25.13   UROCHLOA P. Beauv.

REVISED TREATMENT. Please send comments to Mary Barkworth.
J.K. Wipff
Rahmona A. Thompson

Plants annual or perennial; usually cespitose, sometimes mat-forming, sometimes stoloniferous. Culms 5-500 cm, herbaceous, erect, geniculate, or decumbent and rooting at the lower nodes. Sheaths open; auricles rarely present; ligules apparently of hairs, the basal membranous portion inconspicuous; blades ovate-lanceolate to lanceolate, flat. Inflorescences terminal or terminal and axillary, usually panicles of spikelike primary branches in 2 or more ranks, rachises not concealed by the spikelets; primary branches usually alternate or subopposite, spikelike, and 1-sided, less frequently verticillate, axes flat or triquetrous, usually terminating in a well-developed, rudimentary spikelet; secondary branches present or absent, axes flat or triquetrous; disarticulation beneath the spikelets. Spikelets solitary, paired, or in triplets, subsessile or pedicellate, divergent or appressed, ovoid to ellipsoid, dorsally compressed, in 1-2(4) rows, with 2 florets, lower or upper glumes adjacent to the branch axes. Glumes not saccate basally; lower glumes usually 1/5-2/3 as long as the spikelets, occasionally equaling the upper florets, (0)1-11-veined; upper glumes 5-13-veined; lower florets sterile or staminate; lower lemmas similar to the upper glumes, 5-9-veined; lower paleas if present, usually hyaline, 2-veined; upper florets bisexual, sessile, ovoid to ellipsoid, usually plano-convex, usually glabrous, not disarticulating, mucronate or acuminate; upper lemmas indurate, transversely rugose and verrucose, 5-veined, margins involute, apices round to mucronate, or aristate; upper paleas rugose, shiny or lustrous; lodicules 2, cuneate, truncate; anthers 3. Caryopses ovoid to elliptic, dorsally compressed; embryos 1/2-3/4 as long as the caryopses; hila punctate to linear. x = 7, 8, 9, or 10. Name from the Greek ouros, tail and chloa, grass, a reference to the abruptly awned lemmas of some species.

Urochloa is a genus of approximately 100 tropical and subtropical species. There are 19 species found in the Flora region. Eight species are established introductions, six are native, three are cultivated as grain or forage crops, and two have been found in the region but are not known to be established.

Urochloa differs from Moorochloa in its two or more ranks of panicles and rugose, non-disarticulating, distal florets. The rugose, often mucronate or aristate, distal florets also distinguish it from most species of Panicum.


Simon and Jacobs (2003) transferred Urochloa maxima to a new genus, Megathyrsus. They commented that papers by Gomez-Martinez and Culham (2000), Giussani et al. (2001), Zuloaga et al. (2000), and Aliscioni et al. (2003) all supported inclusion of U. maxima in Panicum subg. Megathyrsus [= Megathyrsus] rather than Urochloa. Their recommendation is followed here, but see discussion in that genus.


SELECTED REFERENCES Aliscioni, S.S., L.M. Giussani, F.O. Zuloaga, and E.A. Kellogg. 2003. A molecular phylogeny of Panicum (Poaceae: Paniceae): Tests of monophylly and phylogenetic placement within the Panicoideae. Amer. J. Bot. 90:796-821. Clayton, W.D. and S.A. Renvoize. 1982. Flora of Tropical East Africa. Gramineae (Part 3). A.A. Balkema, Rotterdam, The Netherlands. 448 pp.; Davidse, G. and R.W. Pohl. 1994. Urochloa P. Beauv. Pp. 331-333 in G. Davidse, M. Sousa S., and A.O. Chater (eds.). Flora Mesoamericana, vol. 6: Alismataceae a Cyperaceae. Universidad Nacional Autónoma de México, Instituto de Biología, México, D.F., México. 543 pp.; Fox, W.E., III and S.L. Hatch. 1996. Brachiaria eruciformis and Urochloa brizantha (Poaceae: Paniceae) new to Texas. Sida 17:287-288; Giussani, L.M., H. Cota-Sanchez, F.O. Zuloaga, and E. A. Kellogg. 2001. A molecular phylogeny of the subfamily Panicoideae (Poaceae) shows multiple origins of C4 photosynthsis. Amer. J. Bot. 88:1993-2012; Gomez-Martinez, R. and A. Culham. 2000. Pp. 136-140 in S.W.L. Jacobs and J. Everett (eds.). Grasses: Systematics and Evolution. International Symposium on Grass Systematics and Evolution (3rd:1998). CSIRO Publishing, Collingwood, Victoria, Australia. 408 pp.; Hall, D.W. 1978. The Grasses of Florida. Ph.D. dissertation, University of Florida, Gainesville, Florida, U.S.A. 498 pp.; Morrone, O. and F.O. Zuloaga. 1992. Revisión de las especies Sudamericanas nativas e introducidas de los géneros Brachiaria y Urochloa (Poaceae: Panicoideae: Paniceae). Darwiniana 31:43-109; Morrone, O. and F.O. Zuloaga. 1993. Sinopsis del género Urochloa (Poaceae: Panicoideae: Paniceae) para México y America Central. Darwiniana 32:59-75; Munshi, J.D., V. Bankisar, J.K. Pal, and N. Pandit. 1995. Cytomixis and chromosome variation in Brachiaria ramosa (L.) Stapf from Diara Land of Bhagalpur, Bihar. Proc. Indian Sci. Congr. 82:73; Pohl, R.W. 1980. Flora Costaricensis: Family #15, Gramineae. Fieldiana, Bot., n.s., 4:1-608; Reed, C.F. 1964. A flora of the chrome and manganese ore piles at Canton, in the Port of Baltimore, Maryland and at Newport News, Virginia, with descriptions of genera and species new to the flora of the eastern United States. Phytologia 10:321-405; Sendulsky, T.1978. Brachiaria: Taxonomy of cultivated and native species in Brazil. Hoehnea 7:99-139; Simon, B.K. and S.W.L. Jacobs. 2003. Megathyrsus, a new generic name for Panicum subgenus Megathyrsus. Austrobaileya 6:571-574; Veldkamp, J.F. 1996. Brachiaria, Urochloa (Gramineae-Paniceae) in Malesia. Blumea 41:413-437; Webster, R.D.1987. The Australian Paniceae (Poaceae). J. Cramer, Berlin and Stuttgart, Germany. 322 pp.; Wipff, J.K., R.I. 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; Zuloaga, F.O., O. Morrone, and L.M. Giussani. 2000. A cladistic analysis of the Paniceae: A preliminary approach. Pp. 123-135 in S.W.L. Jacobs and J. Everett (eds.). Grasses: Systematics and Evolution. International Symposium on Grass Systematics and Evolution (3rd:1998). CSIRO Publishing, Collingwood, Victoria, Australia. 408 pp.

