16 



POACEAE. 



22. P. trifoliiim. 



2(1. P. ritsifdliidii. 



28. P. cqiiiluterale. 



17. P. yasliianum. 



27. P. cpilifoliiim. 



18. P. Webberianum. 

 3(1. /'. commitiutum. 



25. P. ciliifcnDii. 



26. /'. pfnudoijiihesccns. 



Stem leafy almost to 

 the panicle, the 

 leaves usually 3. 

 Leaf-blades without thick 

 white margins. 

 Spikelets exceeding L' mm. in length. 

 Blades of the primary leaves 

 elongate, broadly linear, often 

 2 dm. long and 1.3 cm. wide, 

 spreading. 

 Blades of the primary leaves 

 lanceolate, 

 Rounded or truncate at the 

 base, 

 Cillate, at least on the 



lower half. 

 Eciliate, or sometimes with 

 few hairs at the 

 very base. 

 Leaf-blades spreading : 

 first scale 1/2 as long 

 as the spikelet, acute. 

 Leaf-blades erect : first 

 scale 1/4-^/3 as long as 

 the spikelet, rounded 

 at the apex. 

 Cordate at the base. 

 ft Leaf-sheaths pubescent with long hairs. 



Spikelets over 2.5 mm. long : fruits over 



2 mm. long. 

 Spikelets less than 2.5 mm. long : fruits less 

 than 2 mm. long. 

 •* Middle leaf-blades of the main stem more than 

 1.5 cm. wide, sometimes 3-4 cm. in width, 

 the base cordate and clasping. 

 Stems finally much branched and prostrate, 



forming large mats : spikelets very acute. 20. /'. munuteiisc. 



Stems erect, even in the late state, sparingly 



branched : spikelets obtuse or acutish. 30. P. coinmutatum. 



1. P. molle Sw. Sterile stems 1-2 m. long or less, rooting at the nodes, the 

 fertile stems erect, 6-10 dm, tall or more, the nodes densely barbed: leaf- 

 sheaths often overlapj)ing, papillose-hirsute: blades 1-3 dm. long, glabrous or 

 pubescent, 7-15 mm. wide: panicle 1.5-2 dm. long, its branches spreading or 

 ascending: spikelets about 3 mm. long, glabrous, — Pinelands and roadsides. 

 Nat, from tropical America, — {Ber., BaJi., Ant.) 



2. P. paludivagum Hitchc. & Chase. Stems 6-12 dm, long: blades 2,5 dm. 

 long or less, 6-10 mm, wide: racemes 10-20, the raehis broadly winged, ap- 

 pressed, 2-3,5 cm. long: spikelets ovate, acute, glabrous, — Everglades, — (Ber., 

 Bah., Cuba, Ant.) 



3. P. hemitomon Schult, Stems from stout rootstocks, 6-12 dm, tall or more: 

 blades 3 dm, long or less, 6-12 mm, wide: racemes 6-20, appressed, 4-10 cm. 

 long, the raehis barely if at all winged: spikelets with the scales prominently 

 nerved, the fourth scale smooth, — Everglades, — Maiden-cane. 



4. P. adspersum Trin, Annual: stems 4-6 dm, tall: leaf -blades 2 dm, long or 

 le.ss, 1,5-2 cm, wide, glabrous: panicle 1-2 dm. long: spikelets usually borne in 

 pairs, green, glabrous or pubescent. — Hammocks and cultivated grounds. — 

 (Bah., Cuba, Ant.) 



5. P. Bartowense Scribn, & Mer, Annual: stems erect, commonly 1 m, tall or 

 less, or much branched and decumbent: leaf -sheaths pubescent; blades 2-7 dm. 

 long, 6-28 mm. wide: panicle 1.5-4,5 dm, long: spikelets 2.5-3 mm. long, 

 glabrous, acuminate. — Everglades. — (Bah.) 



6. P. tenerum Berg. Perennial, glabrous, except the sometimes pubescent 

 lower leaf -sheaths: stems erect, 3-8 dm. tall: leaf -blades erect, involute when 

 dry, 1.5 dm. long or less, 1-1.5 mm. wide: panicle narrow, 3-15 cm. long: 

 spikelets about 2.5 mm. long, lanceolate, acute. — Everglades. — (Bah., Cuba.) 



