POACEAE 



89 



Spikelets and leaf-blades not as above, the former obtuse. 

 Spikelets glabrous, or with a few scattered hairs. 

 Spikelets 3 mm. long-. 



Leaf-sheaths, at least the lower ones and those on the 



branches, densely papillose-hispid. 

 Lower leaf-sheaths with scattered papillae from some of 

 which arise hairs. 

 Spikelets not exceeding 1..5 mm. long. 



Leaf-blades pubescent with long weak hairs. 

 Leaf-blades glabrous, or if pubescent the hairs few and 

 very short. 

 Spikelets densely pubescent. 



Leaf-blades glabrous on both surfaces, or the lower surface 

 sometimes with a few scattered long hairs. 

 Spikelets 2 mm. long or less. 



Leaf-blades oblong-lanceolate, broadest at the mid- 

 dle : spikelets about 1..5 mm. long. 

 Leaf-blades broadest below the middle, long-acumi- 

 nate : spikelets a little less than 2 mm. long. 

 Spikelets about 3 mm. long : 

 Broadly obovoid, turgid. 

 Elliptic, not turgid. 

 Leaf-blades pubescent on one or both surfaces. 



Spikelets but little exceeding 1..5 mm. long or less. 



Lower surface of the leaf-blades softly pubescent with 

 usually short hairs, sometimes intermixed with a 

 few stiff ones. 

 Spikelets about 1 mm. long. 

 Spikelets about 1.5 mm. long. 



Upper surface of the leaf-blades glabrous or 

 nearly so, or at first with a few scattered 

 hairs. 

 Leaf-blades conspicuously ciliate on the 



margin with long hairs. 

 Leaf-blades naked on the margin, or some- 

 times with a few scattered hairs. 

 Upper surface of the leaf-blades strongly pubes- 

 cent, sometimes with long stiff hairs. 

 Stems low, slender, usually 2 dm. tall or less. 

 Stems tall, stout, 4 dm. high or more. 



Spikelets obovoid, 1.5 mm. long : pubes- 

 cence on the lower surface of the leaf- 

 blades short. 

 Spikelets elliptic, about 1.75 mm. long: 

 pubescence on the lower surface of 

 the leaf-blades longer and villous. 

 Lower surface of the leaf-blades as well as the upper 

 surface pubescent with long usually stiff hairs. 

 Spikelets 2 mm. long or more. 



Pubescence on the lower surface of the leaf-blades of 

 long stiff spreading hairs. 

 Pubescence on the leaf-sheaths and stems appressed 



or ascending. 

 Pubescence on the sheaths and stems widely 

 spreading. 

 Spikelets about 2 mm. long, obovoid. 



Hairs on the upper surface of the leaf-blades 



similar to those on the lower surface. 

 Hairs on the upper surface of the leaf-blades 

 much longer than those of the lower 

 surface. 

 Spikelets 2. .5-2. 75 mm. long, elliptic. 

 Spikelets purplish. 

 Spikelets yellow. 

 Pubescence on the lower surface of the leaf-blades of 

 either soft and short or appressed hairs. 

 Upper surface of the leaf-blades glabrous, or at 

 least the pvibescence much more scanty than 

 on the lower surface. 

 Stems pubescent below with long stiff' appressed 

 or nearly appressed hairs. 

 Leaf-blades naked on the margins : 



Exceeding 1 cm. in width : spikelets about 



4 mm. long. 

 Less than 1 cm. in width : spikelets 3 mm. 

 long or less. 

 Spikelets 2-2.5 mm. long. 

 Spikelets 3 mm. long. 

 Leaf-blades ciliate on the margin with long 

 hairs. 

 Stems villous below. 

 Both surfaces of the leaf-blades pubescent with 

 short hairs. 

 Stems glabrous or nearly so. 

 Stems strongly pubescent. 



Pubescence minutely villous, or of long and 

 stiff ascending or appressed hairs. 



118. P. Scrihncrkuiuiii . 



104. P. Helleri. 



61. P. Earlei. 



64. P. curtifoUitm. 



88. P. Lindheimeri. 



50. P. arcnicola. 



118. P. Scrihnerianum. 

 104. P. Helleri. 



79. P. leucothrix. 



83. P. ciUosuiii. 



82. P. Tennesseense. 



^. P. fiUcuhiie. 



84. P. lanur/iiiosimi. 



85. P. Thiirovii. 

 87. P. imciplii/lluin. 



93. P. chrysopsidifolmm. 



94. P. pscudopubescens. 



95. P. Atlanticuin. 



96. P. rillosissimum. 



97. P. xavthoxpcniniin. 



119. /'. Ruirnelii. 



98. P. Commonsianuiii. 



99. P. drictij'olium. 



100. P. ciliifcrum. 

 117. P. oligoxanlhes. 



60. P. atiindiiiii. 