1
Branches at the lowest node of the inflorescence verticillate; inflorescences simple, open panicles, the primary branches with well-developed secondary and tertiary branches; plants perennial ..... 18. U. maxima
Branches at the lowest node of the inflorescence not verticillate; inflorescences usually with spikelike branches, secondary branches absent or inconspicuous, sometimes simple panicles; plants annual or perennial (2)
2
Spikelets paired at mid-branch length, sometimes solitary distally (3)
Spikelets solitary at mid-branch length (11)
3
Axes of the primary panicle branches flat; lower glumes (0)1-3-veined (4)
Axes of the primary panicle branches triquetrous; lower glumes 3-7-veined (6)
4
Plants annual; culms 10-35 cm tall; spikelets 1.8-2.2 mm long ..... 2. U. reptans
Plants perennial; culms 20-500 cm tall; spikelets 2.5-5 mm long (5)
5
Upper lemmas awned, the awns 0.5-1.2 mm; lower glumes 3-veined, with 1-3 conspicuous, rigid hairs ..... 8. U. mosambicensis
Upper lemmas unawned; lower glumes 1-3-veined, glabrous ..... 1. U. mutica
6
Spikelets 4.8-6 mm long; hila linear, about 1/2 as long as the caryopses ..... 3. U. texana
Spikelets 2-4.2 mm long; hila punctate (7)
7
Branch axes densely hairy, the hairs papillose-based ..... 4. U. arizonica
Branch axes sometimes densely hairy, with few or no papillose-based hairs (8)
8
Upper glumes with evident cross venation extending from near the bases to the apices; spikelets obovoid; upper glumes and lower lemmas usually glabrous; lower lemmas 7-veined ..... 5. U. fusca
Upper glumes without evident cross venation, or the cross venation confined to the distal 1/2; spikelets ellipsoid; upper glumes and lower lemmas glabrous or pubescent; lower lemmas 5-veined (9)
9
Cauline nodes glabrous; plants 20-120 cm tall; spikelet apices abruptly acuminate ..... 6. U. adspersa
Cauline nodes pubescent; plants 10-70 cm tall, spikelets apices broadly acute to acute (10)
10
Upper glumes 5-veined; upper lemmas 1.8-2.1 mm long; glumes separated by an internode about 0.3 mm long ..... 11. U. villosa
Upper glumes 7-9-veined; upper lemmas 2.3-3.3 mm long; glumes not separated by a conspicuous internode ..... 7. U. ramosa
11
Panicle branches triquetrous, 0.2-0.4 mm wide (12)
Panicle branches flat or crescent-shaped in cross section, 0.5-2.5 mm wide (13)
12
Plants perennial; upper glumes (9)11-13-veined; upper lemmas 2.4-2.8 mm long; glumes not separated by a conspicuous internode; lower florets staminate ..... 17. U. ciliatissima
Plants annual; upper glumes 5-veined; upper lemmas 1.8-2.1 mm long; glumes separated by an internode about 0.3 mm long; lower florets sterile ..... 11. U. villosa
13
Upper lemmas awned, the awns 0.3-1.2 mm long, apices rounded (14)
Upper lemmas unawned; apices variable, with or without a mucronate tip (15)
14
Plants perennial; lower glumes with 1-3 conspicuous, rigid hairs, the lower glumes 1/2-3/4 as long as the spikelet; lower florets staminate ..... 8. U. mosambicensis
Plants annual; lower glumes without conspicuous, rigid hairs; the lower glumes 1/4-1/3(1/2) as long as the spikelet; lower florets sterile ..... 14. U. panicoides
15
Spikelets in a single row along the branches; spikelets 4-6 mm long; lower florets staminate; panicle branch axes crescent-shaped in cross section ..... 10. U. brizantha
Spikelets in 2 rows along the branches; spikelets 2.5-6 mm long; lower florets sterile or staminate; panicle branches flat (16)
16
Lower glumes 5-7-veined; glumes scarcely separated, the internode between them shorter than 0.3 mm (17)
Lower glumes (7)9-11-veined; glumes separated by a conspicuous, 0.3-0.5 mm internode (19)
17
Upper glumes and lower lemmas pubescent, the hairs often longest in the distal 1/3 ..... 9. U. piligera
Upper glumes and lower lemmas glabrous (18)
18
Plants perennial, stoloniferous; lower florets staminate ..... 16. U. arrecta
Plants annual; lower florets sterile ..... 15. U. platyphylla
19
Lower paleas absent; spikelets usually pubescent, sometimes glabrous ..... 9. U. piligera
Lower paleas present; spikelets glabrous (20)
20
Spikelets 3.3-3.7 mm long; base of blades rounded to subcordate, not clasping the stem ..... 12. U. subquadripara
Spikelets 4-6 mm long; base of blades subcordate to cordate, clasping the stem ..... 13. U. plantaginea


