UC-NRLF
B 4 hDD MES
FIRST BOOK OP GRASSES
Hurai
EDITED BY L. H. BAILEY
Bailey: SCHOOL-BOOK OF FARMING.
Carleton: THE SMALL GRAINS.
Chase: FIRST BOOK OF GRASSES.
B. M. Duggar: THE PHYSIOLOGY OF PLANT
PRODUCTION.
J. F. Duggar: AGRICULTURE FOR SOUTHERN
SCHOOLS.
J. F. Duggar: SOUTHERN FIELD CROPS.
Fisk: THE BOOK OF ICE-CREAM.
Gay: BREEDS OF LIVE-STOCK.
Gay: PRINCIPLES AND PRACTICE OF JUDGING
LIVE-STOCK.
Goff: PRINCIPLES OF PLANT CULTURE.
Gourley: TEXT-BOOK OF POMOLOGY.
Guthrie: THE BOOK OF BUTTER.
Harper: ANIMAL HUSBANDRY FOR SCHOOLS.
Harris and Stewart: THE PRINCIPLES OF
AGRONOMY.
Hitchcock: TEXT-BOOK OF GRASSES.
Jeffery: TEXT-BOOK OF LAND DRAINAGE.
Jordan: FEEDING OF ANIMALS, REVISED.
Livingston: FIELD CROP PRODUCTION.
Lyon: SOILS AND FERTILIZERS
Lyon, Pippin and Buckman: SOILS; THEIR
PROPERTIES AND MANAGEMENT.
Mann: BEGINNINGS IN AGRICULTURE.
Montgomery: THE CORN CROPS.
Morgan: FIELD CROPS FOR THE COTTON-
BELT.
Mumford: THE BREEDING OF ANIMALS.
Piper: FORAGE PLANTS AND THEIR CULTURE.
Sampson: EFFECTIVE FARMING.
Smith: AGRICULTURAL METEOROLOGY.
Stubenrauch, Wood and Booth: HORTICULTURE
FOR SCHOOLS.
Thorn and Fisk: THE BOOK OF CHEESE.
Warren: ELEMENTS OF AGRICULTURE.
Warren: FARM MANAGEMENT.
W heeler: MANURE AND FERTILIZERS.
White: PRINCIPLES OF FLORICULTURE.
Widtsoe: PRINCIPLES OF IRRIGATION PRAC-
TICE.
FIRST BOOK OF
THE STRUCTURE OF GRASSES EXPLAINED
FOR BEGINNERS
PY
AGNES CHASE
ASSISTANT AGROSTOLOGIST, UNITED STATES DEPARTMENT
OF AGRICULTURE
•Bforo f 0rk
THE MACMILLAN COMPANY
1922
All rights reserved
QK4ci5
UBR^RY
G
COPYRIGHT, 1922
BY THE MACMILLAN COMPANY
Set up and electro typed. Published November, 1922.
AGRIG, DEPh ftr^4rH D.V.
Printed in the United States of America
PREFACE
Of all plants grasses are the most important to
man. The different kinds are known by very few
even among botanists. This is largely because they
are supposed to be very difficult. When the struc-
ture of grasses is clearly understood, they are not
more difficult to study than are other plants. The
method here offered has been used by the author for
some years in teaching special students.
The introduction explains the method followed.
The body of the primer consists of twelve lessons,
graded from the simplest to the most complex.
Each lesson is accompanied by figures bringing out
the facts in the text. The difference in the size
of the flowering organs is so great that the figures
are not drawn to the same scale. The organs are
enlarged as much as necessary to illustrate the char-
acter discussed.
Grasses of the United States are used for the lessons
and the commoner ones are selected so far as possible;
however, our native grasses cover so wide a range
that the principles laid down in the lessons are ap-
plicable to grasses generally.
AGNES CHASE.
Washington, D. C., August 10, 1922.
494313
TABLE OF CONTENTS
PAGES
INTRODUCTION 1-7
Use of technical terms, 2; Use of Latin names, 4; Tools
needed, 6.
LESSON I 8-16
The grass family, 8; Summary, 16; Review, 16.
LESSON II 17-20
The spikelet and the inflorescence, 17; Summary, 19;
Review, 20.
LESSON III 21-24
Modifications of the spikelet, 21; Summary, 24.
LESSON IV 25-33
Pediceled spikelets of few to many florets, 25; Sum-
mary, 33; Review, 33.
LESSON V 34-41
Sessile spikelets in two-sided spikes, 34; Summary, 41;
Review, 41.
LESSON VI 42-45
Pediceled spikelets with large glumes and other modi-
fications, 42; Summary, 45; Review, 45.
LESSON VII 46-53
Pediceled one-flowered spikelets, 46; Summary, 52;
Review, 53.
LESSON VIII 54-60
Sessile spikelets in one-sided spikes, 54; Summary, 60;
Review, 60.
LESSON IX 61-67
Diversely specialized spikelets, 61; Summary, 67; Re-
view, 67.
vii
viii TABLE OF CONTENTS
PAGES
LESSON X 68-78
Spikelets with membranaceous glumes and hardened
fruits, 68; Summary, 77; Review, 78.
LESSON XI 79-88
Paired spikelets with hardened glumes and thin
lemmas, 79; Summary, 88; Review, 88.
LESSON XII 89-94
Highly specialized unisexual spikelets, 89; Summary,
94; Review, 94.
DIAGRAMMATIC SUMMARY OF THE PRIMARY CHARACTERS
OF THE TRIBES 95-99
Series 1, Poatse, 95; Series 2, Panicatse, 98.
GENERAL INFORMATION FOR THE BEGINNER 100-115
Outline for study of a grass plant, 100; Books, 104;
Botanical names, 108; Classification of plants, 111;
Position of grasses in the plant kingdom, 113; Grasses
in relation to man, 114.
LIST OF ILLUSTRATIONS
FIG. PAGE
1. Vegetative part of a grass plant; part of leaf opened out. . 9
2. Typical complete flower showing calyx, corolla, stamens
and pistils 9
3. Grass flower, showing stamens and pistil and the rudi-
ments of floral envelope 10
4. A floret at flowering time 11
5. Two views of a grain 11
6. Diagram of a flowering branch 12
7. Diagram of a grass spikelet 12
8. Generalized spikelet 13
9. Base of plant and underground parts, roots and rhizomes,
of Poa pratensis 14
10. Forms of inflorescence; A, panicle; B, raceme; C, spike.. 18
11. A, several-flowered spikelet of Bromus secalinus; B, single
floret 25
12. A, spikelet of Festuca ovina; B, lemma detached 26
13. Spikelet of Panicularia septentrionalis 27
14. Spikelet of Poa pratensis 27
15. Palea of Pleuropogon californicus 27
16. Floret of Triodiaflava 28
17. Lemma of Cottea pappophoroides 28
18. A, spikelet of Phragmites communis; B, floret 28
19. Spikelet of Melica mutica 29
20. Florets of Pappophorum vaginatum 29
21. A, part of a panicle of Cynosurus cristatus; B, sterile
spikelet; C, fertile spikelet 30
22. A, fascicle of three sterile and one fertile spikelet of
Achyrodes aureum; B, fertile spikelet 31
23. Pistillate and staminate spikelets of Distichlis spicata. . . 32
ix
x LIST OF ILLUSTRATIONS
FIG. PAGE
24. Staminate and pistillate spikelets of Scleropogon brevi-
folius 32
25. A, part of a spike of Agropyron repens; B, part of rachis
seen from the edge, all but two spikelets removed .... 34
26. Spikelet of Triticum cestivum 35
27. Part of a spike of Lolium multiflorum 36
28. A, part of a spike of Lepturus cylindricus; B, diagram of
rachis, spikelets removed; above, diagram of single
joint 37
29. A, pair of spikelets of Elymus virginicus; B, diagrammatic
figure of the pair of spikelets 38
30. Joint of spike of Hordeum nodosum 40
31. A, spikelet of Avena fatua; B, floret 42
32. Spikelet of Trisetum spicatum 43
33. Spikelet of Danthonia spicata; floret above 43
34. A, spikelet of Notholcus lanatus; B, pair of florets 44
35. Spikelet of Calamagrostis canadensis 46
36. Spikelet of Agrostis hiemalis 47
37. Spikelet of Sporobolus airoides 47
38. Spikelet of Phleum pratense; floret above 48
39. Spikelet of Alopecurus geniculatus 48
40. Pair of spikelets, sterile and fertile (spread apart) of
Lycurus phleoides 49
41. Spikelet of Muhlenbergia foliosa 50
42. A, spikelet of Muhlenbergia Schreberi; B, branchlet with
the minute glumes of two spikelets from which florets
have fallen 50
43. A, spikelet of Milium effusum; B, floret 50
44. A, glumes, and B, floret of Oryzopsis racemosa 51
45. A, glumes, and B, floret of Stipa spartea 51
46. Spikelet of Aristida dichotoma 51
47. A, spikelet of Eleusine indica; B, inflorescence 55
48. A, spikelet of Capriola Dactylon; B, inflorescence 55
49. A, spikelet of Chloris latisquamea; B, fertile lemma spread
out; C, sterile lemma spread out; D, inflorescence. ... 56
LIST OF ILLUSTRATIONS xi
FIG. PAGE
50. A, spikelet of Bouteloua curtipendula; B, fertile lemma
spread out; C, sterile lemma spread out; D, inflores-
cence 57
51. A, spikelet of Bouteloua gracilis; B, fertile lemma spread
out; C, first sterile lemma spread out; D, second sterile
lemma spread out; E, inflorescence 58
52. A, fascicle of Mgo'pogon tenellus; B, lemma, and C, palea,
spread out, of the sterile spikelet; D, lemma and E,
palea of perfect spikelet 61
53. A, fascicle of Hilaria Belangeri; B, glumes of staminate
spikelet; C, two views of the perfect spikelet; D, fertile
floret 62
54. A, bur-like fascicle of Nazia aliena; B, single spikelet;
C, floret 63
55. A, spikelet of Anthoxanthum odoratum; B, pair of sterile
florets below the perfect floret; C, perfect floret 64
56. A, spikelet of Phalaris canariensis; B, fertile floret with
pair of small sterile florets attached at the base 65
57. Spikelet of rice (Oryza saliva) 66
58. Spikelet of Homalocenchrus oryzoides 66
59. A, pistillate spikelet, and B, staminate spikelet of Zizania
paluslris 66
60. A, spikelet of Panicum miliaceum, side view; B, same
seen from the back; C, sterile and fertile florets removed
from the glumes, side view; D, fertile floret 69
61. A, two views of spikelet of Synlherisma sanguinalis;
B, fertile floret; C, inflorescence 70
62. A, two views of spikelet of Paspalum loeve; B, fertile
floret; C, inflorescence 71
63. A, rachis of Paspalum Iceve, spikelets removed; B, rachis
of a Paspalum with paired spikelets; C, cross-section of
rachis, showing raised center and thin margins 71
64. A, part of a raceme of Stenolaphrum secundalum, front
view showing spikelets; B, back view of three
joints 72
xii LIST OF ILLUSTRATIONS
FIG. PAGE
65. A, part of raceme of Axonopusfurcatus; B, inflorescence;
C, cross-section of rachis 73
66. A, spikelet of Erlochloa punctata; B, fertile floret 73
67. A, diagrammatic panicle; B, two branches of panicle
with terminal spikelets removed 74
68. Small part of bristly panicle of Chcetochloa Grisebachii . . 74
69. A, fascicle from panicle of Chcetochloa lutescens; B, spike-
like panicle of same 75
70. Bur of Cenchrus myosuroides 76
71. Bur of Cenchrus pauciflorus 76
72. Base of plant of Amphicarpon Purshii 77
73. A, two views of single joint of raceme of Holcus halepen-
sis; B, diagram of raceme of four joints; C, diagram
of rachis and pedicels 80
74. A, diagram of single joint of raceme of Erianthus sac-
charoides; B, three joints of raceme 81
75. A, single joint of a raceme of Andropogon scoparius; B,
small part of compound inflorescence 82
76. A, single joint of raceme of Manisuris cylindrica; B,
another view of two joints; C, inner face of rachis joint
and pedicel, spikelet removed; D, part of cylindrical,
many-jointed raceme , 83
77. A, single joint of raceme of Rytilix granularis; B, reverse
view; C, diagram of rachis and pedicels of three joints
of raceme, spikelets removed; D, view of inner face of
first glume of sessile spikelet; E, raceme; F, reverse
view 84
78. A, one-jointed raceme of Rhaphis pauci flora; B, base of
raceme and summit of branch; C, the hairy summit of
branch from which raceme has fallen; D, inflorescence 86
79. A, single joint of raceme of Heteropogon contortus; B, per-
fect spikelet from which sterile spikelet has fallen; C,
base of fertile spikelet and its callus; D, raceme; E,
diagram of a raceme; F, diagram of rachis and pedicels
of four joints of raceme 86
LIST OF ILLUSTRATIONS xiii
FIG. PAGE
80. A, two joints of pistillate part of raceme of Tripsacum
dactyloides; B, spikelet removed from the joint; C,
rachis joint from which the spikelet has been removed;
D, inflorescence; E, diagram of rachis of pistillate part;
F, pair of stamin ate spikelets 89
81. A, part of a cross section of an ear of corn, Zea Mays,
showing two pistillate spikelets standing at right angles
to their axis (the cob); B, pistillate spikelet about
flowering time; C, part of raceme of staminate spikelets 91
82. A, pistillate inflorescence of Bulbilis dactyloides; B, pis-
tillate spikelet cut from the rachis; C, pistillate floret;
D, diagram of half a head, showing one of the two rows
of spikelets; E, staminate inflorescence; F, staminate
spikelet 92
83. Diagram of inflorescence of Festucea3 95
84. Diagram of inflorescence of Hordese 95
85. Diagram of inflorescence of Avenea3 95
86. Diagram of inflorescence of Agrostideae 96
87. Diagram of inflorescence of Chloride* 96
88. Diagram of inflorescence of Naziese 96
89. Diagram of inflorescence of Phalaridese 97
90. Diagram of inflorescence of OryzeaB 97
91. Diagram of inflorescence of Zizaniese 97
92. Diagram of inflorescence of Paniceae 98
93. Diagram of inflorescence of Andropogonea? 99
94. Diagram of inflorescence of Tripsacese 99
FIRST BOOK OF GRASSES
FIRST BOOK OF GRASSES
INTRODUCTION
THE purpose of this primer is to give those with
little or no knowledge of botany such an understand-
ing of the structure of grasses as will enable them to
use manuals of botany and other technical works,
to the end that our native grasses may become
better known and their worth and beauty be more
fully appreciated.
The best method of studying any organisms is to
observe and examine the organisms themselves.
Since these can not be provided in a book, drawings
of the objects studied are here offered as the best
substitute. These drawings are purposely somewhat
diagrammatic in order to bring out particular char-
acters that may be less prominent in the actual
plants. While the drawings convey clearer ideas of
structure than can words and are to be used con-
stantly with the text, they can but inadequately
take the place of the plants themselves. The student,
therefore, should collect for study as many different
kinds of living grasses as possible.
The idea of a primer has been kept in mind. The
subject is presented as simply as possible, and only
enough grasses are examined in each lesson to illus-
1
FIRST BOOK OF GRASSES
different modifications and to prepare the
student to comprehend the greater modifications
shown in subsequent lessons.
The classification of grasses, that is, the grouping
together of related forms, is based on the characters
of the aggregate of minute flowers and bracts known
as the spikelet. It is necessary, therefore, for anyone
who wishes to be able to identify a given grass to
understand the structure and modifications of the
spikelet. This primer is really an elementary study
of the morphology of the spikelet. [Morphology is a
branch of science that treats of form and structure.
The study of the morphology of the spikelet enables
one to recognize its various organs under whatever
form they may assume.]
USE OF TECHNICAL TERMS
Many persons who might otherwise make an
effort to learn something about our common wild
flowers and trees, as well as grasses, are deterred
by the sight of the unfamiliar words used in botanical
descriptions. This supposed lion in the way, if one
will but draw near enough to see, is only a "harmless
necessary cat." No boy learns a trade, no girl
learns to sew without learning the names of the tools
used. Words like hames, whippletree, terrets, and a
hundred more, meaningless to the city-bred rider on
a trolley-car, are familiar terms to the farmer.1 Such
1 Mark Twain's description (in "A Tramp Abroad ") of
how they hitch horses in Europe is a good example of the con-
INTRODUCTION 3
terms as carburetor, accelerator, clutch, spark-plug
or magneto, unknown a few years ago, are now
understood by nearly everyone, and those who do
not as yet understand these terms are by no means
deterred thereby from buying (or wishing for) an
automobile. Spikelet, glume, and lemma are words
no more difficult to learn than are hames, crupper,
or whippletree, carburetor, clutch, or magneto. The
reason for using these botanical terms is the same as
that for using the names of the different parts of a
harness; they are simpler and more exact than
would be a descriptive phrase. It is simpler to say
"tenets" than to say "the rings that stick up in the
middle of the harness on the horse's back that you
pass the reins through" and it is simpler to say
fusion caused by want of technical terms: "The man stands
up the horses on each side of the thing that projects from the
front end of the wagon, throws the gear on top of the horses, and
passes the thing that goes forward through a ring, and hauls
it aft, and passes the other thing through the other ring and
hauls it aft on the other side of the other horse, opposite to the
first one, after crossing them and bringing the loose end back,
and then buckles the other thing underneath the horse, and
takes another thing and wraps it around the thing I spoke of
before, and puts another thing over each horse's head, and puts
the iron thing in his mouth, and brings the ends of these things
aft over his back, after buckling another one around under his
neck, and hitching another thing on a thing that goes over his
shoulders, and then takes the slack of the thing which I men-
tioned a while ago and fetches it aft and makes it fast to the
thing that pulls the wagon, and hands the other things up to
the driver."
4 FIRST BOOK OF GRASSES
" glume" when speaking of that organ of a grass than
to say "the little green scale on the outside of the
thing with the seed in it."
In the first lesson nearly all the new words that a
study of grasses will require are explained and illus-
trated by figures. The few additional terms neces-
sary are explained as they are used. No attempt is
made to write a primer of grasses in words of one
syllable nor to produce a work on { i how to know the
grasses" without mental effort. It can not be done.
