infolded over the margins of the equal flat palea;
lodicules 2, truncate; anthers 3, purple; style branches 2, separate, naked two-thirds of
their length. Chromosome number n = 20 from a Costa Rican specimen (reported as T.
gracilis Swallen, which is probably not distinct).

Open brushy roadsides, savannas; Agua Caliente (Cartago), Canas
Gordas. Blooming June to February, possibly yearlong. Elevations
1,100-1,400 m. Southern Mexico to Bolivia.

Thrasya petrosa (Trin.) Chase, Proc. Biol. Soc. Wash. 24:115. 1911.
Panicum petrosum Trin., Gram. Icon. 3, pi. 280. 1836. Figure 213.

Caespitose perennial; culms arching, up to 1.5 m. tall, branching from the base, 2-3
mm. thick, hollow, thin-walled, glabrous or appressed-pilose; nodes appressed-
puberulent; sheaths nearly as long as the elongated internodes, from nearly glabrous to

BURGER: FLORA COSTARICENSIS 567

strongly papillose-pilose with hairs up to 4 mm. long; ligule a brown membrane, up to 1
mm. long; blades very elongate, 4-6 mm. wide, papillose-pilose to nearly glabrous, the
midrib very prominent beneath; leaf margins often revolute. Peduncles 1-several from
the uppermost sheath, exserted up to 45 cm. Inflorescence a slender, arching raceme,
12-28 cm. long; rachis broadly winged, 4-5 mm. wide, clasping the basal parts of the
spikelets. Spikelets ovate, acute, dorsally compressed, 4.5-5.5 mm. long, including the
prominent, fleshy, oblique callus ca. 0.5 mm. long; first glume obsolete or up to 0.5 mm.
long, thin, nerveless, deltoid; second glume 4.5-5.0 mm. long, faintly 5-nerved,
appressed-hispid, ovate, acute; lower lemma 4.0-5.5 mm. long, stiff, appressed-hispid,
ovoid, acute, 4-nerved, readily splitting down the deeply grooved middle; lodicules 2,
truncate, fleshy; anthers 3, 1.8-2.2 mm. long, yellow to orange; pistil absent; palea
equalling the lemma, stiff, acute, grooved down the middle, glabrous; upper floret with a
stiff, dorsally flattened lemma, ovate 3:1, acute, minutely bearded at the apex, faintly
5-nerved, 3.5-4.0 mm. long; palea flat, stiff, 3.2-3.4 mm. long; lodicules 2, truncate,
fleshy; anthers 3, smaller than those of the lower floret or apparently sometimes absent;
style branches naked for ca. two-thirds of their length. Chromosome number n = 20
from a Costa Rican specimen.

Rare in Costa Rica; hilly savannas of the southern General Valley.
July to December. Guatemala to Peru and Paraguay.

Thrasya robusta Hitchc. & Chase, Contr. U.S. Natl. Herb. 18:297.
1917. Figure 213.

Caespitose perennial, in dense clumps; culms up to 200 cm. tall, 2-4 mm. thick, hollow,
appressed-pilose; nodes appressed-pilose; sheaths longer or shorter than the internodes,
glabrous or with a few papillose bristles on the margins; ligule a brownish membrane,
2.0-2.5 mm. long; blades flat, keeled, up to 25 cm. long, 3-15 mm. wide, puberulent; collar
more or less bearded with stiff, erect, white hairs; uppermost blade much reduced.
Peduncles several from the upper sheath, slender, 5-20 cm. long; inflorescence a solitary,
slender, arcuate raceme, 15-30 cm. long; rachis flat, 2.5 mm. wide, infolded around the
bases of the spikelets, the margins sparsely fine-ciliate or glabrous, the tip extending
beyond the spikelets as a naked point. Spikelets ovate 3:1, 3.3-4.5 mm. long, the fleshy
white callus protruding at the base; first glume of one spikelet of the pair up to 1.5 mm.
long, narrowly deltoid, 1-nerved, that of the other member very short and broad; second
glume 3.0-3.5 mm. long, 5-nerved; lower lemma 3.0-3.5 mm. long, deeply grooved along
the center and readily splitting; both second glume and lemma spreading-pilose; lower
floret with 3 purple anthers ca. 1.5 mm. long; palea acute, stiflf, grooved down the center,
equal to the lemma; upper (fertile) floret 2.8-3.1 mm. long, the lemma cartilaginous,
shining, minutely papillose in lines, minutely ciliate at the acute tip; palea similar and of
equal length; stamens 3, purple; caryopsis elliptical 2:1, flat, whitish but purple at base
and apex, 1.4-1.5 mm. long. Chromosome number n = 30 from a Costa Rican specimen.

This species is known in Central America only by the following two
specimens: Guanacaste, along CIA, 15 km. SE of Liberia, elevation
100 m., 18 August 1968, P. & D. 10946; Puntarenas, between San
Antonio and Boruca, elevation 740 m., 22 August 1968, P. & D. 10798.
Trinidad; Costa Rica.

Thrasya trinitensis Mez, Repert. Sp. Nov. Fedde, 15:125. 1918. T.
paspaloides of Hitchc., Man. Gr. W. Ind. 178. 1936, non H.B.K.

568 FIELDIANA: BOTANY

Caespitose perennial, in dense clumps; innovations densely villous; culms 30-65 cm.
tall, erect, simple or branching from the lower nodes; prophylla 2 cm. long; culms
glabrous, hollow, 1 mm. thick; nodes densely bearded with spreading hairs; leaf sheaths
shorter than the internodes, keeled near the apex, papillose-pilose with long hairs and
puberulent between them; ligule a stiff brown membrane, erose-ciliolate at the apex,
0.8-1.3 mm. long; leaf blades flat, strongly keeled beneath, the midrib depressed above,
5-9 cm. long, 1.5-3.0 mm. wide, the uppermost one much reduced, bearing stiff, elon-
gated papillose-based hairs on the midrib, margins, and surfaces, and puberulent among
the long hairs. Peduncles 1-4 from the uppermost sheath, slender, glabrous, or puberu-
lent near the summit, bearded at the base of the raceme, exserted up to 20 cm.; inflores-
cence a solitary, slender, arched raceme, 2-5 cm. long; rachis flattened, up to 2 mm.
wide, the margins foliaceous, the edges conspicuously papillose-ciliate with stiff,
spreading golden hairs up to 2.5 mm. long; rachis tip extended up to 2 mm. beyond the
terminal spikelet. Spikelets 2.5-2.8 mm. long, ovate, with a protruding basal callus,
dorsally compressed, flattened on the first glume side, convex on the second glume side,
rather open at the tip; first glume obsolete or a minute deltoid nerveless scale 0.3-0.5
mm. long; second glume ca. two-thirds as long as the spikelet, 1.3-1.7 mm. long, thin,
ovate, faintly 3-nerved, villous toward the margins; lower (sterile) lemma 2.2-2.5 mm.
long, ovate, acute, stiff, obscurely 4-nerved, deeply grooved along the center and readily
splitting longitudinally into 2 separate segments, the tip and marginal flexures bristly;
flower none; palea slightly shorter, stiff, acute, grooved down the middle; upper (fertile)
floret 1.8-2.0 mm. long, elliptical, blunt, stiff, crested at the apex with a dense fringe of
stiff cilia ca. 0.5 mm. long; margins of lemma inrolled over the edges of the flat palea;
anthers 3, yellow, 1.5 mm. long; styles 2, free, naked for two-thirds of their length;
caryopsis dorsally flattened, elliptical.

Rare; known in Costa Rica only from the following specimen: Indian
Reserve above Buenos Aires de Osa, R. Munoz s.n., 24 August 1969.

This species has generally been known as T. paspaloides; however,
the illustrations in H.B.K. indicate a plant with glabrous sheaths and
without the long hairs on the leaf blades that our specimens show. The
spikelets also lack the elongate bristles on the sterile lemma that the
illustration and South American specimens have. Thrasya trinitensis
occurs in Trinidad and in Belize, Nicaragua, and Costa Rica.

TRACHYPOGON Nees

Plants perennial, caespitose or with short rhizomes; culms unbranched, bearing soli-
tary or rarely digitate terminal racemes of dimorphic spikelets. Spikelets paired, one of
each pair short-pedicellate, persistent, awnless, staminate, dorsally compressed; other
spikelet of each pair longer-pedicellate, deciduous, perfect-flowered, awned, nearly ter-
ete. Rachis of the raceme persistent after maturity of the spikelets, bearing the old
staminate spikelets; awned perfect-flowered spikelets deciduous at maturity, falling
with an oblique, hairy, pointed callus formed of the apical portion of the pedicel; first
glume firm, narrowly elliptical, blunt, its margins inrolled over the second glume and
mostly concealing it; second glume ca. as long as the first, somewhat keeled, 3-nerved,
the apex clasping the base of the awn; lower (sterile) lemma hyaline, 2-nerved, grooved
between the keels, the margins inflexed; fertile lemma narrow, firm except at the
hyaline base, flattened, tapering directly into the base of the awn; awn twisted, hispid,

BURGER: FLORA COSTARICENSIS 569

twice-geniculate, well-exserted; palea absent; styles 2, separate. Staminate spikelets
with the first glume dorsally flattened, rounded on the back, 5-11-nerved, the margins
sharply inflexed and covering the margins of a membranaceous second glume of about
equal length; lower and upper lemma about equal, hyaline; anthers 3.

Trachypogon is a small genus of grasses of warm temperate and
tropical climates of the Americas and Africa. Its closest relative is
thought to be Heteropogon, which differs in having a disarticulating
rachis. The taxonomy of the genus is in confusion, and a new mono-
graph is in preparation by Dr. Davidse, who has kindly named our
specimens. The awned pedicellate spikelets of Trachypogon are highly
distinctive, and mimic the awned florets of species of Stipa. The simi-
larity in appearance is the result of convergent evolution, and the
two genera are widely separated taxonomically. (Panicoideae: An-
dropogoneae.)

KEY TO SPECIES OF Trachypogon

la. Foliage glabrous or nearly so; ligules 2-10 mm. long; first glume glabrous

T. plumosus

Ib. Foliage, especially on lower parts of the plants, densely grayish woolly; ligules 1-3
mm. long; first glume pubescent near the base T. vestittis

Trachypogon plumosus (Humb. & Bonpl. ex Willd.) Nees, Agrost.
Bras. 344. 1829. Andropogon plumosus Humb. & Bonpl. ex Willd., Sp.
PL 918. 1806.

Plants perennial, densely caespitose in small clumps; culms erect, 65-150 cm. tall,
unbranched; internodes cylindrical, glabrous, solid and pithy, 1-2 mm. thick; nodes im-
pressed, upwardly bearded; leaf sheaths glabrous, the lower ones longer than the inter-
nodes; ligules adnate to the sheath margins, stiff, vasculated, pointed, 2-10 mm. long;
leaf blades narrow and elongated, 2-4 mm. wide, narrowed to the base, flat or involute.
Peduncles solitary, terminal, included or exserted up to 10 cm.; raceme slender, erect,
5-18 cm. long. Perfect-flowered spikelets 7.0-9.5 mm. long, including the sharp oblique
hairy basal callus that is 1-2 mm. long; glumes ca. equal, the first coriaceous, narrowly
elliptical, blunt at the apex, the back convex and the margins incurved, nearly covering
the second glume, nerves 5-7; second glume nearly as long, keeled, 3-nerved, the obtuse
apex embracing the base of the awn; lower (sterile) lemma hyaline, 2-nerved, nearly as
long as the glumes, ciliate at the apex; upper (fertile) lemma reduced to the flattened stiff
base of the awn; awn exserted 5-6 cm., twice geniculate, the basal 2 segments short-
hispid and twisted; anthers 3, ca. 3 mm. long, yellow; styles 2, separate, naked below.
Staminate spikelets borne on short pedicels, persistent after flowering, dorsally com-
pressed, narrowly elliptical, ciliate at the obtuse apex; first glume rounded on the back,
rather faintly 5-9-nerved, the margins sharply inflexed over the edges of the 3-nerved
second glume; lower lemma hyaline, 4.5-5.5 mm. long; upper (fertile) lemma hyaline, 4-5
mm. long, narrowly elliptical, ciliate; anthers 3-6 mm. long, yellow.

Dry Curatella-Byrsonima savannas, often on volcanic tuff; mostly
at elevations up to 400 m.; from Bagaces to the Nicaraguan border,
Boruca and Paraiso savannas. July to December.

570 FIELDIANA: BOTANY

Trachypogon vestitus Anderss., Ofvers. Forh. Kongl. Svensk.
Vetensk. Akad. 14:52. 1857.