1.   Urochloa mutica (Forssk.) T.Q. Nguyen
Paragrass

Plants perennial; stoloniferous, straggling. Culms to 5 m long, long-decumbent and rooting at the lower nodes, vertical portion 90-200(300) cm; nodes villous. Lower sheaths with papillose-based hairs, these more dense distally, margins ciliate; collars pubescent; ligules 1-1.5 mm; blades 7.5-35 cm long, 4-20 mm wide, glabrous or sparsely pilose on both surfaces, margins scabrous. Panicles 10-25 cm long, 5-10 cm wide, pyramidal, with 10-30 spikelike branches in more than 2 ranks; primary branches 2.5-8 cm long, 0.4-0.9 mm wide, ascending to divergent, axils pubescent, axes flat, glabrous or with a few papillose-based hairs, secondary branches present or absent; pedicels shorter than the spikelets, scabrous, sometimes with hairs. Spikelets 2.6-3.5 mm long, 1-1.4 mm wide, mostly in pairs, in 2-4 rows, appressed to the branches, purplish to green. Glumes scarcely separate, rachilla internodes short not pronounced; lower glumes 0.6-1.1 mm, 1/5-1/3 as long as the spikelets, glabrous, 0-1(3)-veined; upper glumes 2.6-3.5 mm, glabrous, 5-(7)-veined, without cross venation; lower florets staminate; lower lemmas 2.6-3.3 mm, glabrous, 5-veined, without cross venation; upper lemmas 2.3-2.8 mm long, 1-1.3 mm wide, apices rounded, mucronate; anthers 1-1.5 mm. Caryopses 1.8-2 mm. 2n = 18, 36.

An African species, Urochloa mutica is grown as a forage crop throughout the tropics, but it tends to become weedy. It grows on moist, disturbed soils and is established in the southeastern United States.


2.   Urochloa reptans (L.) Stapf
Sprawling Signalgrass

Plants annual; forming sprawling mats. Culms 10-35 cm, prostrate to decumbent; nodes glabrous or sparsely puberulent. Sheaths glabrous or sparsely pubescent, margins densely ciliate; ligules 0.5-1 mm; blades 2-6 cm long, 4-15 mm wide, adaxial surfaces glabrous or sparsely pubescent with papillose-based hairs, margins ciliate basally. Panicles 1.5-6(8) cm long, 4-5 cm wide, ovoid, with 3-16 spikelike branches in more than 2 ranks; primary branches 1-4 cm long, 0.2-0.5 mm wide, flat, scabrous; secondary branches occasionally present; pedicels shorter than the spikelets, scabrous, glabrous or with long hairs distally. Spikelets 1.8-2.2 mm long, 0.8-1 mm wide, mostly in pairs, in 2-4 rows, appressed to the branches. Glumes scarcely separate, rachilla internodes short, not pronounced; lower glumes 0.2-0.6 mm, 1/5-1/4 as long as the spikelets, 0-1-veined; upper glumes 1.7-2.1 mm, glabrous, 7-veined, without cross venation; lower florets sterile or staminate; lower lemmas 1.7-2.1 mm, glabrous, 5-veined, without cross venation; lower paleas present; upper lemmas 1.5-1.8 mm long, 0.8-1 mm wide, apices rounded, mucronate, mucros to about 0.1 mm; anthers 0.4-0.6 mm. Caryopses 0.8-1.2 mm. 2n = 14(18).

Urochloa reptans is widely distributed in tropical and subtropical regions of the world, growing in disturbed habitats. In the Flora region, it is found primarily in Texas and Louisiana.


3.   Urochloa texana (Buckley) R.D. Webster
Texas Signalgrass, Texas Millet

Plants annual. Culms (20)40-200 cm, erect or decumbent; nodes puberulent; internodes pubescent, at least below the nodes. Sheaths usually with papillose-based hairs, margins shortly ciliate; collars pubescent; ligules 1-1.8 mm; blades 7-24 cm long, 5-20 mm wide, softly pubescent on both surfaces, margins ciliate basally, scabrous distally. Panicles 8-24 cm long, 1-3 cm wide, with spikelike primary branches in more than 2 ranks; primary branches 1-8 cm long, 0.3-0.4 mm wide, appressed to ascending, axes triquetrous, pubescent, with some papillose-based hairs; secondary branches present on the lower branches, short, appressed; pedicels shorter than the spikelets,usually with papillose-based hairs distally. Spikelets 4.8-6 mm long, 1.8-2 mm wide, mostly paired, in 2-4 rows, appressed to the branches. Glumes scarcely separate, rachilla internodes short, not pronounced; lower glumes 2.4-3.2 mm, to 1/2 as long as the spikelets, 5-7-veined, glabrous or sparsely pubescent distally; upper glumes 4-5.5 mm, glabrous or sparsely pilose, 7-9-veined; lower florets staminate (sterile); lower lemmas 4.7-6 mm, glabrous or sparsely pilose, 5-veined; lower paleas present; upper lemmas 3.6-4.1 mm long, 1.7-1.9 mm wide, apices acute, beaked; anthers (1.6) 2.2-2.7 mm. Caryopses 2-3 mm; hilas linear, about 1/2 as long as the caryopses. 2n = 54.

Urochloa texana grows in sandy, moist soils from the southern United States to northern Mexico. Populations in the United States outside of Texas may represent relatively recent introductions.


