Panicum 



Paniceae 



173 



45. Panicum commutatum Schultes. Map 319. This species is restricted 

 usually to the high hills of the unglaciated area, although it is found in 

 Jefferson County on the bluff of the Ohio River and in Jennings County on 

 the sandstone outcrop along the Muscatatuck River near Vernon. It is 

 rather local except in the knobstone, where it is frequent. My no. 27633 

 from Clark County is exceptional in that the whole plant is soft-pubescent, 

 including both surfaces of the leaves. 



Mass. to Mich, and Mo., southw. to Fla. and Tex. 



16. LATIFOLIA 



Culms stout, usually more than 50 cm high; ligules mostly less than 

 1 mm long; blades cordate at the base and long-acuminate at the apex, 

 usually more than 15 mm wide; spikelets 2.7-4.5 mm long, 7-11 nerved; the 

 autumnal phase sparingly branching at the middle nodes, becoming top- 

 heavy, and lodging. 



Sheaths, at least the lower ones and those of the branches, papillose-hispid; spikelets 



2.7-3 mm long (rarely longer) 46. P. clandestinum. 



Sheaths glabrous or softly villous (hairs not stiff as in the preceding species) . 



Nodes glabrous or nearly so; spikelets 3.2-3.7 mm long 47. P. latifolium. 



Nodes retrorsely bearded; spikelets 4-4.5 mm long. 



Blades glabrous or nearly so on both surfaces 48. P. Boscii. 



Blades velvety to the touch beneath 48a. P. Boscii var. molle. 



46. Panicum clandestinum L. Map 320. This species is infrequent to 

 rare in the northern part of the state ; rare, local, or absent in the central 

 counties ; and frequent in most of the southern half of the state. It prefers 

 low ground and is more abundant in areas where the soil is slightly acid. 

 It is generally found on the moist slopes of streams and ditches. It usually 

 forms large colonies, and often specimens with exserted panicles are 

 absent, especially in the autumnal phase. 



N. S. and Que. to Kans., southw. to n. Fla. and Tex. 



