GRAMINEAE (GRASS FAMILY) 



101 



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



wide, or if narrower not conspicuously elongated I. 

 I Blades more than 1.5 cm. wide m. 



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

 m. Spikelets 3.5-4 mm. long. 



Nodes bearded ; plants often pubescent. 

 Blades lanceolate, thick, glabrous above, densely papillose- 

 pubescent beneath 65. P. Ravenelii. 



Blades ovate-lanceolate, thin ; pubescence when present 



soft 72. P. Boscii. 



Nodes not bearded ; plants glabrous or nearly so. 



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

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

 I. Blades not over 1.5 cm. wide n. 

 n. Panicle narrow ; blades erect. 



Plants glabrous or nearly so 66. P. xanthophysum. 



Plants papillose-hispid. 



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



Spikelets 4 mm. long . . 64. 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. mutabile. 



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



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



Nodes bearded ; ligule 3-4 mm. long 65. P. Ravenelii. 



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

 Spikelets obovoid-turgid, blunt ; pubescence spread- 

 ing 63. P. Scribnerianum 



Spikelets narrowly obovoid, subacute ; pubescence 



ap pressed 62. P. oligosanthes. 



j. Spikelets less than 8 LJUI. long p, 

 p. Spikelets glabrous q. 

 q. Spikelets not over 1.5 mm. long. 



Plants pubescent 22. P. strigosum. 



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



q. Spikelets 2-2.5 mm. long r. 

 r. Spikelets 2 mm. long. 



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

 Spikelets elliptical ; culms glabrous. 



Autumnal state erect, branched like a little tree; second 



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

 Autumnal state topheavy -reclining ; fruit covered by 



second glume and sterile lemma 28. P. barbulatum. 



Autumnal state wide!/ trailing ; second glume and 



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

 r. Spikelets 2.5 mm. long. 



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



equaling fruit 26. P. Bicknettii. 



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



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



p. Spikelets pubescent s. 



8. 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 ; culm s glabrous . . . .26. P. Bicknettii. 

 Spikelets rugose-papillose ; culms pubescent, at least belo 

 Nodes bearded ; panicle-branches ascending . . . 

 Nodes not bearded ; panicle-branches spreading . 

 t. Spikelets not attenuate at base u. 



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

 ing soft tufts 



u. Sheaths not retrorsely pilose v. 

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

 w. Ligule 2-5 mm. long. 



Spikelets 2.2 mm. long 



Spikelets 1.5mm. long. 



Panicle not more than half as wide as long; 

 spikelets elliptic 



24. P. con mnguineum 

 28. P. anguttifolium. 



21. P. xalapense. 



47. P. tcoparioides. 



pikelets ellipt . 



Panicle about as wide as long ; spikelets obovoid 



85. P. spretum. 



86. P. Lindheimeri. 