4.   Urochloa arizonica (Scribn. & Merr.) Morrone & Zuloaga
Arizona Signalgrass

Plants annual. Culms 15-65 cm, erect or geniculate, branching from the lower nodes; nodes glabrous or hispid. Sheaths glabrous or with papillose-based hairs, margins ciliate distally; ligules 1-1.6 mm; blades 5-15 cm long, 5-12 mm wide, glabrous. Panicles 6-20 cm long, 2-5 cm wide, ovoid, with 6-12 spikelike primary branches in more than 2 ranks; primary branches 3-7 cm, divergent, axes about 0.4 mm wide, triquetrous, densely pubescent with papillose-based hairs; secondary branches short, divergent; pedicels shorter than the spikelets, with papillose-based hairs. Spikelets 3.2-4 mm long, 1.2-1.6 mm wide, mostly paired, in 2 rows, appressed to the branches. Glumes scarcely separate, rachilla internodes short, not pronounced; lower glumes 1.5-2 mm, to 1/2 as long as the spikelets, glabrous, 5-veined, sometimes with evident cross venation near the apices; upper glumes 2.5-3.2 mm, glabrous or shortly hirsute, 7-veined, with evident cross venation distally; lower florets staminate or sterile; lower lemmas 2.5-3.2 mm, glabrous or shortly hirsute, 5-veined, about as long as the spikelet; lower paleas present; upper lemmas 2.8-3 mm long, 1.2-1.6 mm wide, acute, beaked or mucronate; anthers 0.8-1 mm. Caryopses 1.5-2 mm; hila punctiform. 2n = 36.

Urochloa arizonica is native to the southwestern United States and northern Mexico, but has been introduced and appears to be established in the southeastern United States. It grows in open, dry areas with rocky or sandy soils.


5.   Urochloa fusca (Sw.) B.F. Hansen & Wunderlin
Browntop Signalgrass

Plants annual; tufted. Culms 15-120 cm, geniculate; nodes glabrous or shortly pilose. Sheaths glabrous or hispid, margins ciliate; ligules 1-1.5 mm; blades 3-33 cm long, 5-20 mm wide, glabrous or sparsely pilose on both surfaces, margins smooth or scabrous; collars pubescent. Panicles 5-15 cm long, 2-8 cm wide, simple, with 5-30 spikelike primary branches in more than 2 ranks; primary branches 2-10 cm, appressed to divergent, axils glabrous, axes 0.3-0.5 mm wide, triquetrous, scabrous or sparsely pilose; secondary branches usually present on the lower primary branches; pedicels scabrous and pubescent, shorter than the spikelets. Spikelets 2-3.4 mm long, 1.2-1.8 mm wide, obovoid, yellowish to reddish-brown or bronze-colored at maturity, mostly paired, in 2-4 rows, appressed to the branches. Glumes scarcely separate, rachilla internodes short, not pronounced; lower glumes 1-1.5 mm, at least 1/3 as long as the spikelets, glabrous, (1)3-5-veined; upper glumes (2)2.2-3.1 mm, glabrous, 7-9-veined, cross venation evident throughout; lower florets usually staminate, sometimes sterile; lower lemmas 2-3.1 mm, usually glabrous, 7-veined, cross venation evident throughout; lower paleas present; upper lemmas 1.8-2.9 mm long, 1.1-1.7 mm wide, apices acute to rounded, mucronate; anthers 1-1.6 mm. Caryopses 1-1.7 mm; hila punctiform. 2n = 18, 36.

Urochloa fusca grows from the southern United States to Peru, Paraguay, and Argentina, usually in moist, often disturbed areas at low elevations. It frequently occurs as a weed, but is occasionally grown for forage and grain.

Plants having smaller, more compact panicles and larger (2.4-3.4 mm), mostly yellowish spikelets have been called Urochloa fusca var. reticulata (Torr.) B.F. Hansen & Wunderlin. This variety is mainly found in the southwestern United States, but has been introduced into other areas, including Australia. Urochloa fusca (Sw.) B.F. Hansen & Wunderlin var. fusca usually has larger, more open panicles and smaller (2-2.5 mm), reddish-brown or bronze-colored spikelets. Much intergradation is reported between the two varieties. Further investigation is needed to establish that their recognition is warranted.


6.   Urochloa adspersa (Trin.) R.D. Webster
Dominican Signalgrass

Plants annual. Culms 20-120 cm, geniculate or decumbent, usually rooting at the lower nodes; nodes glabrous. Sheaths glabrous or glabrate, margins ciliate distally; ligules 0.5-1 mm; blades 2-20 cm long, 7-20 mm wide, glabrous. Panicles terminal and axillary, 5-18 cm long, to 1.4 cm wide, with 2-10 spikelike primary branches in more than 2 ranks; primary branches 1.5-9 cm, appressed, axes 0.3-0.8 mm wide, triquetrous, scabrous; secondary branches present or absent, if present, short, restricted to the lowest panicle branches; pedicels scabrous, shorter than the spikelets. Spikelets 2.9-3.8 mm long, 1.2-1.4 mm wide, ellipsoid, apices abruptly acuminate, mostly paired, in 2-4 rows, appressed to the branches. Glumes scarcely separate, rachilla internodes short, not pronounced; lower glumes 1-1.4 mm, glabrous or pubescent, (3)5-veined, 1/3 or less as long as the spikelets; upper glumes 2.8-3.7 mm, glabrous or pubescent, 5-7(9)-veined, cross venation not evident or evident only in the distal 1/2; lower florets sterile; lower lemmas 2.7-3.6 mm, glabrous or pubescent, 5-veined, usually without cross venation; upper florets 2.1-2.9 mm long, 1.3-1.7 mm wide, broadly acute, mucronate; anthers 1-1.2 mm. Caryopses 1.2-1.8 mm; hila punctiform. 2n = 54.

