igo REPORT OF NEW JERSEY STATE MUSEUM. 



aa. Perennial. 



b. Spikelets short pedicelled along one side of the rachis, forming spike- 

 like racemes. P. hemitomon, p. i94 

 bb. Spikelets in open, rarely contracted panicles. 



c. Basal leaves different from culm leaves, usually forming winter 

 rosettes. 

 d. Spikelets glabrous. 



e. Spikelets 3mm. or more long, strongly nerved. 

 /. Spikelets pointed, blades elongated. 



P. depauperatum, p. 198 

 ff. Spikelets blunt, blades not elongated, 3.2-3.3 mm. ; 

 long sheaths or some of them hispid. 



P. scribnerianum, p. 209 

 ee. Spikelets less than 3mm. long. 



f. Second glume and sterile lemma exceeding the fruit 

 and pointed beyond it, spikelets 2.2-2.9 mm. long. 

 g. Spikelets elliptic, fruit 2 mm. long. 



P. aculeatum, p. 210 

 gg. Spikelets ovate, broadest below the middle, 2 mm. 

 or less. 

 h. Sheaths (at least the secondary) hispid. 



P. scabriusculum, p. 210 



hh. Sheaths glabrous. P. cryptanthum, p. 210 



ff. Second glume and sterile lemma, not pointed beyond 



the fruit. 



g. Ligule 2-3 mm. long. P. spretum, p. 202 



gg. Ligule obsolete. 



h. Spikelets 1.5 mm. long or less. 



i. Nodes bearded. P. micro carp on, p. 200 



a. Nodes not bearded. 



j. Spikelets 1.S-1.6 mm. blades SO-80 mm. 

 long, 4-7 mm. wide. 



P. caerulescens, p. 200 

 jj. Spikelets 1.2-1.4 mm., blades not over. 

 30 mm. long, 1.5-3 mm. wide. 



P. ensifolium, p. 207 

 }'}'}. Spikelets 2mm. long or more. 



k. Culms soon prostrate, vine-like, 

 branches divaricate. 



P. lucidum, p. 200 

 kk. Culms not vine-like, branches not 

 divaricate. 



I. Nodes glabrous ; autumnal form 



upright. P. dichotomum, p. igg 



II. Nodes, at least the lowest, 



usually bearded, autumnal form, 



top-heavy and reclining. 



P. barbulatum, p. 200 