USE OF LATIN NAMES
Besides unfamiliar terms there are the unfamiliar
Latin names of the plants which some hesitate to
encounter. But many of the names in common use
for trees and herbs are the botanical names. Mag-
nolia, Rhododendron, Petunia, Asparagus, Chrysan-
themum, Phlox are the Latin botanical names and
are freely used by all without hesitation. Panicum,
Paspalum, Bromus, Festuca, Hordeum are no more
difficult. As in the case of such terms as glume and
lemma, the Latin names of plants are used for the
sake of exactness. Common names of plants, espe-
cially of those which are useful, troublesome, or
conspicuous, are more definitely applied in older
countries where the inhabitants have dwelt in a
region for many generations than they are with us.
Our ancestors brought names of old world plants
with them to their new homes and applied them to
INTRODUCTION 5
plants something like the familiar ones. Conse-
quently, many common names are used in different
parts of the country for widely different plants. In
Illinois " June-grass" is Kentucky blue-grass (Poa
pratensis), a valuable pasture grass; in Maine " June-
grass77 is Danihonia spicata, an almost worthless
little relative of wild oats; and in parts of the West
it is Kceleria cristata. The name " blue-joint77 is
used for three very unlike grasses. On the other
hand, many plants have different names in separate
parts of the country. Around Washington, D. C.,
for example, Azalea is commonly called " honey-
suckle.77 Many economic plants (such as potato,
turnip, and rye) have common names uniform in
any one language but different in distinct languages.
When the Latin name of a plant is used, it is definitely
understood not only throughout the United States
but throughout the world what species is referred
to. However, the primary reason for using the
botanical names is that these indicate the relation-
ship of the plants. All plants of a kind have the
same genus (or generic) name. [Genus is the sin-
gular, genera the plural, generic the adjective.]
Kentucky blue-grass and all its kind are Poa: P.
pratensiSj P. trivialis, P. annua, P. Sandbergii, and
so on. The common names of these, Kentucky
blue-grass or June-grass, rough meadow-grass, spear-
grass, little bunch-grass, respectively, give no clue
to their relationship or kind. Knowing Poa pratensis
anyone hearing of any grass named Poa has an idea
6 FIRST BOOK OF GRASSES
of what it is like; it is something like Poa pratensis.
Some common names, especially those of trees,
indicate the kind: Oak, with black, white, scarlet,
swamp, and post oak, for example, and also hickory
and ash; but for herbs, and especially grasses, the
common name usually gives no indication of the
kind of plant it refers to. Often the name is mis-
leading. Rib-grass is not a grass, but a plantain;
poison ivy is not an ivy, but a sumach. To convey
definite ideas we must use definite terms and definite
names.
TOOLS NEEDED
Any work that one engages in requires tools. For
the study of grasses we need but few. Grass flowers
are too small to be seen distinctly with the naked
eye. A lens magnifying about ten diameters is
necessary. This may be mounted on a stand or it
may be a hand lens. A simple dissecting microscope
with two or three lenses of different magnification
would be more convenient and would well repay the
cost, but it is not absolutely necessary. If one has
only a hand lens, an eye-piece, such as watchmakers
place in the eye, will also be found very useful in dis-
secting, as it leaves both hands free. One or two
dissecting needles are needed. These can be made
by forcing the heads of coarse sewing needles into
a pencil-shaped piece of soft wood. After some prac-
tice one learns to use the nail of the left forefinger
skilfully in dissecting. One can work more rapidly
INTRODUCTION 7
with this and one needle than with a pair of needles.
A scalpel is useful, but the small sharp blade of a
penknife will answer instead. It is well to have a
piece of black paper or cardboard on which to place
hairy spikelets. The hairs on the different parts
show up well against this background.
It is the aim to use, so far as possible, the charac-
ters that may be seen in the different parts of the
spikelet with but little dissection. When further dis-
section is necessary, instructions will be given at the
end of the lesson requiring it.
LESSON I
THE GRASS FAMILY
To most persons grass is almost any green vegeta-
tion of rather low growth, especially such as may be
grazed. To the student of plants, a grass is a
member of the natural family Poacese, or Graminese,
distinguished by its structure.
Grasses are herbs with round or flattened (never
3-angled), usually hollow stems (culms) solid at
the joints (nodes), and 2-ranked, alternate, parallel-
veined leaves, composed of two parts, the sheath,
which surrounds the culm like a tube split down one
side, and the blade, which is usually strap-shaped,
flat, folded, or with rolled margins. At the junction
of the sheath and blade, on the inside, is a small
appendage (the ligule); this is commonly thin in
texture; sometimes it is only a ring of hairs, rarely
it is obsolete. The plants may be annual or peren-
nial. The root, stem, and leaves are the vegetative
part of the plant (Fig. 1). These are all that are
concerned with the life of the individual plant. The
flowers have to do with perpetuating the species.
In grasses the vegetative parts are more uniform
and characteristic than in most other families.
Having stem and leaves of any plant, it can always
be readily decided whether or not it is a grass. The
8
THE GRASS FAMILY
FIG. 2. Typical complete
flower, showing calyx,
corolla, stamens and
' pistils.
only plants that may rea-
sonably be mistaken for
grasses are the sedges. In
these the culms are solid or
pithy, are not jointed, and are
commonly 3-sided; the leaves
are always 3-ranked, and the
sheaths always closed.
The flowers of grasses
are small and inconspicuous.
They consist of a single pistil
with a 1 -celled, 1-ovuled ovary,
two styles, each with a feath-
ery stigma, and three (rarely
one or six) stamens with deli-
cate filaments and 2-celled
anthers. Two minute scales,
called lodicules, situated back
FIG. 1. Vegetative part of a °f the Pistil> at blooming time
grass plant; part of leaf become turgid and force open
opened out. , . ,
the enveloping scales.
In Fig. 2 are shown the parts of a common flower
10
FIRST BOOK OF GRASSES
(the wild prairie rose with long styles). The calyx
and corolla are the floral envelopes; the stamens and
pistils are the essential organs of a flower, the parts
that produce seed. The floral envelopes protect
the essential organs in the bud and, by secreting
nectar which attracts insects or in other ways, com-
monly aid in securing the fertilization of the flower.
The pistil consists of the
ovary, style, and stigma.
The ovary contains the
ovules, which when fer-
tilized develop into the
seeds. The style serves
to lift the stigma into the
air. The stigma is more
or less expanded, has a
viscid surface to which
FIG. 3. Grass flower, showing sta- the pollen-grains adhere
minate, sending their con-
tents in a minute tube which pushes down through
the style to the ovules, fertilizing them.
The grass flower (Fig. 3) is reduced to the essential
organs, the floral envelopes being represented by the
minute lodicules. Each flower is borne in the axil
of a small green bract (the lemma) and is subtended
and enveloped in a second bract (the palea). The
flower with its lemma and palea is termed the floret
(Fig. 4). The ripened ovary (the grain, or caryppsis)
(Fig. 5) consists of a small embryo lying at the base
THE GRASS FAMILY
11
of a mass of starchy endosperm. [Endosperm means
within the sperm or seed. It is the store of food
used by the infant plantlet when
it begins to grow.] ^The "germ" of
a kernel of corn is the embryo,
while the remainder of the kernel
is starchy endosperm. The grain
lies in the palea with the hilum
(the scar of the point of attach-
ment) toward it, and the embryo ^
on the side toward the lemma. *'
Fig. 5 gives two views of a grain, FlG- 4;rfng°t^eat flow"
one showing the hilum, the other
the. embryo. In Fig. 81, A (page 91), are two ker-
nels of corn showing the embryos. The grain with
very few exceptions is permanently in-
closed in the lemma and palea, the ma-
ture floret being the fruit, that is, the
seed with its permanent envelopes. The
florets are borne in two ranks and alter-
nate upon an axis (the rachilla). Below
them are two bracts without flowers
(the glumes). The glumes, rachilla, and
florets together form the spikelet.
Fig. 6 is a diagram of a branch with
leaves and flowers arranged as are the
glumes, lemmas, paleas, and flowers of
a grass spikelet. Fig. 7 is a diagram
of a spikelet for comparison with Fig. 6. [The hy-
pothetical flower-bearing branchlet is never elongate,
12
FIRST BOOK OF GRASSES
as here shown for the sake of comparison. The
palea is immediately above the lemma and the
flower immediately above the palea.] It will be seen
that the spikelet is theoretically a leafy flowering
branch with a jointed main axis, the flowers, except
riRST GLUME
FIG. 6. Diagram of a flowering
branch.
FIG. 7. Diagram of
spikelet.
for the minute lodicules, reduced to the essential
organs. In Fig. 8 a typical grass spikelet is shown,
the lemmas and paleas nearly closed together and
concealing the flowers.
The spikelet is characteristic of grasses and is not
found in any other family except that of the sedges.
THE GRASS FAMILY
13
In the spikelets of sedges the florets are commonly,
but not always, spirally arranged, there never is a
palea, and the fruit is an achene or nutlet. [The
" seeds" of buttercups and
mints are achenes or nut-
lets.]
In grasses specialization
takes place mostly in the
spikelet. By its vegetative
characters we know a given
plant to be a grass, but it
is by its spikelets and their
arrangement that we know
what kind of a grass it is.
The genera of grasses and
the groups of genera called
tribes are based on the
structure of the spikelets
and their arrangement in
the inflorescence.
Before studying the spike-
let we must observe the
relatively few specializations of the vegetative parts.
As hi other plants, stems or parts of stems may be
underground. These underground stems (rhizomes,
or rootstocks) are borne at the base of the main culm
under the earth, spread out horizontally, and in due
time send up shoots which form young plants at a
distance from the parent. Sod-forming grasses have
this kind of underground stem. Kentucky blue-
r/RST
•LUME
FIG. 8. Generalized spikelet.
14 FIRST BOOK OF GRASSES
grass (Poa pratensis, Fig. 9) furnishes an excellent
example. Sometimes the rhizome is thick and woody,
sending up shoots from its nodes, the whole forming a
dense colony, as in gama-grass (Tripsacum dacty-
loides). A rhizome, being a stem, is jointed and
bears scales, which are reduced leaves. By these it
may always be distinguished from a root, which
is not jointed and never bears scales. In some
grasses the shoots
borne at the base
of the culm are
on the surface of
the earth instead
of beneath it.
Such shoots are
stolons, or run-
ners. These, like
rhizomes, are
FIG. 9. Base of plant and underground parts, jointed and bear
roots and rhizomes, of Poa pratensis.
scales or, some-
times, well-developed leaves. Rhizomes and stolons
both bear roots at the under side of the nodes. In a
few species, Bermuda-grass for one, a plant may
produce either rhizomes or stolons according to the
conditions under which it is growing. There is no
real difference between a rhizome and a stolon, the
one is below ground and colorless, the other above
ground and green.
Culms are hollow in most grasses, but in corn,
sugar-cane, sorghum, and related grasses they are
THE GRASS FAMILY 15
pithy. They may be erect, spreading, or creeping;
they may be simple or freely branching. A branch
is borne only at a node in the axil of a sheath, that is,
between the sheath and the culm. It either grows up
parallel with the parent culm until it emerges from
the sheath or the young branch splits the sheath and
grows outward. In manuals of botany these two
methods of branching are called intravaginal, that
is, inside the vagina (Latin for sheath), and ex-
travaginal, outside the sheath. In bunch-grasses,
like orchard-grass and the wheat-grasses of the
West, the branching is intravaginal; in Kentucky
blue-grass, quack-grass, and others producing rhi-
zomes or stolons, the branching is extravaginal.
The branches borne at the middle and upper nodes
of a culm are nearly always intravaginal. If they
spread from the parent culm they do not burst
through the sheath but carry it with them.
Leaves are always borne at the nodes and are
always 2-ranked (see Fig. 1, page 9). In corn and
other large grasses the leaves sometimes appear
to be all on one side instead of 2-ranked. This is
due to a twisting of the culm inside the sheath.
Sometimes in large grasses, particularly in sugar-
cane and in bamboos, the leaves fall, leaving the culm
naked. In relatively few grasses the edges of the
sheath are grown together, forming a tube. Some-
times the blade of the leaf is not developed. This is
always the case in the leaves or scales of rhizomes
(Fig. 9), and often in those of stolons and in the
16 FIRST BOOK OF GRASSES
lowermost leaves of a culm, especially in bamboos.
Blades may be flat or folded (often called con-
duplicate) or involute; that is, rolled lengthwise.
Rarely the inrolled edges are grown together, so
that the blade really has no upper surface. Such
leaves are called terete (meaning rounded). Blades
vary greatly in size, shape, and texture, smoothness
or hairiness. In broad leaves there is sometimes a
narrow neck, or petiole (leaf -stalk), between the
sheath and the blade.
SUMMARY
Grasses are distinguished by jointed, round or
flattened, usually hollow, culms, with solid nodes;
2-ranked leaves, composed of sheath and blade,
with a ligule at their junction; and by the spikelets
with 2-ranked glumes and florets.
REVIEW
(1) How is a grass distinguished from all other plants?
(2) Break a cornstalk and note the arrangement of the torn
fibers standing out of the pith. Compare this with the cut end
of any twig of a tree or shrub. Cut across a wheat, oat, or rye
straw and compare with the cornstalk and with the twig.
(3) Examine the culm (nodes and internodes) above and below
ground and leaves (sheath, ligule, and blade) of any available
(4) How is a rhizome distinguished from a root?
(5) What is the difference between a rhizome and a stolon?
LESSON II
THE SPIKELET AND THE INFLORESCENCE
THEORETICALLY the spikelet is a reduced leafy
branch. In the generalized spikelet shown in Fig. 8
the likeness to a jointed culm with 2-ranked leaves
(Fig. 1) is readily seen, the glumes and lemmas corre-
sponding to sheaths, their blades not developed. The
palea, with two nerves and with its back to the axis,
corresponds to a minute bract (the prophyllum)
borne at the base of a branch in the axil of a sheath.
The prophyllum is always 2-nerved, with its back
(that is, the space between the nerves) against the
main axis and its margins clasping the young branch.
The flower, also, is theoretically an ultimate branch-
let. In the flower-bearing lemmas, therefore, the
palea is developed, while in the glumes, bearing no
flowers, there are no paleas. Glumes and lemmas
are, morphologically, reduced leaves, the lower pair,
not flower-bearing, being termed glumes, the flower-
bearing ones being termed lemmas. (See Fig. 7.)
The jointed axis of the spikelet (the rachilla)
corresponds to the jointed culm and, like it, usually
breaks at the nodes, the internode (the part of the
rachilla between two nodes) remaining attached to
the floret at its base (Fig. 4), just as in a broken
grass stem the internode of the culm remains with
17
18
FIRST BOOK OF GRASSES
the sheath that surrounds it; that is, the break
normally comes just under the node. Rachis
(which means the spine, or backbone) and axis
(the imaginary central line of any body) are
often used inter-
changeably as bo-
tanical terms. In
most recent works
on grasses and in
these lessons, axis
is used for the
main axis of a eom-
pound inflores-
cence, rachis for
the axis or sup-
port of the spike-
lets. In Fig. 10
are shown the axis
of a panicle .(A)
and the rachis of
FIG. 10. Forms of inflorescence: A, panicle; a raceme (B) ' the
B, raceme; C, spike. Qf
(C) is concealed by the overlapping spikelets.
Spikelets are borne pediceled (that is, on a pedicel
or foot stalk) or sessile (without a pedicel) in leafless
panicles, racemes, or spikes (Fig. 10) . These different
types of inflorescence insensibly grade into each
other. The axis and branches of a panicle and the
rachis of a raceme or spike may be as elaborately
modified and specialized as may be the parts of a
THE SPIKELET AND THE INFLORESCENCE 19
spikelet. The axis, rachis, or branches may be
continuous (not jointed), or articulate (jointed) and
usually disarticulating (breaking up). The break-
ing up takes place at definite points and has to do
with scattering the seed. The point of disarticula-
tion is the same in grasses of the same kind (or
genus) and is usually alike in related genera, and
for this reason is of great importance in the classifica-
tion of grasses. When there are no joints in the axis
or branches, the disarticulation comes in the spikelet,
either above the glumes and between the florets or
below the glumes. Modifications of these two ways
of disarticulating will be met with later. The study
of the form of inflorescence and the modification of
its parts will be carried on together with that of the
spikelet.
SUMMARY
A spikelet consists of glumes and florets, in two
ranks and alternate on the rachilla, the florets consist-
ing of lemma, palea, and the inclosed flower. Every
organ found in the most highly specialized spikelet
is to be interpreted as an elaboration or a reduction
of one of these parts. The spikelet is the unit of the
inflorescence; the floret is the unit of the spikelet.
The spikelet is always simple; that is, the rachilla
never branches. The floret is always 1 -flowered
with never more than one lemma and one palea; the
glumes and florets are always alternate, two consecu-
tive ones never being borne one above the other.
20 FIRST BOOK OF GRASSES
These basic facts kept in mind will aid in the recogni-
tion of complicated or congested spikelets and in the
correct interpretation of their parts.
REVIEW
(1) Examine a spikelet of a brome-grass, such as cheat or
chess. Separate the florets from each other and from the glumes.
Note that these disjoint without tearing. Open out the lemma
and palea. Note that these permanently adhere at their base;
that they can only be torn or cut apart.
(2) Name the parts of a spikelet.
(3) What is their arrangement?
(4) What is the difference between a rachis and a rachilla?
LESSON III
MODIFICATIONS OF THE SPIKELET
TAKING the generalized spikelet as a beginning,
examine Figs. 4 and 8. Note that the glumes and
lemmas have nerves or veins (fibre-vascular bundles)
running from the base to the apex or nearly to it,
one nerve in the middle and an equal number on
each side, there being an odd number of nerves in
the glumes and lemmas. In the palea there are only
two nerves; none in the middle. The modifications
and variations of spikelets will be studied, as nearly
as possible, in the order of their increasing com-
plexity. No attempt should be made to fix in mind
the forms of specialization here enumerated. This
lesson is only meant to put one on the lookout for
modifications, so that one may be prepared to recog-
nize a given organ under various guises.
(1) Spikelets differ in size. (Bromus or brome-
grass, meadow fescue, and blue-grass are examples.)
(2) The number of florets may be reduced to one
or increased to twenty or more.
(3) The parts of the spikelet vary in their relative
sizes. The glumes may be large and the florets small
or the florets large and the glumes small.
(4) The rachilla joints may be slender or thick, so
short that the florets appear to be opposite, or nearly
21
22 FIRST BOOK OF GRASSES
as long as the florets themselves; the node at the
base of the floret (the callus) is sometimes prolonged
into a sharp point; the uppermost rachilla joint may
bear no floret and may extend into a little bristle.