Caespitose perennial in small clumps; plants 40-110 cm. tall, erect; culms unbranched;
internodes 1-2 mm. thick, cylindrical, pithy or hollow, glabrous; nodes densely upwardly
bearded; foliage mostly aggregated near the base; leaf sheaths copiously hairy with soft,
grayish trichomes; pubescence most prominent on the lower sheaths; ligule a stiff mem-
brane, 1-3 mm. long, adnate to the sheath margins; leaf blades elongated, 2-5 mm. wide,
flat or folded, usually densely grayish-pubescent with soft spreading hairs on both sur-
faces. Peduncles solitary, terminal, included or exserted up to 14 cm.; inflorescence a
solitary terminal raceme, very slender, 5-23 cm. long. Awned spikelets 8-9 mm. long,
including the callus, perfect-flowered, disarticulating with a very oblique, densely hairy
basal callus; mature spikelets nearly terete in cross section; first glume 7-9-nerved,
rounded on the back, the margins incurved and nearly concealing the second glume,
blunt, lower portions of the back loosely pubescent; second glume ca. as long as the first,
narrow, 3-nerved, with longitudinal grooves on both sides of the midrib; apex clasping
the base of the awn; lower lemma hyaline, ciliate, ca. 6 mm. long; upper (fertile) lemma
reduced to the stiff, flattened base of the awn; lodicules 2, truncate; anthers 3, yellow, ca.
3.8 mm. long; styles 2, separate, naked below, stigmas laterally exserted, brownish.
Awnless spikelets 5.7-7.0 mm. long, staminate; first glume narrowly elliptical, blunt,
9-11-nerved, rounded on the back, loosely pubescent on the lower portion, its lateral
flanges clasping the margins of the keeled, 3-nerved, ciliate second glume; lower lemma
5-6 mm. long, hyaline, ciliate; upper (fertile) lemma narrower, 4-6 mm. long, hyaline,
faintly nerved; anthers 3, yellow, ca. 4 mm. long.

Rare; rocky savannas along the CIA, 2-3 km. S of La Cruz; elevation
ca. 220 m. June to October.

TRINIOCHLOA Hitchcock

Caespitose perennials; leaf sheaths with united edges. Inflorescence a terminal pani-
cle. Spikelets 1-flowered, disarticulating above the subequal, 1-nerved, purplish, usually
short glumes; floret 1, slender, subcylindric; lemma faintly 7-9-nerved, the margins
somewhat inrolled over the palea; callus oblique, bearded with straight erect hairs; apex
of lemma acuminate, membranaceous, bidentate; awn inserted on the back, ca. one-third
below the apex, geniculate, twisted below the first bend; palea firm, ca. as long as the
lemma, nearly enveloping the narrowly cylindrical caryopsis, 2-nerved, the nerves very
close together, scabrid, an indented purple line between them; rachilla not produced
beyond the palea. (Pooideae: Meliceae.)

Triniochloa stipoides (H.B.K.) Hitchc., Contr. U.S. Natl. Herb.
17:303. 1913. Podosaemum stipoides H.B.K., Nov. Gen. & Sp. 1:131.
1816. Figure 214.

Caespitose perennial, the culms in small clumps, 50-135 cm. tall; culms glabrous,
hollow, ca. 1 mm. thick; nodes glabrous; internodes elongated, mostly covered by the
overlapping sheaths; sheaths 15-30 cm. long, prominently ribbed, scabrid or the lower-
most puberulent; ligules prominent, membranaceous, lacerate, 5-10 mm. long; leaf
blades 10-25 cm. long, 2-3 mm. wide, often folded, scabrid beneath, puberulent and with
scattered long weak hairs above; peduncle up to 25 cm. long, puberulent; panicles soli-
tary, terminal, 15-25 cm. long, open, pyramidal, with relatively few branches and

FIG. 214. Triniochloa stipoides. A, spikelet; B, panicle.

571

572 FIELDIANA: BOTANY

spikelets; the spikelets long-pedicellate, lying parallel to the branches, nearly terete,
11-13 mm. long; glumes subequal, purplish, ovate, acute, overlapping, much shorter
than the floret, 1-nerved, the first 3.5-4.5 mm. long, the second 4-5 mm. long; floret
subcylindric, 11-13 mm. long, firm, scabrid; lemma faintly 7-9-nerved; awn 15-20 mm.
long; anthers 3, yellow, 4 mm. long. Chromosome number n = 16 from a Costa Rican
specimen.

Rare, open areas, Irazu, 2,000-3,300 m.; near San Marcos, 1,900 m.;
Chirripo Grande. Inflorescences have been seen on the plants from
November to February. Mexico to Colombia, Venezuela, and Bolivia.

The genus is placed tentatively in the tribe Meliceae on the basis of
its closed sheaths and basic chromosome number of x = 8.

TRIPLASIS Beauvois

Caespitose or rhizomatous annuals or perennials; spikelets borne in small terminal or
axillary panicles; cleistogenes borne concealed in lower sheaths; spikelets several-
flowered; disarticulation above the glumes and between the florets; glumes equal, 1-
nerved; lemmas 3-nerved, bilobed, the midnerve projecting as a short awn; lateral
nerves conspicuous, silky-pubescent, parallel to the midnerve; palea bowed out, the
keels strongly villous-ciliate on the upper portion.

Triplasis is a genus of two species, native to the southeastern
United States. It appears most closely related to Tridens, Gouinia,
and Leptochloa. The habit of producing cleistogenes within the sheaths
and the disarticulating culms are distinctive. (Chloridoideae: Eragros-
teae.)

Triplasis purpurea (Walt.) Chapm., var. caribensis Pohl, Iowa
State J. Res. 47:76. 1972. Aira purpurea Walt., Fl. Carol. 78. 1788.
Figure 215.

Probably perennial; culms 60-75 cm. long, branching only at the base, in dense tufts;
short rhizomes occasional; nodes appressed-pilose to nearly glabrous, not prominent;
leaves 17 to 21 per culm, the blades successively shorter from base to apex of the culm;
sheaths mostly overlapping, scabrid; ligule a dense ring of white hairs, 0.5-1.0 mm. long;
lower blades 10-15 cm. long, 2-4 mm. wide, scabrid, the midribs not evident; uppermost
blade much reduced, less than 1 cm. long. Peduncle included or exserted up to 3 cm.;
exserted inflorescences terminal and axillary from upper nodes; terminal panicle few-
branched, very open, with few spikelets appressed to the branches. Spikelets laterally
compressed, 6-8 mm. long, disarticulating above the glumes and between the florets;
first glume 2 mm. long, 1-nerved, lanceolate, bifid at the apex; second glume similar,
2.5-3.0 mm. long; florets 2-3; rachilla pilose at the apex of the internodes; lemma 3.6 mm.
long, lanceolate, 3-nerved, the lateral nerves near the margin; lemma bifid ca. 1 mm. at
the tip, with a minute awn arising between the teeth; nerves all finely ciliate; palea 2.7
mm. long, bowed outward, strongly ciliate on the upper third of the keels; anthers 3, 2
mm. long, purplish. Plants producing concealed cleistogenes at most nodes and disar-
ticulating into separate internodes at maturity; cleistogenes usually 1-flowered. Cleis-
togene borne within a strongly folded rigid prophyllum and consisting of a single floret

FIG. 215. Triplasis purpurea var. caribensis. A, growth habit; B, a spikelet and two
florets; C, terminal panicle.

573

574 FIELDIANA: BOTANY

with delicate and nearly glabrous lemma and palea; rachilla prolonged behind the palea
as a minute bristle; glumes lacking. In some sheaths, a stiff peduncle bearing several
more prophyllate cleistogenes occurs. No evidence of stamens can be found in the cleis-
togenes, suggesting that the production of the caryopses is apomictic. Chromosome
number n = 20 from the type collection.

The plants are common on the sandy beach of the Caribbean at the
Limon Airport, and at Playa Westfalia. They have been seen blooming
from June to September, but may have a much longer blooming sea-
son. Type of the variety: Prov. de Limon, sandy open beach, between
Limon Airport and the Rio Banano along Caribbean Coast; elevation 2
m., scattered but forming an extensive stand, Pohl & Davidse 11080,
16 September 1969. Plants which are apparently identical were col-
lected at Travesia, Puerto Cortes, Honduras (Dickson 2017, in EAP).

This variety is similar to T. purpurea var. purpurea of the United
States, but differs in its taller and stouter culms, in the much larger
number of leaf-bearing nodes, in the perennial habit and occasional
production of rhizomes, and in the absence of the long, pustulose-based
trichomes of var. purpurea.

TRIPSACUM Linnaeus

REFERENCES: H. Cutler & E. Anderson, A preliminary survey of the
genus Tripsacum. Ann. Missouri Bot. Gard. 28:249-269. 1941. L. F.
Randolph, Variation among Tripsacum populations of Mexico and
Guatemala, Brittonia 22:305-337. 1970.

Stout erect perennials, the culms arising from short, thick rhizomes; internodes solid,
maizelike; leaf blades large, broad, flat; inflorescences terminal on the main culm and
axillary from the upper sheaths. Inflorescences spikelike, 1-many borne at the apex of
each stout peduncle. Individual inflorescence a spikelike rame, the basal portion con-
sisting of a series of thick, bony, hollow internodes, each enclosing a solitary pistillate
spikelet; successive spikelets borne on opposite sides of the rachis, their first glumes
closing off the hollow in which the remainder of the spikelet is hidden; individual inter-
nodes of the pistillate portion of the inflorescence separating at maturity, falling with the
enclosed pistillate spikelets; upper portion of the rame with a flattened, jointed, non-
disarticulating rachis, each internode bearing at its base 2 staminate spikelets, either
both sessile or one pedicellate; all the staminate spikelets borne on the same side of the
flattened rachis. Pistillate spikelets: First glume rigid, dorsally flattened, triangular-
ovate, acute, closing off the hollow of the rachis completely, its margins sharply inflexed
and clasping the second glume; second glume as long as the first, ovate, acuminate, firm,
many-nerved; lower (sterile) lemma membranaceous, ovate, acuminate, with a hyaline
palea; upper (fertile) lemma hyaline, its palea well-developed, nearly as long as the
lemma; flower pistillate; ovary tapering into a short style; stigmas 2, linear, short-
bearded for their full length. Staminate spikelets: Awnless, oblong, triangular in cross
section; first glume facing away from the rachis, firm, many-nerved, its margins sharply
inflexed, clasping the edges of the strongly-keeled, membranaceous, boat-shaped second

BURGER: FLORA COSTARICENSIS 575

glume; florets 2, nearly equal; lemmas and paleas hyaline; lemma of lower floret flat, that
of the upper floret keeled; paleas ca. equal to the lemmas; lodicules 2, truncate; anthers
3, large; ovary absent.

The genus Tripsacum is closely related to Zea (maize and teosinte)
and has been experimentally crossed with it. The pistillate portion of
the inflorescence is similar to the pistillate spike of teosinte. The basic
chromosome number of Tripsacum, however, is x = 9 whereas that
of Zea is x = 10. The pistillate spikelets are solitary, but those of
maize are paired. Tripsacum, like Zea, is native only to the western
hemisphere and is most diverse in the tropics, a single species ex-
tending northward to the midwestern United States. (Panicoideae:
Andropogoneae . )

Tripsacum laxum Nash, N. Amer. Fl. 17:1:81. 1909.

Tall, vigorous perennial, the culms to 4-5 m. tall, the bases becoming decumbent and
rooting; internodes 2-3 cm. thick, solid, glabrous; nodes glabrous, dark; sheaths mostly
overlapping, glabrous; ligule a thin membrane, ca. 1 mm. long; upper leaf blades up to 80
cm. long, 4-8 cm. wide; lower surface glabrous, the upper sparsely papillose-pilose near
the base or merely papillose. Terminal inflorescences with 5-8 fascicled rames; axillary
inflorescences usually of a single rame; individual rames with a basal portion usually 3-4
cm. long, consisting of 4-6 internodes bearing pistillate spikelets, the segments 6-9 mm.
long, thick and rigid, shiny; pistillate spikelets 5-8 mm. long; staminate upper portion of
the rame up to 30 cm. long; staminate spikelets paired, one subsessile and the other on a
pedicel 3-4 mm. long; spikelets obovate, acute; first glume as long as the spikelet,
dorsally flattened, 10-15-nerved, minutely hispid on the back, the margins scabrous-
ciliate.

This species has been cultivated for forage in Costa Rica, and at
times persists as a fence-row or roadside plant. We have collected
semi- wild plants from the vicinities of Turrialba, Villa Neilly, and Bar-
bacoas, at elevations from 600-1,100 m. The plants are apparently
sterile, producing practically no good pollen. One of our specimens has
the pistillate spikelets heavily infected with ergot. Dr. Randolph
states that this species is known only from cultivation or as an escape.

The following other types of Tripsacum have been collected by us or
recorded by others from Costa Rica.

Tripsacum latifolium Hitchc., Bot. Gaz. 41:294. 1906. (Atypical).
Figure 216.

The sparsely hispid leaf blades are much narrower than those of P. laxum, and have
only a single rame on each peduncle. Chromosome number from this specimen was
n = 36, with much meiotic abnormality, including formation of univalents and quadriva-
lents. Pollen was all sterile.

The above specimen, named as T. latifolium by Dr. Randolph, was
collected on the beach of the Bay of Nicoya at Manzanillo (P. & D.

FIG. 216. Tripsacum latifolium. A, inflorescences with pistillate basal portions and
staminate terminal parts; B, two segments of the pistillate rachis; C, portion of the
staminate part of the rachis.

576

BURGER: FLORA COSTARICENSIS 577

11624)- The colony should be studied again and more complete material
obtained.

Tripsacum maizar Hernandez & Randolph, Sec. Agric. Ganad.
(Mexico) Of. Est. Exp. Fol. Teen. 4:7. 1950.

This species has densely hispid sheaths. The terminal inflorescences have numerous
rames, and the staminate portions of the rames are elongate, slender, and drooping.