Urochloa adspersa grows in southern Florida, the West Indies, and Argentina. It prefers moist, open areas, often on coral limestone. It has also been found on ballast dumps in Mobile, Alabama, and in Philadelphia, Pennsylvania and Camden, New Jersey, but it has not persisted at these locations.


7.   Urochloa ramosa (L.) T.Q. Nguyen
Browntop Millet

Plants annual; tufted. Culms 10-65 cm, decumbent, rooting or not at the lower nodes; nodes pubescent. Sheaths usually puberulous, sometimes glabrous or sparsely pilose, margins ciliate; ligules 0.8-1.7 mm; blades 2-25 cm long, 4-14 mm wide, glabrous, margins scabrous. Panicles 3-13 cm, simple, with 3-15 spikelike primary branches; primary branches 1-8 cm, divergent, axils glabrous, axes 0.4-0.6 mm wide, triquetrous, glabrous, scabrous, or pubescent, with or without some papillose-based hairs; secondary branches, if present, confined to the lower branches; pedicels shorter than the spikelets, scabrous or pubescent. Spikelets 2.5-3.4 mm long, 1.3-2 mm wide, ellipsoid, apices broadly acute to acute, paired, appressed to the branches. Glumes scarcely separated, rachilla internode between the glumes not pronounced; lower glumes 1-1.5 mm, 1/3-1/2 as long as the spikelets, glabrous, 3-5-veined; upper glumes 2.5-3.4 mm, usually puberulent, sometimes glabrous, margins sometimes somewhat pubescent, 7-9-veined, without evident cross venation; lower florets sterile, lower lemmas 2.4-3.3 mm, usually puberulent or occasionally glabrous, margins not ciliate, without cross venation, 5-veined; upper lemmas 2.3-3.3 mm, acute, mucronate; anthers 0.7-1.2 mm. Caryopses 1.2-2.3 mm; hila punctiform. 2n = 36 (usually); also 14, 28, 30, 32, 34, 42, 46, 72 [additions from Munshi et al. 1995].

A weedy species of tropical Africa and Asia, Urochloa ramosa has spread throughout the tropics and subtropics, including the southeastern United States. It is considered a weed in the Flora area, but it is cultivated in India as a grain and forage crop; the grain is sometimes used for birdseed.


8.   Urochloa mosambicensis (Hack.) Dandy
Sabi Grass

Plants perennial; cespitose, with or without stolons. Culms 20-150 cm; nodes pubescent; internodes with papillose-based hairs. Sheaths pubescent, lower sheaths pilose, upper sheaths with papillose-based hairs; ligules 1-2 mm; blades 3-30 cm long, (1.5) 3-20 mm wide, with scattered papillose-based hairs, margins scabrous. Panicles 3-12.5 cm, with 2-6(15) spikelike branches in 2 ranks; primary branches 2-10 cm, appressed to ascending, axes 0.8-1.4 mm wide, flat, winged, hispid, hairs not papillose-based; secondary branches present; pedicels shorter than the spikelets, scabrous, with 1-3 conspicuous hairs. Spikelets (3)4-5 mm long, 1.5-2 mm wide, solitary (rarely paired), appressed to the branch axes, bases glabrous or with a tuft of hairs. Glumes scarcely separated, rachilla internode between the glumes not pronounced; lower glumes 2.7-3.3 mm, (1/2)2/3-3/4 as long as the spikelets, 3-veined, mostly glabrous but often with 1-3 conspicuous, stiff hairs emanating from the midvein at approximately mid-length; upper glumes (3)4-5 mm, glabrous or pubescent, 5-veined; lower florets staminate; lower lemmas (3)4-5 mm, glabrous or pubescent, 5-veined, with or without a setose fringe along the margins; lower paleas present; upper lemmas 2.2-2.6 mm, apices rounded, shortly awned, awns 0.5-1.2 mm; anthers 1.2-1.5 mm. 2n = 30, 42.

Urochloa mosambicensis is native to Africa. It was recently found in southern Texas (Wipff et al. 1993) and is expected to spread. It is grown for forage and hay in Africa.


9.   Urochloa piligera (F. Muell. ex Benth.) R.D. Webster
Wattle Signalgrass

Plants annual. Culms 15-60 cm, erect or decumbent, sometimes rooting at the lower nodes; nodes glabrous. Sheaths glabrous, margins sometimes ciliate; ligules 0.7-1.5 mm; blades 4-15 cm long, 3-11 mm wide, usually glabrous, sometimes pubescent, margins scabrous. Panicles 3-12 cm, with 3-5 spikelike branches in 2 ranks, smooth or scabrous, glabrous or pubescent; primary branches 2-6 cm, divergent to reflexed, axils glabrous, axes 1.1-1.6 mm wide, flat, winged, without papillose-based hairs, margins smooth or scabrous; secondary branches rarely present; pedicels shorter than the spikelets, scabrous. Spikelets (3.3)3.8-4.9 mm long, 1.5-1.8 mm wide, ellipsoid, solitary, usually overlapping, appressed to the branch axes, pubescent or sometimes glabrous, in 2 rows, sometimes appearing 1-rowed. Glumes separated by 0.3-0.5 mm; lower glumes 1.9-2.7 mm, 9-11-veined, glabrous; upper glumes 3.2-4.1 mm, 7-9-veined, glabrous or pubescent, margins glabrous or pilose, when pilose, the basal hairs shorter than the distal hairs; lower florets sterile; lower lemmas 3.1-4.7 mm, resembling the upper glumes in texture and pubescence, 5-7-veined; lower paleas absent; upper lemmas 2-4 mm, apices recurved, rounded, mucronate; anthers 1.5-1.7 mm. 2n = unknown.

