MANUAL OF THE GRASSES OF THE UNITED STATES 601 



9a. Spikelets suborbicular or broadly obovate or broadly oval. 



Spikelets turgidly plano-convex, 3.5 to 4 mm. long.... 39. P. difforme. 

 Spikelets depressed plano-convex or lenticular, 2.2 to 3.4 mm. long. 

 Spikelets solitary; glume and sterile lemma firm. 



Spikelets orbicular, 3 to 3.2 mm. long, scarcely one-third as thick; 

 blades usually equaling the base of the panicle or overtopping it. 



36. P. CIECULAEE. 

 Spikelets longer than broad, more than one-third as thick; panicle 

 usually much exceeding the blades. 

 Sheaths and blades pilose, mostly conspicuously so. 



35. P. LONGIPILUM. 

 Sheaths and blades from glabrous to sparsely pilose. 



34. P. LAEVE. 

 Spikelets paired and solitary in the same raceme (rarely all solitary or 

 all paired). 

 Spikelets 2.2 to 2.5 mm. (rarely to 2.8 mm.) long; foliage not con- 

 spicuously villous 37. P. PRAECOX. 



Spikelets 2.7 to 3.4 mm. long; lower sheaths and blades mostly con- 

 spicuously villous at least at base 38. P. lentiferum. 



9b. Spikelets elliptic to oval or obovate. 



Culms decumbent at base, rooting at the lower nodes (occasional plants 

 in dry situations erect), branching. 

 Spikelets turgidly plano-convex, 3 to 3.2 mm. long; culms rather stout. 



6. P. PUBIFLORUM. 



Spikelets depressed plano-convex; culms rather slender. 



Spikelets glabrous 7. P. lividum. 



Spikelets pubescent 8. P. hartwegianum. 



Culms erect to spreading, not rooting at the nodes. 



Racemes solitary, rarely paired; spikelets usually solitary, 1.3 to 1.6 



mm. long 30. P. saugetii. 



Racemes 2 or more, commonly 3 to 8. 



Spikelets about 1.3 mm. long, obovate, glandular-pubescent. 



25. P. BLODGETTII. 



Spikelets 1.5 mm. or more long, elliptic or elliptic-obovate, the ob- 

 scure pubescence not glandular. 

 Nodes or some of them appressed-pilose ; spikelets green or purplish. 



26. P. CAESPITOSUM. 

 Nodes glabrous; spikelets pale or brownish. 



Spikelets 1.7 to 2 mm. long; racemes slender, lax. 



Foliage glabrous or nearly so; spikelets elliptic-obovate. 



27. P. LAXUM. 

 Foliage softly pilose; spikelets broadly ovate. 



29. P. VIRLETII. 

 Spikelets 2.2 to 2.5 mm. long; racemes rigid. 



28. P. PLEOSTACHYUM. 



1. Dissecta. — Blades flat; rachis foli- 



aceous. Aquatics, subaquatics, 2. Paspalum acuminatum Raddi. 



or plants of wet ground. (Fig. 863.) Culms decumbent at base, 



1. Paspalum dissectum (L.) L. sometimes extensively creeping, 30 



(Fig. 862.) Glabrous, olive green, to 100 cm. long; blades 4 to 12 cm. 



creeping, freely branching, the flower- long; 5 to 12 mm. wide; racemes 3 



ing branches ascending, 20 to 60 cm. to 5, erect or ascending, 3.5 to 7 



long; blades thin, 3 to 6 cm. long, cm. long; rachis 3 to 3.5 mm. wide; 



4 to 5 mm. wide; panicles terminal spikelets solitary, 3.5 mm. long, 



and axillary, the racemes 2 to 4, abruptly pointed. % — In shallow 



usually erect, 2 to 3 cm. long; rachis water or wet open ground, from 



2 to 3 mm. wide; spikelets solitary, southern Louisiana and Texas to 



obovate, subacute, 2 mm. long. % Argentina. 



— On muddy and sandy banks of 3. Paspalum fluitans (Ell.) Kunth. 



ponds and ditches or in shallow water, (Fig. 864.) Annual aquatic; culms 



New Jersey; Illinois to Oklahoma, mostly submerged, rooting at the 



south to Florida and Texas; Cuba, nodes, 30 to 100 cm. long; sheaths 