Two old cultivated specimens from Finca Las Concavas and the San
Jose area are in the U.S. National Herbarium. The labels indicate that
the plants bore the common name of Maicillo.

TRISETUM Persoon

Tufted or rarely stoloniferous perennial grasses; inflorescence a terminal panicle.
Spikelets laterally compressed, 2-several-flowered; glumes unequal or subequal, the
second nearly as long as the spikelet, faintly nerved; disarticulation above the glumes
and between the florets; lemmas faintly 5-nerved, awned from the back above the
middle, or nearly awnless in one species; the apex 2- or 4-toothed; paleas slightly
shorter than the lemmas; rachilla prolonged above the uppermost floret as a usually
hairy bristle.

A genus of ca. 75 species, in temperate and cold climates of both
hemispheres, related to Deschampsia and Aira. (Pooideae: Aveneae.)

KEY TO SPECIES OF Trisetum

la. Awn minute, straight, not exserted from glumes T. pringlei

Ib. Awn conspicuous, usually longer than lemma, geniculate and well exserted from

glumes 2

2a. Panicle open, pyramidal, branches verticillate, naked at base; lemmas 4-toothed

at apex T. tonduzii

2b. Panicles slender, narrowly cylindrical, the branches appressed, mostly bearing
spikelets to their bases; lemmas not 4-toothed 3

3a. Glumes shorter than florets, the first narrow, 1-nerved, second ovate, 3-nerved;
lemmas scabrous-roughened T. irazuense

3b. Glumes nearly as long as spikelet, equal, linear, 1-nerved; lemmas smooth, gla-
brous T. deyeuxioides

Trisetum deyeuxioides (H.B.K.) Kunth, Rev. Gram. 1:102. 1829.
Avena deyeuxioides H.B.K., Nov. Gen. & Sp. 1:147. 1816. Figure 217.

Caespitose perennial, in small clumps; culms leafy, slender and weak, unbranched,
hollow, thin-walled, glabrous, the bases often decumbent; nodes glabrous, dark, not
prominent; sheaths ca. as long as the interned es, glabrous or the lower weakly pubes-
cent; ligule a lacerate-ciliolate membrane, 0.5-3.5 mm. long, one side decurrent onto the
sheath margin; blades lax, 8-16 cm. long, 2-6 mm. wide, usually glabrous, scabrid.
Panicle solitary, terminal, loose and nodding, 10-20 cm. long, 1-4 cm. wide, the branches
up to 7 cm. long, ascending, densely covered with spikelets; aspect plumy because of the
abundant long hairs of the rachilla segments. Spikelets numerous, appressed along the
branches of the panicles, laterally compressed, 5-6 mm. long, 2-flowered, disarticulating

FIG. 217. Trisetum species. T. deyeuxioides: A, spikelet; T. pringlei: B, spikelet; T.
irazuense: C, spikelet; T. tonduzii: D, spikelet.

578

BURGER: FLORA COSTARICENSIS 579

above the glumes and at the base of the second floret; glumes linear, equal, nearly as
long as the spikelet, 1-nerved, scabrous on the keel, folded, acute, the keel greenish, the
margins silvery or purple; first glume 4.2-5.5 mm. long, the second 4.9-5.5 mm. long;
florets 2; lemmas narrowly lanceolate, the lower 4.2-5.0 mm. long, the upper shorter,
rounded on the back, bidentate at the tip, glabrous; callus oblique, sparsely short-
bearded with hairs up to 0.5 mm. long; awn 5-7 mm. long, inserted about the middle of
the back, geniculate, exserted from the glumes, the basal segment loosely contorted;
palea nearly as long as the lemma; rachilla segments slender, ca. 1.5 mm. long, the apex
with abundant silky white hairs up to 3 mm. long; anthers 2, 1.5 mm. long, yellow;
caryopsis linear, soft, the endosperm remaining pasty. Chromosome number n = 14
from Costa Rican material.

Occasional in moist open places, especially along roads and in brush,
in and around the Meseta Central; elevations from 1,100-2,500 m.;
June to November. Mexico, Guatemala, Honduras, Costa Rica,
Panama, to Ecuador.

Trisetum irazuense (Kuntze) Hitchcock, Proc. Biol. Soc. Wash.
40:82. 1927. Calamagrostis irazuensis Kuntze, Rev. Gen. PL 2:763.
1891. T. scabriflorum Hitchc., Contr. U.S. Natl. Herb. 24:358. 1927.
Figure 217.

Perennial; 45-105 cm. tall; culms unbranched, erect, or the bases decumbent and
rooting, 1-2 mm. thick, hollow, mostly glabrous, or retrorsely pubescent below the dark,
contracted nodes; sheaths more or less retrorsely pilose, sometimes densely so; ligule
membranaceous, 1-3 mm. long, sometimes hairy on the back, decurrent on the sheath
margin; blades flat, 10-33 cm. long, 2-5 mm. wide, more or less pilose on both surfaces,
the uppermost blade often reduced. Peduncle slender, up to 30 cm. long; inflorescence
terminal, solitary, a narrow, somewhat loose panicle, nodding, 13-30 cm. long, 1-3 cm.
wide, the branches ascending, up to 6 cm. long, naked at the base, rather densely
flowered; spikelets appressed along the branches, overlapping, borne on pedicels of
varying lengths. Spikelets narrow, 6-9 mm. long, with 2-4 florets; first glume 3-5 mm.
long, narrowly triangular, 1-nerved, scabrous on the upper half of the keels; second
glume narrowly obovate, 3.8-6.5 mm. long, 3-nerved, green between the nerves and
with a broad whitish margin; lowermost lemma 4.3-6.0 mm. long, the others successively
shorter, the terminal as short as 3.0 mm.; lemmas lanceolate, shortly bidentate at the
apex, rugose and scabrous all over the rounded back; callus hairs scanty, ca. 0.5 mm.
long; awn 6-9 mm. long, inserted ca. one-third below the apex, geniculate; paleas slightly
shorter than their lemmas; rachilla internodes slender, bearded, 1.7-2.0 mm. long, the
hairs longest at the apex, ca. 1.5 mm. long; anthers 3, 1.0-1.3 mm. long, tan. Caryopsis
soft, the endosperm pasty.

Pastures and devastated areas, Irazii and Turrialba; 2,600-2,800 m.
elevation. August to November. Mexico to Panama; Colombia and
Venezuela to Ecuador.

Several of our recent specimens from Irazu are vegetatively much
larger and more vigorous than the specimens from Turrialba, possibly
because of the increased soil fertility added by the eruption of Irazu.

Trisetum pringlei (Scribn.) Hitchc. Proc. Biol. Soc. Wash. 40:82.

580 FIELDIANA: BOTANY

1927. Graphephorum pringlei Scribn. in Beal, Gr. N. Amer. 2:561.
1896. Figure 217.

Perennial, in small clumps; plants erect, 30-80 cm. tall; the culms erect or with decum-
bent bases, unbranched, slender, hollow, glabrous; culm nodes 2, dark, contracted, one
near the base, the other at midculm; sheaths elongated, glabrous or retrorsely puberu-
lent or velvety; ligules membranaceous, erose, 1-2 mm. long, prolonged into a sheath
auricle on one side; blades mostly basal, 4-12 cm. long, 2-5 mm. wide, more or less
puberulent beneath, longitudinally ridged and scabrous above, often involute. Peduncle
5-15 cm. long; panicle solitary, terminal, slender but nodding, the branches whorled,
ascending, up to 8 cm. long, naked near the base; spikelets mostly short-pedicellate,
appressed to the branchlets, often purplish. Spikelets narrowly oblong, laterally com-
pressed, 4.5-6.5 mm. long, disarticulating above the glumes and between the florets;
first glume narrowly ovate, acute, 1-nerved, 1.5-2.6 mm. long; second glume narrowly
ovate to oblong, acute, 3-nerved, 3.5-4.5 mm. long; florets 2-3, the lemmas rounded on
the back, scabrous or short-pubescent on the lower two-thirds of the back, 5-nerved,
often purplish above, tapering to an acute apex, awnless or with a short straight awn
less than 1 mm. long just below the apex; lowermost lemma 3.6-4.0 mm. long, the upper
ones successively shorter, to 2.8 mm. long; paleas ca. three-fourths as long as the
lemmas, scabrid on the keels; rachilla internodes bearded, ca. 1.5 mm. long, the terminal
one to two-thirds as long as its lemma; anthers 3, purple, 0.7-1.2 mm. long. Chromosome
number n = 14 from Costa Rican material.

This species has been collected from the upper cinder cone of Irazu,
and from paramos of Cerro Asuncion, Cerro Buena Vista, and Chirripo
Grande, at altitudes of 3,150-3,400 m. Blooming from June to De-
cember. The population from Irazii has pronouncedly pubescent lem-
mas, whereas those from the Cordillera de Talamanca population are
much less so. Southern Mexico and Guatemala; Costa Rica; Volcan
Chiriqui, Panama.

Trisetum tonduzii Hitchc., N. Amer. Fl. 17:558. 1939. Figure 217.

Perennial; plants 45-85 cm. tall; culms erect, or in very moist places, becoming decum-
bent and trailing, terminating in dense moplike clusters of foliage, with new culms
arising from them; branching from the bases of the culms. Culms hollow, glabrous, the
nodes dark, glabrous; sheaths glabrous or occasionally slightly retrorsely hispid on the
collar, mostly overlapping; ligule membranaceous, lacerate-ciliolate, decurrent on one
sheath margin, 1.5-3.0 mm. long; blades firm, up to 21 cm. long, 4-6 mm. wide, glabrous
or loosely pubescent above, often becoming involute, especially toward the apex. Pedun-
cle glabrous, 6-10 cm. long; panicles ovoid-pyramidal, many-flowered; branches verticil-
late, up to 7 per node, naked below, rather densely flowered on the outer two-thirds.
Spikelets laterally compressed, 4.5-6.5 mm. long; glumes subequal, 4.0-6.5 mm. long,
usually purple, lanceolate, acute or awn-tipped, the first 1-3-nerved, the second 3-
nerved; florets 2; lower lemma 3.8-6.0 mm. long, lanceolate, rounded on the back,
slightly scabrid, usually purple toward the tip, the nerves faint; apex bifid above the
insertion of the awn, each lobe acuminate and terminating in 2 awnlike teeth; awn
geniculate and loosely spiral, 7-13 mm. long, well exserted from the spikelet; upper floret
similar but smaller, its lemma 2.8-5.0 mm. long; callus of the lemmas strongly white-
bearded, the hairs ascending, up to half the length of the lemma; rachilla segments
white-bearded, especially near the summit; sterile rachilla segment above the second

BURGER: FLORA COSTARICENSIS 581

lemma ca. 2 mm. long; paleas slightly shorter than the lemmas; anthers 3, 1.7-2.0 mm.
long, purple. Caryopsis soft, the endosperm pasty. Chromosome number n = 14 from
Costa Rican material.

This handsome species occurs near the craters of Poas, Irazu, and
Turrialba, at elevations of 2,600-3,400 m. It grows on volcanic mud and
cinders and in meadows, often on steep slopes. It was characterized by
Hitchcock as being rhizomatous. Our observations suggest, rather,
that the culms become decumbent and finally produce dense fascicles of
foliage near their tips. June to August. Endemic to the volcanoes of the
Meseta Central.

UNIOLA Linnaeus

REFERENCE: H. 0. Yates, Revision of grasses traditionally referred
to Uniola, I. Uniola and Leptochloopsis. Southwestern Nat. 11:372-
394. 1966.

Harsh perennial beach grasses, stoloniferous or rhizomatous; spikelets in panicles,
strongly compressed and keeled; disarticulation below the glumes; glumes subequal,
shorter than the lowermost floret, acute, 3-nerved; glumes and lemmas all compressed-
keeled; lower 2-6 lemmas empty; lemmas broad, acute, strongly keeled, chartaceous,
3-9-nerved; palea bowed, shorter than the lemma. (Chloridoideae: Unioleae.)

Uniola pittieri Hackel, Oesterr. Bot. Z. 52:309. 1902. Figure 218.

Stout stoloniferous perennial; culms 75-150 cm. tall, unbranched, erect; stolons stout,
extensive, abundant, up to 18 m. long; culms 3-4 mm. thick, hollow, glabrous; nodes
glabrous, not prominent, rarely exposed; leaf sheaths mostly longer than the internodes,
overlapping, glabrous except for ciliolate upper margins; collar dark, sometimes pu-
berulent; auricular hairs prominent, cottony; ligule a dense circle of hairs, ca. 1 mm.
long; leaf blades coriaceous, flat, tapering to a long involute tip, up to 70 cm. long and 15
mm. wide, scabrous, glabrous except for some pubescence just above the ligule, strongly
ridged above; leaves about 6-7 per culm. Peduncle solitary, terminal, included or ex-
serted up to 20 cm., cylindrical, hollow, glabrous; panicle rather dense, cylindrical,
narrow, about 20-40 cm. long; rachis and branches angular, scabrid; spikelets very
numerous, densely overlapping along the short, ascending branches, borne in 2 rows
along the lower sides of the branches, subsessile, the pedicels 1 mm. long or less;
disarticulation below the glumes only; spikelets 8-25 mm. long, very strongly laterally
compressed, the lemmas and glumes winged, especially near the tips; glumes 3-6 mm.
long, lanceolate, 3-nerved, acute; florets 10-20, the lower several empty and without
paleas; most of the florets sterile; lemmas 4.5-5.5 mm. long, ovate, acute, the keel
incurved; nerves usually 5, green-striped when young; glabrous but the margins mi-
nutely ciliolate; keel scabrous; palea strongly bikeeled, the nerves conspicuous, the keels
ciliolate; anthers 3, 2-3 mm. long, yellow; caryopses not seen. Chromosome number n =
20 from a Costa Rican specimen.

