ing at the simple floriferous ends; ligule a scale 0.5-1 mm. long; blades 3-12 cm. 

 long. 2-6 mm. broad, membranous and usually flat or folded, or the tip on drying 

 loosely involute, basally broader than the summit of the sheath; sheaths slightly 

 keeled at summit, the corner with a few soft hairs and often the lower sheaths 

 (when emergent) visibly pubescent ("var. indutum") but these usually lost in 

 specimens; racemes usually 2, rarely 1 or 3, 15-70 mm. long, erect or somewhat 

 spreading, often arcuate, floriferous essentially to the base; rachises broadly 

 triangular in transection, 1-1.5 (-2) mm. broad; spikelets attached nearly at the 

 margin by the short pedicels, solitary, elliptic, (2.5-) 2.7-3 (-3.2) mm. long, 

 greenish to stramineous, blunt to somewhat pointed; first glume usually present, 

 minute, triangular; second glume microscopically pubescent; sterile lemma gla- 

 brous or rarely with a few microscopic hairs near midrib. Incl. var. indutum 

 Shinners. 



Margins of fresh ponds, streams and lakes, in marshes and on mud and in shal- 

 low water, sometimes in brackish areas, in Okla. (Grady and Washita cos.), fre- 

 quent in e., s.e. and n.-cen. Tex., Edwards Plateau and Trans-Pecos, infrequent 

 in Rio Grande Plains and Plains Country, N. M. (Dona Ana and DeBaca cos.) 

 and Ariz. (Pinal, Santa Cruz and Mohave cos.), summer-fall; widespread in the 

 warmer parts of the world, in Am. n. to N. J., Tenn., Ark., Okla., Ut., Ida. and 

 Wash. 



13. Paspalum vaginatum Sw. Fig. 149. 



Long-decumbent perennial; culms 5-25 dm. long, compressed, 3-4 mm. thick 

 on the long axis, extensively creeping and freely rooting, branched, ascending 

 only at the simple floriferous ends; ligule a scale about I mm. long; blades 2.5-15 

 cm. long, 3-8 mm. broad, firm and stiffly straight, basally narrower than the 

 summit of the sheath and folded, tapering to a long-involute tip (occasionally 

 near semibrackish water the blades persistently flat); sheaths keeled, the corners 

 ciliate; panicle axis 1-10 (-15) mm. long; racemes 1 or 2 (or 3), 2-8 cm. long, 

 divaricate; rachises often naked for the basal 2-5 mm., 1-2 mm. broadly tri- 

 angular or occasionally very narrowly winged; spikelets attached nearly at the 

 margin by the broad short pedicels, solitary, ovate-elliptical, 3.1-4.2 (-4.5) mm. 

 long, glabrous, stramineous, pointed; first glume very rarely present; sterile lemma 

 thin and often transversely wrinkled; fruit pointed, nearly as long as spikelet, 

 apically glabrous. 



Moist saline to brackish sands at edges of lagoons, bays and river-mouths, 

 rarely in sub-brackish ponds near the coast, s.e. Tex. and Rio Grande Plains, 

 frequent, summer-fall-early winter; widespread in warm coastal areas of the 

 world, in Am., n. to N. C. and the Gulf States. 



14. Paspalum acuminatum Raddi. Fig. 147. 



Long-decumbent aquatic or subaquatic perennial; culms 3-10 dm. long, 1-3.5 

 mm. thick, soft, freely rooting and rather freely branching, ascending and 

 emergent only at the end; ligule a membranous scale 1-3 mm. long; blades 3-20 

 cm. long, 2-12 mm. broad, flat, thin; panicle axis 1-3 cm. long; racemes 2 or 3 

 (to 5?), 3-7 cm. long, ascending, usually somewhat arcuate; rachis 3-3.5 mm. 

 broad, with the spikelets borne in a very narrow central rib, the remainder of 

 the rachis forming foliaceous wings; spikelets solitary, elliptic, 3.3-3.5 mm. long, 

 glabrous, greenish, apically abruptly pointed beyond the fruit; first glume absent; 

 fruit blunt, apically with some minute cilia. 



In fresh water ponds or wet open ground, in the Tex. Rio Grande Plains, rare 

 (Cameron and Brooks cos.), spring-fall; lowlands, widespread but scattered in 

 trop Am., n. to s. La. and s. Tex. 



301 