(5) The glumes may vary in shape, in texture,
and in the number of their nerves and may be gla-
brous (smooth) or pubescent (hairy) ; sometimes they
are reduced to rudiments and sometimes they are
suppressed.
(6) The lemma is subject to such great modifica-
tions that we shall now note only the simplest ones.
As in the glumes, the shape and texture and the
number of nerves vary. The summit of the lemma
may be acute (pointed) or acuminate (long-pointed)
or obtuse (blunt) or it may be lobed or cleft. The
nerves may be faint or strong, or may extend into
awns (bristles) beyond the body of the lemma. The
lemma is sometimes minute, but it is never sup-
pressed.
(7) The palea is always 2-nerved, but in a few
grasses the nerves are so close together as to appear
like a single one. In others they are far apart and
the palea may split between them. The palea differs
in size and texture. In a few genera it is reduced or
even suppressed.
(8) Spikelets are compressed (flattened) laterally
(sidewise), as in Figs. 11-14, or dorsally (on the
back), as in Figs. 60-66. The side or back of a
spikelet is recognized from the position of the florets
on the rachilla. The palea side of the floret is always
MODIFICATIONS OF THE SPIKELET 23
toward the rachilla. Taking this as the " front"
of a floret, the back (or dorsum) is the back of the
lemma. Spikelets with many florets, or those in
which the glumes or lemmas are folded on the mid-
nerve, are generally laterally compressed; those with a
single fertile floret and with convex (rounded) glumes
and lemma are generally dor sally compressed.
(9) Spikelets are sometimes unisexual (of one sex)
instead of perfect (having both stamens and pistil).
The two kinds, pistillate (the ovule-producing) and
staminate (pollen-producing) may be borne on a
single plant, as in corn, with pistillate spikelets in the
ear and staminate spikelets in the tassel, or in differ-
ent plants, as in salt-grass and buffalo-grass. Grasses
with staminate and pistillate spikelets on the same
plants are monoecious (which means dwelling in one
house) ; those with staminate and pistillate spikelets
on different plants are dioecious (dwelling in two
houses). The unisexual spikelets of a single species
may be similar in appearance, or they may be very
unlike, as in corn.
(10) Some grasses with perfect spikelets bear in
addition staminate spikelets or neuter spikelets (hav-
ing neither stamens nor pistils). These additional
spikelets may be similar in appearance to the perfect
ones or very unlike them. They are borne in the
same inflorescence as the perfect spikelets and are
usually paired with them.
(11) The florets of a single spikelet may be of two
kinds, perfect and sterile, the sterile being either
24 FIRST BOOK OF GRASSES
staminate or neuter. In spikelets like those of Figs.
11-14, with several to many florets, the uppermost
florets are commonly sterile (not perfecting seed),
though they are like the fertile florets in appearance
and have rudimentary stamens and pistils. In some
grasses the sterile florets are very different from the
fertile ones and may be borne above or below them
on the rachilla. The position of sterile florets in the
spikelet is the same in large series of related grasses;
hence it is of great importance in classifying genera.
The type of modification of the sterile floret is also
uniform within a genus, and generally in related
genera. It commonly consists of a lemma without a
palea, but there may be a rudimentary or even a
well-developed palea.
These types of modification will be brought out
and illustrated in the succeeding lessons.
SUMMARY
All spikelets are built on the simple plan of 2-
ranked florets with a pair of glumes at the base.
The spikelet as a whole and each of its organs is
subject to modification. The palea and one or both
glumes may be suppressed; the lemma may be re-
duced but is never suppressed. The position and
type of modification of sterile florets are of impor-
tance in classification.
The parts of a spikelet, however complex, are
recognizable as rachilla, glumes, lemma, or palea.
LESSON IV
PEDICELED SPIKELETS OF FEW TO MANY
FLORETS
TAKING the spikelet of cheat or chess (Bromus
secalinus), Fig. 11, as a starting point, we have
one but little different from the
diagrammatic spikelet (Fig. 8).
[Names incidentally mentioned
should not be memorized.] The
lemmas are convex on the back,
several -nerved, 2-toothed at the
apex and bear an awn from be-
tween the teeth. The awn is
the midnerve extending beyond
the body of the lemma. The
rachilla joints are short, bring-
ing the florets (Fig. 11, B) close
together. The articulation is
above the glumes and between FlG- *L A,
. ered spikelet of Bromus
the florets. The palea is grown secalinus; B, single
fast to the grain. All species of floret'
Bromus have spikelets of this character, differing
in size, texture, length of the awn, which may be
much longer or reduced to a mucro (a minute point)
or even suppressed, in being glabrous, as in cheat, or
pubescent. The pubescence may cover the lemma
25
26
FIRST BOOK OF GRASSES
or be along the margins only. These differences
distinguish the species. A genus is composed of one
to many species having few to several important
characters in common, and presumably descended
from a common ancestor. Groups of species having
less important characters in common form related
genera. Festuca (Fig. 12) is related to Bromus,
having few to several-flowered
spikelets, disarticulating above
the glumes and between the
florets and with several-nerved
lemmas; but the lemmas are
awned from the tip, or pointed
only, and not toothed, and
the palea is not grown to the
grain.
A large number of grasses
have laterally compressed
spikelets of this general type,
disarticulating above the
FIG. 12. A, spikelet of Fes-
tuca ovina; B, lemma de- glumes and between the tew
tached- to many florets. They are
sorted into genera and the genera separated from
each other chiefly according to the modifications
of the lemma. In Panicularia (Fig. 13) the lemmas
are broad and obtuse with strong parallel nerves.
In Poa (Fig. 14) the lemmas are keeled on the back,
and have five nerves converging toward the acute
but never awned apex. The species figured (Ken-
tucky blue-grass, Poa pratensis) and many others
PEDICELED SPIKELETS 27
are villous (having soft curly hairs) on the lower
part of the midnerve and the marginal nerves and
have a tuft of white cottony hairs at the
base, but this pubescence is not found in
all the species.
In all the grasses mentioned so far,
the spikelets are borne in panicles (see
Fig. 10, A). Spikelets much
like those of Panicularia (Fig.
13) but borne in a raceme
and having awned lemmas
are found in Pleuropogon
(shown in Fig. 10, B). In
these spikelets the palea is
crested or winged on the nerves
(Fig. 15, showing a three quar- FlG. 14.' 'Spike.
ter view of a palea removed let °.f Poa
x tensis.
from the floret).
Returning to Fig. 11, A, we
Sp!keiet30f note the midnerve of the lemma
extending as an awn beyond the
minutely toothed apex. The mid-
nerve and the two lateral nerves
as well are extended into awns in Triodia
flava (Fig. 16, the floret seen from the back) ;
the apex of the lemma is toothed and the
nerves are villous below. In Fig. 17 (floret J
of Cottea pappophoroides opened out and™
seen from the back) the lemma is lobed and nine to
eleven of its many nerves are extended into awns.
28
FIRST BOOK OF GRASSES
After the foregoing the spikelet and its parts will
be recognized in most of the genera of the group
having few to many-flow-
ered pediceled spikelets.
As stated in Lesson III
the florets in a single spike-
let may be of two kinds.
The simplest spikelet of
this type is found in the
FIG. 16. i /r>7
Floret of reed (Phragmites commu-
flava.
floret is staminate or neu- FIG. 17. Lemma of
ter and its lemma is much longer Cotiea ^^horoides-
than in the other florets (Fig. 18, A). In the per-
fect floret (Fig. 18, B) it will be seen that the palea
is very much shorter than the lemma, that the
FIG. 18. A, spikelet of Phragmites communis', B, floret.
rachilla bears copious long soft hairs, and that in-
stead of disarticulating at its summit and remaining
PEDICELED SPIKELETS
29
attached to the floret next below, it disarticulates at
its base, remaining as a tiny feathery stem to the
floret next above, its copious long hairs carrying the
floret before the wind, dispersing the
seed. [The hairs are much more co-
pious than shown in the figure; they
are slighted to avoid obscuring the
difference in the florets.]
Another spikelet with two kinds of
florets is shown in Fig. 19 (Melica
mutica). In this the lemmas of the FlG- i»: Spikelet of
upper florets are reduced in size,
changed in shape, and contain no flower. Two or
three of them are crowded together in a little club-
shaped body. In the species figured, this modifica-
tion is more marked than in most of the species.
In Fig. 20 is shown
a side view of the
florets of a spikelet of
Pappophorum vagina-
turn, the glumes re-
moved. The lowest
floret is perfect. Its
broad lemma is cut into
many spreading awns
(compare with Fig. 17).
The two to four other
florets are crowded on
the very short rachilla and are sterile ; their lemmas
are similar to that of the one fertile floret. The
FIG. 20. Florets of Pappophorum
vaginatum.
30
FIRST BOOK OF GRASSES
rachilla does not disarticulate, the sterile florets re-
maining permanently attached to the fertile one, the
numerous awns of all together forming a pappus-like
crown which carries the seed before the wind. [Pap-
pus is the "down" on the seed of a dandelion, thistle,
or other plant of their family.]
Next we shall examine the inflorescence of a grass
having spikelets entirely of sterile florets in addition
to spikelets of fer-
tile florets. Ex-
amine Fig. 21, A
(Cynosurus crista-
tus), which shows
a small part of a
spike-like panicle.
The spikelets are
borne on minute
FIG. 21. A, part of a panicle of Cynosurus Pe^icels On Very
cristatus; B, sterile spikelet; C, fertile short Compound
branches. The
lower one to three spikelets of each little branch
are sterile, the lemmas containing no flowers (Fig.
21, B). The upper one to three spikelets are smaller
and fertile (Fig. 21, C). When the bracts of the
sterile spikelet are all alike empty, why are all
but the lower pair called lemmas, instead of glumes?
In many cases the nature of modified organs can
only be recognized by their correspondence to or-
gans in the same relative position in allied but
more simple forms. In all the spikelets examined
PEDICELED SPIKELETS
31
so far (and in all but a very small number of
grasses) the bracts above the lower pair are flower-
bearing or have a palea, which indicates their struc-
tural identity. Corresponding parts in a modified
spikelet are, therefore, regarded as lemmas. In the
grass just examined the sterile spikelets remain on
the panicle branches after the fall of the ripened
fertile florets from their glumes.
In Fig. 22, A (Achy r odes
aureum), is shown a fascicle
of one fertile and three
sterile spikelets of another
grass. In this the fascicles
hang from the short slen-
der branches of a narrow
panicle and disarticulate
from them, falling entire.
This is the first example we
have had so far of disartic-
ulating branches of the in-
florescence. In the figure
the fascicle is seen from the
inner face to show the fer-
tile spikelet, which from
the outside is nearly hid-
den by the sterile ones. Fig. 22, B, shows a sepa-
rate fertile spikelet. It will be seen that except
for the glumes, the two forms are strikingly dif-
ferent. The fertile spikelet is reduced to one
fertile and one rudimentary floret, both awned,
FIG. 22. A, fascicle of three sterile
and one fertile spikelet of
Achyrodes aureum; B, fertile
spikelet.
32
FIRST BOOK OF GRASSES
while the sterile spikelets are many-flowered and
awnless.
We shall next examine a grass having unisexual
spikelets (see Lesson III, page 23), the two forms
borne on different plants (dioecious).
(In the group with relatively simple
spikelets which we are now studying
there are no monoecious grasses).
In Fig. 23 are shown the pistillate
and staminate spikelets of salt-grass
(Distichlis spicata). They differ but
little in appearance and are both
FIG. 23. Pistillate
and staminate
spikelets of Dis-
tichlis spicata.
borne in narrow
panicles. [9 sig-
nifies female, d*
male. These signs
are commonly
used to indicate
pistillate and sta-
minate plants,
respectively.]
In Fig. 24 are
seen the strikingly
diverse staminate
and pistillate spikelets of another dioecious species
Fig. 24. Staminate and pistillate spikelets of
Scleropogon brevifolius.
PEDICELED SPIKELETS 33
(Scleropogon brevifolius). The lemmas of the stam-
inate spikelet are merely pointed; those of the
pistillate spikelet bear three long slender twisted
spreading awns. The pistillate florets fall from the
glumes as a whole (the rachilla not disarticulating
between them) and roll before the wind as tiny
tumble weeds.
SUMMARY
The inflorescence and the two to several-flowered
spikelets of the brome-grasses, blue-grasses and their
relatives are comparatively simple. In a few genera
sterile spikelets are developed and in a few others
the spikelets are unisexual.
REVIEW
Collect specimens of orchard-grass, meadow fescue, any
species of brome-grass, or of Poa, or of any available grasses
having laterally compressed, few to several-flowered spikelets.
Identify the different parts of the spikelets. Lemmas may be
spread out for examination by cutting off the very base with a
sharp knife or scalpel. Spikelets of tough or rigid texture if
soaked in water for a few minutes may be dissected without
tearing. If very tough or hard, boiling the spikelets in water
with a little glycerine (a drop of glycerine to about a teaspoonful
of water) will make them manageable and keep them from drying
out during dissection.
LESSON V
SESSILE SPIKELETS IN TWO-SIDED SPIKES
RETURNING
FIG. 25. A, part of a
spike of Agropy-
ron repens', B,
part of rachis
seen from the
edge, all but
two spikelets re-
moved.
again to the spikelet of Bromus
secalinus (Fig. 11), we shall strike
out in another direction. Differ-
entiation among living beings does
not follow a line, but radiates like
waves following the falling of a peb-
ble in the water, or rather like waves
of sound, in all directions. Hence we
can not follow an unbroken line in
studying the increasing complexity
of the inflorescence of grasses. We
can only return to the center and
start out on another line. Compare
Fig. 10, A and B, with C, and with
Fig. 25 (couch-grass or quack-grass,
Agropyron repens). A raceme is a
panicle reduced to its lowest terms.
Eliminating the pedicels of the spike-
lets of a raceme we have a spike, the
spikelets set directly upon the rachis.
In such an inflorescence the rachis
is usually more or less thickened. In
Fig. 25, A, part of a spike is shown
from the flat side of the spikelet.
The rachis is jointed and a spikelet is
34
SESSILE SPIKELETS IN TWO-SIDED SPIKES 35
borne at each joint, alternating on opposite sides.
The rachis is thickened and the joints slightly hol-
lowed on alternate sides. (See Fig. 25, B, a diagram-
matic illustration of the rachis seen from the edge
with all but two spikelets removed.)
The spikelet is not very different from that of
Bromus (Fig. 11) and as
in that, the ripened
florets fall from the
glumes.
In the group of
grasses taken up in this
lesson the specialization
is mostly in the rachis
and in the position of
the relatively simple
spikelets.
In Fig. 26, a spikelet
of cultivated w h e a t
(Triticum cestivum), we
have the same type of
spikelet as in Fig. 25 but with fewer and much
plumper florets, with broader lemmas slightly toothed
at the apex, and with long awns that are scabrous
(rough, like a file). [Awns form the " beard" of
wheat.] The spikelets are borne on a jointed rachis
as in Fig. 25 (Agropyron repens) but the joints are
shorter, bringing the spikelets closer together and
hiding the rachis. In this, cultivated wheat, the
florets do not readily fall from the glumes but re-
FIG. 26. Spikelet of Triticum cestivum.
36 FIRST BOOK OF GRASSES
main in the spike and the ripened grain is thrashed
from them. This persistence of the lemma and
palea has been fixed by selection in cultivation. In
the closely related emmer (Triticum dicoccum) the
rachis breaks at the joints, each
joint remaining attached to its
spikelet.
Compare Fig. 27 (Lolium multi-
florum) with Fig. 25. Note that in
Fig. 25 the spikelets are borne
flat side against the rachis, while
in Fig. 27 they stand with their
edges against the rachis. The
rachis itself is of the same type as
that in Fig. 25. The diagram-
matic rachis with two spikelets
seen edgewise (Fig. 25, B) is shown
from the same position as is Fig.
27. In this, as in Agropyron, the
rachis is continuous (not disartic-
ulating) and the florets fall. If
FIG 27. Part of a spike we separate a spikelet from the
of Lohum multiflorum. * r
rachis we find that the first glume
(the one that would be against the rachis) is sup-
pressed, the first floret lying directly against the
rachis. In the single spikelet borne at the summit
of the rachis the first glume is developed and it
about as large as the second. When but one glume
is present, we know which glume it is and which is
suppressed by the position of the first floret, which
SESSILE SPIKELETS IN TWO-SIDED SPIKES 37
is always above the first glume.
When no glume is found below the
first floret, it is obvious that it is the
first glume which is suppressed.
In Fig. 28 (Lepturus cylindri-
cus) we have a greatly thickened,
strongly nerved rachis with spike-
lets placed as in Fig. 27 but reduced
to the second glume and a single
floret. This little spikelet is sunken
in the hollow of the rachis joint,
the second glume fitting snugly
over the hollow, the whole forming
a long, slender, wiry cylinder. At
maturity the rachis disarticulates
with the spikelets firmly embedded
in the joints. (See diagram of
rachis, Fig. 28, B, and, -above, a
joint with spikelet removed, show-
ing the hollow, and a second with
the spikelet in position.) The plant
bearing these spikes grows along
mud flats near the sea. The rachis ,
. . FIG. 28. A, part of
joints are cylindrical and readily spike of Lepturus
roll down the slope to the water. %£*%'B^r
Being corky, they are carried by
the lightest ripples and are thus
spread over wide areas. The grain
germinates within its little cell, and the young roots
and leaves push aside the water-soaked glume.
spikelets removed;
above, diagram of
single joint.
38
FIRST BOOK OF GRASSES
Returning to Fig. 25 with its one spikelet at
each joint, flat against the rachis, compare with it
Fig. 29 (Elymus vir-
ginicus, or rye-grass).