Urochloa piligera is an Australian species that has been found in Florida. Webster (1987) stated that U. piligera has glabrous and pubescent forms that are identical except in the presence or absence of spikelet vestiture. Currently, only the pubescent form has been found in the Flora area (Hall 1978). The glabrous form is sometimes confused with U. subquadripara. Urochloa piligera lacks a lower palea, and has larger and, usually, closely overlapping spikelets; U. subquadripara has well-developed paleas and smaller (3.3-3.8 mm), well-separated spikelets.


10.   Urochloa brizantha (Hochst. ex A. Rich.) R.D. Webster
Palisade Signalgrass

Plants perennial; shortly rhizomatous. Culms (30)100-200cm, erect or geniculately ascending, occasionally branched; nodes glabrous. Sheaths glabrous or pubescent between the veins, margins glabrous; collars glabrous; ligules 1-2.2 mm; blades 9-40 cm long, 6-20 mm wide, glabrous or hispidulous on both surfaces, margins usually ciliate basally. Panicles 3-20 cm long, 2.5-3 cm wide, with 1-7(16) spikelike primary branches in 2 ranks; rachises scabrous and pubescent; primary branches 4-16(20) cm, ascending to divergent, axils glabrous, axes 0.5-1.2 mm wide, narrowly winged and crescentric (the margins inrolled to produce a crescent-shaped cross section), mostly scabrous, margins ciliate with papillose-based hairs; secondary branches absent; pedicels shorter than the spikelets, glabrous, scabrous. Spikelets 4-6 mm long, 1.8-2.2 mm wide, ovoid to ellipsoid, with 0.3-0.5 mm calluses, solitary, in 1 row (rarely in 2 rows at the base of the lower branches), appressed to the branches. Glumes separated by about 0.5 mm; lower glumes 1.8-3.3 mm long, about 1/3 as long as the spikelets, 7-11-veined; upper glumes 3.6-5.9 mm, 7-veined, glabrous or pubescent, without evident cross venation; lower florets staminate; lower lemmas 3.8-5.8 mm, glabrous or pubescent, 5-veined; lower paleas present; upper lemmas 3.3-5.6 mm long, 1.6-2 mm wide, ellipsoid, apices acute, mucronate; anthers about 2.2-2.5 mm. 2n = 18, 36, 54.

Urochloa brizantha, a native of tropical Africa, was first reported from the Flora region in 1993 (Fox and Hatch 1995). It is considered a sporadic introduction in the Flora area.

Clayton and Renvoize (1982) report that Urochloa brizantha intergrades with U. decumbens (Stapf) R.D. Webster, and intermediates are often difficult to separate, although they do not seem to be very common in the wild. The forms widely introduced throughout the tropics as forage were selected from among these intermediates. The selection most commonly used as a forage has the inflorescence characters of U. brizantha and the habit features of U. decumbens. Davidse and Pohl (1994) reported that the material introduced into Mesoamerica is referable to U. decumbens. Although U. decumbens has not been reported in the Flora area, it is expected in Florida, because it is widely used as forage in the tropics. The two taxa can be distinguished by their panicle branches: Urochloa decumbens has flat, ribbonlike panicle branches 1-1.8 mm wide, whereas U. brizantha has crescentric panicle branches 0.5-1.2 mm wide.


11.   Urochloa villosa (Lam.) T.Q. Nguyen
Hairy Signalgrass

Plants annual; loosely tufted or sprawling. Culms 7-50 cm, geniculate, decumbent to prostrate at the base, often much-branched below, usually rooting at the nodes; nodes pubescent; Sheaths usually pubescent, sometimes densely so, rarely glabrous, margins ciliate; ligules 0.3-1.1 mm, blades 1-7 cm long, 2-9.3 mm wide; usually densely puberulous on both sides, margins basally ciliate or scabrous. Panicles (1.5)4.5-8 cm long, with 4-12 spikelike primary branches in 2 ranks; primary branches 0.7-3.3 cm, axes 0.2-0.3 mm wide, triquetrous, pubescent; secondary branches rarely present; pedicels shorter than the spikelets. Spikelets 2-2.8 mm, solitary (or paired), in 1 row, appressed to the branch axes. Glumes separated by about 0.3 mm; lower glumes 0.7-1.5 mm, 1/3-1/2 as long as the spikelets, 3-veined; upper glumes glabrous or pubescent; 5-veined, lower florets sterile; lower lemmas similar to the upper glumes; lower paleas present; upper lemmas 1.8-2.1 mm, granulose to rugulose, acute, mucronate; anthers 0.9-1.3 mm. 2n = 36.

Urochloa villosa is a tropical African and Asian species that Reed (1964) reported collecting from chrome and iron ore piles in Newport News, Virginia in 1959. His voucher specimens, acquired by the Missouri Botanical Garden in 2001, were not available for examination prior to publication of this volume, so the description is from Veldkamp (1996) and Clayton and Renvoize (1982). No additional collections have been reported in the Flora area.


