Panicum 



Paniceae 



171 



o sd 



Map 316 



Panicum oligosanthes Schultes 



culms bearded, sheaths with conspicuous white marks, and very short 

 ligules. 



Vt, Wis. to Kans., southw. to n. Fla. and Tex. ; Mex. and Venezuela. 



14. OLIGOSANTHIA 



Culms rather stout; spikelets obovate, 3-4 mm long, usually papillose- 

 hirsute, strongly 7-9-nerved; autumnal phase with the branches more or 

 less crowded toward the summit. 



Ligule less than 0.5 mm long; blades papillose-hispid above and below; spikelets 



papillose-hirsute 41. P. Leibergii. 



I.igule more than 0.5 mm long; blades not papillose-hispid; spikelets not papillose. 

 Culms and at least the lower sheaths with an appressed pubescence; ligules mostly 

 1.5 mm long with longer hairs intermixed; spikelets oblong-obovate, mostly 



3.5-4 mm long and 1.7-1.9 mm wide 42. P. oligosanthes. 



Culms and sheaths with a spreading pubescence; ligules about 1 mm long; spikelets 

 bluntly obovate, mostly 3-3.5 mm long and 2 mm wide 43. P. Scribnerianum. 



41. Panicum Leibergii (Vasey) Scribn. Map 315. Very local in the 

 northern part of the state, where it is found in dry, sandy or gravelly soils, 

 usually in prairie habitats. The pH value was taken for only one specimen 

 and it was 6.01. 



N. Y. to Man. and N. Dak., southw. to Ind. and Kans. 



42. Panicum oligosanthes Schultes. Map 316. Local in the lake area 

 and reappearing on the low dunes of the southwestern part of the state. 

 It grows in very sandy, dry soils on open, wooded dunes and cleared, open 

 dunes and sand knolls. It is usually associated with Panicum Scribner- 

 ianum which is the more common species. These two grasses are closely 

 related and most easily separated in the field. The leaves of this species 

 are narrower and the upper ones are relatively longer and more spreading. 



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



43. Panicum Scribnerianum Nash. (Panicum oligosanthes var. Scrib- 

 nerianum (Nash) Fern.) Map 317. Rather frequent in the lake area 



