66 American Midland Naturalist Monograph No. 2 



27. Blades 12-30 mm. wide; stems 50-120 cm. tall; panicle 7- 

 15 cm. long; sandy soil. June-Aug P. eland estiniim L. 



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

 long. 



28. Blades copiously pilose on both surfaces; panicles 2-4 



cm. long; dry ground, n.w. 111., not common 



P. wilcoxianum Vasey 



28. Blades scabrellous above, pilose beneath; panicles 4-8 

 cm. long, some of them usually more or less con- 

 cealed among the basal leaves; dry soil. June-July .... 

 P. perlongum Nash 



26. Spikelets less than 2.7 mm. long. 

 29. Sheaths with spreading hairs. 

 30. Spikelets 2.2-2.7 mm. long. 



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

 sparsely pilosulous or nearly glabrous; dry 

 woods, local. May-July.. P. linearifolmm Scribn. 



31. Blades 5-10 mm. wide, 6-10 cm. long; ligule 4-5 



mm. long; dry sandy soil. June-July 



P. villosisshnian Nash 



30. Spikelets 1.3-1.9 mm. long; ligule 3-5 mm. long. 



32. Upper surface of blades glabrous or with a few 



long hairs toward the base, the lower surface 

 glabrous or puberulent; moist ground. June-July 

 P. tennesseense Ashe 



32. Upper surface of blades not glabrous. 



33. Upper surface of blades pilose, the hairs 3-5 

 mm. long. 



34. Stems conspicuously villous with horizontal 

 hairs 4-5 mm. long; dry soil, chiefly in 



the n. half of the state. June-July 



P. praecochis Hitchc. & Chase 



34. Stems with shorter hairs. 



35. Axis of panicle pilose; the lowest pani- 

 cle branches often tangled or impli- 

 cate; wet mieadows or swamps in the 



n. half of the state. June-July 



P. tmpltcatiim Scribn. 



35. Axis of panicle puberulent; branches 

 ascending, not tangled; sandy soil, n. 



111. June-July P. mcridtonalc Ashe 



33. Upper surface of blades with somewhat ap- 

 pressed hairs 1-2 mm. long; meadows, com- 

 mon. May-Sept P. huachucac Ashe 



29. Sheaths with appressed hairs; ligule 1-1.5 mm. long; 

 blades glabrous or nearly so on the upper surface, puber- 



