GENERA OF GRASSES OF THE UNITED STATES. 229 



Annual or perennial grasses, of various habit. Species probably 

 about 500, mostly confined to the warmer regions of both hemi- 

 spheres, about 150 species being found in the United States. 



Type species : Panicum miliaceum L. 



Panicum L., Sp. PI. 55, 1753 ; Gen. PI., ed. 5, 29. 1754. Twenty species are 

 described. The first ten and the fifteenth are now referred to other genera. Of 

 the species considered typical by Linnaeus, as indicated by the description in 

 his Genera Plantarum, Panicum miliaceum is the only one cultivated and is 

 therefore chosen as the type. 1 



Eatonia Raf., Journ. de Phys. 89: 104. 1819. A single species, E. purpura- 

 scens, which is the same as Panicum virgatum, is included. 



Steinchisma Hal, Bull. Bot. Seringe 1 : 220. 1830. " Panicum divaricatum, P. 

 hians " are cited, both names applying to the same species, P. Mans Ell. 



Phanopyrum (Raf.) Nash, in Small, Fl. Southeast. U. S. 104. 1903. Based 

 on " Panicum, subgenus Phanopyrum Raf.," with a single species, P. gymnocar- 

 pon (Ell.) Nash. 



Chasea Nleuwl., Amer. Midi. Nat. 2: 64. 1911. A new name proposed for 

 " Panicum of the authors not of Linnaeus or only in part," the name Panicum 

 being applied to Chaetochloa. 



Among the species of the United States two subgenera are recog- 

 nized, besides Panicum proper. 



Subgenus Paurochaetium Hitchc. and Chase. Perennials with 

 tufted culms, erect narrow blades, narrow, more or less spikelike 

 inflorescence, the ultimate branchlets produced beyond the uppermost 

 spikelets as a bristle 1 to 6 mm. long, the apiculate fruits transversely 

 rugose. There are four species within our limits, one from Florida, 

 three from Texas. This subgenus shows a transition to Chaetochloa. 



Subgenus Dichanthelium Hitchc. and Chase. Perennials forming 

 a usually well-marked rosette of winter leaves, having a vernal phase 

 of simple culms and terminal panicles of small, perfect, but usually 

 sterile spikelets, and an autumnal phase produced by the branching 

 of the culms after the maturity of the primary panicles, the sec- 

 ondary leaves and panicles usually much reduced, the spikelets cleis- 

 togamous and fruitful, sometimes hidden in the sheaths. There are 

 105 species within our limits, the species being especially abundant 

 on the Atlantic Coastal Plain. A representative of this subgenus is 

 Panicum dichotomum L. (fig. 138). A common species in the East- 

 ern States is P. clandestinum L. (PI. XVII), one of the most robust 

 representatives of the group. This has bristly sheaths and cordate 

 clasping blades as much as an inch wide. It grows in moist soil and 

 furnishes a moderate amount of forage. 



The remaining species belong for the most part to true Pani- 

 cum, called by some the subgenus Eupanicum. The more important 

 of these are the following: Panicum barbinode Trin., Para grass, a 

 perennial with stout stolons as much as 15 feet long, culms 3 to 6 feet 

 tall from a creeping base, bearded nodes, and panicles 4 to 6 inches 

 long, consisting of several spikelike racemes of glabrous spikelets 



1 For a full discussion of the type species of Panicum, see Hitchcock and Chase, Contr. 

 U. S. Nat. Herb. 15: 13. 1910. 