In this there are two
spikelets at each joint
of the rachis, the first
glumes back to back,
the spikelets somewhat
distorted, each pair
reaching around the
edges of the rachis. The
figure shows a pair of
spikelets and two joints
of the rachis, with the
pair of spikelets next
above, on the opposite
side of the rachis, lightly
sketched in behind; two
more internodes of the
rachis, with spikelets re-
moved, are shown by
dotted lines. A dia-
grammatic sketch of a
pair of spikelets, the dis-
tortion reduced, is shown
FIG. 29. A, pair of spikelets of Ely- . „
mua virginicus; B, diagrammatic aDOVe. A Comparison OI
figure of the pair of spikelets. the diagrammatic spike-
let with the spikelet in Fig. 25 will show the structural
similarity. In their natural position the spikelets,
SESSILE SPIKELETS IN TWO-SIDED SPIKES 39
overlapping on the short joints and extending around
the edges of the rachis, so that at least one is seen
nearly edge-wise, form a spike that may well be con-
fusing to the beginner, especially when, as in the
species shown in Fig. 29 and several others, the glumes
stand out like a 4-rayed involucre below the ap-
pressed florets. However, a single joint with its
spikelets attached cut out of the spike readily dis-
closes the structure. In some species of Elymus
there are three spikelets and occasionally four or
five at a node, the distortion being correspondingly
greater. In several species the glumes are so narrow
as to appear like bristles or awns only. In most of
the species the rachis is continuous and can not be
disjointed. In a closely related genus, Sitanion, the
rachis disarticulates at the base of each joint, the
slender rigid joint remaining as a tiny sharp-pointed
stem below the cluster of long-awned spikelets. The
awn-like glumes of Sitanion commonly split between
the nerves, sometimes to the very base, appearing
like a cluster of awns below the florets.
In Elymus and Sitanion the spikelets are all alike
(or some occasionally variously aborted) and all
sessile (set directly on the rachis). In Fig. 30 (Hor-
deum nodosum, one of the wild barleys), a group of
three spikelets and a joint of the rachis are shown.
As in Sitanion the rachis disarticulates at the base
of the internode, the joint remaining attached to the
spikelets above it. Note that the central spikelet is
sessile and the lateral ones pediceled, that the lower
40
FIRST BOOK OF GRASSES
floret of the central spikelet is well developed while
those of the lateral florets are rudimentary, and that
the back of the floret is turned from the rachis with
the glumes (bristle-like in this species) at the sides
or back, contrary to the arrangement characteristic
of grass spikelets. The
problem of the glumes
in Hordeum has not
been satisfactorily
solved. It appears prob-
able that the reduced
rachilla joint between
the second glume and
the floret is twisted
and bent inward, bring-
ing the glumes at the
side or back of the
floret. In the culti-
vated barley the rachis
does not break up, as
in the wild species, the
continuous rachis having been fixed by selection.
The florets fall from the spike in thrashing, or in
naked or hull-less barley the grains fall from the
lemma and palea, as in wheat. In cultivated 2-rowed
barley the lateral spikelets are pediceled and sterile,
as in the wild species, but in 4-rowed and 6-rowed
barley the lateral spikelets are sessile and fertile,
characters fixed by selection.
The grasses characterized by the " spicate in-
FIG. 30. Joint of spike of Hcrdeum
nodosum.
SESSILE SPIKELETS IN TWO-SIDED SPIKES 41
florescence dealt with in this lesson form the barley
tribe, which from the standpoint of man is the most
important group of grasses, if not of all plants, in the
world, containing wheat, barley, and rye.
SUMMARY
The specialization in spicate inflorescence is chiefly
in the rachis and next in the position of the relatively
simple spikelets.
When the glumes are distorted, standing side by
side, as often found in species of Elymus, or when
one of them is suppressed, we can tell which is which
from the fact that the first, or lowermost, floret is
always above or on the same side of the spikelet as
the first glume.
REVIEW
Collect heads of wheat, rye, barley, quack-grass, species of
Elymus, Lolium, or squirrel-tail grass (one or more of these will
be found anywhere in the United States). Note whether the
rachis readily disjoints. If so, separate out a single joint with
the spikelets attached. Note where the rachis breaks, at the
summit or base of the joint; note the number of spikelets at a
joint and the number of florets to a spikelet. Distinguish the
individual spikelets and their parts. If the rachis does not dis-
joint, cut across the middle of the internodes, taking out a single
joint with attached spikelets. Note the number of spikelets to a
joint; whether there are one or two to several fertile florets to the
spikelet and whether the spikelet is placed flatwise or edgewise
to the rachis.
Note how spikes bearing spikelets with scabrous awns push
themselves forward when handled.
LESSON VI
PEDICELED SPIKELETS WITH LARGE GLUMES
AND OTHER MODIFICATIONS
TURNING again to the spikelet of Bromus secalinus
(Fig. 11), compare with it Fig. 31 (wild oats,
Avenafatua). The
glumes are greatly
enlarged and the
rachilla joints are
so short that the
florets appear to
be almost oppo-
site. The awn,
instead of extend-
ing from the apex
of the lemma, pro-
trudes from the
back and is
twisted for about
half its length.
We noted in Les-
son IV that the
awn is an exten-
sion of the mid-
nerve. This fact is well shown in the floret of wild
oats (Fig. 31, B, the floret seen from the back), in
42
FIG. 31. A, spikelet of Avenafatua; B, floret.
PEDICELED SPIKE LETS WITH LARGE GLUMES 43
which the midnerve leaves the body of the lemma
about the middle of its back and becomes a free
awn, while the lemma above the departure of the
awn is nerveless. This is invariably the case when
FIG. 32. Spikelet of Trisetum
spicatum.
the awn is dorsal (that is, pro-
truding from the back); the
lemma is always nerveless
above it.
Compare Figs. 31 and 32
(Trisetum spicatum). It will
be seen that they are the same
type of spikelet. In Trisetum
the awn is loosely twisted
and is borne nearer the apex
of the lemma, which is tipped
with two slender teeth.
In Danthonia spicata (Fig. 33) the florets are more
numerous and are smaller in proportion to the
glumes. The broad strongly twisted awn arises from
FIG. 33. Spikelet of Danthonia
spicata; floret above.
44
FIRST BOOK OF GRASSES
between the teeth or lobes of a bidentate (2-toothed)
apex (see floret above, seen from the back).
In these three spikelets, as in all but a few of the
grasses of the oat tribe, the florets fall from the
glumes which remain on the pedicel. In velvet
grass, Notholcus lanatus (Fig.
34), the spikelet falls entire.
The articulation of the spikelet,
taken throughout the grass
family, is so nearly uniform for
related genera that it is relied
on to differentiate large series.
(See Lesson II, on inflorescence) .
There are exceptions to the
mode of articulation character-
istic of the group as a whole
in the case of a few genera in
three of our tribes. Such exceptions are puzzling
to the beginner, leading him astray in using keys.
We must learn to observe all the characters of the
inflorescence and base our judgment on the sum total
of the characters, remembering that " Nature does
as she pleases" and rejoicing that in grasses she at
least pleases to keep invariably to the 2-ranked
arrangement of the spikelets. (See the summary of
Lesson II). In Lesson IV, Figs. 18 and 19, we
observed spikelets in which the florets were of two
kinds. In Notholcus lanatus the lower floret is per-
fect and awnless and the upper is staminate and
bears a hook-like awn from the back (Fig. 34, B,
FIG. 34. A, spikelet of
Notholeus lanatus; B,
pair of florets.
PEDICELED SPIKELETS WITH LARGE GLUMES 45
florets removed from the glumes. Note the curved
and exceptionally long lowermost rachilla joint.)
In Sphenopholis, closely related to Trisetum
(Fig. 32) , the spikelets fall entire, as in velvet-grass.
In tall oat-grass (Arrhenatherum elatius) the spikelets
bear one perfect awnless floret and one staminate
awned floret, as in velvet-grass, but their position is
reversed, the staminate being below and the perfect
above.
SUMMARY
In the oat and its relatives the large glumes and
the awn of the lemmas are the most prominent
characters, although in species of some genera the
awn is wanting. Pubescence is commonly con-
spicuous. The inflorescence is an open or contracted
panicle.
REVIEW
Collect panicles of wild oats or awned specimens of cultivated
oats (cultivated oats growing wild commonly bear awns), of
Danthonia, one or more species of which are to be found through-
out most of the United States, and any of the related grasses
available, and examine the spikelets. Place a floret with a
twisted awn in a drop of water and observe the result. In awn-
less florets of cultivated oats note that the midnerve of the lemma,
if it is not at all produced into an awn, stops abruptly at the
point where the awn would arise normally and that the lemma is
nerveless above this point, just as if it were awned.
LESSON VII
PEDICELED ONE-FLOWERED SPIKELETS
TURN to the spikelet of wild oats (Fig. 31) and in
imagination eliminate all but the lowest floret and
the glumes. Better still, with a spikelet of oats in
hand break off all above the lowest floret. Now we
have a large model or pattern of the reduced spikelet
of a very large number of grasses, red-top, timothy,
and their kind.
Examine Calamagrostis canadensis (Fig. 35, the
floret raised from its glumes) and note how it corre-
sponds to the pattern obtained
by reducing the spikelet of oats
to a single floret. The only
vestige remaining of the other
florets is the minute rachilla
joint back of the palea (shown,
exaggerated somewhat, in Fig.
35). In all but a few genera the
rachilla is entirely suppressed.
Compare Fig. 35 with Fig. 32
and note that Trisetum reduced to a single floret
would closely resemble Calamagrostis.
In Agrostis (Fig. 36) the rachilla is normally
suppressed. In two species in the far West it is
present as a minute rudiment. In most of the species
46
FIG. 35. Spikelet of Cala-
magrostis canadensis.
PEDICELED ONE-FLOWERED SPIKELETS 47
the palea also is suppressed or represented by a
rudiment only (Fig. 36, Agrostis hiemalis, the floret
with palea wanting, raised from the
glumes). Here we have specialization
through elimination, the spikelet reduced
almost to its lowest terms, one floret
with no palea, no awn, no callus hairs.
In this particular species the very open
panicles break off and roll before the
wind as tumbleweeds, scattering the FIG. 36. Spike-
seed. Several species of Agrostis have J?* °f Ag™s~
i I 11 ** hiemahs.
awned lemmas and some have callus
hairs, shorter and less copious than in Calamagrostis.
In Sporobolus (Fig. 37, the floret raised from the
glumes and containing a mature grain)
the nerves of the palea are wide
apart and the internerve (the space
between the nerves) is thin in texture
and readily splits as the grain matures.
In some species it splits to the apex,
resulting in an object sorely puzzling
to the beginner, the two halves appear-
ing like two 1 -nerved lemmas or paleas,
in addition to the lemma itself. It is
FIG. 37. spike- in such cases as this that a knowledge
lot of sporo- Of the structure of the grass spikelet is
bolus airoides. 3
necessary for the correct interpretation
of the organs observed. In this genus and in a few
others the pericarp (meaning around the fruit), the
wall of the ripened ovary which forms a covering
48
FIRST BOOK OF GRASSES
for the grain and is usually grown fast to it, is free
from the grain. In most of the species it is a loose
thin sac, which readily tears when moistened, leav-
ing the grain naked. In one of our species (Sporobo-
lus heterolepis) the pericarp is firm,
like a thin shell about the grain.
In Cinna the two nerves of the
palea are so close together that
they appear to be a single nerve.
In one of the species this nerve
may be easily split into two, dem-
onstrating the derivation of the
apparent single nerve.
In several genera the glumes are
enlarged. In timothy (Fig. 38)
they are firm in texture, strongly
keeled, and abruptly awned, while
the lemma is much smaller, thin in
texture, and awnless. The spike-
lets are so congested on the short
branches of the cylindrical spike-like
panicle that the beginner may be
puzzled to know just what is the
unit of inflorescence. Keeping in
mind that a spikelet never is com-
pound, the student will divide and
redivide the cluster until he finds
an object having a single pair of
glumes containing the floret. FIG. 39. Spikelet of
. LA,. <• ,1 i Alopecurus gemcu-
Another modification of the glumes iatus.
FIG. 38. Spikelet of
Phleum pratense;
floret above.
PEDICELED ONE-FLOWERED SPIKELETS 49
is shown in Alopecurus (Fig. 39). The margins are
grown together for half their length. As in Notholcus
lanatus (Fig. 34) the articulation is an exception to
that generally characteristic of its allied genera, the
spikelets falling entire. The lemma bears a delicate
dorsal awn and the palea is suppressed. In most
species of Alopecurus the panicle is as dense and
spike-like as that of timothy.
In some genera the glumes are reduced (see Fig.
42), and in a few species the first glume is suppressed.
In Lesson IV, Fig. 21, we
noted perfect and sterile
spikelets in the same panicle
and in Fig. 22 we found the
spikelets falling in clusters of
three sterile and one perfect
spikelet. In Lycurus (Fig. 40)
the spikelets are in pairs on
the ultimate branchlets of the
spike-like panicle, the lower
spikelet sterile, the upper per-
fect. The ultimate branchlet
itself falls with the spikelets T
. , . , FIG. 40. Pair of spikelets,
attached, aS. in AchyrodeS sterile and fertile (spread
(Fig. 22) . Lycurus shows an- apart) of Lycurus Phleoides-
other peculiar character in the 2-nerved first glume,
one lateral nerve being undeveloped or very faint.
The midnerve is extended into a long awn and the
one lateral nerve is usually extended into a shorter
awn, but is sometimes a mere tooth.
50
FIRST BOOK OF GRASSES
bergia foliosa.
The glumes and lemma in the spikelets so
far examined in this lesson have been of like
texture, membranaceous (like a membrane or
skin).
In Muhlenbergia (Figs. 41 and 42) the lemma is
firmer in texture than the
glumes. In some species
of the genus the glumes
are much reduced, and in
some they are well devel-
oped and often awned.
The lemmas are promi-
4i. spike- nently 3-nerved and are
awned or mucronate, that
, . , ,
is, the rmdnerve extend-
ing in a minute point.
In four of our genera the lemma at
maturity is firm and
hard in texture and
the nerves are
scarcely visible. In
Milium (Fig. 43) the
lemma is rigid,
smooth, and shining
and the palea is of
FIG. 43. A, spikelet
of Milium effusum; like texture. In Ory-
zopsis (Fig. 44) the
lemma bears an awn that readily disarticulates
at its base. The palea is nearly inclosed by the
lemma.
FIG. 42. A, spike-
let of Muhlen-
bergia Schreberi;
B, bran chief
with the minute
glumes of two
spikelets from
which florets
have fallen.
PEDICELED ONE-FLOWERED SPIKELETS 51
In Stipa (Fig. 45) and Aristida (Fig. 46) the palea
is entirely inclosed in the lemma. The callus (see
FIG. 44. A, glumes,
and B, floret of Ory-
zopsis racemosa.
FIG. 45. A, glumes,
and B, floret of Stipa
spartea.
FIG. 46. Spikelet of
Aristida dichotoma.
page 22) is developed into a needle-like point that
readily penetrates clothing or works its way into the
wool of sheep.
52 FIRST BOOK OF GRASSES
In Stipa the awn is composed of all the nerves of
the lemma, forming a solid slightly flattened elongate
body, the point of departure from the body of the
lemma being marked by an abrupt contraction or a
ring of hairs. In some species the lower part of the
awn is plumose (covered with soft fluffy hairs, like a
feather).
In Aristida the awn is divided into three; that is,
the three nerves at first unite, then separate. The
lemma tapers into the awn with no visible junction,
as in Stipa. Sometimes the undivided part of the
awn is elongate, forming a slender neck and some-
times this neck is twisted. In Aristida dichotoma,
the species shown (Fig. 46), the lateral awns are much
shorter than the central one. In many species the
three are subequal, and one or all may be recurved or
loosely twisted at the base. They are never tightly
twisted, as in Stipa.
SUMMARY
The specialization in this group of grasses con-
sists in the reduction of the relatively simplified
spikelet to a single floret. In most of the genera the
spikelets are very small. The glumes may be re-
duced to rudiments or suppressed or may be well
developed and somewhat elaborated. The lemma
may be delicate or indurate (hardened) and may be
awned from the back or the summit. The palea
shows more modification in this group than in any
other. It may be suppressed or it may be as long as
PEDICELED ONE-FLOWERED SPIKELETS 53
the lemma ; the two nerves may be coherent, appear-
ing as one, or widely separated with the delicate
internerve splitting. The rachilla may be extended
beyond the base of the palea, a vestige of the sup-
pressed florets, or it may be produced into a sharp
callus below the lemma. The inflorescence is always
a panicle, but this may be diffuse or dense and
cylindrical or capitate (like a head).
REVIEW
Collect panicles of redtop, timothy, or of any grass with
laterally compressed 1-flowered spikelets. If the inflorescence
is dense, distinguish the individual spikelets. Dissect the
spikelets and note whether any of the organs are suppressed.
Note the point of attachment of the awn, if any.
If possible, collect panicles of any species of Stipa. Lay a
few of the florets in a little water and note the result. Note that
twisted awns or the twisted parts of an awn are flattened.
LESSON VIII
SESSILE SPIKELETS IN ONE-SIDED SPIKES
As stated in Lesson V, development does not follow
a single line, so, having come to the end of one line,
we must repeatedly return to the center and start in
a new direction. In the group of grasses taken up
in this lesson the principal character common to
all is the spicate inflorescence. In the grasses related
to barley (Lesson V) we found solitary 2-sided spikes,
the spikelets sessile on opposite sides of the rachis.
In the present group we have 1 -sided (unilateral)
spikes, the spikelets sessile or nearly so along one
side of the rachis. The spikelets themselves range
from the simple one of yard-grass, Eleusine indica
(Fig. 47), to highly specialized ones. Compare
Fig. 47, A, with Figs. 11 and 14. It will be seen that,
although the glumes and lemmas of Eleusine are
strongly keeled, the spikelets are of the same type;
but these spikelets are very differently arranged
(Fig. 47, B), being crowded and imbricate (over-
lapping like shingles) in two rows on one side of the
rachis. Two to several of these spikes are borne
together, digitate or nearly so. [Digitate means
arranged like fingers (digits), but as a botanical
term it indicates an arrangement more like that
54
SESSILE SPIKELETS IN ONE-SIDED SPIKES 55
FIG. 47. A, spikelet of Eleusine indica; B, inflorescence.
of a bird's toes, the spikes borne on so short an axis
that they appear to spring from the same point.]
In Lesson VII we
obtained the pat-
tern of the 1 -flowered
spikelet by eliminat-
ing all but the lowest
floret and the glumes
from a several-flow-
ered spikelet. Elimi-
nating all but the
lowest floret of Eleu-
sine we have a model
of the spikelet of Bermuda-grass, Capriola Dactylon
(Fig. 48, A). A vestige of the eliminated florets re-
FIG. 48. A, spikelet of Capriola Dactylon,
floret raised above the glumes; B, in-
florescence.
56
FIRST BOOK OF GRASSES
mains in the prolonged rachilla, often with a rudi-
mentary floret at its apex. The arrangement of the
inflorescence (Fig. 48, B ; three of the spikes indicated
in skeleton only) is the same as in Eleusine.