Uniola pittieri is common on sandy beaches along the Pacific Coast
and has been collected from the area of Puerto Limdn. Inflorescences
may be found on the plants at almost all seasons of the year. Baja
California to Ecuador and Colombia, on sea beaches.

FIG. 218. Uniola pittieri. Panicle, spikelet, stolon, plant base.

582

BURGER: FLORA COSTARICENSIS 583

Like the North American U. paniculata, this species appears to be
almost sterile, reproducing primarily by the very extensive stolons.
The inflorescences are decorative and are sometimes sold in stores,
either in the natural state or gilded. The plants are valuable as sand
binders on the low dunes just back of the storm beaches.

UROCHLOA Beauvois

Leaf blades flat, broad; inflorescence a panicle of simple one-sided racemes, the
spikelets short-pedicellate, solitary or paired in 2 rows along the lower sides of a
triquetrous rachis, with their first glumes turned away from the midrib of the rachis.
Spikelets disarticulating below the glumes, dorsally compressed, ovate, awnless; first
glume much shorter than the spikelet; second glume and lower (sterile) lemma subequal,
as long as the spikelet, 5-7-nerved in our species; lower lemma with a palea ca. as long,
and a staminate flower; upper (fertile) floret slightly shorter than the lower one, elliptic,
the lemma stiff or rigid, rugulose, terminating in a short mucro; palea of similar length
and texture; lodicules 2; anthers 3; styles separate; caryopsis elliptical, with a large
embryo.

Tropics of the Old World, with the exception of the following intro-
duced species. About 20 species. The genus is closely related to
Brachiaria, but the position of the spikelets is reversed, the first
glumes of the spikelets facing outward, and the fertile lemmas are
mucronate. Also, the following species has a chromosome number base
of x = 7, which occurs in other species of Urochloa, whereas that of
Brachiaria is usually x = 9. (Panicoideae: Paniceae.)

Urochloa reptans (L.) Stapf, Fl. Trop. Africa 9:601. 1920. Panicum
reptans L., Syst. Nat. 10:870. 1759. Brachiaria reptans (L.) Gard. &
C. E. Hubb., Hook. Icon. PL 3363:3. 1938. Figure 219.

Duration indefinite; culms decumbent and rooting from the nodes of the prostrate
portions; erect branches 10-40 cm. long; internodes 1 mm. or less thick, hollow, thick-
walled, glabrous; nodes elongate, light-colored, puberulent; leaf sheaths much shorter
than the internodes, finely and densely papillose-ciliate on the overlapping margin, the
surfaces glabrous or sparsely papillose-hispid; ligule a short, densely ciliate membrane,
in total 0.7-1.0 mm. long; leaf blades cordate-ovate 2.5-7.5:1, 2.5-6.5 cm. long, 6-10 mm.
wide; margins prominently papillose-hispid ciliate on the cordate base, the surfaces
glabrous, sparsely papillose-hispid or puberulent; margins with a thick band of scleren-
chyma. Peduncle 3-11 cm. long; inflorescences terminal on leafy branches, 4-6 cm. long
and ca. as wide, composed of 3-10 short ascending racemes, 1-3 cm. long, solitary or
paired along the central rachis; racemes simple or with short secondary branches near
the base; spikelets paired or solitary along the lower 2 sides of the triquetrous scabrous
rachis; pedicels short, unequal, scabrous or bearing a few papillose-based hairs. The
orientation of spikelets is with the first glume outward when the spikelets are solitary;
arrangement is less definite when they are paired or clustered. Spikelets 1.8-2.1 mm.
long, ovate 2:1, acute, glabrous; first glume 0.3-0.5 mm. long, blunt, collar-like, nerve-
less; second glume and lower (sterile) lemma equal, as long as the spikelet; second glume
7-nerved; lower lemma 5-nerved, with an equal palea and a staminate flower; upper

FIG. 219. Urochloa reptans. A, blooming plant; B, two views of a spikelet; C, fertile
floret.

584

BURGER: FLORA COSTARICENSIS 585

(fertile) lemma elliptical 1.7:1, rigid, rugulose, 1.6-1.7 mm. long, with a definite mucro
ca. 0. 1 mm. long; areole (germination lid) visible at the base of the lemma; palea of equal
length and similar texture; lodicules 2, truncate; anthers 3, yellow-orange, 0.7-1.0 mm.
long; style branches naked below; stigmas purple; caryopsis broadly elliptical 3:2,
whitish, ca. 1.2 mm. long, with a large embryo. Chromosome numbern = 7 from a Costa
Rican specimen.

Occasional at low elevations below 100 m. in Guanacaste, mostly
near the Pacific Coast; open roadsides, savannas. June to October.
Introduced from the Old World; southern United States, eastern
Mexico, El Salvador, Costa Rica; West Indies and northern South
America.

VETIVERIA Bory

Densely caespitose tall perennial, forming large clumps; basal leaves abundant, stiff,
erect, folded; flowering rare; inflorescence a large solitary terminal panicle of verticillate
stalked rames. Spikelets paired at each node of the disarticulating rachis, one sessile and
one pedicellate. Spikelets laterally compressed, echinate, awnless, the members of each
pair equal and fertile. (Panicoideae: Andropogoneae.)

Vetiveria zizanioides (L.) Nash, in Small, Fl. S.E. U.S. 67. 1903.
Phalaris zizanioides L., Mant. PI. 183. 1771. Anatherum zizanioides
(L.) H. & C., Contr. U.S. Natl. Herb. 18:285. 1917. Chrysopogon
zizanioides (L.) Roberty, Mon. Androp. 291. 1960. Figure 220.

Perennial in large dense clumps; foliage mostly basal, the leaf sheaths closely overlap-
ping, strongly compressed and keeled; ligules densely ciliate, 0.5-1.5 mm. long; leaf
blades scarcely distinguished from the sheaths, stiff and erect, folded, with a conspicu-
ous keeled midrib below, the basal blades up to 1 m. or more long, 6-8 mm. wide; sheaths
and blades glabrous except for the upper leaf surface just above the ligule. Culms rarely
produced, up to 2 m. tall, solid, somewhat compressed, their leaves shorter than the
basal ones. Inflorescence a solitary terminal panicle of rames, borne on a glabrous
peduncle up to 50 cm. long; panicle open-cylindrical, with numerous verticillate ascend-
ing slender branches (rames), the longer ones up to 10 cm. long; spikelets paired, one
sessile and one pedicellate, at each node of the readily disarticulating rachis. Spikelets
lanceolate, purplish; glumes stiff, echinate with short, stiff, pustulose-based bristles in
lines along the keels and lateral nerves, equal, 3-5-nerved, 4.0-5.5 mm. long, completely
concealing the florets; lower floret sterile, consisting of a membranaceous, faintly 3-
nerved narrowly lanceolate lemma, slightly shorter than the glumes; fertile upper floret
with membranaceous, faintly nerved narrow lemma shorter than the lower lemma, and a
linear palea ca. half as long as the lemma; lemma tip sometimes bifid and with a minute
awn tip arising between the teeth; lodicules 2, truncate, fleshy; anthers 3, yellow, 1.8-2.0
mm. long; style branches naked below. Chromosome number n = 10 from a Costa Rican
specimen.

Commonly used as a hedge plant in the Meseta Central, planted
along the top of road embankments in a continuous row, to prevent
erosion. Usually cultivated, but volunteer colonies, apparently from
seed, may be found near cultivated stands. Blooming is rare, but we

FIG. 220. Vetiveria zizanioides. A, panicle of rames; B, culm base; C, segment of a
rame, with sessile and pedicellate spikelets.

586

BURGER: FLORA COSTARICENSIS 587

have two blooming specimens, one from Guayabo, and the other from
Venecia. Low to middle elevations. October to January.

This Asiatic species is cultivated in warm climates. The roots can be
used to produce a perfume (vetiver or khus-khus). It is naturalized to
some extent in the southern United States and the Caribbean Islands.
We have specimens from Honduras and Costa Rica.

VULPIA Gmelin

REFERENCES: J. Henrard, A study in the genus Vulpia, Blumea
2:299-326. 1937. R. I. Lonard & F. W. Gould, The North American
species of Vulpia (Gramineae), Madrono 22:217-230. 1974. E. Paunero,
Notas sobre gramineas 2. Consideraciones acerca de las especies es-
panolas del genero Vulpia Gmel., Anales. Inst. Bot. Cavanilles 22:81-
114. 1964.

Slender tufted annual grasses; inflorescence a solitary terminal panicle; spikelets with
several florets; glumes shorter than the florets, the first shorter and narrower than the
second, 1-nerved, the second usually 3-nerved; lemmas slender, with a hard callus, often
with inrolled margins, obscurely 5-nerved, tapering into a slender awn; palea nearly as
long as the lemma; anther one, usually retained within the cleistogamous floret.

About 25 species, especially numerous in Mediterranean Europe,
western North America, and South America. The genus is closely
related to Festuca, from which it differs in having annual species with
a single anther and predominantly cleistogamous reproduction. Hy-
brids between the two genera have been reported. (Pooideae: Poeae.)
KEY TO SPECIES OF Vulpia

la. Lemmas ciliate on upper margins V. myuros var. hirsuta

Ib. Lemmas not ciliate V. bromoides

Vulpia bromoides (L.) S.R. Gray, Natur. Arrange. Brit. PL 2:124.
1821. Festuca bromoides L., Sp. PL 75. 1753. Festuca dertonensis
(All.)Asch. & Graebn., Syn. Mitteleurop. Fl. 2:558. 1901. Figure 221.

Short-lived annual, in small clumps; plants 20-65 cm. tall; culms erect or with decum-
bent bases, slender, glabrous, hollow, unbranched or branching just above the base;
prophylla prominent, up to 22 mm. long; foliage scanty, mostly basal; culms with 2 nodes;
sheaths shorter than the internodes, glabrous; ligule a minute membranaceous fringe;
blades flat or folded, soft and weak, 3-7 cm. long, ca. 1 mm. wide, puberulent above.
Peduncle long-exserted, 15-25 cm. long, slender, glabrous; panicle solitary, terminal,
slender, 2-12 cm. long, the short branches paired or solitary, erect and appressed to the
rachis, few-flowered, the spikelets mostly overlapping. Spikelets 7-10 mm. long,
excluding the awns; first glume 2.3-4.3 mm. long, subulate, 1-nerved; second glume
narrowly lanceolate, 3-nerved, 4.6-6.7 mm. long; florets 4-7; lemmas narrowly lanceo-
late, 5.5-7.0 mm. long, with inrolled margins, faintly 5-nerved, glabrous or scabrid
above, tapering into an awn 7-10 mm. long; palea nearly as long as its lemma; anther
single, 0.4-1.5 mm. long. Chromosome number n = 7 from Costa Rican material.

FIG. 221. Vulpia species. V. bromoides: A, panicle; B, spikelet; V. myuros var.
hirsuta: C, spikelet; D, floret.

588

BURGER: FLORA COSTARICENSIS 589

Disturbed open areas, cinder slopes, roadsides; probably blooming
yearlong; elevations 2,000-3,000 m. Introduced from Europe; western
United States and Canada, Baja California, Guatemala, South
America.

Vulpia myuros (L.) K. Gmelin, var. hirsuta Hack., Cat. Gram.
Port. 24. 1880. Festuca myuros L., var. hirsuta (Hack.) Asch. &
Graebn., Syn. Mitteleurop. Fl. 2:558. 1901. Vulpia megalura (Nutt.)
Rydb. Bull. Torrey Bot. Club 36:538. 1909. Festuca megalura Nutt.,
Acad. Philadelphia 11:1:188. 1848. Figure 221.

Short-lived annual, caespitose, erect in small clumps, 10-70 cm. tall; culms un-
branched, ca. 1 mm. thick, hollow, glabrous; nodes glabrous; sheaths glabrous, auricled;
ligule a short membrane, 0.2-0.7 mm. long; blades mostly 10 cm. or less long, 1-2 mm.
wide, folded or involute, glabrous or the upper surface puberulent. Inflorescence a
slender, erect terminal panicle, 5-20 cm. long, the branches appressed; spikelets mostly
very short-pedicelled, appressed to the branches. Spikelets 8-10 mm. long, excluding the
awns; first glume acicular, 1-nerved, 0.2-2.0 mm. long; second glume subulate, 1-nerved,
3.0-4.5 mm. long; lemmas narrowly lanceolate, scaberulous in lines, obscurely 5-nerved,
their upper margins conspicuously ciliate with soft hairs; lowermost lemma 5.5-8.0 mm.
long, the upper ones successively shorter, their apices usually at one level; awns 7-17
mm. long; paleas ca. three-fourths the length of the lemmas, scabrous on the keels;
anther 1, purplish, 0.3-1.2 mm. long. Chromosome number n = 21 from the Costa Rican
material.

