GRAMINEAE (GRASS FAMILY) 101 



'.'. Leaves oblong-lanceolate to ovate-lanceolate, more than 5 mm. 



wide, or if narrower not conspicuously elongated /. 

 / I'.ladi-s more tiiuii l.r>cin. wide in. 



nt. Spikelet.s'i Mini, long 1 ; at least the lower sheaths papillose-hispid 71. P. clandtttinum. 

 in. Spikelets 3.54 mm. long. 



Nodes bearded ; plants often pubescent. 

 Blades lanceolate, thick, glabrous above, densely papillose- 

 pubescent beneath 66. P. Rnnenelii. 



Blades ovate-lanceolate, thin ; pubescence when present 



soft 72. /'. Hoticii. 



Nodes not bearded ; plants glabrous or nearly so. 



Panicle spreading ; blades 2. 5 cm. or more wide . . 78. P. latifulium. 

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



I. Blades not over 1.5 cm. wide n. 

 n. Panicle narrow ; blades erect. 



Plants glabrous or nearly so . . . . . . . 66. P. xanthophytum. 



Plants papillose-hispid. 



Spikelets not over 3 mm. long 67. P. Wilcoviaiium. 



Spikelets 4 mm. long M. P. Leibergii. 



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. mutabilt. 



Blades not ciliate, green, scabrous 70. P. aculealum, 



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



Nodes bearded ; ligule 3-4 mm. long 66. P. Ravenelii. 



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

 Spikelets obovoid-turgid, blunt ; pubescence spread- 

 ing 68. P. Scribnerianum 



Spikelets narrowly obovoid, subacute ; pubescence 



appressed 62. P. oligosanthes. 



t. Spikelets less than $ Liin. long p. 

 ji. Spikelets glabrous </. 



q. Spikelets not over 1.5 mm. long. 



Plants pubescent 22. P. strigosum. 



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



q. Spikelrts ^-'.'.5 nun. long r. 

 r. Spikelets 2 mm. long. 



Spikelets obovoid-turgid ; culms crlsp-puberulent . . 60. P. lancearium. 

 Spik'^lets elliptical ; culms glabrous. 



Autumnal state erect, branched like a little tree; second 



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

 Autumnal state topheavy-reclining ; fruit covered by 



second glume and sterile lemma 28. P. barbulatum. 



Autumnal state wideiy trailing: second glume and 



sterile lemma shorter than the fruit . . . . 80. P. Ivcidum. 

 r. Spikelets 2.5 mm. long. 



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



equaling fruit 26. P. SiekneUii. 



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



forming a point beyond the fruit 29. P. yadkinense. 



p. Spikelets pubescent *. 



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

 from the base only, or none. 



Sheaths glabrous 20. P. Werneri. 



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. linearifolium. 



8. 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. aciculare. 



Spikelets 2.5 mm. long. 



Spikelets not papillose ; culms glabrous . . . .26. P. Bicknellii. 

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

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

 Nodes not bearded ; panicle-branches spreading . . 23. P. anyustifolium . 

 t. Spikelets not attenuate at base n. 



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

 ing soft tufts 21. P. xalapense. 



u. Sheaths not retrorsely pilose . 

 e. Sheaths, or all but the lowest, glabrous w. 

 to. Ligule 2-5 mm. long. 



Spikelets 2.2 mm. long 47. P. tcoparioides 



Spikelets 1.5mm. long. 

 Panicle not more than half as wide as long; 



spikelets elliptic 85. P. ajiretum. 



Panicle about as wide as long ; spikelets obovoid 86. P. Lindheimeri. 



