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 011 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 pubescence 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. Scribnerianum. 

 104. P. Helleri. 



61. P. Earlei. 



64. P. curtifolitim. 



88. P. Lindhetmeri, 

 50. P. arcnicola. 



118. P. Swibnerianwn. 

 104. P. Helleri. 



79. P. leucothrix. 



83. P. ciliosiini. 



82. P. Tennesseense. 



86. P.filiculme. 



84. P. lanuginosum. 



85. P. Thurmvit. 



87. P. unciphyllum. 



93. P. chrysopsidifolium. 



94. P. pscudopubescens. 



95. P. Attanticum. 



96. P. vittosissimum. 



97. P. xanthospermum. 



119. P. Rai'cnelii. 



98. P. Common&ianum. 



99. P. strictifolium. 



100. P. dliiferum. 

 117. P. oligosanthes. 



). P. anmduin. 