12.   Urochloa subquadripara (Trin.) R.D. Webster
Armgrass Millet

Plants annual or short-lived perennials. Culms 10-70 cm, decumbent, branching and rooting at the lower nodes; nodes glabrous; internodes glabrous or sparsely pilose distally. Sheaths mostly pubescent or glabrous, margins ciliate; ligules 0.5-1.3 mm; blades 2-15(27) cm long, 3-10 (12) mm wide, glabrous or pubescent; margins scabrous, sometimes ciliate basally; bases subcordate, not clasping the stems. Panicles 2.5-13(22) cm, with 3-6(9) spikelike primary branches in 2 ranks; primary branches 2-7 cm, ascending to reflexed, axes 0.7-1.2 mm wide, flat and narrowly winged, margins scabrous; secondary branches absent; pedicels shorter than the spikelets, scabrous. Spikelets 3.3-3.8 mm long, 1-1.4 mm wide, solitary, appressed to the branches, in 2 rows. Glumes separated by 0.3-0.5 mm; lower glumes 1.4-1.7 mm, 1/3-1/2 as long as the spikelets, 9-11-veined, glabrous; upper glumes 2.7-3.4 mm, glabrous, 7-9-veined; lower florets sterile; lower lemmas 2.7-3.4 mm, glabrous, 5-veined, without evident cross venation; lower paleas present; upper lemmas 2.6-3.4 mm, apices rounded to acute, mucronate; anthers 1.1-1.35 mm. Caryopses 1.6-2.5 mm. 2n = 36, 54, 72, 84.

Urochloa subquadripara, native to tropical Asia and Australasia, is established in Florida and, reportedly, Georgia, although no specimens documenting its presence in Georgia have been located. A weedy species that has been introduced into the tropics worldwide, it is reported to have good drought tolerance, and is used as forage in tropical Asia. Its weediness and drought tolerance suggest that it might also become a troublesome weed in some parts of the Flora region.

Urochloa subquadripara is similar to U. distachya (L.) T.Q. Nguyen, and the two taxa are sometimes treated as one species (e.g., Pohl 1980; Morrone and Zuloaga 1992, 1993). They are maintained here as separate species pending further research. Urochloa distachya supposedly has shorter (2.4-3 mm) spikelets and shorter (1.9-2.3 mm) upper florets.

Urochloa subquadripara can also be confused with the glabrous form of U. piligera, but it differs in having a well-developed palea and smaller (3.3-3.8 mm), well-separated spikelets.


13.   Urochloa plantaginea (Link) R.D. Webster
Plantain Signalgrass

Plants annual. Culms 20-100 cm, decumbent, geniculate, branching and rooting at the lower nodes; nodes glabrous. Sheaths mostly glabrous, except the margins ciliate, with papillose-based hairs; ligules 0.5-1.5 mm; blades 3-21 cm long, 6-20 mm wide, glabrous, bases subcordate to cordate, clasping the stems, margins sometimes ciliate basally. Panicles 6-25 cm long, 2-7 cm wide, with 3-8 spikelike primary branches in 2 ranks; primary branches 2-11 cm, axes 1-1.5 mm wide, flat, margins scabrous; secondary branches absent; pedicels shorter than the spikelets, glabrous or scabrous. Spikelets (4)4.5-6 mm long, 1.9-2.2 mm wide, solitary, appressed to the branch axes, in 2 rows. Glumes separated by an internode of about 0.5 mm; lower glumes 1.5-2.5 mm, to 1/3 as long as the spikelets, broadly ovate, glabrous, 9-11-veined; upper glumes 3-4.2 mm, glabrous, 7(-9)-veined, without evident cross venation; lower florets sterile; lower lemmas 3-4.2 mm, glabrous, 5-veined; lower paleas present; upper lemmas 2.7-3.6 mm long, 1.5-2 mm wide, apices rounded; anthers 0.7-1 mm. Caryopses 2-2.5 mm. 2n = 36, 72.

Urochloa plantaginea, native to western and central Africa, is found from the southern United States to Argentina. It is now established in the southeastern United States, growing in loose sand and loam soils. Although considered a weed in the Flora area, Sendulsky (1978) stated that it provided good forage.

Hall (1978) reported Urochloa oligobrachiata (Pilg,) Kartesz [= Brachiaria platytaenia Stapf] in Florida. This report was based on one collection, but the voucher specimen has not been verified. Urochloa oligobrachiata is similar to U. plantaginea, but differs in having acute to acuminate lower glumes and shortly awned upper lemmas. It is native to western Africa.


14.   Urochloa panicoides P. Beauv.
Liverseed Grass

Plants annual. Culms (5)10-55(100) cm, erect to decumbent, usually rooting at the lower nodes; nodes pubescent; internodes glabrous or sparsely pubescent. Sheaths hispid, margins ciliate distally; ligules1-1.5 mm; blades (2)5-25 cm long, 5-18 mm wide, both surfaces usually with papillose-based hairs, rarely glabrous, bases rounded to subcordate, ciliate, with papillose-based hairs. Panicles 3.5-10 cm long, 2-7 (10) cm wide, with 2-7(10) spikelike primary branches in 2 ranks; primary branches 1-7 cm, axes about 0.9-1.2 mm wide, flat, scabrous and ciliate with papillose-based hairs; secondary branches rarely present; pedicels shorter than the spikelets, frequently with 1-5 long hairs. Spikelets 2.5-4.5(5.5) mm long, about 1.5-2 mm wide, ellipsoid, solitary, in 2 rows, appressed to the branches. Glumes scarcely separated; lower glumes 1-1.6 mm, 1/4-1/3(1/2) as long as the spikelets, 3-5-veined, clasping the base of the spikelets, glabrous; upper glumes 3.2-4.3 (5) mm, 9-11(13)-veined, glabrous; lower florets sterile; lower lemmas 3.2-4.3 (5) mm long, glabrous, 5(-7)-veined; lower paleas present; upper lemmas 2.6-3.5 mm long, about 1.5 mm wide, apices rounded, awned, awns (0.3)0.6-1 mm; anthers 0.8-1 mm. Caryopses 2-2.5 mm. 2n = 30, 36, 48.

Urochloa panicoides is native to Africa, and is considered a noxious weed by the U.S. Department of Agriculture. In the Western Hemisphere, it has been introduced into the southern United States, Mexico, and Argentina. Within the Flora region, it has been reported from disturbed sites in the southern and Gulf Coast areas of Texas (Wipff et al. 1993), but it is expected to spread. Populations from New Mexico have been destroyed.

