632 MISC. PUBLICATION 200, U. S. DEPT. OF AGRICULTURE 



Spikelets puberulent. 



Spikelets 1.1 mm. long. Winter blades bluish green, not glossy. 



80. P. COXCIXXIUS. 

 Spikelets 1.3 to 1.5 mm. long. 



Blades involute, falcate, with long stiff hairs on margin near base. Plants stiff 



and wiry 86. P. breve. 



Blades not involute, or at tip only, not falcate. 



Plants bright green; winter blades conspicuous, glossy green. 



79. P. FLAVOVIREXS. 



Plants olive; winter blades not conspicuous nor glossy.— 81. P. exsifolium. 



12. Lancearia 



Spikelets, 1.5 to 1.6 mm. long 87. P. portoricexse. 



Spikelets 2 mm. long or more. 



Blades, or some of them, at least 8 mm. wide, glabrous on the upper surface; fruit papil- 

 lose-roughened 90. P. webberiaxum. 



Blades not more than 6 mm. wide (or if wider, puberulent on the upper surface) ; fruit 

 smooth and shining. 

 Spikelets 2.4 to 2.6 mm. long. Blades narrowed toward the base. 



91. P. PATEXTIFOLIUM. 



Spikelets not more than 2.1 mm. long. 



Blades firm, glabrous above; culms stiffly ascending 88. P. laxcearium. 



Blades lax, softly puberulent on both surfaces; culms decumbent.... 89. P. patulum. 



13. Oligosanthia 



Nodes bearded; blades velvety-pubescent beneath. 



Plants lax, soft-velvety throughout; spikelets not more than 3 mm. long. 



93. P. MALACOPHYLLUM. 



Plants stiff, pubescence harsh; spikelets about 4 mm. long 97. P. ravexelii. 



Nodes not bearded (or but obscurely so in P. wilcoxianum) ; blades not velvety. 

 Panicle narrow, branches erect, or spreading only at anthesis. Blades erect. 

 Spikelets not more than 3 mm. long; blades not more than 6 mm. wide. 



92. P. WILCOXIAXUM. 



Spikelets 3.7 to 4 mm. long; blades 8 to 20 mm. wide. 



Blades papillose-hispid 98. P. leibergii. 



Blades glabrous on both surfaces 99. P. xaxthophysum. 



Panicle about as wide as long. 



Spikelets narrowly obovate, subacute; plants olivaceous, appressed-pubescent. 



96. P. OLIGOSAXTHES. 



Spikelets broadly obovate, turgid, blunt; plants green, the pubescence, if present, not 

 appressed. 

 Blades erect, not more than 6 mm. wide; plants copiously hirsute throughout. 



92. P. WILCOXIAXUM. 



Blades ascending or spreading, rarely less than 8 mm. wide, usually wider; plants not 

 hirsute throughout. 

 Spikelets 3.2 to 3.3 mm. long; blades firm; sheaths or some of them more or less 



hispid 95. P. scribxeriaxum. 



Spikelets not more than 3 mm. long; blades rather thin; sheaths, or some of them, 

 glabrous or sparsely hispid 94. P. helleri. 



14- Pedicellata 

 Culms erect or leaning; blades thin, 5 to 9 cm. long, narrowed toward the base. 



100. P. PEDICELLATUM. 



Culms decumbent; blades thick, not more than 5 cm. long, not narrowed toward the base. 



101. P. XODATUM. 



15. Scoparia 



Pubescence soft-villous or velvety. Spikelets abruptly pointed 102. P. scoparium. 



Pubescence when present not velvety. 

 Spikelets elliptic. 



Spikelets 3 mm. long; second glume and sterile lemma pointed beyond the fruit. 



103. P. ACULEATUM. 



Spikelets not more than 2.8 mm. long; second glume and sterile lemma scarcely, if at 

 all, pointed beyond the fruit. 



