126 



GRAMINEAE. 



VOL. L 



of the outermost, the outer ones membranous, the inner one indurated and subtending a 

 palet and perfect flower. Stamens 3. Styles separate ; stigmas plumose. Grain ovoid or 

 oblong, free. [Greek name for some grass, used by Hippocrates.] 



About 1 60 species, widely distributed in tropical and temperate regions, most abundant in 

 America. Type species: Panicnm dissectuni L. 



P. mucronatum. 

 P, disscctum. 



Wings of the rachis broad, membranous, inrolled on the spikelets. 



Racemes 20 or more ; spikelets elliptic, acute, about J4" long, pubescent. i. 

 Racemes less than 10; spikelets oval, obtuse, i" long or more, glabrous. 2. 

 Wings of the rachis narrow, not membranous nor inrolled on the spikelets. 



Racemes i-many, never conjugate at the summit of the culm, always distant one from the other. 

 One to several raceme-bearing naked branches arising from the uppermost leaf-sheath. 

 Leaf-blades glabrous on the lower surface, midnerve sometimes sparsely pubescent. 

 Spikelets about J4" long ; leaves more numerous at the base of the stem. 



3. P. longipcdunculatuin. 

 Spikelets i" long or more; leaves scattered. 



Blades firm, appressed-pubescent on the upper surface with short hairs. 



4. P. stramineum. 

 Blades thin, membranous, glabrous on the upper surface. 



Leaf-blades densely pubescent on both surfaces. 

 Pubescence of copious soft short appressed hairs. 

 Stems prostrate ; lower leaf-blades 4' long or less. 

 Stems erect ; lower leaf-blades 6' long or more. 

 Pubescence of long stiff spreading hairs. 

 Culms long-hirsute below the racemes. 

 Culms glabrous. 



Spikelets less than i" long. 

 Spikelets over i" long. 



Racemes on the main culm i, or sometimes 2 ; 



not thick. 



Racemes on the main culm 2 or 3 

 blades thick. 



5. P. ciliatifolinm. 



6. P. psammophilum. 



7. P. Bush ii. 



8. P. pubesccns. 



9. P. sctaccum. 



spikelets glabrous ; leaf-blades 



10. P. Mnhlcnbcrgii. 

 spikelets usually more or less pubescent ; leaf- 



11. P. deb He. 



No branches arising from the uppermost leaf-sheath. 



Spikelets rounded or obtuse at the apex ; not ciliate on the margins. 

 Spikelets i 1 /*" long or less. 



Fruiting scale white to yellowish. 

 Spikelets singly disposed. 



Spikelets oval, l /2 as thick as broad or more, the outer scales firm. 



Leaf-sheaths glabrous, or sometimes ciliate on the margins ; blades glabrous, or 



sparingly hirsute on the upper surface. 

 Leaf-sheaths as well as the blades hirsute. 

 Spikelets circular or nearly so, ^-| as thick as broad, the 



usually wrinkled. 

 Spikelets in pairs. 

 Fruiting scale deep seal brown. 

 Spikelets more than 1^/2" long. 



Leaf-blades short, the larger ones usually 6' long or less 



12. P. lacve. 



13. P. plenipilum. 

 outer scales thin 



14. P. circulars. 



15. P. laeviglume. 



16. P. Bosciannm. 



and 



Leaf-blades long, exceeding 8' : racemes long. 

 Spikelets acute, ciliate with very long hairs. 

 Racemes conjugate at the summit of the culm, rarely in 3's or with 

 distance below. 



racemes short. 



17. P. difforme. 



1 8. P. floridanum. 

 P. dilatatiim. 



19. 



an additional one a short 

 20. P. distichinn. 



i. Paspalum mucronatum Muhl. Water Paspalum. Fig. 288. 



Paspalum paniculatum Walt Fl. Car. 75. 1788. Not L. 



1759- 



Paspalum mucronatum Muhl. Cat. 8. 1813. 

 Ceresia fluitans Ell. Bot. S. C. & Ga. i : 109. 1817. 

 Paspalum fluitans Kunth, Rev. Gram. 24. 1829. 



Culms ascending, 6'-3 long, from a floating or creep- 

 ing base, branched. Sheaths very loose or inflated, 

 smooth or scabrous, glabrous or pubescent; blades 3'- 

 12' long, :}'-i' wide, acuminate, scabrous; racemes 20- 

 loo, -5' long, alternate or whorled, slender; rachis 

 flat, thin, exceeding the spikelets, long-acuminate, 

 scabrous, its margins nearly enclosing the spikelets ; 

 spikelets in two rows, *"-" long, elliptic, pubescent ; 

 outer scales very thin, 2-nerved, the first one usually a 

 little the longer. 



In water or on mud, Virginia to southern Illinois and 

 Missouri, south to Florida and Texas. Also in tropical 

 America. Sept. 



