1 46 . G RA M I N E\ K 3 49 



21. Blades 7-12 mm wide, not cordate; spikelets sparsely 



pilose to nearly glabrous, 2-2.2 mm long; Lake 

 Co., Fuller & Graham 9400 P. borealc Nash 



20. Spikelets l.,3-1.9 mm long, puberulent or nearly 

 glabrous. 



22. Blades usually 1.5-2.5 cm wide, ciliate toward the 



base, otherwise glabrous; nodes glabrous or nearly 

 so; panicle 8-25 cm long, not more than half as 

 wide as long; moist ground, chiefly in s. 111. but 

 extending northward to Peoria Co 



P. polyanthes Schult. 



22. Blades 4-14 mm wide; panicle often about as wide 

 as long. 

 23. Ligule of conspicuous hairs 3-5 mm long; sandy 



soil in open woods. June-Sept 



P. lindhcimcri Nash 



23. Ligule obsolete or nearly so; sandy soil in the s. 



half of 111. June- July P. sphaerocarpon Ell. 



19. Sheaths pubescent. 



24. Sheaths conspicuously pilose, the hairs either retrorse or 

 horizontally spreading. 

 25. Spikelets 1.9-2 mm long; wooded slopes nearly 

 throughout 111. May-July P. xalapense HBK. 



25. Spikelets 2-2.5 mm long; sandy soil, locally in the n. 



half of 111 P. villosissimum Nash 



24. Sheaths not retrorsely pilose. 



26. Spikelets 2.7-3 mm long. 



27. Blades 12-30 mm wide; stems 50-120 cm tall; 

 panicle 7-15 cm long; sandy soil. June- Aug. 



Deer-tongue Grass P. clandestinum L. 



27. Blades 2-6 mm wide; stems 8-40 cm tall; pan- 

 icles 2-8 cm long. 

 28. Blades copiously pilose on both surfaces; 

 panicles 2-4 cm long; dry ground, n.w. 

 111. ; Carroll, Whiteside, and Winnebago 



counties P. wilcoxianuni Vasey 



28. Blades scabrellous above, pilose beneath; 

 panicles 4-8 cm long, some of them usual- 

 ly more or less concealed among the basal 

 leaves; diy soil in the n. counties. June- 

 July P. perlongum Nash 



26. Spikelets less than 2.7 mm long. 

 29. Sheaths with spreading hairs. 

 30. Spikelets 2.2-2.6 mm long. 



31. Blades 2-4 mm wide, 10-30 cm long; 

 spikelets sparsely pilosulous or nearly 

 glabrous; dry woods, local. May-July 

 P. linearifolium Scribn. 



