MANUAL OF THE GRASSES OF THE UNITED STATES 639 



Blades erect; branches, when present, from the lower nodes only. 



8. P. WERNERI. 

 Blades spreading; branches from upper nodes 24. P. bicknellii. 



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

 Culms soon prostrate, vinelike; branches divaricate. 



Plants bright green; culms lax; spikelets not more than 2.1 mm. long. 



38. P. LUCIDUM, 

 Plants grayish green; culms stiff; spikelets 2 5 mm. long. 



39. P. SPHAGNICOLA. 



Culms not vinelike; branches not divaricate. 

 Spikelets 2.3 to 2.6 mm. long. 



Blades, or some of them, at least 8 mm. wide; fruit papillose-roughened. 



90. P. WEBBERIANUM. 



Blades not more than 6 mm. wide; fruit smooth and shining. 



91. P. PATENTIFOLIUM. 



Spikelets 2 mm. long. 



Culms wiry, crisp-puberulent; blades ciliate at base. 



88. P. LANCEARIUM. 



Culms glabrous; blades not ciliate. 



Blades erect, firm; spikelets turgid, strongly nerved; plants grayish 



olive 36. P. ROANOKENSE. 



Blades spreading; spikelets not turgid. 



Autumnal phase branched like a little tree; nodes glabrous or some 



sparsely pilose . 33. P. dichotomum. 



Autumnal phase topheavy-reclining; nodes, at least the lower, 



bearded, rarely glabrous 34. P. barbulatum. 



lb. Spikelets pubescent. 

 6a. Spikelets 3 mm. or more long. 



7a. Blades elongate, those of the midculm at least 15 times as long as wide. 

 Secondary panicles from basal sheaths only. 



Spikelets pointed, about 3.5 mm. long 5. P. depauperatum. 



Spikelets blunt, about 3 to 3.2 mm. long 6. P. perlongum. 



Secondary panicles from upper branches. 



Spikelets attentuate at base, pustulose-pubescent; lowermost sheaths softly villous. 



20. P. FUSIFORME. 

 Spikelets not attentuate at base, not pustulose; lowermost sheaths glabrous or 

 hispid. 



Upper leaves approximate, sheaths glabrous 112. P. equilaterale. 



Upper leaves distant; at least the lower sheaths hispid.. .. 103. P. aculeatum. 

 7b. Blades not elongate, usually less than 10 times as long as wide. 

 8a. Blades velvety-pubescent beneath. 



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



93. P. MALACOPHYLLUM. 



Spikelets 4 mm. long or more. 



Sheaths ascending-hirsute; ligule 3 to 4 mm. long 97. P. ravenelii. 



Sheaths downy-pubescent; ligule obsolete 115. P. boscii var. molle. 



8b. Blades not velvety-pubescent beneath. 



9a. Sheaths glabrous or minutely puberulent only. 



Nodes bearded; spikelets 4 mm. long or more 115. P. boscii. 



Nodes not bearded; spikelets not more than 3.8 mm. long. 

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



114. P. LATIFOLIUM. 



Spikelets scarcely more than 3 mm. long. 



Spikelets turgid, blunt; blades mostly less than 1 cm. wide. 



94. P. HELLERI. 



Spikelets not turgid; blades more than 1 cm. wide. 



Panicle narrow, the branches ascending; spikelets on long stiff pedicels. 



25. P. CALLIPHYLLUM. 



Panicle as broad as long, the branches spreading. 

 Plants glaucous; basal blades conspicuously ciliate. 



110. P. MUTABILE. 



Plants not glaucous; basal blades not ciliate, or at the base only. 

 Culms erect, or autumnal phase leaning; blades symmetrical, broadly 



cordate 109. P. commutatum. 



Culms decumbent; blades usually unsymmetrical and falcate, nar- 

 rowed to the scarcely cordate base 111. P. joorh. 