Cultivated field, San Juan de Chicoa, Irazu. November. Introduced
from Europe. This species is widespread in western United States and
is known from Mexico and Guatemala. The Costa Rican occurrence
probably represents a recent introduction, since it is from the same
site as our only collections of Nassella linearifolia and Muhlenbergia
ramulosa, both Mexican species.

ZEA Linnaeus

Tall caespitose annual grass with thick, solid culms, often reaching a height of 3-5 m.
Monoecious, with the staminate spikelets borne in a terminal paniculate inflorescence
made up of several to many rames bearing paired staminate spikelets, one member of
each pair sessile or subsessile and the other pedicellate; glumes of staminate spikelets
soft, herbaceous, many-nerved, equal, concealing the 2 hyaline equal florets; flowers
with 3 large anthers. Pistillate spikelets borne on an axillary spike (cob, mazorca) that is
covered and concealed by numerous overlapping bracteal leaves, only their elongated
styles or silks protruding at the tip; spikelets paired, borne in longitudinal rows, cover-
ing the entire surface of the cob; compression dorsal; first glume, second glume, and
lower (sterile) lemma represented by small scales or chaff on the surface of the cob; lower
floret without a flower except in unusual strains; upper floret developing an enlarged
naked kernel that very tardily disarticulates, usually only by human action, from the
remainder of the spikelet, leaving the bracts on the cob; kernels usually mutually com-
pressed and becoming angular at maturity; style 1, becoming the elongated "silk," with-
out evidence of separate stigmas.

590 FIELDIANA: BOTANY

Zea mays L., Sp. PI. 971. 1753.

This is the common maize of the Americas, of which a myriad of
strains exist. Tropical forms, such as are planted in Costa Rica, are
very tall and slow-growing, the culms often being supported by
numerous prop roots. The species is unknown except in cultivation,
although wild maize [Zea mexicana (Schrad.) Reeves & Mangelsd.]
occurs from southern Mexico to Honduras. This is commonly called
teosinte and may occasionally be cultivated.

ZEUGITES P. Browne

Perennial grasses; leaf blades tessellate, borne on pseudopetioles; inflorescence a
panicle; spikelets several-many flowered, disarticulating below the glumes; lowermost
floret pistillate, all the others staminate; glumes tessellate, the first broader than the
second.

The only close relative of Zeugites in Central America is Orthoclada.
Both genera have uncinate microhairs on the epidermis. (Arun-
dinoideae: Centosteceae.) In classical Latin, the name Zeugites was
regarded as masculine. By common taxonomic usage, it has been used
as feminine.

KEY TO SPECIES OF Zeugites

la. Leaf blades 25-45 cm. long, 4-7 cm. wide; culms 1-4 m. tall, erect to arching

Z. pittieri
Ib. Leaf blades 2-5 cm. long, 1-2 cm. wide; culms weak, decumbent

Z. mexicana

Zeugites mexicana (Kunth) Trin. ex Steud., Nom. Bot. ed. 2. 2:798.
1841. Senites mexicana (Kunth) Hitchc., Contr. U.S. Natl. Herb.
17:370. 1913. Despretzia mexicana Kunth, Rev. Gram. 2:485. PL 157.
1831. Figure 222.

Sprawling perennial, occasionally rhizomatous in litter; branching profuse, often with
several branches from one axil; prophylla prominent, 1.5-2.0 cm. long; culms 1-2 mm.
thick, hollow, smooth and shining, glabrous, brownish; leaf sheaths shorter than the
internodes, glabrous or hirsute; ligule 1-2 mm. long membranous, sometimes hirsute on
the back; leaf blades borne on slender pseudopetioles 7-10 mm. long, with a purplish
hairy pulvinus below the apex; blades ovate, flat, 2.5-4.0 cm. long, 7-19 mm. wide,
glabrous or occasionally with a few long trichomes above; peduncles slender, glabrous,
up to 15 cm. long. Inflorescence a delicate, open, oblong-pyramidal panicle, terminal on
the culm or leafy erect branches; branches few, spreading, the spikelets solitary at the
tips of the branches. Spikelets laterally compressed, 6-8 mm. long, disarticulating below
the glumes and at the base of the staminate floret; glumes 2-3 mm. long, the first broadly
oblong, truncate, the apex truncate and ciliolate, 5-7-nerved; second glume narrower,
oblong, blunt, 3-5-nerved; basal floret pistillate, the lemma 3.5-4.5 mm. long, narrowly

FIG. 222. Zeugites mexicana. A, blooming plant; B, spikelet, showing glumes, pistil-
late lowermost floret, and upper staminate florets.

591

592 FIELDIANA: BOTANY

oblong, blunt, erose, 9-11-nerved, palea slightly longer than the lemma, rachilla joint
nearly as long as the lemma; staminate florets 1 or 2, occasionally the second reduced to a
rudiment, disarticulating as a unit from the apex of the rachilla joint of the pistillate
floret; lemmas 3.0-3.5 mm. long, ovate, acute, 3-5-nerved; anthers 3, 1.5-2.0 mm. long.

Rare; forests, brushy slopes, wet roadsides; 1,500-2,000 m. eleva-
tion. Costa Rican collections are known from Santa Maria de Dota,
Cerro de Piedra Blanca above Escazu, and Los Cartages. The small
size of the plants and their tendency to grow under brush make them
very inconspicuous, and they are probably often overlooked. They are
recognizable at all seasons by their peculiar foliage, but blooming is
sparse and restricted entirely to the short-day season of the year, from
October to January. Southern Mexico to Colombia, Venezuela, and
Bolivia.

Zeugites pittieri Hack.. Oesterr. Bot. Z. 52:373. 1902. Figure 223.

Caespitose perennial; culms in small clumps from hard knotty crowns, erect or arch-
ing, up to 4 m. long, branching above, the larger ones 0.5-1.0 cm. thick; internodes
glabrous, smooth and shining, hollow; nodes glabrous, not prominent; prophylla brown,
shining, 2 cm. long; leaf sheaths strongly ridged, 15-25 cm. long, truncate and promi-
nently auriculate, minutely puberulent; leaf blades borne on flattened pseudopetioles 3-7
mm. long, which are densely hirsute above; blades flat, the larger ones 25-45 cm. long,
45-70 mm. wide, ovate, lower ones much reduced; blades provided with minute bicellular
hairs having oblique cross- walls; uncinate microhairs present. Peduncle thick, stiff, 4-10
cm. long. Inflorescences borne at the apex of the culms and from upper leaf axils;
inflorescence a somewhat congested panicle, 20-30 cm. long, ovoid; branches bearing
spikelets nearly to their bases. Spikelets numerous, overlapping, lying parallel to the
branches, laterally compressed, disarticulating below the glumes, 12-20 mm. long; first
glume 4.5-5.5 mm. long, broadly obovate as folded, nerves 9-11, with cross-nerves;
glumes ciliolate at tip and base; second glume 4-5 mm. long, 7-8-nerved, oblong as folded;
lowermost floret pistillate, its lemma broadly ovate, saccate on the keel above the base,
the lower portions firm and shining, callus pilose, tip ciliolate, nerves 7-13, tip acute or
sometimes minutely awned from a bifid apex; lodicules 2, truncate, vasculated; pistil
with 2 elongated naked styles bearing plumose stigmas; palea nearly as long as the
lemma; staminate florets 6-14; lemmas 3.5-5.0 mm. long, ovate, acute or minutely awn-
tipped, glabrous, nerves 7-8; stamens 3, the anthers 2.5 mm. long, yellow; lodicules 2,
truncate, vasculated; palea nearly as long as the lemma. Chromosome number n = 24
from Costa Rican specimens.

Rare; brushy hillsides, 850-1,250 m. The type is Pittier 1617 from
Alto de Rodeo. The following recent specimens are also known:
Heredia, Puente de Mulas, P. & D. 11350, 1U84; San Jose, Guayabo
de Mora, P. & D. 11401, San Gabriel, P. & D. 11736. Blooming plants
were seen from late October to late February. This species does not
occur elsewhere. Material reported to be of this species from
Guatemala by Swallen (Grasses of Guatemala, 1955) is apparently Z.
latifolia (Fourn.) Hemsl., a more northern species.

FIG. 223. Zeugites pittieri. A, panicle and pseudopetiolate leaf blade; B, spikelet.

593

FIG. 224. Zoysia tenuifolia. A, raceme; B, rhizomatous base of plant; C, spikelet; D,
floret.

594

BURGER: FLORA COSTARICENSIS 595

ZOYSIA Willdenow
Nomen Conservandum

REFERENCES: Ian Forbes, Jr., Chromosome numbers and hybrids in
Zoysia, Agronomy J. 44:194-99. 1952. W. D. Clayton & F. R.
Richardson, The tribe Zoysieae Miq., Stud. Gram. XXXII, Kew Bull.
28:37-48. 1973.

Rhizomatous or stoloniferous perennials; inflorescence a solitary erect terminal
raceme; pedicels solitary. Spikelets appressed to the rachis, laterally compressed, disar-
ticulating entire; first glume absent; second glume stiff, acute or awn-tipped, the mar-
gins united below; floret one, concealed within the folded glume; lemma thin, 1-nerved,
awnless; palea present or absent; stigmas and anthers exserted at the apex of the floret
at anthesis; flower without functional lodicules, protogynous. (Chloridoideae: Zoysieae.)

Zoysia tenuifolia Willd. ex Trin., Mem. Acad. Imp. Sci. St.-
Petersbourg, Ser. 6, Sci. Math. Seconde Pt. Sci. Nat. 2:96. 1838. Fig-
ure 224.

Stoloniferous perennial, often forming loose mounds if not mowed; foliage very fine-
textured; sheaths and blades glabrous, the sheaths overlapping; ligule a minute ciliate
fringe; leaf blades involute, 0.1-0.2 mm. thick, 2-3 cm. long. Peduncles included or
exserted up to 1 cm.; raceme of 5-20 spikelets, these borne on erect pedicels and ap-
pressed to the rachis. Spikelets 2.5-2.8 mm. long, awnless; second glume stiff, lanceolate
as folded; floret completely concealed within the glume; lemma narrowly lanceolate,
1-nerved. Chromosome number n = 20 (Forbes, 1952).

This species is rarely cultivated for lawns and may escape from
cultivation. A large stand of it occurs around the weather station at the
CATIE in Turrialba. It also occurs on the grounds of the experiment
station at Guapiles, in Limon, and on the Campus of the University of
Costa Rica, as well as in a park in Managua. Blooming has been ob-
served in July, August, and December. South Pacific and eastern Asia;
occasionally cultivated in subtropical and tropical regions.

The nomenclature of this genus is in confusion. Forbes believes that
the taxa he studied cytologically and genetically constitute a single
species, but the genus is in need of further study.

INDEX

New taxa and references to illustrations are in boldface. Common
names and Latin names in synonymy are italicized.

Aciachne 22

Aciachne pulvinata 22, 23

Acroceras 24

Acroceras oryzoides 24

Acroceras zizanioides 24, 25

Aegopogon 26

Aegopogon cenchroides 26, 27

Aegopogon tenellus 28

Aegopogon tennellus var. abortivus 28

Aequiglumae 185

African stargrass 163

Agropyron 28

Agropyron attenuatum 29, 30

Agrostis 30

Agrostis alba 32

Agrostis bacillata 31, 37

Agrostis gigantea 32

Agrostis hoffmannii 38

Agrostis indica 544

Agrostis laxissima 35

Agrostis palustris 35

Agrostis perennans 32, 34

Agrostis pittieri 33, 35

Agrostis purpurascens 546

Agrostis pyramidata 547

Agrostis radiata 127

Agrostis stolonifera 35

Agrostis stolonifera var. palustris 35

Agrostis subpatens 36, 37

Agrostis tenuis 36

Agrostis tolucensis 33, 38

Agrostis turrialbae 33, 38

Agrostis virginica 547

Agrostomia aristata 125

Aira 39

Aira caryophyllea 39, 40
Aira flexuosa 171
Aira indica 513
Aira laxa 346
Aira purpurea 572
Aira spicata 513
Alectoridia quartiniana 58
Amphilophis piptatherus 234
Anthaenantia 307
Anatherum zizanioides 585
Andropogon 41, 174, 517
Andropogon amaurus 495
Andropogon angustatus 174
Andropogon bicornis 42, 43
Andropogon bracteatus 263
Andropogon brevifolius 518
Andropogon citratus 158
Andropogon condylotrichus 234
Andropogon fastigiatus 175
Andropogon flaccidus 518
Andropogon glomeratus 43, 44
Andropogon hirtiflorus 520
Andropogon incompletus 533
Andropogon insulare 188
Andropogon latifolius 283
Andropogon leucostachyus 44
Andropogon leucostachyus ssp.

loanus 45

Andropogon microstachyus 520
Andropogon pertusus 93
Andropogon plumosus 569
Andropogon selloanus 45
Andropogon semiberbis 520

596

BURGER: FLORA COSTARICENSIS

597

Andropogon setosus 535
Andropogon tener 521
Andropogon inrgatus 268
Andropogon virginicus 46
Andropogon virginicus var. abbreviatus

Anthephora 46

Anthephora hermaphrodita 46, 47
Anthoxanthum 48, 257
Anthoxanthum odoratum 48, 49
Apogonia ramosa 147
aquatic grass 315, 400, 446
Arberella 501
Arberella costaricensis 501
Aristida 50

