MANUAL OF THE GRASSES OF THE WEST INDIES 341 
purple, 1 to 3 times as long as the spikelets, sometimes longer; spike- 
lets 2 to 2.5 or even 3 mm long, ovoid, planoconvex; fertile lemma 
transversely rugose with close narrow ridges (fig. 310). 
This species is exceedingly variable in general appearance, due to 
the variation in the color and length of the bristles, which are long 
early in the season and in cultivated soil and short in plants in dry 
situations. 
Open ground pastures, cultivated soil, and moist ground, United 
States to Argentina; common at low and medium altitudes. To be 
found on all the West Indian islands. 
FIGURE 310.—Setaria geniculata, X 1 (Chase 2981). FIGURE 311.—Setaria tenaz, X 1 (Tracy 9090). 
7. Setaria tenax (L. Rich.) Desv., Opuse. 78. 1831. 
Pamcum tenax L. Rich., Act. Soc. Hist. Nat. Paris 1: 106. 1792. 
Cayenne. 
Setaria biconvera Griseb., Fl. Brit. W. Ind. 555. 1864. Trinidad. 
Chaetochloa tena.c Hitche., Contrib. U.S. Natl. Herb. 22: 176. 1920. 
Perennial; culms scabrous below the panicle, 1 to 1.5 m tall, often 
geniculate at base; sheaths villous on the margin, densely hispid on 
the collar; ligule densely pilose, 2 to 3 mm long; blades flat, as much 
as 35 cm long and 2 cm wide, narrowed at base, acuminate; panicles 
rather densely flowered, narrowed toward summit but not attenuate, 
15 to 30 cm long, 2 to 3 cm wide, the branches ascending, the lower 
about 2 cm long; bristles 1 or 2 below each spikelet, 1 to 2 cm long, 
flexuous, retrorsely scabrous and often also antrorsely toward the 
base, sometimes barblets directed both ways intermixed, pale or 
tawny, becoming implicate and somewhat one-sided with age; spike- 
