/ to Texas and a key to Uroch/oaofTexas. Phytoneuron

StephanL. Hatch

S.M. Tracy Herbarium (TAES)

Department of Ecosystem Science and Management

Texas A&M University

College Station, TX 77843-2138, U.S.A.

s-liatch@tamu.edu

ABSTRACT

Urochloa subquadripara is reported as introduced into Texas. A key to separate the 13 species
of Urochloa in Texas is presented along with an image of the newly reported species.
KEY WORDS: Poaceae, Urochloa, Texas, introduced, invasive plant

Urochloa P. Beauv. is primarily a grass genus of Old World origin. Thirteen of the estimated
100 species (Wipff & Thompson 2003) worldwide occur in Texas. This genus was separated from
closely related or similar Paniceae by Wipff et al. in 1993. Urochloa (Wipff & Thompson 2003) is
described as having terminal and axilliary panicle inflorescences with 2 to several spicate primary
unilateral branches. Spikelets are solitary, paired, or in ti iplets and occur in 1-2 (4) rows per primary
branch. With 2 florets per spikelet, the upper floret is fertile, indurate and rugose to verrucose, the
lower floret sterile or staminate. A key to three Urochloa species was published by Wipff et al.
(1993).

Eight of the Texas taxa are introduced (five invasive) and five are native to North America. The
introduced taxa are native to tropical or subtropical regions of the world and their points of
introduction appear to be from the coast or south Texas and following a period of adaptation move
inland and/or to the north.

Urochloa subquadripara (Trin.) R.D. Webster has recently been collected in south Texas
(Hidalgo County). The specimens were identified (Wipff & Thompson 2003) and verified using

specimens in the S.M. Tracy Herbarium (TAES) at Texas A&M University.

This new introduction to Texas is recent. Taxonomic keys had not keyed or described Urochloa
subquadripara in the United States (Hitchcock 1935). Hitchcock (1951) gave mention of the species
without including it in the key, stating that it is occasionally planted in Florida as a potential forage
crop. Later, Hall (1978) and others, including Wunderlin (1982) and Wipff and Thompson (2003)
have included the species in descriptions and keys. Mas and Garcia M. (1990) discussed the
occurrence of the species in Puerto Rico and reported it to be a good forage.

Urochloa subquadripara was not reported as being found in Texas by Gould (1975) and others,
including Hatch et al. (1990), Fox and Hatch (1996), Wipff et al. (1993), and most recently Jones et
al. (1997). Following are the species description, voucher information, and a digital image of U.

subquadripara, and a key to Urochloa of Texas.

Sci. J. 7: 214. 1931. TROPICAL SlGNALGRASS.

Urochloa subquadripara (Trin.) A. Hitchc, Li^
Fig. 1. Creeping annuals or short-lived
perennials. Culms 40 cm long, apex erect,
decumbent and rooting at nodes, nodes glabrous.
Leaves mostly cauline. Sheaths terete, shorter
than internodes. Ligules ca 1-1.3 mm long, a
ciliate membrane. Blades to 25 cm long, 4-11
mm wide, flat (thin), glabrous or pubescent,
margins not crisp. Panicles of 3-8 spicate
primary unilateral branches; branches to 9 cm
long (Fig. 1), 1 per node, pedicels scabrous
(short). Spikelets 3.3-3.7 mm long. First
glumes 1.5-1.7 mm long, one half spikelet or
less spikelet length. Second glumes 3.1-3.6 mm
long (apex not reticulate- veined). Lower florets
neuter (apex not reticulate- veined). Lower floret
paleas well-developed. Upper floret lemmas
3.1-2.5 mm long, ca 1 mm wide, oval,
stramineous. Chromosome numbers 2n= 36,
54, and 72. Flowering period May to August.

Distribution. Texas: a disturbance species
of sandy loam soil that is new to Texas (Area 6),
Hidalgo County. General: native to tropical Asia,
introduced into Florida, reportedly Georgia,
Mexico, and the Lesser Antilles.

Voucher Specimens: TEXAS. Hidalgo Co.:

Weslaco, USDA-ARS Laboratory (near
GIS/Remote Sensing Building), 2413 East
Highway 83, growing in a yard. 19 Aug 2008,
Everitt s.n. (TAES) and 1 Jun 2008, Everitt s.n.
(TAES); Weslaco, Memorial Elementary School,
1700 South Border, E side of school, 19 Aug
2008, Everitt s.n. (TAES).