FIG. 49. A, spikelet of Chloris latisquamea; B,
fertile lemma spread out; C, sterile lemma
spread out; D, inflorescence.
Compare Figs. 48 and 49 (Chloris latisquamea).
In the latter, the upper florets instead of being sup-
pressed are developed into one or a few sterile florets,
consisting of modified lemmas without paleas. Turn
to Lesson III in which sterile florets are discussed
SESSILE SPIKELETS IN ONE-SIDED SPIKES 57
(page 23). In Melica (Fig. 19) we had an example
of such sterile florets, and in Chloris we have another.
In each case, the sterile lemmas if spread out show
their derivation from the ordinary fertile lemmas.
In grama grass, Bouteloua
(Figs. 50 and 51), is found
the greatest specialization
of the sterile floret. It
is often more prominent
than the fertile floret and
so modified that its deriva-
tion is not always obvious.
The pattern of its lemma,
however, is like that of
the fertile one, 3-nerved,
the nerves extending into
awns (Figs. 50, C and 51, C.)
The internerves are com-
monly broadened and re-
duced (as in Fig. 51, C), or
even suppressed. There is
usually a single such floret,
but in some species there are FIG. 50
two, or even three. A second
sterile lemma when present
may have a single awn or be
awnless, or even nerveless (Fig. 51, D). In a few
species the sterile floret sometimes incloses a palea
and stamens. Note that in Bouteloua the spikes are
not digitate, as in the foregoing genera, but are
A, spikelet of Boute-
loua curtipendula; B, fertile
lemma spread out; C, sterile
lemma spread out; D, in-
florescence.
58
FIRST BOOK OF GRASSES
racemose (Figs. 50, D, and 51, E); that is, the axis
between the spikes is elongate instead of greatly re-
duced. (In Fig. 10, B, is shown a raceme of spike-
lets; in Bouteloua we have a raceme of spikes, each
FIG. 51. A, spikelet of Bouteloua gracilis; B, fer-
tile lemma spread out; C, first sterile lemma
spread out; D, second steri'e lemma spread out;
E, inflorescence.
composed of few to many sessile spikelets.) In Boute-
loua gracilis (Fig. 51) and related species the florets,
as is usual in this group, fall from the glumes, these
remaining on the rachis. In B. curtipendula (Fig. 50)
and its relatives, the entire spike falls from the
main axis,
SESSILE SPIKELETS IN ONE-SIDED SPIKES 59
In an allied genus, Cathestecum (which looks like a
diminutive Bouteloua) with but one species in the
United States, the spikes consist of three spikelets
crowded on the short rachis, the uppermost fertile,
the two lower staminate or neuter. The spikes fall
as a whole from the axis.
In Lesson III (page 24) it is stated that the posi-
tion of sterile florets in the spikelets is the same in
large series of related grasses. In the spikelets so far
studied in this lesson the sterile florets are above the
perfect one. There is a single exception to this rule
in Campulosus, in which the two lower lemmas are
well developed but empty, the third fertile, and the
upper one to three empty, like the lower.
In two genera in this group, Spartina and Beck-
mannia, the spikelets fall entire. (See Lesson VI,
page 44, on exceptions). In Spartina the spikelets
are strictly 1-flowered; in Beckmannia they are
usually 1-flowered, but sometimes a second floret is
developed.
Throughout we have seen widely different forms,
such as Eleusine and Bouteloua, connected by inter-
mediate forms like Capriola and Chloris. Such an
intermediate between pediceled spikelets, as in
Bromus, Poa, and others of Lesson IV, and sessile
spikelets, as in the group we are now studying, is
found in Leptochloa, in which the spikelets are ar-
ranged along one side of the slender rachises, but are
borne on very short pedicels. The spikelets of our
other genera in this highly specialized group present
60 FIRST BOOK OF GRASSES
no special difficulty, except those of buffalo-grass,
to be studied later.
SUMMARY
In this group the spikelets are sessile in 1 -sided
spikes, solitary, digitate, or racemose. In most of
the genera the upper florets are sterile, their lemmas
greatly modified, or they are wholly suppressed.
REVIEW
Collect the inflorescence of Bermuda-grass, yard-grass, any
of the grama-grasses, or of any available grass with 1-sided
spikes. Note the arrangement of the spikes on the main axis;
distinguish the individual spikelets and identify their parts.
LESSON IX
DIVERSELY SPECIALIZED SPIKELETS
IN Lesson IV,
Fig. 22 (page 31),
we had an example
of fertile and ster-
ile spikelets in the
same fascicle, the
fascicle falling as a
whole. Because the
type of spikelet
showed kinship
with grasses having
many-flowered lat-
erally compressed
spikelets, Achy-
rodes is placed with
them, although in
its fascicles falling
as a whole it forms
an exception. In
the grasses we are
about to study in
the present lesson,
clustered spikelets
are the characteris-
tic specialization.
FlQ
52 A)fascicle of &g0pogon tenellus;
B» lemma, and C, palea, spread out, of
sterile spikelet; D, lemma and E, palea of
perfect spikelet.
61
62
FIRST BOOK OF GRASSES
Examine Fig. 52 (^Egopogon) in which A represents a
fascicle (spread apart) of one fertile and two sterile
spikelets attached to the branch which falls with
them. These little fascicles are racemose and nodding
on the main axis.
In Hilaria (Fig. 53) the plan is the same, but the
fascicles are sessile on the axis and erect, the spikelets
are sessile in the fascicle, the glumes are elaborated
FIG. 53. A, fascicle of Hilaria Belangeri; B, glumes (inner face) of stami-
nate spikelet; C, two views of perfect spikelet; D, fertile floret.
and very unsymmetrical, and the sterile spikelets
have two florets. The species figured is the com-
monest one. The fascicles of some of the other
species are even more fantastic than these. The
glumes and lemma are always sharply folded and
compressed laterally. In one species the glumes of
the sterile spikelets are broad and fan-shaped, in
another they are curiously lobed and awned. In
all the species they are exceedingly variable, but in
each they follow a general pattern. The glumes of
DIVERSELY SPECIALIZED SPIKELETS
63
the fertile floret are often slightly adnate to (grown
to) those of the sterile spikelets, making the fascicle
somewhat difficult to dissect. It is in such cases as
this that the fundamental concept of the structure
of a grass spikelet enables one to recognize the
spikelet and its parts. So much elaboration for the
production of a single grain is very exceptional in
grasses, which as a whole tend to the elimination of
non-essentials.
A third grass having spikelets in little fascicles is
Nazia (see Fig. 54). This is probably not closely
related to ^Egopogon
and Hilaria, but is
commonly grouped
with them because
of its fascicles falling
entire. This little
bur-like fascicle is
composed of two
spikelets, both usu-
ally perfect (some-
times with a third reduced one). The minute first
glumes are back to back, and the large second glumes,
covered with stout hook-like hairs, face outward.
Note that the glumes are not folded as in ^Egopogon
and Hilaria but convex. These spikelets afford an
excellent example of spine-like hairs. Hairs are an
outgrowth of the epidermis (skin) and have no
connection with the fibrous structure of the plant.
The " thorns" of the rose furnish a well-known
FIG. 54. A, bur-like fascicle of Nazia
aliena; B, single spikelet; C, floret.
64
FIRST BOOK OF GRASSES
example. However stout they may be, they may
readily be broken from the bark without tearing
the wood. The thorns of hawthorns, plums, and
locusts, on the contrary, however slender, can not be
broken off. Being reduced branches, the woody
fiber (vascular bundles) extends into them from the
skeleton of the plant.
In all the spikelets figured heretofore the sterile
florets when present were above the perfect floret.
In a group of grasses repre-
sented by only three genera
in the United States, the
spikelets bear a pair of sterile
florets below the single per-
fect floret and these fall at-
tached to the fertile one. In
sweet vernal-grass, or An-
thoxanthum (Fig. 55) the
sterile florets consist of
empty lemmas unequally
awned from the back and
divided above the insertion
of the awn. The fertile floret
much smaller, awnless,
A be-
ginner, in dissecting this
spikelet, might mistake this fertile floret for the
grain and so take the sterile florets for a lemma and a
very peculiar palea. Whenever a spikelet or any
of its parts seems to present a marked departure
is
FIG. 55. A, spikelet of Anthox-
anthum odoratum; B, pair of
sterile florets below the per- smooth, and shining,
feet floret; C, perfect floret.
DIVERSELY SPECIALIZED SPIKELETS 65
from the normal type (such as a 1-awned palea would
be), it is advisable to reexamine and to reconsider.
A close examination of this fertile floret will reveal
the thin edges of the lemma infolding the palea.
A grain may always be recognized by the embryo
at the base on the back. (See Fig. 5, A).
In Torresia (called holy-grass, vanilla-grass, or
Seneca-grass) the sterile florets are awnless and con-
tain paleas and stamens. Like Anthoxanthum, the
whole plant is fragrant. These are
the grasses of which sweet-grass bas-
kets are made.
In Phalaris the glumes are enlarged
and strongly keeled or, as in canary-
grass, P. canariensis (Fig. 56), wing-
keeled, and the sterile florets are re-
duced to small empty lemmas. In
one species, P. minor, the first sterile
floret is reduced to a minute rudi-
ment, and in the common reed
canary-grass, P. arundinacea, both
sterile lemmas are narrow and hairy. FlG 56 A" spikelet
In Lesson VII, Fig. 42 (page 50), we of Phalaris cana-
. , , ,11-1 riensis; B, fertile
had an example of greatly reduced floret with pair of
glumes. In rice, Oryza sativa (Fig.
57), the glumes are minute, and the
lemma and palea are indurate (hardened) and com-
pressed laterally. Some varieties of rice have an
awned lemma. In an allied genus, Homalocenchrus
(Fig. 58), the glumes are wholly suppressed.
66
FIRST BOOK OF GRASSES
FIG. 57. Spike-
let of rice
(Oryza saliva) .
FIG. 58. Spike-
let of Homa-
locenchrus ory-
zoides.
In Lesson IV, Figs. 23 (page 32) and
24 (page 32), we had unisexual spike-
lets, the staminate and pistillate on
distinct plants. Wild rice, Zizania
palustris (Fig. 59, A and B), is monoe-
cious, staminate and pistillate spikelets
borne in the same panicle, the awn-
less staminate ones pendulous on the
spreading lower branches, the awned
pistillate ones erect on the ascending
upper branches. In the pistillate spike-
let the suppressed glumes are repre-
sented by a very shallow ridge around
the base of the spikelet. The staminate
flower consists of six stamens instead
of three, as in the grasses studied here-
tofore. The palea of this spikelet is
FIG. 59. A, pistillate spikelet, and B, staminate spike-
let, of Zizania palustris.
DIVERSELY SPECIALIZED SPIKELETS 67
anomalous in that it has three nerves. Throughout
the grasses the palea has two nerves, rarely sup-
pressed, as in Agrostis, where the palea itself is much
reduced, or so close together as to be merged into one,
but in no case are more than two nerves known. The
problem presented by this spikelet has not been sat-
isfactorily solved. It is possible that the two organs
are, respectively, the second glume and the lemma,
the first glume and the palea being suppressed. In
the pistillate spikelet the palea is 2-nerved. In the
perennial wild rice of the southeastern states, Zizani-
opsis miliacea, this 3-nerved organ is present in both
the staminate and pistillate spikelets, and in another
related genus, Luziola, both bracts of the spikelets
are several to many nerved.
SUMMARY
In the highly specialized spikelets studied in this
lesson the various organs are identified (1) by their
position, bearing in mind that the bracts of a spikelet
are 2-ranked and alternate on the rachilla, and
(2) by their resemblance to corresponding organs in
allied grasses.
REVIEW
Hilaria, Nazia, and ^Egopogon are found only in the South-
west, but the other grasses studied in this lesson are widespread.
In any region in the United States will be found one or more of
them. Collect any that are available, examine the inflorescence,
distinguish the spikelets, and identify their parts.
If in a species of Phalaris but one sterile floret is found below
the perfect one, how can you tell which of the pair is suppressed?
LESSON X
SPIKELETS WITH MEMBRANACEOUS GLUMES
AND HARDENED FRUITS
ALL the spikelets heretofore studied have been
more or less compressed laterally (that is, a detached
spikelet under observation lies on its side, the two
ranks of glumes and lemmas to right and left of the
rachilla, as in Figs. 11-14) and, with relatively few
exceptions, the articulation has been above the
glumes, these remaining on the pedicel after the fall
of the florets. These two characters in common
pertain to more than half of all our grasses. In
many of the laterally compressed spikelets the
florets themselves are dorsally compressed (see
Fig. 11, B). We come now to a lesser group, in
which the spikelets are dorsally compressed (the
spikelet under observation lying on its face or back,
the two ranks above and below the rachilla). In
this group of grasses the rachilla joints are usually
so short that the glumes and lemmas are borne one
immediately above the other. The rachilla is never
prolonged beyond the base of the fertile floret, as in
many of the spikelets heretofore studied.
Examine Fig. 60. Note that the first glume is
much smaller than the second. Turn to Fig. 11
(page 25). In imagination, remove the glumes and
68
SPIKELETS WITH HARDENED FRUITS
69
all but the two lower florets. The result is compara-
ble to the two florets (Fig. 60, C) of Panicum, but
in this genus the lower floret is staminate or sterile,
and its lemma and palea differ in form and texture
from those of the perfect floret (Fig. 60, D). The
sterile lemma (commonly termed the " third glume"
in all but recent books) resembles the second
glume and incloses a small thin palea, while the
FIG. 60. A, spikelet of Panicum miliaceum, side view; B, same
seen from the back; C, sterile and fertile florets removed
from the glumes, side view; D, fertile floret.
fertile lemma is indurate, its nerves obscured in the
thickened tissue, and firmly clasps a palea of like
texture. At maturity the gram is inclosed in this
fast-locked little case (the whole commonly termed
the fruit) and germinates within it, sending its rootlet
through a thin place near the base of the lemma
(seen as a crescent-shaped depression at the back)
and thrusting its sprout between the lemma and
palea at the summit or side. In dissecting a spikelet
of Panicum or its related genera the palea of the
70
FIRST BOOK OF GRASSES
sterile floret often adheres to the palea side of the
fruit (the mature fertile floret) as a small thin scale,
difficult for the beginner to account for unless he
understands the structure of the spikelet.
This type of
spikelet is charac-
teristic of the large
number of grasses
forming the millet
tribe. In Panicum
the inflorescence is
an open or con-
tracted panicle. In
crab-grass, Synthe-
risma sanguinalis
(Fig. 61) and its
relatives, the spike-
lets are borne in
1 -sided racemes,
much like those
of Bermuda-grass
(Fig. 48). In the
crab-grasses the
first glume is mi-
nute or suppressed, and the second is commonly
much shorter than the sterile lemma and the fertile
floret. The fertile lemma and its palea are less
indurate than those of Panicum and the margin of
the lemma is thin in texture and flat instead of being
firm and inrolled, as in Panicum.
FIG. 61. A, two views of spikelet of Synthe-
risma sanguinalis; B, fertile floret; C, in-
florescence.
SPIKELETS WITH HARDENED FRUITS
71
In Paspalum (Fig. 62) the spikelets are more like
those of Panicum in texture, and the margin of the
fertile lemma is firm and inrolled, as in that genus.
The first glume is wholly suppressed except in a few
species. The spikelets are subsessile in two rows on
one side of a rachis, either single (Figs. 62 and 63, A)
FIG. 62.
A, two views of spikelet of Paspalum
; B, fertile floret; C, inflorescence.
FIG. 63. A, rachis of
Paspalum Iceve, spike-
lets removed; B, ra-
chis of a Paspalum
with paired spikelets;
C, cross-section of
rachis, showing raised
center and thin mar-
gins.
or in pairs (Fig. 63, B). [In descriptions these are
often referred to as 2-rowed or 4-rowed, respectively.]
In species with paired spikelets some of the secondary
ones (those next the center of the rachis) are always
abortive. The racemes in Paspalum are sometimes
solitary and sometimes digitate, as in Syntherisma,
72
FIRST BOOK OF GRASSES
but more commonly they are racemose on the main
axis (as in Fig. 62). The rachis is sometimes winged,
and in a few species the broad wings fold up over the
base of the spikelets.
In Reimarochloa (represented by but one species
in the United States) the spikelets are arranged as
in Paspalum, but both glumes are suppressed except
in the uppermost
spikelet. (Recall
Lolium, Lesson V,
Fig. 27, page 36).
If it were not for its
obvious relation-
ship to Paspalum,
in which an occa-
sional first glume is
developed in sev-
eral species and reg-
ularly in a few, the
spikelet of Reima-
rochloa might be
taken to be strictly
1-flowered with
only the first glume
suppressed except in the terminal spikelet.
In Paspalum we have seen a slightly broadened
rachis (Fig. 63). In Stenotaphrum, or St. Augustine-
grass (Fig. 64), the rachis is broad, thick, and corky,
and the spikelets are partly embedded in it. At
maturity the rachis breaks up into short joints with
FIG. 64. A, part of raceme of Stenotaphrum
secundatum, front view showing spikelets;
B, back view of three joints.
SPIKE LETS WITH HARDENED FRUITS
73
the spikelets attached. (Recall Lepturus, Lesson V,
Fig. 28, page 37.)
In Syntherisma, Paspalum, Reimarochloa, and
Stenotaphrum, with subsessile spikelets borne on one
side of a rachis, the spikelets
are placed with the back of the
fertile lemma against the rachis,
that is, with the first glume
(developed or hypothetical),
sterile lemma, and the palea of
the fertile floret outward. In
Axonopus (Fig. 65), Brachiaria,
and Eriochloa the spikelets are
reversed, the back of the fertile
lemma being turned from the
rachis and the palea toward
it. In Axonopus the first glume
is wholly suppressed. In Erio-
chloa (Fig. 66) the first glume
is reduced
to a m i-
nute sheath
around the
enlarged rachilla joint below the
second glume and grown fast to it.
The fertile lemma is tipped with
a minute awn, which breaks off
readily.
FIG. 66. A, spikeiet of In barnyard-grass, Echinochloa
Crusgalli, is the same type of spike-
FIG. 65. A, part of raceme
of Axonopus furcatus; B,
inflorescence; C, cross-
section of rachis.
74
FIRST BOOK OF GRASSES
let as in Panicum, but the second glume and sterile
lemma are awned or awn-tipped, and the pointed
tip of the palea is not inclosed in the lemma, which
also is sharp-pointed. The glumes and sterile lemma
bear spine-like hairs, but not so thick as those of
Nazia.