Urochloa panicoides has morphological forms with glabrous, pubescent, or setosely-fringed spikelets. Although the three forms have been recognized taxonomically, Clayton and Renvoize (1982) state that they appear to be of no taxonomic significance. Only the glabrous form is known to occur in the Flora area.


15.   Urochloa platyphylla (Munro ex C. Wright) R.D. Webster
Broadleaf Signalgrass

Plants annual. Culms 25-100 cm, decumbent, rooting at the lower nodes; nodes glabrous. Sheaths glabrous or sparsely pilose; ligules 0.5-1 mm; blades 2.5-17.5 cm long, 3-13 mm wide, glabrous or sparsely pilose, bases subcordate, not clasping the stems, margins ciliate basally, with papillose-based hairs. Panicles 6-16 cm long, 2-2.5 cm wide, with 2-8 spikelike primary branches in 2 ranks; primary branches 3-8 cm, axils pubescent, axes 1.3-2.5 mm wide, flat, usually glabrous, occasionally pilose dorsally; secondary branches rarely present; pedicels shorter than the spikelets, scabrous and sparsely pilose. Spikelets 3.8-5 mm long, 2-2.5 mm wide, ovoid, bi-convex; solitary, appressed to the branches, in 2 rows. Glumes scarcely separated; lower glumes 1.2-1.8 mm, to 1/3 as long as the spikelets, obtuse, glabrous, 5(-7)-veined, not clasping the base of the spikelets; upper glumes 3.2-4.7 mm, glabrous, 7(-9)-veined; lower florets sterile; lower lemmas 3.2-4.7 mm, glabrous, 5-veined; lower paleas present; upper lemmas 2.8-3.4 mm long, 1.8-2.3 mm wide, apices incurved, broadly acute to rounded, mucronulate; anthers about 1 mm. Caryopses 1.5-2.2 mm. 2n = 36.

Urochloa platyphylla is a weedy species found in open, sandy soil in the southeastern United States, West Indies, and South America. Morrone and Zuloaga (1993) considered reports of its occurrence in Mexico as doubtful, possibly being based on misidentified specimens of Urochloa plantaginea.


16.   Urochloa arrecta (Hack. ex T. Durand & Schinz) Morrone & Zuloaga
African Signalgrass

Plants perennial; stoloniferous. Culms 50-120 cm, branching and rooting at the lower nodes; nodes glabrous. Sheaths glabrous, margins ciliate; ligules about 1 mm; blades 5-15 cm long, 7-15 mm wide, glabrous, bases subcordate, margins scabrous. Panicles (5)9-18(25) cm long, 3-4 cm wide, with 4-10(15) spikelike primary branches in 2 ranks; primary branches (1)2-5(10) cm, axes 0.5-2 mm wide, glabrous, margins scabrous; secondary branches rarely present; pedicels shorter than the spikelets, mostly scabrous, apices with hairs. Spikelets (3)3.3-4.4 mm long, 1.4-1.7 mm wide, ellipsoid, solitary, imbricate, in 2 rows, appressed to the branches. Glumes scarcely separated; lower glumes 1.5-1.8 mm, glabrous, 5-veined, not clasping the base of the spikelets; upper glumes 3.4-4.1 mm, glabrous, 7-veined; lower florets staminate; lower lemmas 3.4-4.1 mm, glabrous, 5-veined; upper lemmas 2.7-3.5 mm long, 1.3-1.6 mm wide, apices rounded, incurved; anthers 1.6-1.8 mm. 2n = unknown.

Urochloa arrecta is native to Africa, but it has been introduced into Florida and Brazil as a forage grass. It is reported to be established in Collier County, Florida.


17.   Urochloa ciliatissima (Buckley) R.D. Webster
Fringed Signalgrass, Sandhill Grass

Plants perennial; shortly rhizomatous or with long stolons. Culms 10-40 cm, erect to ascending, solitary or in small clumps; nodes retrorsely villous; internodes glabrous. Sheaths glabrous or with papillose-based hairs; ligules 0.5-1.5 mm; blades 1-7(9) cm long, 2-5 mm wide, glabrous or pilose on both surfaces, margins ciliate basally, with papillose-based hairs. Panicles 3-6 cm long, 0.5-1 cm wide, with 2-6 spikelike primary branches in 2 ranks; rachises scabridulous; primary branches 0.5-2 cm, appressed, axes 0.3-0.4 mm wide, triquetrous, scabridulous, glabrous or puberulent; secondary branches rarely present; pedicels shorter than the spikelets, scabridulous. Spikelets 3-4.5 mm long, 1.5-2 mm wide, plano-convex, solitary, in 2 rows, appressed to the branch axes. Glumes scarcely separate, rachilla between the glumes not pronounced; lower glumes 2.8-3.2 mm, 5-7-veined, glabrous or with long hairs basally; upper glumes 3-4.5 mm, (9)11-13-veined, without cross venation, mostly puberulent, margins pilose-fringed; lower florets staminate; lower lemmas 3-4.5 mm, 7-9-veined, without cross venation, mostly puberulent, margins pilose-fringed; lower paleas present; upper lemmas 2.4-2.8 mm long, 1.3-1.4 mm wide, plano-convex, apices broadly acute to rounded, mucronate; anthers about 1 mm. Caryopses 1.8-3 mm. 2n = 36.

Urochloa ciliatissima is endemic to Texas, Oklahoma, and Arkansas, and grows on sandy soils. Reports of its occurrence in Mexico are based on misidentifications (Morrone and Zuloaga 1993).


Urochloa maxima (Jacq.) R.D. Webster See Megathyrsus