Aristida americana 96
Aristida arizonica 55
Aristida breviglumis 57
Aristida capillacea 51, 52
Aristida jorullensis 53, 54
Aristida laxa 53
Aristida orizabensis 55
Aristida orizabensis var. pseudo-

spadicea 55

Aristida pseudospadicea 55
Aristida recurvata 56
Aristida spadicea 53
Aristida ternipes 54, 56
Aristida tincta 57
aromatic 50, 587
Arrocillo 108
Arroz 348
Arthraxon 57

Arthraxon quartinianus 58, 59
Arthrostylidium 58
Arthrostylidium harmonicum 502
Arthrostylidium maxonii 502
Arthrostylidium pittieri 504
Arthrostylidium pubescens 58, 61
Arthrostylidium ? racemiflorum 507
Arthrostylidium venezuelae 60
Arundinaria pubescens 60
Arundinaria standleyi 60, 62
Arundinaria viscosa 69
Arundinella 62
Arundinella berteroniana 62
Arundinella confinis 63, 64
Arundinella deppeana 63, 64
Arundinoideae 8, 482
Arundo 65

Arundo australis 482
Arundo donax 65, 66
Arundo donax var. versicolor 67
Arundo phragmites 482
Arundo selloana 153
Atheropogon medius 100
Aulonemia 67
Aulonemia patriae 68
Aulonemia laxa 68
Aulonemia viscosa 69, 70
Avena 71

Avena deyeuxioides 577
Avena sativa 71, 72
Axonopus 71
Axonopus affinis 74
Axonopus anomalus 82
Axonopus aureus 75, 76
Axonopus blakei 80
Axonopus capillaris 75, 83
Axonopus centralis 77, 85
Axonopus chrysites 75
Axonopus chrysoblepharis 76, 78
Axonopus compressus 78, 79
Axonopus poiophyllus 80, 81
Axonopus purpusii 81, 82
Axonopus rhizomatosus 80
Axonopus scoparius 82, 83
Axonopus volcanicus 84, 85

bamboo 7, 8, 486
Bambusa 86, 87

Bambusa subgenus Guadua 87, 128
Bambusa arundinacea 87, 88
Bambusa paniculata 89, 90
Bambusa vulgaris 91, 92
Bambusa vulgaris var. striata 93
Bambusa vulgaris forma vittata 93
Bambusoideae 7
Bent grass 38
Berchtoldia bromoides 123
Bermuda grass 161
beverage, flavoring 160
Bothriochloa 93
Bothriochloa pertusa 93, 94
Bouteloua 95

Bouteloua alamosana 96, 97
Bouteloua americana 96, 98
Bouteloua chondrosioides 98, 99
Bouteloua disticha 99

598

FIELDIANA: BOTANY

Bouteloua filiformis 101
Bouteloua heterostega 101
Bouteloua media 98, 100
Bouteloua pilosa 99
Bouteloua pubescens 101
Bouteloua repens 97, 100
Brachiaria 101
Brachiaria brizantha 102
Brachiaria distachya 102, 107
Brachiaria fasciculata 103
Brachiaria mollis 104
Brachiaria mutica 105, 106
Brachiaria plantaginea 105, 107
Brachiaria reptans 583
Brachiaria subquadripara 103
Brachypodium 108
Brachypodium latifolium 110
Brachypodium mexicanum 108, 109
Brachypodium subulatum 110
Briza 110

Briza minor 110, 111
Brizopyrum pilosum 287
Bromus 112

Bromus carinatus 112, 113
Bromus catharticus 114
Bromus exaltatus 113, 114
Bromus laciniatus 112
Bromus unioloides 114
Bromus virgatus 247
Broom corn 537
Buffel grass 463

Cabrera chrysoblepharis 78

Calamagrostis 114

Calamagrostis intermedia 115, 116

Calamagrostis irazuensis 579

Calamagrostis nuda 116, 117

Calamagrostis pittieri 116, 117

Calinguero 319

Cana de Azucar 512, 513

Cana brava 253

Canary grass 475

Canuela 295, 319

Carrizo 67, 291, 321

Cenchrus 118

Cenchrus brownii 119, 120

Cenchrus ciliaris 462

Cenchrus echinatus 119, 120

Cenchrus granularis 253

Cenchrus incertus 120, 121

Cenchrus insularis 119

Cenchrus multiflorus 470

Cenchrus myosuroides 121

Cenchrus pauciflorus 121

Cenchrus pilosus 120, 121

Cenchrus setosus 467

Cenchrus viridis 119

Centeno 522

Chaetium 122

Chaetium bromoides 123, 124

Chloridoideae 8

Chloris 123, 234

Chloris aristata 125, 126

Chloris gayana 125

Chloris orthonoton 125

Chloris petraea 236

Chloris radiata 126, 127

Chloris rufescens 125

Chrysopogon zizanioides 585

Chusquea 127, 141, 142, 558-565

Chusquea coronalis 129, 130

Chusquea heydei 131

Chusquea lanceolata 142

Chusquea lehmannii 563

Chusquea longifolia 131

Chusquea meyeriana 132, 133

Chusquea pittieri 134, 135

Chusquea scabra 136

Chusquea simpliciflora 137

Chusquea subtessellata 561

Chusquea tonduzii 138, 139

Chusquea venezuelae 60

Chusquea virgata 139, 140

Cinna 143

Cinna glomerata 44

Cinna poaeformis 143, 144

cleistogenes 572

cleistogamous habit 393, 411, 451, 587

climbers 138, 141, 390, 504

Coelorachis 143

Coelorachis aurita 145, 146

Coelorachis ramosa 146, 147

Coix 147

Coix lacryma-jobi 148, 149

Cola de Coyote 44

Cola de venado 44, 65

Cornucopiae perennans 32

Cortaderia 148

Cortaderia atacamensis 152

Cortaderia bifida 150, 151

BURGER: FLORA COSTARICENSIS

599

Cortaderia haplotricha 151, 152

Cortaderia nitida 152

Cortaderia selloana 151, 152

coumarin 50

Creeping bent 36

Cryptochloa 153

Cryptochloa concinna 154, 155

Cryptochloa granulifera 156, 157

Cymbachne fastigiata 175

Cymbopogon 158

Cymbopogon citratus 158, 159

Cynodon 160

Cynodon dactylon 161, 162

Cynodon dactylon var. sarmentosus 163

Cynodon nlemfuensis 161, 162

Cynodon plectostachyus 163

Cynosurus 163

Cynosurus aegyptius 167

Cynosurus cristatus 163, 164

Cynosurus indicus 203

Cynosurus virgatus 306

Dactylis 165

Dactylis glomerata 165, 166
Dactyloctenium 165
Dactyloctenium aegyptium 167, 168
Danthonia 169
Danthonia alpina 171
Danthonia decumbens 169, 170
Danthonia haplotricha 152
Deschampsia 171
Deschampsia flexuosa 171
Deschampsia pringlei 172, 173
Despretzia mexicana 590
Deyeuxia intermedia 115
Deyeuxia nuda 117
Deyeuxia poaefortnis 143
Diandrochloa glomerata 214
Diandrolyra 499
Dichanthelium 351
Diectomis 172
Diectomis angustata 174
Diectomis fastigiata 175, 176
Digitaria 175
Digitaria abortiva 183
Digitaria abyssinica 178, 179
Digitaria adscendens 183, 192
Digitaria aequiglumis 185
Digitaria argillacea 180, 187
Digitaria bicornis 181, 182

Digitaria ciliaris 182, 183
Digitaria costaricensis 183, 184
Digitaria decumbens 185
Digitaria diversiflora 181
Digitaria filiformis var. villosa 186, 187
Digitaria hirsuta 181
Digitaria horizontalis 182, 186
Digitaria insularis 188, 191
Digitaria leucocoma 186
Digitaria longiflora 188, 189
Digitaria panicea 194
Digitaria pittieri 190, 191
Digitaria sanguinalis 192
Digitaria setigera 192
Digitaria velutina 187, 193
Digitaria vestita 180
Digitaria villosa 186
Digitaria violascens 191, 193
Dimorphostachys botterii 404
Dinebra chondrosioides 99
Dinebra repens 100

Echinochloa 194

Echinochloa colonum 195, 196

Echinochloa crusgalli 197

Echinochloa crus-pavonis 197, 198

Echinochloa crus-pavonis var. crus-
pavonis 197

Echinochloa crus-pavonis var. macera
197

Echinochloa guadeloupensis 199

Echinochloa polystachya 197, 198

Echinochloa polystachya var. spectabilis
199

Echinochloa pyramidalis 199, 200

Echinochloa spectabilis 199

Echinolaena 201

Echinolaena gracilis 201, 202

Echinolaena polystachya 497

Elephante 467

Eleusine 203

Eleusine indica 203, 204

Elytrostachys 205

Elytrostachys clavigera 205, 206

English ryegrass 311

Epicampes emersleyi 331

Eragrostoideae 8

Eragrostis 207

Eragrostis acutiflora 209

Eragrostis amabilis 222

600

FIELDIANA: BOTANY

Eragrostis arida 225
Eragrostis cilianensis 210, 211
Eragrostis ciliaris 212, 213
Eragrostis curvula 212
Eragrostis domingensis 221
Eragrostis ekmanii 226
Eragrostis glomerata 214, 215
Eragrostis hypnoides 214, 216
Eragrostis limbata 218
Eragrostis maypurensis 217, 218
Eragrostis megastachya 210
Eragrostis mexicana 218, 219
Eragrostis pectinacea 219, 220
Eragrostis pilosa 221
Eragrostis prolifera 215, 221
Eragrostis simpliciflora 218, 222
Eragrostis tenella 213, 222
Eragrostis tenuifolia 223, 224
Eragrostis tephrosanthos 225
Eragrostis viscosa 225
Eremochloa 226

Eremochloa ophiuroides 226, 227
Erianthus 512
Eriochloa 228

Eriochloa distachya 228, 229
Eriochloa polystachya 229, 230
Eriochrysis 231

Eriochrysis cayanensis 231, 232
erosion control 228, 400, 583, 585
Estrella africana 163
Euclasta 233

Euclasta condylotricha 233, 235
Eustachys 234
Eustachys petraea 236, 237

Festuca 236

Festuca amplissima 238, 243
Festuca arundinacea 239, 240
Festuca breviglumis 239, 241
Festuca bromoides 587
Festuca capillata 244
Festuca chiriquensis 241, 242
Festuca decumbens 169
Festuca dentonensis 587
Festuca dolichophylla 242, 243
Festuca elatior 239
Festuca filiformis 304
Festuca megalura 589
Festuca mexicana 108
Festuca myuros var. hirsuta 589

Festuca ovina 240, 244

Festuca rubra 240, 244

Festuca tenuifolia 240, 244

Festuca tolucensis 245

Festucoideae 8

fishing poles 484

forage, excellent 71, 84, 105, 125, 185,

319, 374, 462, 463
forage, good 73, 161, 165, 177, 231, 287,

311, 400, 431, 467, 575

Gamalote 422

Gigante 467

Glyceria 245

Glyceria fluitans var. plicata 245

Glyceria plicata 245, 246

golf greens 36

Gordura 319

Gouinia 247

Gouinia virgata 247, 248

grain crops 71, 148, 522, 537

Grama 95, 161

Graphephorum pringlei 580

Guadua 87

Guadua paniculata 89

Guinea 374

Gymnopogon 249

Gymnopogon fastigiatus ssp. fastigiatus

249, 250

Gymnothrix 466
Gymnothrix bambusiformis 460
Gymnothrix complanata 465
Gymnothrix distachya 465
Gymnothrix grisebachiana 465
Gymnothrix mexicana 465
Gynerium 251
Gynerium sagittatum 251, 252

Hackelochloa 253

Hackelochloa granularis 253, 254

Helopus brachystachys 228

hedge planting 585

Heteropogon 569

Hierochloe 255

Hierochloe davidsei 255, 256

Hierochloe mexicana 257

Holcus 257

Holcus bicolor 537

Holcus halepensis 537

BURGER: FLORA COSTARICENSIS

601

Holcus lanatus 257, 258

Holcus pertusus 93

Homolepis 259

Homolepis aturensis 259, 260

Hydrochloa caroliniensis 315

Hymenachne 259

Hymenachne amplexicaulis 261, 262

Hymenachne donacifolia 261

Hyparrhenia 263

Hyparrhenia bracteata 263, 264

Hyparrhenia rufa 265, 266

Hypogynium 267

Hypogynium spathifolius 268

Hypogynium virgatum 268, 269

Ichnanthus 268

Ichnanthus axillaris 272

Ichnanthus nemorosus 270, 271

Ichnanthus pallens 272, 273

Ichnanthus tenuis 271, 274

Imperata 275

Imperata brasiliensis 275

Imperata caudata 275

Imperata contracta 275, 277

injurious 118, 136, 301, 302, 457, 512

insect interaction 335

introductions, early 165

Isachne 276

Isachne arundinacea 278, 279

Isachne polygonoides 278, 280

Ischaemum 281

Ischaemum ciliare 281

Ischaemum indicum 281, 282

Ischaemum latifolium 282, 283

Ischaemum ophiuroides 226

Ischaemum rugosum 282, 284

Ischaemum secundatum 549

Italian ryegrass 311

Ixophorus 285

Ixophorus unisetus 285, 286

Janeiro 231
Jaragud 267
Jarava ichu 551
Java grass 495
Jengibrillo 431
Job's tears 148
Johnson grass 539
Jouvea 287