Observe the diagrammatic panicle in Fig. 67, A.
In imagination, remove all the terminal spikelets
FIG. 67. A, diagrammatic
panicle; B, two branches
of panicle with terminal
spikelets removed.
^r FIG. 68. Small part of bristly
panicle of Chcetochloa Grise-
bachii.
from a branch. The result is Fig. 67, B. Compare
Fig. 68 with this. It will be seen that the bristles
of the latter are branches of the panicle which are
without spikelets at their tips but which bear sub-
sessile spikelets at or toward their base. This
SPIKELETS WITH HARDENED FRUITS 75
modification of sterile branches and branchlets into
rough bristles is found in the millets (Chsetochloa),
common millet, yellow foxtail, and green foxtail.
These branchlets are the " involucre of bristles "
referred to in many manuals and descriptions. The
spikelets fall from their
pedicels, as in Panicum,
and the bristles remain
on the axis. In most
of the species the pani-
cles are dense and
spike-like, the spikelet-
bearing branches fas-
cicled ' and very short
and the sterile ones, or
bristles, long and slen-
der. In yellow fox-
tail, Chcetochloa lute-
scens (Fig. 69), the fas-
cicle consists of several
branches, only one of
them spikelet-bearing, FIG< 69. A
the others transformed
into slender bristles.
Between the ordinary panicle represented in Fig. 67
and the bristly spike-like one of yellow foxtail (Fig.
69, B) there is every degree of gradation.
A further specialization of sterile branches is shown
in the sand-burs (Cenchrus). Compare Fig. 70 with
Fig. 69, A. . Instead of the nearly simple fascicle of
fascicle from panicle of
Chcetochloa lutescens; B, spike-like
panicle of same.
76
FIRST BOOK OF GRASSES
branchlets found in the millets, the sand-burs have a
complex fascicle of many compound branches. The
primary branches disarticulate from the axis, and
the whole fascicle, or bur, falls entire with the spike-
let permanently inclosed, the grain eventually
germinating within it. The simplest form of sand-
bur is in Cenchrus myosuroides (Fig. 70). The struc-
ture of this will be comprehended if we conceive of
FIG. 70. Bur of Cenchrus
myosuroides.
FIG. 71. Bur of Cenchrus pauciflorus.
a dense fascicle of branches with but one of them
bearing a single sessile spikelet, the others branching
at the base and surrounding the spikelet-bearing one.
In the common inland sand-bur, Cenchrus pauci-
florus (Fig. 71), the sterile branches are much thick-
ened and flattened and are grown together below,
their free summits sharp and spine-like. The nu-
merous secondary branchlets, in the form of stout
spines, spread from the body of the bur formed by
the cohesion of the main branches surrounding the
one or few sessile spikelets.
SPIKELETS WITH HARDENED FRUITS
77
In all the seed-bearing spikelets so far examined,
the stamens and stigmas project at flowering tune,
resulting in cross fertilization of the ovules. A few
grasses bear cleistogamous (close-fertilized) as well as
openly fertilized spikelets.
Such spikelets do not
open, and there is usually
but a single small stamen
which empties its pollen
directly on the short stig-
mas. The grain is larger
than that of open-fer-
tilized spikelets. Two of
our native grasses, form-
ing the genus Amphicar-
pon, related to Panicum, FlG- 72-
are remarkable in that
they produce large cleistogamous spikelets under-
ground from subterranean branches (Fig. 72). The
plants also bear terminal panicles of ordinary and
much smaller spikelets, but these seldom perfect
seed.
SUMMARY
In Panicese, the millet tribe, the spikelets fall
entire. They bear one perfect floret with a sterile
floret below it. The lemma and palea of the perfect
floret are indurate. The sterile lemma resembles the
second glume, the two simulating a pair of glumes,
while the first glume is small and looks like an addi-
78 FIRST BOOK OF GRASSES
tional one (in some older works it is called the acces-
sory valve or glume) or is entirely suppressed. The
genera differ chiefly in the arrangement of the spike-
lets hi the inflorescence. In a few genera some of the
panicle branches are without spikelets and are
transformed into bristles or burs.
REVIEW
Collect the inflorescence of broom-corn millet, old witch-grass,
or of as many species of Panicum as are available, and dissect
the spikelets. Collect heads of barnyard-grass and compare the
spikelets with those of Panicum. Compare the spine-like hairs
with those of Nazia, Fig. 54.
Collect the inflorescence of crab-grass and of any species of
Paspalum available; note the arrangement of spikelets and com-
pare the form and texture of the fruit (fertile floret) with that of
Panicum.
Collect heads of common millet or of yellow or green foxtail.
Remove enough branches from the axis to show clearly the form
and arrangement of the few remaining.
If available, examine a sand-bur, splitting the bur with a
sharp knife.
LESSON XI
PAIRED SPIKELETS WITH HARDENED GLUMES
AND THIN LEMMAS
IN the sorghum tribe, which we are about to study,
the spikelet, as in the millet tribe, falls entire and is
dor sally compressed, but the glumes are hardened
and the lemmas thin, while in the millet tribe the
glumes are thin and the fertile lemma and palea are
hardened. The glumes entirely inclose the two
florets. The midnerve of the first glume is com-
monly suppressed, while a pair of nerves near the
margin is often prominent and sometimes keeled, or
even winged. The second glume may be like the
first or the midnerve may be slightly keeled. The
lower floret consists of an empty lemma only, the
upper of a perfect flower with a small thin often
awned lemma (sometimes so small as to appear
like a bit of membrane at the base of the awn) and a
minute palea (sometimes suppressed).
Examine Fig. 73, A, and compare it with Figs. 21
(p. 30), 22 (p. 31), 30 (p. 40), 40 (p. 49), 52 (p. 61),
and 53 (p. 62). In all the figures referred to, fertile
spikelets are associated with sterile ones. These
are grouped in various ways. In the sorghum tribe
the typical arrangement is a jointed raceme with a
sessile perfect spikelet and a pediceled sterile spikelet
79
80
FIRST BOOK OF GRASSES
(staminate or neuter) at each joint, the rachis dis-
articulating at the summit of each joint, this and the
pedicel of the sterile spikelet remaining attached at
their base to the per-
fect spikelet as a pair
of little stalks. In
this group of grasses
specialization consists
chiefly in modifications
of the axes of inflores-
cence and secondarily
in the modification of
the spikelets. In Fig.
73, A (Johnson-grass,
Holcus halepensis) , are
two views of a single
joint, consisting of the
sessile perfect spikelet
with the attached ra-
chis joint and the ped-
icel with its staminate
spikelet. Fig. 73, B, is
a diagram of a raceme
FIG. 73, A, two views of single joint of four SUCh joints and
of raceme of Holcus halepensis; B, 73 Q a diagram of the
diagram of raceme of four joints; , . .. ,. . ,
C, diagram of rachis and pedicels; D, raCfllS and pedicels, trie
inflorescence. spikelets removed and
the points of disarticulation shown by dotted lines.
In sorghum, or Holcus, these little racemes are borne
on the ultimate branchlets of a panicle (Fig. 73, D).
PAIRED SPIKELETS
81
In the closely related Indian-grass, Sorghastrum, the
racemes are reduced to one or two joints, and the
sterile spikelets are wholly suppressed, the slender
hairy pedicel alone being developed.
Compare F i g.
74, A, a diagram-
matic single joint
of Erianihus sac-
charoides, with Fig.
73, A, and Fig. 74,
B, three joints of a
long raceme, with
Fig. 73, B. It will
be seen that, while
the spikelets are
paired, the pedi-
celed spikelet is as
large as the sessile
one and, like it,
is awned. In this
genus the pediceled
spikelet is usually
perfect. The ra-
cemes are long and ,
, , FIG. 74, A, diagram of single joint of raceme
Slender and CO- of Erianthus saccharoides; B, three joints
piously hairy, and ofraceme-
are crowded on a stout main axis forming large,
dense, woolly panicles. In sugar-cane the inflores-
cence is like that of Erianthus, but the spikelets
are awnless.
82
FIRST BOOK OF GRASSES
Examine Fig. 75, A, a joint of a raceme of one of
the broom sedges (Andropogon scoparius). It will
be seen to have the same general plan as a joint of
sorghum, and the racemes, shown in Fig. 75, B,
though slender and flex-
uous, are in structure
similar to the racemes of
sorghum. The entire in-
florescence, however, is
very different. In sorg-
hum and Erianthus the
inflorescence is a leafless
terminal panicle, such as
is common in grasses.
The diagrammatic inflores-
cence (Fig. 75, B) shows
that the racemes of the
broom-sedge are borne on
numerous slender leafy
of Andropoion " scoparius; B, branches arising in the
r2cencpeart * compound ™°~ axils of leaves on the
main culm or branches,
the whole forming a compound inflorescence. The
leaves, especially the ultimate ones immediately
below the racemes, are mostly reduced to blade-
less sheaths and are sometimes bright colored.
Such transformed leaves subtending or surround-
ing single inflorescences are commonly termed
spathes.
In some species the racemes are partly inclosed
FIG. 75. A, single joint of raceme
PAIRED SPIKELETS
83
in the spathes. The racemes may be solitary (that
is, one to a branch, as shown) or two to several,
digitate, on a single branch. In some species the
sterile spikelet is suppressed, only the pedicel being
developed. In a few species of Andropogon the
racemes are in leafless panicles,
as in Erianthus, but the pedi-
celed spikelets are sterile and
awnless.
Examine Fig. 76, A (Mani-
suris cylindrica), and compare
it with 73, A. In Holcus and
Erianthus the rachis joint and
the pedicel of the second spike-
let are about equal in thick-
ness. In Fig. 75 the rachis
joint is stouter than the pedi-
cel. In Manisuris the rachis
joint is greatly thickened and
hollowed out below on the inner
face. (See Fig. 28, p. 37, for an F 7,
v ? / , . FlG- 76> A » single joint of
earlier example of a thickened raceme of Manisuris
rachis.) The pedicel of the ster-
ile spikelet is also thickened,
but much less so, and the two
lie close together (instead of
spread apart, as in Figs. 73 to 75) and entirely cover
the second-glume side of the spikelet which fits into
the cavity formed by the rachis joint and pedicel.
Fig. 76, C, shows the inner faces of the rachis" joint
lindrica; B, another view
of two joints; C, inner face
of rachis joint and pedi-
cel, spikelet removed; D,
part of cylindrical many-
jointed raceme.
84
FIRST BOOK OF GRASSES
and pedicel, the perfect spikelet removed. The
spikelets are awnless and the marginal nerves of the
first glume are winged at the
summit. This inflorescence and
that of Lepturus (Fig. 28) are so
similar in appearance and func-
tion, disjointing with the mature
seed permanently attached, that
the student may wonder why
they are placed in tribes so re-
mote as the barley grasses and
sorghum. The two illustrate
what is not seldom shown in
nature, that very different struc-
tures may arrive at the same
function, although the forms
from which they are derived were
very remote. The inflorescence
of Lepturus is a spike, and its
FIG. 77? A, single joint of spikelet shows it to be a reduced
raceme of Rytnix granu- and specialized relative of Lo-
laris; B, reverse view; v rrn . a „ , T
c, diagram of rachis num. Ine inflorescence 01 Mani-
and pedicels of three gur jg jg a raceme with tWO Spike-
jomts of raceme, spike- . • »'- i
lets removed; D, view lets at a joint, one pediceled, and
giUToTse^LpLett; the perfect spikelet not greatly
E, raceme; F, reverse different from that of sorghum.
We have just observed the
rachis joint and pedicel lying closely pressed together.
In Rytilix (Fig. 77, A) they are adnate (grown to-
gether). Examine the diagram of three joints with
PAIRED SPIKELETS 85
the spikelets removed (Fig. 77, C) and note that the
rachis joints (the thicker parts) form a central axis
with the pedicels borne on alternate sides, just as they
are in Holcus (Fig. 73, C). In this raceme we have
just the reverse of the arrangement of Manisuris. In
that, the fertile spikelet fits into a cavity formed
by the rachis joint and pedicel while in Rytilix the
rachis joint and pedicel fit into a cavity formed by
the fertile spikelet. (See Fig. 77, D, showing the
inside face of the first glume of the perfect spikelet,
and examine the two views of the joints, A and B,
and the two views of the raceme, E and F). The
sterile spikelet is well developed but usually contains
no flower. The perfect spikelet with its peculiar
gray, ridged and pitted, subglobose first glume sug-
gests the achene of some species of Scleria (a sedge).
The whole inflorescence is very unlike that of any
other known grass.
Return to Fig. 73, A, and compare with it Fig.
78, A (Rhaphis pauciflora), which shows a raceme
reduced to a single joint consisting of the sessile
perfect spikelet and two pediceled sterile spikelets,
the rachis joint (found in Holcus and the others
studied) often being replaced by a second pedicel and
sterile spikelet. This second sterile spikelet is not
always developed. In Rhaphis this 1-jointed raceme
has a sharp hairy callus at the base. Fig. 78, B (the
base of a raceme and the summit of a branch, the
hairs removed), shows the source of this callus. The
racemes are borne on the long slender branches of a
86
PlRST BOOK OF GRASSES
spreading panicle (Fig. 78, D) which disarticulate
obliquely below the raceme, the line of articulation
bordered by a dense brush of hairs (Fig. 78, C). The
FIG. 78. A, one-jointed raceme of FIG. 79. A, single joint of raceme
Rhaphis pauciflora; B, base of
raceme and summit of branch;
C, hairy summit of branch from
which raceme has fallen; D, in-
florescence.
of Heteropogon contortus; B, per-
fect spikelet from which sterile
spikelet has fallen ; C, base of fer-
tile spikelet and its callus; D, ra-
ceme; E, diagram of raceme;
F, diagram of rachis and pedicels
of four joints of raceme.
sterile spikelets with their pedicels fall off before the
maturity of the perfect spikelet, which, with its
hairy callus and long awn, closely resembles a mature
floret of Stipa (Fig. 45).
PAIRED SPIKELETS 87
In Heteropogon (Fig. 79) is a more complicated
arrangement. In A is shown a joint of the raceme,
consisting of the sessile perfect awned spikelet and
the pediceled large pale sterile spikelet, with the
short hairy rachis joint below forming a pointed
callus. In Fig. 79, C, is seen the base of the fertile
spikelet and the callus, with enough hairs removed to
expose the very base of the pedicel, which has fallen
with the sterile spikelet, and (to the left) the oblique
scar from which the rachis joint next above has
disarticulated. The articulation is at the base of the
rachis joint instead of at the summit, as in Holcus
and the others (Figs. 73-77), and forms a callus to the
spikelet next above. The rachis joints are very
short and the fertile spikelets (except their awns) are
hidden by the overlapping sterile spikelets, the long
flexuous awns forming a tangle beyond the end of the
raceme (Fig. 79, D). Besides having this modified
rachis and large unsymmetrical sterile spikelets, the
raceme of Heteropogon presents a further modifica-
tion in that its lower two or three pairs of spikelets
are all sterile, instead of each pair consisting of a
perfect and a sterile one, as typical for the sorghum
tribe. In these lower pairs the sessile spikelet is
staminate and the pediceled one empty, but both
have large unsymmetrical glumes and appear to be
alike. Examine the diagram of the raceme (Fig.
79, E, the rachis greatly lengthened to show the
structure and arrows indicating the points of dis-
articulation) and contrast it with Fig. 73, B. Fig.
88 FIRST BOOK OF GRASSES
79, F, is a diagram of the rachis of four joints, show-
ing the points of disarticulation. Contrast it with
Fig. 73, C.
The mature fertile spikelets of Rhaphis and
Heteropogon closely resemble mature fruits of Stipa
and function in the same way, disseminating the seed
by attaching themselves by their sharp calluses to
passing animals and securing their hold by the un-
twisting and twisting of their hygroscopic (moisture-
sensitive) awns. They afford another example of
the same function performed by different organs.
SUMMARY
The grasses of the sorghum tribe have spikelets
with hardened glumes and thin lemmas. Typically
they are arranged in pairs, one sessile and perfect,
the other pediceled and sterile on a jointed rachis,
forming racemes. In several genera the rachis is
elaborately modified.
REVIEW
Collect the inflorescence of Johnson-grass and of any of the
broom-sedges. Break the raceme into single joints, noting the
points at which it readily separates. Examine the spikelets and
the rachis and distinguish the rachis joint from the pedicel.
If you had a panicle of Rhaphis (Fig. 78, D) from which all
the sterile spikelets with their pedicels had fallen, how would
you know it was not a species of Stipa?
Make diagrams of the inflorescence of any available species
of the sorghum tribe.
LESSON XII
HIGHLY SPECIALIZED UNISEXUAL
SPIKELETS
EXAMINE Fig. 80,
gama-grass (Tripsacum
dactyloides) . This grass
is monoecious (see p. 23).
The pistillate spikelets
are borne on the lower
part of the one to three
stout digitate racemes
and the staminate spike-
lets on the upper part of
the same racemes (Fig.
80, D). The part of the
rachis bearing the stami-
nate spikelets is rela-
tively slender and falls
off after flowering time;
the part bearing the pis-
tillate spikelets is greatly
thickened and disarticu-
lates with the spikelets
permanently embedded
in the joints. Fig. 80, A,
shows two joints with
spikelets embedded ; B, a
FIG. 80. A, two joints of pistillate
part of raceme of Tripsacum dac-
tyloides; B, spikelet removed from
the joint; C, rachis joint from
which spikelet has been removed;
D, inflorescence; E, diagram of
rachis of pistillate part; F, pair
of staminate spikelets.
90 FIRST BOOK OF GRASSES
spikelet removed from its joint; C, the joint from
which a spikelet has been removed; and E, a diagram
of the rachis. Compare the joints with those of
Manisuris (Fig. 76). Note that in Tripsacum the
pistillate part is a simple spike with no vestige of a
second spikelet. The structure of the spikelet is
similar to that of spikelets of the sorghum tribe, hav-
ing firm glumes (the first hard and like the rachis
joint in texture), a thin sterile lemma, and a very
thin fertile lemma and palea. The staminate spike-
lets are in pairs (Fig. 80, F) and one of each pair is
usually on a very short pedicel. The glumes are
much like those of different species of Andropogon;
both florets are staminate, their lemmas and paleas
thin.
Indian corn, or maize (Zea Mays), the most
highly specialized grass known, is believed to be
related to Tripsacum. It is monoecious, but the
staminate and pistillate spikelets are borne in distinct
inflorescences. The staminate spikelets are in pairs
on a slender rachis forming racemes, these arranged
in a panicle, the "tassel," at the summit of the culm.
