HITCHCOCK AND CHASE — NORTH AMERICAN PANICUM. 



145 



Blades not elongated, about 10 times as long as wide. 

 Culms soon prostrate, vine-like; branches divari- 

 cate. 

 Plants bright green ; culms lax; spikelets not 



over 2.1 mm. long 114. 



Plants grayish green ; culms stiff; spikelets 2.5 



mm. long 115. 



Culms not vine-like; branches not divaricate. 

 Spikelets 2.3 to 2.6 mm. long. 

 Blades, or some of them, at least 8 mm. wide; 



fruit papillose-roughened 166. 



Blades not over 6 mm. wide; fruit smooth 



and shining 167. 



Spikelets 2 mm. long. 

 Culms wiry, crisp-puberulent; blades ciliate 



at base 164. 



Culms glabrous; blades not ciliate. 

 Blades erect, firm; spikelets turgid, 



strongly nerved; plants grayish olive. 112. 

 Blades spreading; spikelets not turgid. 

 Nodes glabrous; autumnal form erect, 



branched like a little tree 109. 



Nodes, at least the lowest, usually 

 bearded; autumnal form topheavy- 



reclining 110. 



Spikelets pubescent. 

 Spikelets 3 mm. or more long. 

 Blades elongated, those of the mid-culm at least 15 times as 

 long as wide. 

 Secondary panicles from basal sheaths only. 



Spikelets pointed, about 3.5 mm. long 82. 



Spikelets blunt, 3 mm. or less long 83. 



Secondary panicles from upper branches. 

 Spikelets attenuate at base, pustulose-pubescent; 



lowermost sheaths softly villous 95. 



Spikelets not attenuate at base, not pustulose; lower- 

 most sheaths glabrous or hispid. 



Upper leaves approximate; sheaths glabrous 187. 



Upper leaves distant; at least lower sheaths hispid. 180. 

 Blades not elongated, usually less than 10 times as long as 

 wide. 

 Blades velvety-pubescent beneath. 

 Spikelets 3 mm. long; plants velvety- villous through- 

 out 169 . 



Spikelets 4 mm. or more long. 

 Sheaths ascending-hirsute; ligule 3 to 4 mm. long. . 173. 



Sheaths downy-pubescent; ligule obsolete 191a. 



Blades not velvety-pubescent beneath. 

 Sheaths glabrous or minutely puberulent only. 



Nodes bearded; spikelets 4 mm. or more long 191. 



Nodes not bearded; spikelets not over 3.8 mm. long. 

 Spikelets 3.5 to 3.8 mm. long; blades 2 cm. or 



more wide 190. 



41616°— vol 15—10 10 



P. lucidum. 

 P. sphagnicola. 



P. webberianum. 

 P. patentifolium. 



P. lancearium. 



P. roanokense. 



P. dichotomum. 



P. barbulatum. 



P. depauperatum. 

 P. perlongum. 



P.fusiforme. 



P. equilaterale. 

 P. aculeatum. 



P. malcophyllum. 



P. ravenelii. 

 P. boscii molle. 



P. boscii. 



P. latifolium. 