Jouvea pilosa 287
Jouvea straminea 288, 289

Khus-khus 587
Kikuyo 465

Ldgrimas de San Pedro 148

Lamarckia tenella 28

Lasiacis 291

Lasiacis divaricata var. divaricata 292

Lasiacis divaricata var. leptostachya

292

Lasiacis glabra 297
Lasiacis leptostachya 292
Lasiacis 1 means 292
Lasiacis longiligula 301
Lasiacis ludda 301
Lasiacis maxonii 295
Lasiacis nigra 293, 294
Lasiacis oaxacensis var. maxonii 295
Lasiacis oaxacensis var. oaxacensis 293
Lasiacis procerrima 295, 2%
Lasiacis rhizophora 295
Lasiacis rugelii var. pohlii 297
Lasiacis rugelii var. rugelii 297
Lasiacis ruscifolia var. ruscifolia 297
Lasiacis ruscifolia var. velutina 299
Lasiacis scabrior 299
Lasiacis sloanei 299
Lasiacis sorghoidea 293
Lasiacis sorghoidea var. sorghoidea 300
Lasiacis standleyi 300
Lasiacis velutina 299
lawn grass 36, 38, 161, 228, 244, 495,

549, 595
Leersia 301

Leersia hexandra 302, 303
Leersia distichophylla 302
Leersia grandiftora 302
Leersia ligularis var. grandiflora 302,

303

Lemon grass 158
lemon odor 158
Leptochloa 304
Leptochloa filiformis 304, 305
Leptochloa filiformis x L. virgata 306
Leptochloa scabra 305, 306
Leptochloa virgata 305, 306
Leptocoryphium 307

602

FIELDIANA: BOTANY

Leptocoryphium lanatum 307, 308

Lithachne 309

Lithachne pauciflora 309, 310

Lolium 311

Lolium perenne 311, 312

Lolium perenne var. aristatum 311

Lolium perenne var. italicum 311

Lorenzochloa 313

Lorenzochloa erectifolia 313, 314

Love grass 207-226

Luziola 313

Luziola fragilis 315, 316

Luziola subintegra 317, 318

Maicillo 577

Maize 590

Manisuris 145

Manisuris aurita 145

Manisuris ramosa 147

Megastachya simpliciflora 222

Melinis 319

Melinis minutiflora 319, 320

Merostachys 319

Merostachys multiramea 321

Merostachys sp. indet. 321, 322

Mesosetum 321

Mesosetum pittieri 323, 324

Milium compressum 78

Millet 523

Miscanthus 512

Molasses grass 319

Muhlenbergia 323

Muhlenbergia attenuata 330

Muhlenbergia beyrichiana 472

Muhlenbergia breviculmis 326

Muhlenbergia calcicola 326, 333

Muhlenbergia ciliata 326, 327, 335

Muhlenbergia diversiglumis 326, 327,

335

Muhlenbergia emersleyi 331
Muhlenbergia erectifolia 313
Muhlenbergia flabellata 328, 329
Muhlenbergia frondosa 335
Muhlenbergia implicata 330, 335
Muhlenbergia lehmanniana 330
Muhlenbergia minutissima 331
Muhlenbergia nebulosa 335
Muhlenbergia nigra 331
Muhlenbergia polypogonoides 332
Muhlenbergia quadridentata 330

Muhlenbergia ramulosa 331, 333
Muhlenbergia schreberi 335
Muhlenbergia setarioides 332, 334
Muhlenbergia tenella 327, 335
Muhlenbergia tenuissima 330, 335

Nassella 336

Nassella linearifolia 336, 552

Natal grass 510

Oats 71

odor 50, 158, 255, 319, 587

oil droplets 290

Olyra 337

Olyra concinna 154

Olyra lateralis 337, 339

Olyra latifolia 338, 340

Olyra pauciflora 309

Olyra sarmentosa 338

Olyra standleyi 341

Oplismenus 342

Oplismenus burmannii 342, 343

Oplismenus crus-pavonis 197

Oplismenus hirtellus 343, 344

Oplismenus polystachyus 197

Oplismenus setarius 345

Oplismenus tennis 274

Orchard grass 165

ornamental 65, 67, 93, 112, 153, 214,

475, 484, 523, 549, 582, 583
Orthoclada 345
Orthoclada laxa 346, 347
Oryza 346
Oryza latifolia 348
Oryza sativa 348, 349
Oryzoideae 8
Oryzopsis 551
Oryzopsis florentula 336

Pangola 185

Pangola grass 177

Panicoideae 9

Panicum 350

Panicum (subgenus Dichanthelium) 357,

359, 370, 376, 392

Panicum (subgenus Paurochaetium) 523
Panicum abyssinicum 178
Panicum altum 392

BURGER: FLORA COSTARICENSIS

603

Panicum amplexicaule 261

Panicum aquaticum 353, 354

Panicum arundinaceum 278

Panicum arundinariae 354, 355

Panicum aturense 259

Panicum axillare 272

Panicum boliviense 355, 371

Panicum brizantkum 102

Panicum burmannii 344

Panicum campylostachyum 565

Panicum cayennense 356

Panicum chiriquiense 376

Panicum chrysites 75

Panicum ciliare 183

Panicum ciliatum var. pubescens 356

Panicum colonum 195

Panicum cordovense 357, 358

Panicum costaricense 366

Panicum dactylon 161

Panicum discrepans 359, 360

Panicum distachyon 102

Panicum distickum var. lancifolium

381

Panicum divaricatum 292
Panicum donacifolium 261
Panicum elephantipes 359
Panicum errabundum 361
Panicum fasciculatum 103
Panicum filiforme 186
Panicum frondescens 361, 362
Panicum geminatum 398
Panicum geniculatum 524
Panicum ghiesbreghtii 363
Panicum glutinosum 364
Panicum grande 364, 365
Panicum haenkeanum 366
Panicum helobium 366
Panicum hirsutum 367
Panicum hirtellum 344
Panicum hirticaulum 368
Panicum irregulare 368, 369
Panicum laterale var. a 338
Panicum latifolium 300
Panicum laxiflorum 370
Panicum laxiflorum var. pubescens 356
Panicum laxum 370, 373
Panicum maximum 371, 372
Panicum megiston 374
Panicum mertensii 374, 375
Panicum milleflorum 381, 383

Panicum molle 104

Panicum muticum 105

Panicum myuros 516

Panicum nemorosum 270

Panicum oaxacense 293

Panicum olivaceum 374

Panicum oryzoides 24

Panicum pallens 272

Panicum paludivagum 398

Panicum pampinosum 368

Panicum paniculiferum 527

Panicum pantrichum 376, 377

Panicum parcum 378

Panicum parvifolium 378, 379

Panicum parviglume 380

Panicum petrosum 566

Panicum pilosum var. lancifolium 381

Panicum pilosum var. pilosum 381, 382

Panicum pittieri 190

Panicum plantagineum 105

Panicum poiretianum 528

Panicum polygonatum 373, 383

Panicum polygonoides 278

Panicum procerrimum 295

Panicum pulchellum 377, 384

Panicum purpurascens 105

Panicum pyramidale 199

Panicum reflexopilum 392

Panicum reptans 583

Panicum rhizophorum 295

Panicum rudgei 384, 385

Panicum rugelii 297

Panicum ruscifolium 297

Panicum sanguinale 183

Panicum schiffheri 386

Panicum sellowii 386

Panicum setarium 345

Panicum sloanei 299

Panicum sorghoideum 300

Panicum spectabile var. guadeloupense

199

Panicum sphaerocarpon 387
Panicum stenodes 379, 388
Panicum stenodoides 388
Panicum strigosum 357
Panicum subquadriparum 102
Panicum tenax 532
Panicum tenerum 388
Panicum trichanthum 388, 389
Panicum trichoides 389, 390

604

FIELDIANA: BOTANY

Panicum violascens 193

Panicum virgultorum 355

Panicum viscidellum 390, 391

Panicum vulpisetum 532

Panicum xalapense 370

Panicum zizanoides 24

paper 484

Para grass 105, 231

Paratheria 392

Paratheria prostrata 393, 394

Pariana 395, 397

Pariana parvispica 395,396

Pariana zingiberina 397

Parodiella erectifolia 313

Paspalidium 397

Paspalidium geminatum 398, 399

Paspalidium geminatum var. paludi-

vagum 398, 399
Paspalum 400

Paspalum (group Dissecta ) 408
Paspalum (group Parviflora) 453
Paspalum (group Plicatula) 415, 440
Paspalum (group Virgata) 457
Paspalum (subgenus Ceresia) 424, 438
Paspalum acuminatum 404, 405
Paspalum bicorne 181
Paspalum boscianum 440
Paspalum botterii 404, 406
Paspalum candidum 405, 407
Paspalum capillare 75
Paspalum centrale 408, 4Q9, 415
Paspalum clavuliferum 408, 410
Paspalum conjugatum 411, 412
Paspalum convexum 413, 414
Paspalum corypheum 415, 415
Paspalum costaricense 416, 417
Paspalum decumbens 418
Paspalum densum 455
Paspalum dilatatum 418
Paspalum distichum 419, 420, 458
Paspalum fasciculatum 421, 421
Paspalum fluitans 446
Paspalum humboldtianum 422, 423
Paspalum jimenezii 424, 425, 453
Paspalum lanatum 307
Paspalum lineare 426
Paspalum longiflorum 188
Paspalum maculatum 438
Paspalum microstachyum 426, 427
Paspalum minus 428, 428

Paspalum multicaule 410, 429
Paspalum notatum 428, 430
Paspalum nutans 431, 432
Paspalum orbiculatum 433, 433
Paspalum paniculatum 434, 435
Paspalum parviflorum 410, 434
Paspalum paspaloides 419
Paspalum pectinatum 436, 437
Paspalum pictum 438
Paspalum pilosum 438, 439
Paspalum pittieri 408
Paspalum plenum 457
Paspalum plicatulum 440, 441
Paspalum plicatulum var. glabrum 442
Paspalum plicatulum var. plicatulum

440
Paspalum plicatulum var. villosissimum

442

Paspalum propinquum 451
Paspalum prostratum 446
Paspalum pulchellum 442, 443
Paspalum pumilum 444, 445
Paspalum purpusii 82
Paspalum reclinatum 405, 445
Paspalum repens 405, 446
Paspalum saccharoides 446, 447
Paspalum saurae 431
Paspalum scabrum 448
Paspalum scoparium 82
Paspalum serpentinum 448, 449
Paspalum serratum 404
Paspalum setaceum 450
Paspalum squamulatum 451, 452
Paspalum standleyi 451
Paspalum stellatum 453, 454
Paspalum tonduzii 455
Paspalum turri forme 455, 456
Paspalum vaginatum 420, 457
Paspalum virgatum 458, 458
Pasto africano 465
Pasto Guinea 374
Pasto Kikuyo 465
Pasto lloron 214
Pasto Saw Juan 475
pasture grass 32, 38, 73, 161, 244
Pata de gallina 205
Paurochaetium 118, 523
Pennisetum 459

Pennisetum bambusiforme 460, 461
Pennisetum cenchroides 462

BURGER: FLORA COSTARICENSIS

605

Pennisetum ciliare 462

Pennisetum clandestinum 463, 464

Pennisetum complanatum 461, 465

Pennisetum distachyum 461, 465

Pennisetum frutescens 468

Pennisetum karwinskyi 470

Pennisetum nervosum 468

Pennisetum purpureum 461, 466

Pennisetum setosum 461, 467

Pennisetum tempisquense 468, 469

Pennisetum vulcanicum 461, 468

Pentarraphis 470

Pentarraphis annua 470, 471

Pereilema 472

Pereilema beyrichianum 472

Pereilema crinitum 473, 474

Perennial ryegrass 311

perfume 587

Peyritschia 172

Peyritschia pringlei 172

Phalaris 473

Phalaris aquatica 475

Phalaris arundinacea f. picta 475

Phalaris canariensis 475, 476

Phalaris minor 475

Phalaris velutina 193

Phalaris zizanioides 585

Pharus 475

Pharus cornutus 478, 479

Pharus glaber 478, 479

Pharus latifolius 478, 479

Pharus latifolius var. angustifolius 481

Pharus mezii 480

Pharus parvifolius 480

Pharus virescens 481

Phleum indicum 281

Phragmites 482

Phragmites australis 482, 483

Phragmites communis 482

PhyUostachys 484

Phyllostachys aurea 484, 485

Phyllostachys bambusoides var. aurea

484

Piptatherum confine 63
Piptochaetium 551
Pitilla 544, 546
Poa 486

Poa acutiflora 209
Poa amabilis 222
Poa annua 487, 489

Poa chirripoensis 488, 490
Poa cilianensis 210
Poa ciliaris 212
Poa curvula 212
Poa domingensis 221
Poa glomerata 214
Poa hypnoides 214
Poa maypurensis 217
Poa mexicana 218
Poa orizabensis 491
Poa pectinacea 219
Poa pilosa 221
Poa pratensis 488, 489
Poa prolifera 221
Poa talamancae 489, 491
Poa tenella 222
Poa tenuifolia 223
Poa trivialis 489, 491
Poa viscosa 225
Podosaemum ciliatum 326
Podosaemum implicatum 330
Podosaemum stipoides 570
Podosaemum tenellum 335
Podosaemum tenuissimum 335
Pogonatherum amaurum 495
poisonous 50
Pollinia praemorsa 495
Polydon distichum 99
Polypogon 493