The pistillate spikelets are in pairs, crowded in 8 to
16 rows (rarely more) always an even number, on a
greatly thickened compound axis, the "cob/' borne
in the axils of the leaves and enveloped in numerous
leafy bracts ("husks"), the long styles (the "silk")
protruding from the summit, the whole called "tEe
"ear." The staminate spikelets (Fig. 81, C) are
much like those of Tripsacum and contain two
HIGHLY SPECIALIZED UNISEXUAL SPIKELETS 91
staminate florets. The pistillate spikelets stand at
right angles to their axis, the cob (Fig. 81, A). The
glumes are minute, scarcely covering the ovary at
flowering time (Fig. 81, B), and in the ripened grain
remain as chaff on the cob, the greatly enlarged
grain being naked.
This grain, "a kernel
of corn," remains on
the axis until loosened
by force.
Indian corn is
known only in culti-
vation. The problem
of its origin has not
yet been solved. We
only know that it
originated somewhere
in America, probably
on the uplands of
the tropics. It was
widely cultivated by the aborigines when the western
continents were discovered. The problem of the
morphology of the ear of corn has not yet been satis-
factorily solved, but it is not at all difficult to recog-
nize the individual spikelets, both staminate and
pistillate.
The student who has come this far will find it pos-
sible to dissect the inflorescence of any of our grasses,
with the possible exception of buffalo-grass, and to
distinguish the spikelets and the different organs.
FIG. 81, A, part of cross-section of an
ear of corn, Zea Mays, showing two
pistillate spikelets standing at right
angles to their axis (the cob); B, pis-
tillate spikelet about flowering time;
C, part of raceme of staminate spike-
lets.
92
FIRST BOOK OF GRASSES
Buffalo-grass (Bulbilis dactyloides) is placed in the
same tribe as the grama-grasses (page 57), but it has
been left until the last, so that the student might have
greater experience to draw on. It is dioecious (p. 23),
and the staminate and pistillate inflorescences are
strikingly different. (Recall Fig. 24, p. 32).
Examine Fig. 82, B,
showing a pistillate
spikelet with a small
narrow first glume and
a very large, broad, 3-
toothed second glume,
entirely infolding the
body of the floret. The
floret, removed from
the glume, is shown
in Fig. 82, C. Its 3-
toothed lemma ap-
proaches in form the
lemma of some of the
grama-grasses. (Com-
FIG. 82. A, pistillate inflorescence of
Bulbilis dactyloides; B, pistillate
spikelet cut from the rachis; C, pis-
tillate floret; D, diagram of half a
head, showing one of the two rows This pistillate
of spikelets; E, staminate inflores- i , •, .
cence; F, staminate spikelet. *€t as presented IS not
at all puzzling, the
large thick second glume with overlapping edges en-
tirely inclosing the floret being the only remarkable
feature. These spikelets, however, are borne in the
curious inflorescence shown in Fig. 82, A. These little
hard white heads are borne, mostly two together, on
HIGHLY SPECIALIZED UNISEXUAL SPIKELETS 93
a very short slender axis, in the axils of broadened
sheaths at the summit of short culms and very much
overtopped by the blades. If we cut off the base of
one of these little heads we have three to five such
spikelets, as shown in Fig. 82, B, which had been
held rigidly together by the hard thickened base,
the overlapping backs of the second glumes forming a
thick white wall surmounted by their green-toothed
summits. The base can be nothing but a rachis,
shortened, broadened, and thickened, though all
trace is lost of the junction of the spikelets and the
rachis. Fig. 82, D, is a diagram of half a head, show-
ing one of the two rows of spikelets. Compare this
with Fig. 51, E, showing a great number of spikelets
on an elongate rachis. As in Bouteloua gracilis the
spikelets stand nearly at right angles to the rachis
and the first glume is inward, that is, it would be
against the rachis, as in Bermuda-grass, if the spike-
lets were appressed. The difficulty the student en-
counters in comprehending the pistillate inflores-
cence of buffalo-grass is not so much due to its
complexity as to the difficulty of dissecting the
rigid little structure, and also to the suppression
or deformity of some of the organs. When spike-
lets are closely crowded, as in the Cenchrus bur,
in some species of millet, and in buffalo-grass, some
of them are nearly always deformed from pressure.
In buffalo-grass one or two of the spikelets hi a
head are not fully developed. The first glume is
commonly reduced to a minute scale in two or
94 FIRST BOOK OF GRASSES
three of the spikelets, and sometimes it is sup-
pressed.
The staminate inflorescence (Fig. 82, E) resembles
the spikes of grama-grass (Fig. 51, E) but the spike-
lets (Fig. 82, F) are awnless, and the second floret is
well developed and contains a staminate flower.
«
SUMMARY
In the case of greatly modified structures the
different organs are to be interpreted by their relative
position and by their analogy to corresponding
organs in related grasses.
REVIEW
Collect the inflorescence of Tripsacum if available, disjoint
it and dissect the spikelets.
Examine a very young ear of corn and note that the spikelets
are always in pairs (consequently an ear of corn always has an
even number of rows). Distinguish the glumes and lemmas.
Examine the staminate spikelets.
If available, collect buffalo-grass and dissect the staminate
and pistillate inflorescence, preparing the latter by boiling it a
few moment's in water to which a few drops of glycerine have
been added. When no glume but the large thickened one is
found in the pistillate spikelet of buffalo-grass, how do you know
which glume that is?
FIG. 83.
DIAGRAMMATIC SUMMARY OF THE PRIMARY
CHARACTERS OF THE TRIBES
SERIES I— POAT^E
Spikelets laterally compressed; florets mostly falling from the
persistent glumes
1. FESTUCE^J, fescue tribe
Spikelets many-flowered.
Glumes relatively small.
Lemmas awned from summit
or awnless.
Inflorescence a panicle.
[Contains fescues, brome-
grasses, and blue-grass.]
2. HORDED, barley tribe
Spikelets 1- to many-flowered,
sessile on opposite sides of a
jointed rachis, forming a
spike.
Rachis rather than spikelets
specialized.
Inflorescence a solitary spike.
[Contains wheat, rye, and
barley.]
3. AVENE.E, oat tribe
Like Festucese, but glumes en-
larged and florets fewer in
number.
Rachilla joints short.
Lemmas awned from the back.
Inflorescence a panicle.
[Contains oats.]
95
FIG. 84.
FIG. 85.
96
FIRST BOOK OF GRASSES
4. AGROSTIDE^, timothy tribe
Like Festucese reduced to its
lowest terms; spikelets 1-
flowered.
Lemmas awnless or awned, the
awn from back or summit.
Glumes sometimes awned,
sometimes suppressed.
Inflorescence a panicle.
[Contains redtop and
timothy.]
FIG. 86.
5. CHLORIDES, grama tribe
Spikelets 1- to several-flowered,
sessile on one side of a con-
tinuous rachis.
All but the lowest floret com-
monly sterile and variously
modified.
Inflorescence of two to several
1-sided spikes, solitary, race-
mose or digitate.
[Contains grama-grasses.]
FIG. 87.
6. NAZIE^E, curly-mesquite
tribe.
Spikelets 1- or 2-flowered, in
fascicles, the whole falling
from the main axis entire.
[Not a natural tribe, some of
the genera included not
being closely related.]
FIG. 88.
SUMMARY OF PRIMARY CHARACTERS 97
7. PHALARIDE^, canary-grass
tribe
Spikelets with one perfect
floret and two sterile florets
below, these falling attached
to the fertile floret.
Inflorescence a panicle.
[Contains canary-grass and
sweet vernal-grass.]
FIG. 89.
8. ORYZE^E, rice tribe
Spikelets 1-flowered, falling
from the pedicel entire.
Glumes reduced or suppressed.
Inflorescence a panicle.
[Contains rice.]
FIG. 90.
9. ZIZANIE^E, Indian rice tribe
Plants monoecious.
Spikelets 1-flowered, falling
Glu.ne-s suppressed.
Inflo^ ycence a panicle.
[ ,ild or Indian rice.]
98 FIRST BOOK OF GRASSES
SERIES IL— PANICAT.E
Spikelets dorsally compressed, falling entire, singly or together
with parts of the axis.
10. PANICE^, millet tribe
Spikelets with one perfect ter-
minal floret and a sterile
floret below.
Rachilla joints very short.
Glumes membranaceous, the
first small, suppressed in
some genera; sterile lemma
like the second glume, the
two appearing like a pair of
glumes.
Fertile lemma and palea in- FIG. 92.
durate.
Inflorescence a panicle or of
one to many racemes, these
digitate or racemose on the
main axis.
[Contains millets and crab-
grasses.]
SUMMARY OF PRIMARY CHARACTERS 99
11. ANDROPOGONE^J, sorghum
tribe
Spikelets paired, one perfect
and sessile, the other sterile
and pedicellate, borne on a
jointed rachis.
Fertile spikelets with one per-
fect terminal floret and a
sterile lemma below; falling
with joints of rachis and
sterile pediceled spikelet at-
tached.
Glumes indurate, inclosing the
florets; lemmas very thin;
palea often suppressed.
[Contains sugar-cane, Johnson-
grass and broom-sedges.]
12. TRIPS ACE-*;, corn tribe
Plants monoecious.
Pistillate spikelets with one
perfect terminal floret and a
sterile lemma below, falling
embedded in the joints of
the rachis. 'Persistent on
the thick compound axis in
Zea.)
Staminate spikelets 2-flowered
in pairs, racemose.
[Contains gama-grass and
Indian corn.J
FIQ. 93.
FIG. 94.
GENERAL INFORMATION FOR THE BEGINNER
It is hoped that after completing the twelve les-
sons the student will be eager to study and identify
the grasses of his region.
To aid the beginner in the study of the plant, the
following outline is offered, suggesting points to be
observed :
OUTLINE FOR STUDY OF A GRASS PLANT
Duration — Annual: Winter annual, summer annual.
Perennial: Without rhizomes (with or without winter
rosette) ; with rhizomes (these short or long, thick, knotty,
or slender) .
Habit — Erect, ascending, prostrate, geniculate, creeping, rooting
at nodes, or stoloniferous. Tufted or culms few or solitary.
Culm — Height; slender or robust; simple or branching (from
upper nodes, lower nodes, all nodes) ; glabrous, scabrous,
or pubescent (throughout or below nodes or inflorescence) .
Nodes: Glabrous or pubescent (hairs appressed, spreading,
retrorse, i. e., pointing backward).
Sheaths: Close, loose, or spreading; glabrous or pubescent
(note margin and summit) ; open (as common) or closed.
Ligule: Length; membranaceous; hairy (stiff or delicate);
obsolete.
Blades: Erect or spreading, length and width. Shape:
Rounded, clasping or narrowed at base; flat, folded, or
involute. Texture: Thin, thick, rigid, lax. Surface:
Glabrous, pubescent (pilose, villous, hispid), scabrous
(note each surface and margin).
100
GENERAL INFORMATION' \ .o . , 101
Inflorescence — Terminal only on main culm' and .branches, or
axillary also. Simple or compound. 'Pa6i6k, R0$J(2p9&j&
and width), loose or compact, few-flowered or many-
flowered, nodding or erect. Raceme, size, etc. Spike,
size, etc.
Axis of panicle: Size, pubescence, etc.; branches solitary,
fascicled or whorled, flexuous or stiff, ascending, spread-
ing or reflexed.
Axis of raceme or spike: Continuous or disjointing; slender,
stout, narrow, winged; pubescence.
Spikelet — Pediceled or sessile; laterally or dorsally compressed;
falling entire, alone, or with joints of axis; florets falling
from the glumes; number of florets.
Glumes: Similar or unlike; size (compared to spikelet, one-
half, one-third, etc.); shape, awned, toothed, etc.; tex-
ture, nerving, pubescence.
Lemma: Fertile or sterile, size, shape, texture, pubescence.
Palea: Flower bearing or empty, size (sometimes obsolete),
shape, texture.
It will further the student's self -training if he writes
down the characters of the first few grasses studied
and of any particularly puzzling or interesting later
ones, making drawings of the spikelet and its parts
or diagrams of complicated inflorescences. One
should not hesitate to make drawings merely because
he "can not draw." However crude a sketch may
be it is of great value, not only as a record of observa-
tions, but for its training in powers of observation.
The one who " never could draw" is the very one
who should make frequent drawings, however crude
they may be.
Anyone wishing to make a serious study of grasses
102 ; FIRST BOOK OF GRASSES
should prepare an herbarium, that is, a collection of
plants pressed and dried in such a way that they may
be mounted by gummed straps to sheets of heavy
paper and arranged in folders for reference. Grasses
so prepared keep indefinitely. A circular giving
" Directions for preparing herbarium specimens of
Grasses" (Bureau of Plant Industry Document 442,
1909) may be obtained without charge on request
to the office of the Systematic Agrostologist, Bureau
of Plant Industry, United States Department of
Agriculture, Washington, D. C.
In studying grasses the first thing is to understand
the structure of the plant in hand, particularly its
inflorescence; the second is to learn its relationship
to other grasses and what name has been applied to
it. The latter is what is meant by " identifying" or
" determining" a plant. Practically all the grasses
of the United States are described in one or more
manuals of botany or state floras. Most of these
manuals give "keys" to genera and species. [The
word key is used figuratively — an instrument by
means of which a way is opened.] A key is an ar-
rangement of contrasting characters by which,
choosing one and rejecting the other, the student is
led to the name which applies to the plant in hand.
For example, take Figs. 23, 27, 45, 48, 65, and 76,
and trace them through the following key, read-
ing both of the lines having like indention, these
giving the contrasting characters from which to
choose.
GENERAL INFORMATION 103
Spikelets laterally compressed, the florets falling from the per-
sistent glumes.
Inflorescence a panicle, spikelets pediceled.
Plants dioecious; spikelets several-flowered DISTICHLIS.
Plants perfect; spikelets 1-flowered STIPA.
Inflorescence a spike, spikelets sessile.
Spike solitary; spikelets several-flowered, borne on opposite
sides of the rachis LOLIUM.
Spikes several, digitate; spikelets 1-flowered, borne on one
side of the rachis CAPRIOLA.
Spikelets dors ally compressed, the spikelets falling entire or to-
gether with joints of the rachis.
Spikelets all alike, solitary (borne singly) on a continuous
rachis AXONOPUS.
Spikelets of two kinds borne in pairs, one sessile and per-
fect, the other pediceled and sterile, the rachis articu-
lated ANDROPOGON.
In actual work, of course, one never has so simple a
problem as that. With exceptions (such as are noted
pages 44 and 59) and closely related genera and
species, it often demands careful weighing of all the
facts to use an extended key successfully, but it is
excellent training in judgment.
The name reached in the key is verified or rejected
by reading the description in the text and noting how
the characters of the plant agree with those specified.
When the description does not apply tt) the plant in
hand, one must return to the key and try again.
104 FIRST BOOK OF GRASSES
BOOKS
The plants one obtains for himself, and he studies
them by means of the few tools mentioned before
(p. 6). To identify the plants requires books.
A recently published work, "The Genera of
Grasses of the United States," by A. S. Hitchcock,
Bulletin 772, United States Department of Agricul-
ture, giving keys to tribes and genera, descriptions
and illustrations of all the genera, and notes on the
more important species, as well as indications of
exceptions, most helpful to the beginner, is the first
book which the student should acquire. It may be
obtained from the Superintendent of Documents,
Government Printing Office, Washington, D. C.,
at 40 cents a copy. The farmer, the agricultural
student, or the botanist who wishes only to be able
to identify any conspicuous or useful, weedy or
injurious grass of his neighborhood requires nothing
more than this and the manual of botany covering
his region. The following are the current manuals:
From Maine to Virginia and west to Minnesota
and Missouri, inclusive: Gray's New Manual of
Botany, 7th edition, 1908 (grasses, by A. S. Hitch-
cock) ; Britton's Manual of the Flora of the Northern
States and Canada, 3d edition, 1907 (grasses, by
G. V. Nash), extending west to the western boundary
of Kansas and Nebraska; Britton and Brown's
Illustrated Flora of the Northern United States,
Canada, and the British Possessions, second edition,
GENERAL INFORMATION 105
1913, 3 volumes (grasses, by G. V. Nash, in vol-
ume 1).
From North Carolina to Florida and west to
Oklahoma and Texas: Small's Flora of the South-
eastern United States, 1903 (grasses, by G. V.
Nash).
The Rocky Mountain region and east to the Black
Hills of South Dakota: Coulter and Nelson's New
Manual of Botany of the Central Rocky Mountains,
1909 (this does not cover the Mexican flora that
extends into southern New Mexico and Arizona);
Rydberg's Flora of the Rocky Mountains and Adja-
cent Plains, 1917.
There is no manual covering the flora of the South-
west, but Wooton and Standley's Flora of New
Mexico (Contributions United States National Her-
barium, Vol. 19, 1915), includes also most of the
species of Arizona. This work gives keys to the
genera and species and descriptions of the genera
but not of the species.
California: Jepson's Flora of California, 1912.
(Grasses, by A. S. Hitchcock).
Washington: Piper's Flora of the State of Wash-
ington (Contributions United States National Her-
barium, Vol. 11, 1906), giving keys but not descrip-
tions; Piper and Beattie's Flora of the Northwestern
Coast, 1915, with keys and descriptions; and Piper
and Beattie's Flora of Southeastern Washington and
adjacent Idaho, 1914, with keys and descriptions.
Oregon, Utah, and Nevada, and most of Idaho
106 FIRST BOOK OF GRASSES
are not yet covered by manuals, but manuals of ad-
joining regions include most of the species.
Besides these general manuals there are: Hitch-
cock's Text-Book of Grasses, 1914, with illustrations,
treating of economic grasses and their uses and also
of the morphology and the classification of grasses;
Grasses of Iowa, Part II, by Pammel, Ball, and
Scribner (Iowa Geological Survey, Supplementary
Report, 1905), with keys, descriptions, and illustra-
tions; Grasses of Illinois, by Edna Mosher (Univer-
sity of Illinois Agricultural Experiment Station
Bulletin 205, 1918), with keys, descriptions, and
illustrations; Manual of Farm Grasses, by A. S.
Hitchcock, 1921.
A helpful little bulletin is Lyman Carrier's " Iden-
tification of Grasses by Their Vegetative Char-
acters" (Bulletin 461, United States Department of
Agriculture, to be obtained from the Superintendent
of Documents, Government Printing Office, Wash-
ington, D. C., for 5 cents). One should always have
the inflorescence for accurate identification, but
there are occasions when one would be glad to iden-
tify a seedling if possible.
