172 



Paniceae 



Panicum 



50 



Map 317 



Panicum Scribnerlanum Nash 



50 



Map 319 



Panicum commutatum Schultes 



where it is found in very sandy, dry soil on open dunes and sand hills and 

 sometimes in rather dry, gravelly soil. Our specimens from the western 

 part of the state are from sand dunes and sandy knolls. 

 Maine to B. C, southw. to Md., Tenn., Tex., and Ariz. 



15. COMMUTATA 



Culms tufted, glabrous or puberulent ; ligule obsolete or nearly so ; blades 

 relatively broad, cordate at the base ; spikelets pubescent. 



Culms and sheaths usually densely crisp-puberulent (sometimes sparsely so) ; blades 

 generally less than 12 mm wide; spikelets 2.2-2.5 (2.7) mm long... 44. P. Ashei. 



Culms and sheaths generally nearly glabrous or only sparingly puberulent (not crisp- 

 puberulent) ; blades or some of them usually more than 12 mm wide; spikelets 

 2.5-3 mm long, generally about 2.7 mm long 45. P. commutatum. 



44. Panicum Ashei Pearson. Map 318. This species, as now known in 

 the state, is restricted to the unglaciated area, with the exception of a 

 typical specimen which I have from Porter County found on a sandy black 

 oak and white pine ridge about 4 miles southwest of Michigan City. In the 

 southern part of the state it is found mostly on the crests and slopes of 

 chestnut oak ridges. 



No single character will separate Indiana specimens of this grass from 

 those of the next. The two plants intergrade to such an extent that it is 

 questionable whether an attempt should be made to keep them separate, 

 even regarding one as a variety, as has been done by Fernald (Rhodora 36 : 

 83-87. 1934). If all of our forms of this species complex are considered 

 as one species, then the same treatment applied to borderline species in 

 other groups would unite them. This case seems to be a decision between 

 the "grouping" and the "splitting" of forms (species) . Until an exhaustive 

 study is made of the group, any disposition made of these plants must be 

 mere opinion or for convenience. For these reasons I am following Hitch- 

 cock and treating our plants as two species. Such treatment leaves the 

 problem open to future study. 



Mass. to Mich, and Mo., southw. to n. Fla., Miss., and Okla. 