Polypogon elongatus 493, 494
Polytrias 495
Polytrias amaura 495, 496
Polytrias praemorsa 495
Pooideae 8
Pseudechinolaena 497
Pseudechinolaena polystachya 370, 497,
498

Raddia 499
Raddia concinna 154
Raddia costaricensis 499, 500
Ray Ingles 311
Redtop 32

Reed canary grass 475
Reimaria Candida 407
Reimarochloa 393
Rhipidocladum 501
Rhipidocladum harmonicum 502
Rhipidocladum maxonii 502, 503
Rhipidocladum pittieri 504, 505

606

FIELDIANA: BOTANY

Rhipidocladum racemiflorum 505, 507

Rhodes grass 127

Rhynchelytrum 508

Rhynchelytrum repens 508, 509

Rhynchelytrum roseum 508

Rhytachne 145

Rice 348

rosary beads 148

Rottboellia 145, 510

Rottboellia aurita 145

Rottboellia aurita ssp. stigmosa 147

Rottboellia exaltata 510, 511

Rottboellia granularis 253

Ruby grass 510

Rye 522

Ryegrass 311

Saccharum 512

Saccharum cayennense 231

Saccharum contractum 276

Saccharum officinarum 513, 514

Saccharum sagittatum 251

Sacciolepis 513

Sacciolepis indica 513, 515

Sacciolepis myuros 515, 516

scandent 138, 141, 390, 504

Schizachyrium 516

Schizachyrium brevifolium 517, 519

Schizachyrium brevifolium var. bre-
vifolium 518

Schizachyrium brevifolium var. flac-
cidum 518

Schizachyrium condensatum 521

Schizachyrium hirtiflorum 518

Schizachyrium microstachyum 519, 520

Schizachyrium microstachyum ssp.
elongatum 521

Schizachyrium sanguineum 520

Schizachyrium semiberbe 520

Schizachyrium tenerum 521

seashore 583

Secale cereale 522

Sehima ciliare subvar. ophiuroides 226

Senites mexicana 590

Setaria 522

Setaria anceps 524

Setaria geniculata 524, 525

Setaria italica 523

Setaria liebmannii 526

Setaria magna 527

Setaria paniculifera 527
Setaria poiretiana 528, 529
Setaria scandens 530
Setaria sphacelata 524
Setaria tenacissima 530, 531
Setaria tenax 531, 532
Setaria viridis 530
Setaria vulpiseta 531, 532
Sieglingia 171
Sieglingia decumbens 169
Sontol 158, 160
Sorghastrum 533
Sorghastrum agrostoides 536
Sorghastrum incompletum 533, 534
Sorghastrum nutans 536
Sorghastrum setosum 534, 535
Sorghum 536
Sorghum bicolor 537
Sorghum, grain 537
Sorghum halepense 537, 538
Sorghum sudanense 539
Sorghum vulgare 537
Spartina 539

Spartina spartinae 540, 541
spines 89, 118, 136, 301, 302, 512
Sporobolus 540
Sporobolus argutus 547
Sporobolus ciliatus 542, 543
Sporobolus cubensis 542, 543
Sporobolus indicus 544, 545, 546
Sporobolus jacquemontii 544
Sporobolus minutissimus 331
Sporobolus poiretii 544
Sporobolus purpurascens 546
Sporobolus pyramidatus 547
Sporobolus ramulosus 332
Sporobolus virginicus 547, 548
Stegosia exaltata 510
Stenotaphrum 549
Stenotaphrum secundum 549
Stenotaphrum secundatum 549, 550
Stipa 551

Stipa florentula 336
Stipa hans-meyeri 552, 553
Stipa ichu 551, 552
Stipa linearifolia 336
Streptochaeta 553
Streptochaeta sodiroana 554, 556
Streptochaeta spicata 555, 556
Streptogyna 555

BURGER: FLORA COSTARICENSIS

607

Streptogyna americana 555, 557
Streptogyna crinita 558
Sudan grass 539
sugar 512, 513
Sugarcane 512
Swallenochloa 128
Swallenochloa longiligulata 559, 560
Swallenochloa subtessellata 561, 562
Swallenochloa vulcanalis 563, 564
Sweet sorghum 537
Syntherisma abyssinica 178
Syntherisma argillacea 180
Syntherisma. villosa 186
syrup 537

tabasheer 89

tea (beverage) 160

Teosinte 590

thorns, root 136

Thrasya 565

Thrasya campylostachya 565, 566

Thrasya gracilis 566

Thrasya paspaloides 567

Thrasya petrosa 566, 566

Thrasya robusta 566, 567

Thrasya trinitensis 567

timber 484

toxic 50

Trachypogon 568

Trachypogon plumosus 569

Trachypogon rufus 265

Trachypogon vestitus 570

Trichachne insularis 188

Trichachne pittieri 190

Trichochloa berteroniana 62

Trichochloa tenella 335

Tricholaena repens 508

Tricholaena rosea 508

Tridens 572

Trigo adlay 148

Triniochloa 570

Triniochloa stipoides 570, 571

Triplasis 572

Triplasis purpurea var. caribensis 572,

573

Triplasis purpurea var. purpurea 574
Tripsacum 574

Tripsacum hermaphroditum 46
Tripsacum latifolium 575, 576

Tripsacum laxum 575
Tripsacum maizar 577
Trisetum 577

Trisetum deyeuxioides 577, 578
Trisetum irazuense 578, 579
Trisetum pringlei 578, 579
Trisetum scabriflorum 579
Trisetum tonduzii 578, 580
Triticum attenuatum 29
Turbard 413
Turvurd 413

Uniola 581

Uniola paniculata 583

Uniola pittieri 581, 582

Urochloa 583

Urochloa reptans 583, 584

Urochloa uniseta 285

Valota pittieri 190

vanilla (odor) 50, 255

vetiver 587

Vetiveria 585

Vetiveria zizanioides 585, 586

Vilfa arguta 547

Vilfa jacquemontii 544

Vilfa ramulosa 332

Vilfa spartinae 540

vines 138, 141, 390, 504

Vulpia 236, 587

Vulpia bromoides 587, 588

Vulpia megalura 589

Vulpia myuros var. hirsute 588, 589

weedy 42, 50, 125, 161, 177, 205, 223,

276, 381, 413, 434, 508, 523
Weeping love grass 214

Yerba elefante 467

Zacate amargo 73, 78, 79
Zacate Bermuda 161
Zacate bianco 287
Zacate buffet 463
Zacate de Honduras 287
Zacate ilusion 510
Zacate imperial 84

608 FIELDIANA: BOTANY

Zacate de Johnson 539 Zea mexicana 590

Zacate de limdn 158, 159, 160 Zeugites 590

Zacate pard 105 Zeugites latifolia 592

Zacate ray 311 „ . . cnn

rj j j riA Zeugites mexicana 590,591

Zacate de seda 510

Zacate ta/fuara 276 Zeugites pittieri 592, 593

Zea 589 Zoysia 595

Zea mays 590 Zoysia tenuifolia 594, 595

Families of seed plants known or expected to occur in Costa Rica and adjacent
areas numbered according to the sequence of Engler's Syllabus der Pflanzenfami-
lien, edition 11, reworked by L. Diels (1936).

1 Cycsdaceae

2 Taxaceae

3 Podocarpaceae

4 Araucanaceae

5 Pinaceae

6 Cupressaceae

7 Gnetaceae

8 Typhaceae

9 Potamogetonaceae

10 Najadaeeae

11 Alismataceae

12 Butomaceae

13 Hydrpcharitaceae

14 Triuridaceae

15 Gramineae

16 Cyperaceae

17 Pafmae

18 Cyclanthaceae

19 Araceae

20 Lemnaceae

21 Mayacaceae

22 Xyridaceae

23 Eriocaulaceae

24 Bromeliaceae

25 Commelinaceae

26 Pontederiaceae

27 Juncaceae

28 Liliaceae

29 Haemodoraceae

30 Amaryllidaceae

31 Velloziaceae

32 Dioecoreaceae

33 Iridaceae
24 Musaceae

36 Zingiberaceae

36 Cannaceae

37 Marantaceae

38 Burmanniaceae

39 Orchidaceae

40 Caeuarinaceae

4 1 Piperaceae

42 Chlpranthaceae

43 Lacistemaceae

44 Salicaceae

45 Garry aceae

46 Myricaceae

47 Juglandaceae

48 Batid aceae

49 Betulaceae

50 Fagaceae

51 Ulmaceae

52 Moraceae

53 Urticaceae

54 Podoatemonaceae

55 Proteaccae

56 Olacaceae

57 Opiliaceae

58 Loranthaoeae

59 Aristolpchiaceae

60 Raffleaiaceae

61 Balanophoraceae

62 Polygonaceae

63 Chenopodiaceae

64 Amaranthaceae

65 Nyctaginaceae

66 Phytolaccaceae

67 Aizoaceae

68 Portulacaceae

69 Baa«Uace*e

70 Caryophyllaceae

71 Nymphaeaceae

72 Ceratophyllaceae

73 Ranunculaceae

74 Berberidaceae

75 Menispermaceae

76 Magnoliaceae

77 Anonaceae

78 Myriaticaceae

Monimiaceae

154

Cactaceae

Laura ceae

155

Thymelaeaceae

Htrnandiaceae

156

Elaeagnaceae

Papaveraceae,

157

Lythraceae

incl. Fumariaceae

158

Punicaceae

Capparidaceae

159

Lecythidaceae

Cruciferae

160

Rhizophoraceae

Tovariaceae

161

Cornbretaceae

Resedaceae

162

Myrtaceae

Moringaceae

163

Melastomataceae

Droseraceae

164

Onagraceae

Crassulaceae

165

Halorrhagaceae

Saxifragaceae

166

Araliaceae

Brunelliaceae

167

Umbelliferae

Cunoniaceae

168

Cornaceae

Hamamelidaceae

169

Clethraceae

Rosa ceae

170

M on ot r opaceae

Connaraceae

171

Pyrolaceae

Legurninosae

172

Ericaceae

97
98
99

Krameriaceae
Oxalidaceae
Geraniaceae

173
174

175

Theophrastaceae
Myrsmaceae
Primulaceae

100

Tropaeolaceae

176

Plumbaginaceae

101

Linaceae,

177

Sapotaceae

incl. Humiriaceae

178

Ebenaceae

102

Erythroxylaceae

179

Symplocaceae

103

Zygophyllaceae

180

Styracaceae

104

Rutaceae

181

Oleaceae

105

Simarubaceae

182

Loganiaceae

106

Burseraceae

183

Gentianaceae

107

Meliaceae

184

Apocynaceae

108

Malpighiaceae

185

Asclepiadaceae

109

Trigoniaceae

186

Convolvulaceae

110

Vochysiaceae

187

Polemoniaceae

111

Polygalaceae

188

Hy drophyl laceae

112

Dichapetalaceae

189

Boraginaceae

113

Euphorbiaceae

190

Verbenaceae

114

Callitrichaceae

191

Labiatae

115

Buxaceae

192

Solanaceae

116

Coriariaceae

193

Scrophulariaceae

117

Anacardiaceae

194

Bignoniaceae

118

Cyrillaceae

195

Pedaliaceae

119

Aquifoliaceae

196

Martyniaceae

120

Celastraceae

197

Orobanchaceae

121

Hippocrateaceae

198

Gesneriaceae

122

Staphyleaceae

199

Lentibulariaceae

123

Icacinaceae

200

Acanthaceae

124
125

Hippocastanaceae
Sapmdaceae

201
202

Plantaginaceae
Rubiaceae

126

Sabi aceae

203

Caprifoliaceae

127

Balsaminaceae

204

Valerianaceae

128

Rhamnaceae

205

Dipsacaceae

129

Vitaceae

206

Cucurbitaceae

130

Elaeocarpaceae

207

Campanulaceae

131

Tiliaceae

208

Compositae

132

Malvaceae

133

Bombacaceae

134

Sterculiaceae

135

Dilleniaceae

136

Actinidiaceae

137

Ochnaceae

138

Gary oca raceae

139

Marcgraviaceae

140

Quiinaceae

141

Theaceae

142

Guttiferae

incl. Hypericaceae

143

Elatinaceae

144

Cistaceae

145

Bixaceae

146

Cochlospermaceae

147

Violaceae

148

Flacourtiaceae

149

Turneraceae

150

Passifloraceae

151

Caricaceae

162

Loasaceae

153

Begoniaceae

Field Museum of Natural History
Roosevelt Road at Lake Shore Drive
Chicago, Illinois 60605
(312) 922-9410

UNIVERSITY OF ILLINOIS-URBANA

Internet Archive Audio

Featured

Top

Images

Featured

Top

Software

Featured

Top

Books

Featured

Top

Video

Featured

Top

Mobile Apps

Browser Extensions

Archive-It Subscription

Save Page Now

Full text of "Family #15, Gramineae"

See other formats