GRAMINEAE (GEASS FAMILY) 



101 



fc. Leaves oblonff-lanceolate to ovate-lanceolate, more than 5 mm, 

 wide, or if narnnver not conspicuously elongated I. 

 I. Blades move than 1.5 era. wide m. 

 m. Spikelets 3 mm. long ; at least the lower sheaths papillose-hispid 71. P. clandesHnum. 

 m. Spikelets 3.5-4 mm. long. 



Nodes bearded ; plants often pubescent. 

 Blades lanceolate, thick, glajbrous above, densely papillose- 

 pubescent beneath 65. -P. J?av6neM. 



Blades ovate-lanceolate, thin ; pubescence when present 



soft 72. -P. Boacii. 



Nodes not bearded ; plants glabrous or nearly so. 



Panicle .spreading ; blades 2.5 cm. or more wide , , 78. P. latifoliwm. 

 Panicle narrow ; blades rarely over 1.8 cm. wide , . 66. P, icanthophyaum. 

 J. Blades not over 1.5 cm. wide n. 

 n. Panicle narrow ; blades erect. , 



Plants glabrous or nearly so 66. P. xanihophysum. 



Plants papillose-hispid. 



Spikelets not over 8 mm. long 67. /*. Wzlcoinianum. 



Spikelets 4 mm. long ^. P. Le^berg^^. 



n. Panicle spreading, about as wide as long o. 

 o. Spikelets 3 mm, long; blades 1.2-2 dm. long. 



Blades ciliate, glaucous, smooth 59. P. mutabile. 



Blades not ciliate, green, scabrous 70. /*. aculeatuTn. 



O. Spikelets 3.5-4 mm. long ; blades not over 1 dm. long. 



Nodes bearded ; ligule 8-4 mm. long 65. P. BaveneUi. 



Nodes not bearded ; ligule 1-2 mm. long. 

 Spikelets obovoid-turgid, blunt; pubescence spread- 

 ing 63. P. Seribnerianum 



Spikelets narrowly obovoid, subacute ; pubescence 



appressed 62. P. oligoaanthea. 



|. Spikelets less than S Uim. long p, ' 



p. Spikelets glabrous q. 



q. Spikelets not over 1.5 mm. long. 



Plants pubescent 22. P. etrigomm. 



Plants glabrous, except bearded nodes 81. P. microearpon. 



g. Spikelets 2-2.5 mm. long r. 

 r. Spikelets 2 mm. long. 



Spikelets obovoid-turgid; culms crisp-puberulent , . 60. P, lancearium. 

 Spikf'lets elliptical; culms glabrous. 



Autumnal state erect, branched like a little tree; second 



glume shorter than the fruit and sterile lemma . . 27. P. dwhotommm. 

 Autumnal state topbeavy-reclining ; fruit' covered by 



second glume and sterile lemma 28. P. bardulatum. 



Autumnal state widei/ trailing; second glume and 



sterile lemma shorter than the fiuit . . . , 80. P. lucidum. 

 r. Spikelets 2.5 mm. long. 



Culms 2-4: dm, high; second glume and sterile lemma 



equaling fruit 26. P. Bicknellii. 



Culms 5-12 dm. high ; second glume and sterile lemma 



forming a point beyond the fruit 29. P. yadkin&nae, 



p. Spikelets pubescent s. 



s. Blades elongated, not over 5 mm. wide; secondary panicles 



from the base only, or none. ^ ,^ 



Sheaths glabrous 20. P. Wemert. 



Sheaths pilose. 

 Spikelets turgid, blunt ; panicle-branches ascending ; 



culms few in a tuft 18. P. perlongum, 



Spikelets subacute ; panicle-branches spreading; culms 



numerous in a tuft 19. P. ^^near^fol^um. 



a. Blades usually not conspicuously elongated; secondary 

 panicles not at the base t. 

 t. Spikelets obovate-turgid, blunt, attenuate at base. . 



Spikelets 2 mm. long 25. P. actculare. 



Spikelets 2.5 mm. long. „ «• t 7»-j 



Spihelets not papillose ; culms glabrous .... 26. P. BicfcnelUi. 

 Spikelets rugose-papillose ; culms pubescent, at least below. 

 Nodes bearded ; panicle-branches ascending . . . 24. P. eojiaangmneum 

 Nodes not bearded ; panicle-branches spreading , . 28. P. angumfohum. 

 t Spikelets not attenuate at base u. , , t ^ 



w. Sheaths conspicuously retrorse-pilose ; culms simple, form- 



ing soft tufts '21. P.xalapmee. 



u. Sheaths not retrorselv pilose v. 

 fb. Sheaths, or all but the lowest, glabrous W. 

 w. Ligule 2-5 mm. long. .^ t» ^ -^ 



Spikelets 2.2 mm. long 47. P, scopaHotdea. 



Spikelets 1.5 mm. long. 

 Panicle not more than half as wide aa long; 



spikelets elliptic ^^- ■?■ ^Pretum. 



Panicle about as wide as long; spikelets obovoid 36. P. Undheimeri. 



