long, 3-5 mm. broad, flat or folded; panicle axis 3-12 cm. long, curviflexuous; 

 racemes 3 to 8, 15-50 mm. long, ascending and curved, floriferous to the base, 

 the lower racemes with a few hairs in the axils: rachises 1.5-2.5 mm. broad, thin, 

 purplish-olive to olive-purple, rather elongate, spreading, the rather elongate 

 spreading pedicels attached along a very narrow central rib. the lateral portions 

 of the rachis foliaceous and winglike and usually sparsely papillose-pilose mar- 

 ginally; spikelets paired or rarely a few also solitary in the same raceme, (2.1-) 

 2.3-2.7 (-2.9) mm. long, obovate, bluntly pointed, with nearly parallel plane 

 surfaces or at least very compressed plano-convex, yellowish-green or occasionally 

 with a purplish cast; first glume always absent; second glume and sterile lemma 

 essentially glabrous. 



Moist tight clay loam in ditches, tanks, wet savannahs, swamps aqd flooded 

 pasturelands, and in resacas and shallow lakes, s.e. Tex. and coastal parts of Rio 

 Grande Plains, frequent, spring-fall; widespread in warmer parts of Am., n. to 

 Ala., La. and Tex. 



10. Paspalum Hartwegianum Fourn. Fig. 147. 



Tufted stoloniferous perennial; floriferous culms 5-15 dm. long, slightly com- 

 pressed, 2-5 mm. thick on the long axis, ligule a scale 1-3 mm. long; blades 

 10-35 cm. long, 2-6 mm. broad, flat or folded; sheaths keeled; panicle axis 5-15 

 cm. long, mostly straight and slender; racemes (3 or) 4 to 8, 2-9 cm. long, 

 ascending or somewhat spreading, often slightly curved, floriferous to the base, 

 the lower ones usually with a few long hairs in the axils; rachises 1.5-2 mm. 

 broad, thin, olive or purplish-olive, the rather elongate spreading pedicels at- 

 tached along a very narrow central rib. the lateral portions of the rachis foliaceous 

 and winglike; spikelets paired, rarely also a few in the same raceme solitary, 

 (2.2-) 2.5-2.9 (-3.2) mm. long, obovate, slightly pointed, with nearly parallel 

 plane surfaces or at least very compressed plano-convex, yellowish-green; first 

 glume always absent; second glume and sterile lemma shortly and uniformly 

 pubescent. 



Moist tight soil, wet prairies, alkaline meadows, in mud and shallow water 

 of irrigation ditches and streams, in the Tex. Rio Grande Plains, frequent, spring- 

 fall; much of Mex. n.w. to Son.; Tex. 



11. Paspalum pubiflonim Fourn. Fig. 147. 



Loosely tufted perennial; culms 3-15 dm. long, compressed, 2-3 mm. thick 

 on the long axis, decumbent and freely rooting in the basal third to half the 

 length but usually mostly ascending; ligule a scale 1-3 mm. long; blades 6-30 

 cm. long, 5-13 mm. broad, mostly flat, marginally crisped and basally papillose- 

 pilose; lower sheaths usualy papillose-pilose; panicle axis 8-62 mm. long; racemes 

 2 to 4 (to 6), 2-10 cm. long, ascending or spreading, floriferous to the base or 

 infrequently with a naked basal portion 1-3 mm. long and a few long hairs in the 

 axil; rachises 1.5-2 mm. broad, broadly triangular, olive-green; spikelets attached 

 even along the margins, paired or rarely in the same raceme a few of them soli- 

 tary, (2.3-) 2.7-2.9 (-3.2) mm. long, obovate, turgidly plano-convex, greenish 

 to stramineous or with a purplish cast, blunt to very slightly pointed; first glume 

 small, triangular, usually absent or much-reduced; second glume and sterile lemma 

 microscopically pubescent to rarely glabrate. Incl. var. ghibrum Scribn. 



Moist garden loam and moist usually calcareous soil at edges of streams, ponds 

 and lakes, along streams and irrigation ditches, in wet meadows, in Okla. (Hughes 

 and Cherokee cos.), throughout Tex. (but rare in Plains Country), spring-fall; 

 lowlands of s.e. U.S. n. to N.C., O.. Ind., 111.. Mo. and Kan.; much of Mex.; Cuba. 



12. Paspalum distichum L. Knotgrass. Fig. 148. 



Long-decumbent perennial; culms 5-15 dm. long, compressed, 2-3 mm. thick 

 on the long axis, extensively creeping, freely rooting, somewhat branched, ascend- 



298 