One who finds interest and delight in the study of
grasses will want to accumulate a working library.
A bibliography of even the most important works
would be too long to be included here and would
be out of place in a first book of grasses. How-
ever, it may be well to mention a number of pa-
pers on grasses that have been issued in the past
GENERAL INFORMATION 107
few years by the United States Department of
Agriculture and the United States National Her-
barium which can be purchased for a small amount
from the Superintendent of Documents or, the few
out of print, from dealers in second-hand books.
Hitchcock, A. S. North American Species of Leptochloa. U. S.
Dept. Agr., Bur. PL Ind. Bull. 33, 24 pp., with plates.
1903.
North American Species of Agrostis. U. S. Dept. Agr.,
Bur. PL Ind. Bull. 68, 68 pp., with plates. 1905.
Mexican Grasses in the United States National Herbarium.
Contr. U. S. Nat. Herb. 17, pp. 181-389. 1913.
The North American Species of Ichnanthus; The North
American Species of Lasiacis. Contr. U. S. Nat. Herb.
22, 31 pp., with plates. 1920.
Revisions of North American Grasses: Isachne, Oplis-
menus, Echinochloa, and Chaetochloa. Contr. U. S.
Nat. Herb. 22, pp. 115-208, with text figures. 1920.
and Chase, Agnes. The North American Species of
Panicum. Contr. U. S. Nat. Herb. 15, 396 pp., with
text figures. 1910.
Tropical North American Species of Panicum. Contr.
U. S. Nat. Herb. 17, pp. 459-539, with text figures.
1915.
Grasses of the West Indies. Contr. U. S. Nat. Herb. 18,
pp. 261-471. 1917.
Griffiths, David. The Grama Grasses: Bouteloua and Related
Genera. Contr. U. S. Nat. Herb. 14, pp. 343-428, with
plates. 1912.
Merrill, Elmer D. North American Species of Spartina. U. S.
Dept. Agr., Bur. PL Ind. Bull. 9, 16 pp. 1902.
Piper, C. V. North American Species of Festuca. Contr. U. S.
Nat. Herb. 10, 48 pp., with plates. 1906.
108 FIRST BOOK OF GRASSES
Scribner, F. L., and Merrill, E. D. The Grasses of Alaska.
Contr. U. S. Nat. Herb. 13, pp. 47-92. 1910.
Shear, C. L. A Revision of the North American Species of
Bromus Occurring North of Mexico. U. S. Dept. Agr.
Div. Agrost. Bull. 23, 66 pp., with text figures. 1900.
Chase, Agnes. The North American Species of Brachiaria; The
North American Species of Cenchrus. Contr. U. S.
Nat. Herb. 22, pp. 33-77, with text figures. 1920.
The North American Species of Pennisetum. Contr. U. S.,
Nat. Herb. 22, pp. 209-234, with text figures. 1921.
BOTANICAL NAMES
In the introduction, the reasons were given for
using Latin names of plants. It will have been
noticed that these names are made up of two words,
the generic name (a noun) and the specific (an
adjective or a noun in the possessive case or in apposi-
tion), and that the generic name is placed first, like
the surnames of persons in a directory.
Both words of the name are generally supposed to
refer to some characteristic or property of the plant
to which it is applied, as Lepturus (slender tail)
cylindricus (cylindric) and Erianthus (woolly flower)
saccharoides (like Saccharum, that is, sugar-cane),
but often botanical names do not fit any better than
do names of persons — Paul (meaning small) Baker
may be a tall blacksmith, or Martha (meaning bitter)
Stern may be sweet and gentle. Many of the Lin-
naean genera bear the ancient classic Greek or Latin
names, such as Quercus for the oak and Ulmus for
the elm. In many other cases Linnaeus used classic
GENERAL INFORMATION 109
names but applied them, not as anciently used, but
to a different group. Bromus to the Greeks was the
oat, but Linnaeus used it for the brome-grasses ;
Zizanion was the tares (supposed to be Lolium
temulentum) sown by the enemy among the wheat,
in the parable of Scripture, but Linnaeus used the
feminine form of the word for our wild rice. On the
whole, however, botanical names are more or less
descriptive, and it is helpful as well as interesting to
be mindful of their meaning, especially of the names
of species. Any plant with the name "asper" or
"scaber" will be rough in some part; "pubescens"
will be hairy; "alba" will have white flowers or bark
probably, and "rubra" red. The name Bromus
secalinus implies that the species was a weed in the
rye (Secale) fields of Europe, as it is in our wheat
fields. Holcus halepensis was known in the early
ages from Aleppo (Haleb) in Syria, and Phalaris
canariensis from the Canary Islands.
The present system of botanical nomenclature
dates from 1753, when Linnaeus 's Species Plantarum
was published, using binomials (names of two words)
for all the species. Before this, plants were given
phrase names, more or less descriptive, such as
"Panicum with lax drooping panicle, the sheaths of
the leaves pubescent," for proso millet (Panicum
miliaceum) or "Grass with a very long spike, like
cat-tail," for timothy. These phrase names were
in Latin, of course. Linnaeus's binomial plan so
simplified the hitherto cumbersome system that
110 FIRST BOOK OF GRASSES
it was everywhere adopted in less than a gen-
eration.
In botanical works it will be noted that plant
names are followed by the initial, abbreviation, or
the full name of a person, as Poa pratensis L.,
Phragmites communis Trin. This stands for the
name of the person who gave the plant the name,
L. for Linnaeus, Trin. for Trinius. It has often hap-
pened that the same species has been given different
names by men working in various places and not in
touch with each other. In such cases the name first
given is the one now generally used. It has also
happened that two species in a genus have been
given the same name. In this case the name stands
for the earlier one and the second is renamed. These
superabundant names constitute what is termed
synonymy. (Synonyms are two or more names for
the same thing.) Superabundant names are also
due to the fact that many species when first de-
scribed were placed in genera to which more intensive
study shows they do not belong. Triodia flava, for
example, was first named Poa flava by Linnaeus, and
Danthonia spicata was named Avena spicata by him.
When these species are placed in Triodia and Dan-
thonia, respectively, the name of the original author
is given in parenthesis with the name or abbreviation
of the person who made the change following it;
thus, Triodia flava (L.) Hitchc., Danthonia spicata
(L.) DC,
GENERAL INFORMATION 111
CLASSIFICATION OF PLANTS
As stated in the introduction (page 2), the clas-
sification of grasses is based on the characters of the
spikelet. The classification of plants is itself but a
human attempt to show natural relationship, and the
attempt is based on knowledge of but an infinitesimal
part of the plant kingdom. The plants occupying
the earth today are the survivors of millions of
generations. Countless forms have become extinct.
Some of these are known from fossils, but far more
have vanished, leaving no record. Linnaeus said
" Nature never makes jumps." Connecting links
exist or have existed between the greatest extremes.
When no such link is known, we conjecture that the
missing intermediates are among the countless ex-
tinct forms. Human minds approaching a given
problem from various angles form different con-
jectures; hence it is, that botanists of different
periods or even of the same period, have diverse
ideas of relationships. The species that Linnaeus
described under Poa, for example, are today recog-
nized as belonging in three genera and his species of
Panicum in nine genera. As a vastly greater number
of plants are known today, botanists have wider
knowledge on which to base conclusions, but the
main difference between the Linnaean and the
present-day idea of genera is due to the modern
concept of a genus as a network of related species as
contrasted with the earlier concept of a genus as a
112 FIRST BOOK OF GRASSES
sort of receptacle built of certain characters and
open to any species having those characters. Lin-
naeus's idea of Cenchrus, for example, was primarily a
genus of bur-grasses, and, besides what is now recog-
nized as Cenchrus (represented by Figs. 70 and 71),
he included in it a species of Nazia (Fig. 54) and a
Mediterranean grass in which the "bur" is composed
of the rigid lobes of the lemmas of the dense head of
spikelets, as well as a plant that is not a grass.
This brief explanation is offered to save the begin-
ner undue bewilderment when he finds in using
different books that the standard excuse offered by
botanists of all times and places, that the Latin name
of a plant is the same throughout the world, is not as
true as could be wished.
It will be noted hi using botanical works that cer-
tain characters are accepted as generic, that is, as
indicating that species having these characters in
common belong to a single genus. Such are the
5-nerved keeled lemmas of Poa. Other characters,
sometimes quite as conspicuous, such as the pu-
bescence or want of it in Poa, and the presence or
absence of an awn in Bromus and Festuca, are re-
garded as specific, that is, as differentiating species.
It might seem as though by some revelation certain
characters are known to be generic and others to be
specific. Such is not the case. A species consists of a
group of individuals presumably capable of freely
inter-breeding. A genus is a group of species which
in the sum total of their characters are so much alike
GENERAL INFORMATION 113
as to warrant the assumption that they have had a
common ancestor. Characters taken as generic and
specific are analogous to theories or working hypoth-
eses. We use them as far as they work ; if they do not
work, we discard them for other characters. Botany
is a science of living things, and its problems can
never be settled once for all. It is this enduring
interest that makes it so fascinating.
POSITION OF GLASSES IN THE PLANT KINGDOM
Flowering plants (excluding the pines and their
allies) fall into two rather distinct groups, (1) mono-
cotyledons, characterized by an embryo having a
single cotyledon and by stems having woody fibers
not in layers but distributed through them (as seen
in the cornstalk) and not increasing in thickness by
age, and (2) dicotyledons, with an embryo having
two cotyledons and stems with their woody fibers
forming a zone between pith and bark and increasing
in thickness by annual layers. Cotyledons are the
seed leaves. Anyone will have observed that sprout-
ing corn, rye, and other grasses send up a single leaf
first, while squash, radishes, lettuce, and morning-
glories, for example, have a pair of opposite seed
leaves. Grasses belong in the first class, with sedges,
rushes, lilies, and the like. They form a highly
specialized family with a greater number of species
than any other except the orchids and the com-
posites (asters, dandelions, thistles, and their kinds).
114 FIRST BOOK OF GRASSES
Grasses have been so successful in the struggle for
existence that they have a wider range than any other
family, occupying all parts of the earth and exceed-
ing any other in the number of individuals. They
reach the limits of vegetation (except for lichens and
algae) in the polar regions and on mountain tops,
endure both cold and torrid desert conditions, form
the main part of the vegetation of vast prairies,
plains, savannas, and steppes of both hemispheres,
and occupy great stretches of marsh and tide flats,
where they are building up dry land. Bamboos, the
largest of grasses, form extensive forests and dense
jungles. Grasses range in height from less than an
inch, full grown, to over a hundred feet, and they
have developed all manner of contrivances for the
dissemination of their seeds.
GRASSES IN RELATION TO MAN
Of all plants, grasses are by far the most important
to man. The grains of wheat, barley, rye, oats, rice,
corn, sorghum, and millet form the staple food of the
greater part of mankind, while the animals that
furnish food and labor, wool, mohair, and leather
live principally on grasses. The grains are also
sources of starch, alcohol, and glucose. Sugar and
sirup are obtained from sugar-cane and varieties of
sorghum, and of late years enormous quantities of
cooking oil are secured from the germ of the corn.
Grasses furnish the material for brooms and brushes
GENERAL INFORMATION 115
and are an important source of fiber for paper-making
and cordage. Tons of essential oils used in per-
fumeries are annually extracted from grasses. In a
great part of Asia and Oceanica bamboo forms the
principal or only timber for buildings and bridges
and furnishes the material for all manner of tools,
utensils, and furniture.
INDEX
Achyrodes, 61
aureum, 31
^Egopogon, 62
tenellus, 61
Agropyron repens, 34
Agrostideae, 96
Agrostis, 46, 47
hiemalis, 47
Alopecurus, 49
geniculatus, 48
Amphicarpon Purshii, 77
Andropogon, 83
scoparius, 82
Andropogonese, 99
Anthers, 9
Anthoxanthum, 64, 65
odoratum, 64
Aristida, 51, 52
dichotoma, 51, 52
Arrhenatherum elatius, 45
Avena fatua, 42
Avenese, 95
Awns, 22, 35
Axonopus furcatus, 73
Bamboos, 114, 115
Barley, cultivated, 40
tribe, 95
wild, 39
Barnyard-grass, 73
Beckmannia, 59
Bermuda-grass, 14, 55, 93
Binomials, 109
Blade, 8, 9, 16
Blue-grass, Kentucky, 13, 15,
26
Botanical names, significance
of, 108
Bouteloua, 57, 58
curtipendula, 57, 58
gracilis, 58, 93
Brachiaria, 73
Bromus, 25, 26
secalinus, 25
Broom sedges, 82
Buffalo-grass, 60, 92, 93
Bulbilis dactyloides, 92
Bunch grasses, 13
Calamagrostis, 46, 47
canadensis, 46
Callus, 22
Campulosus, 59
Canary-grass, 65
reed, 65
tribe, 97
Capriola Dactylon, 55
Caryopsis, 10
Cathestechum, 59
Cenchrus, 75
117
118
INDEX
Cenchrus, continued
bur, 93
myosuroides, 76
pauciflorus, 76
ChaBtochloa, 75
Grisebachii, 74
lutescens, 75
Cheat, 75
Chess, 75
Chlorideae, 96
Chloris, 57
latisquamea, 56
Cinna, 48
Classification, 111
Cleistogamous spikelets, 77
Corn, Indian, 90
tribe, 99
Cottea pappophoroides, 27, 28
Couch-grass, 34
Crab-grass, 70
Culms, 8, 14
Curly-mesquite tribe, 96
Cynosurus cristatus, 30
Danthonia spicata, 43
Dioecious, 23, 32
Distichlis spicata, 32
Echinochloa Crusgalli, 73
Eleusine, 54, 55, 56
indica, 54, 55
Elymus, 39, 41
virginicus, 38
Embryo, 10, 11
Emmer, 36
Endosperm, 11
Erianthus, 82
saccharoides, 81
Eriochloa punctata, 73
Fescue tribe, 95
Festuca ovina, 26
Festucese, 85
Filaments, 9
Floret, 10, 11
Flower, of grass, 9
typical, 9
Foxtail, green, 75
yellow, 75
Fruit, 11
Gama-grass, 14, 89
Genus, 5
Genera, 5, 111
Generic characters, 112
Glumes, 11, 17
Grain, 10, 11
Grama-grass, 57, 92, 94
tribe, 96
Graminese, 8
Grass, description of, 8
flower, 10
Grasses, bunch, 13
in relation to man, 114
position of, in plant king-
dom, 113
sod-forming, 13
Green foxtail, 75
Herbarium, use of a, 102
Heteropogon, 87, 88
contortus, 86
INDEX
119
Hilaria Belangeri, 62
Hilum, 11
Holcus, 83, 85
halepensis, 80
Holy-grass, 65
Homalocenchrus, 65
oryzoides, 66
Hordese, 95
Hordeum, 40
nodosum, 39, 40
Indian corn, 90, 91
-grass, 81
rice tribe, 97
Inflorescence, 18
Melica mutica, 29
Milium effusura, 50
Millet tribe, 77, 98
Millets, 75
Monoecious, 23
Morphology, 2
Muhlenbergia foliosa, 50
Schreberi, 50
Nazia aliena, 63
Nazieae, 96
Nodes, 8
Notholcus lanatus, 44, 49
Johnson-grass, 80
Oat, 45
tribe, 95
Oats, wild, 42
Oryza sativa, 65, 66
Kentucky blue-grass, 13, 15, 26 Oryzese, 97
Oryzopsis, 50
racemosa, 51
Ovary, 9, 10
Ovules, 10
Leaves, 15
Lemma, 10, 11, 17
Leptochloa, 59
Lepturus, 84
cylindricus, 36
Ligule, 8, 9
Lodicules, 9, 10
Lolium multiflorum, 36
Luziola, 67
Lycurus phleoides, 49
Maize, 90
Manisuris, 83, 84, 90
cylindrica, 83
Manuals of botany in current Pedicel, 18
use, 104 Pericarp, 47
Palea, 10, 11
Panicatse, 98
Panicese, 77, 98 f
Panicle, 18
Panicularia septentrionalis, 27
Panicum, 69, 70, 71
miliaceum, 69
Pappophorum vaginatum, 29
Paspalum, 71, 73
, 71
120
INDEX
Petiole, 16
Phalaridese, 97
Phalaris arundinacea, 65
canariensis, 65
minor, 65
Phleum pratense, 48
Phragmites communis, 28
Pistils, 9, 10
Pleuropogon californicus, 27
Poa, 26
pratensis, 14, 26, 27
Poacese, 8
Poatse, 95
Prophyllum, 17
Quack-grass, 15, 34
Raceme, 18
Rachilla, 11
Rachis, 18
Reed, 28
canary-grass, 65
Reimarochloa, 72
Rhaphis, 85, 88
pauciflora, 85, 86
Rhizomes, 13, 14
Rice, 65, 66
tribe, 97
wild, 66
Rootstocks, 13
Rye-grass, 38
Rytilix, 84, 85
granularis, 84
Saint Augustine-grass, 72
Salt-grass, 32
Sand-bur, 75, 76
Scleropogon brevifolius, 32, 33
Seneca-grass, 65
Sheath, 8, 9
Sitanion, 39
Sod-forming grasses, 13
Sorghastrum, 81
Sorghum, 80, 82
tribe, 99
Spartina, 59
Spathes, 82
Sphenopholis, 45
Spike, 18
Spikelet, 11, 17, 19
Sporobolus airoides, 47
heterolepis, 48
Stamens, 9, 10
Stenotaphrum, 72, 73
secundatum, 72
Stigma, 9, 10
Stipa, 51, 52, 88
spartea, 51
Stolons, 14
Styles, 9, 10
Sugar-cane, 81
Sweet vernal-grass, 64
Synonyms, 110
Syntherisma, 73
sanguinalis, 70
Timothy, 48
tribe, 96
Torresia, 65
Tribes, primary characters of,
95
Triodia flava, 27, 28
Tripsacese, 99
INDEX
121
Tripsacum, 90
dactyloides, 14, 89
Trisetum, 43, 46
spicatum, 43
Triticum sestivum, 35
dicoccum, 36
Vanilla-grass, 65
Velvet-grass, 44
Wheat, 35
Wild oats, 42
rice, 66
Yard-grass, 54
Yellow foxtail, 75
Zea Mays, 90, 91
Zizania palustris, 66
Zizaniese, 97
Zizaniopsis miliacea, 67
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