KEY TO THE UROCHLOA SPECIES OF TEXAS

1 . Panicle branches verticillate at inflorescence base; plants perennial

1 . Panicle branches single or paired at the inflorescence base; plants annual or perennial.

2. Spikelets single at mid-branch.

3 . Panicle branches triquetrous in cross-section

3. Panicle branches crescent shaped or flat in cross-section.

4. Upper lemmas awned, awns 0.4-1.3 mm long.

5. Plants annual; leaf blade margins crisp, usually with pappilos

.. U. ciliatissima

4. Upper lemmas awnless or slightly mucronate; awns less than 0.25 mm long.

6. Spikelets in single row on panicle branches U. briztmtha

6. Spikelets in 2 rows on branches.

7. First glumes 5-7-veined; glumes separated by an internode less than 0.3 mm long;

spikelets more than 4 mm long U. ptatyphylla

7. First glumes (7-) 9-11-veined; glumes separated by an internode 0.3-0.5 mm long;
spikelets 3.3-3.7 mm long U. subquadripara

2. Spikelets paired at mid branch.

8. Panicle branches triquetrous in cross-section.

9. Spikelets 5-6.2 mm long V. texana

9. Spikelets 2.2^.1 mm long.

10. Second glumes and lower lemma apices reticulate- veined U.fusca

10. Second glumes and lower lemma apices not reticulate-veined.

11. Panicle branches with dense papillose hairs V. arhonica

11. Panicle branches with few or no papillose hairs V. ramosa

8. Panicle branches flat in cross-section.

12. Spikelets 1.8-2.2 mm long; culms less than 35 cm tall; plants annual U. reptans

12. Spikelets more than 2.5 mm long; culms more than 30 cm tall; plants perennial.

13. Upper lemmas awned, awns 0.5-1. 1 mm long; panicle branches 2-8

U. mvsambicemis

13. Upper lemmas awnless to murcronate, mucro less than 0.3 mm long; panicle branches
usually 10-25 U. mutica

ACKNOWLEDGEMENTS

Thanks to James Everett, D. Lynn Drawe, and Robert I. Lonard for seeking an identification of

this newly introduced grass into South Texas and sending voucher specimens.

LITERATURE CITED

Fox, W.E., III and S.L. Hatch. 1996. Brachiaria eruciformis and Urochloa brizantha (Poaceae:

Paniceae) new to Texas). Sida 17: 287-288.
Gould, F.W. 1975. The grasses of Texas. Texas A&M University Press, College Station.
Hall, D.W. 1978. The grasses of Florida. Ph.D. dissertation, Univ. of Florida, Gainsville.
Hatch, S.L., K.N. Gandhi and L.E. Brown. 1990. Checklist of the vascular plants of Texas. Texas

Agri. Exp. Sta. Bull. MD 1655.
Hitchcock, AS. 1935. Manual of the grasses of the United States. U.S. Govt. Printing Office.

U.S.D. A Misc. Publ. 200, Washington D.C.
Hitchcock, AS. 1951. Manual of the grasses of the United States. Revised A Chase. U.S. Govt.

Printing Office. U.S.D. A Misc. Publ. 200, Washington D.C.
Jones, S.D., J.K. Wipff and P.M. Montgomery. 1997. Vascular plants of Texas — a comprehensive

checklist including synonymy, bibliography and index. Univ. of Texas Press, Austin.

Mas, E.G. and O. Garcia Ivlolinari. 1990. Guia illustrada de yerbas communes en Puerto Rico. Univ.

de Puerto Rico-RCM, Colegio de Ciencias Agricolas, Servicio de Extension Agricola.
Wunderlin, R.P. 1982. Guide to the vascular plants of central Florida. Univ. Presses of Florida,

USF, Tampa.
Wipff, J.K. and RA. Thompson. 2003. Urochloa. Pp. 492-507 in M.E. Barkworth, K.M. Capels, S.

Long, and M.B. Piep. Magnoliophyta: Commelinidae (in part): Poaceae, part 2. Flora of North

America North of Mexico, Volume 25. Oxford Univ. Press, New York
Wipff, J.K., RI. Lonard, S.D. Jones and S.L. Hatch. 1993. The genus Urochloa (Poaceae: Paniceae)

in Texas, including one previously unreported species for the state. Sida 15: 405-413.