140 Chase — Notes on Genera of Panicece. IV. 



Nb. (Paspalum repens Berg.)," are included, the first of which is here 

 taken as the type. 



Dimorpliostachys Fourn. Compt. Rend. Acad. Sci. Paris. 80 : 441. 

 1875. This genus is proposed because of the presence of the first glume 

 of the spikelet, this ghune in the lower of the pair of spikelets being 

 larger than in the upper. The author says the group contains eleven 

 species, but four of which he mentions, Panicum monostachyum H. B. K. 

 Paspalum pilosum Lam., Paspalum oajacense Steud., and Paspalum 

 pedunculatum Poir. Fournier does not here actually transfer any species 

 to Dimorpliostachys . His first named species, which we take as the type, 

 was, together with the others given in his posthumous work (Mex. PI. 

 2 : 14-16. 1S86*), published under this genus by Hemsley (Biol. Centr. 

 Amer. Bot. 3 : 499. 1885), as I), monostachya Fourn., based on Panicum 

 monostachyum H. B. K. 



The section Harpostachys of Panicum established by Trinius (Mem. 

 Acad. Petersb. VI. Sci. Nat. :l 2 : 227. L834) for species having a simple, 

 solitary raceme, if typified by the first group of species included in it, 

 Panicum decumbens Roem. & Schult. (based on Paspalum ihcumbens 

 Sw., of which P. pedunculatum Poir. is a synonym) and Panicum mono- 

 stachyum H. B. K.j is synonymous with Dimorphostachys. In this sec- 

 tion, however, Trinius included a number of remote species, the wholly 

 artificial character on which it is based bringing together, besides the 

 two species of Paspalum mentioned above, Thrasya paspaloides II. B. K. 

 and congeners; Panicum repandum Nees, a species related to P. obtusum 

 H. B. K., Ecliinolaena hirta, and Panicum sclerochloa Trin. and other 

 species referable to Mesosetum. 



Wirtgenia Nees ; Doell in Mart, Fl. Bras. 1' 2 : 40. 1877. ' ' Wirtgenia pas- 

 paloides Nees ab Esenb. in herb. Reg. Berolin.", a herbarium name for 

 the species Nees published as Anachyris paspaloides, is here given as a 

 synonym of Paspalum malacoph yllum Trin. 



The relationship of the various species upon which are based the inn- 

 posed genera here included as synonyms of Paspalum together with the 

 history of these groups will be discussed in the projected revision of 

 North American species of Paspalum. 



Description. — Inflorescence of 1 to numerous, simple, spike-like racemes, 

 along a common axis; spikelets plano-convex, usually obtuse, subsessile 

 (rarely on pedicels as long as the spikelets) solitary or in pairs, in two 

 rows on one side of a narrow or dilated raehis, the back of the fertile 

 lemma turned toward it ; t first glume typically wanting ( regularly present 

 in a few species, occasionally present in others; in a few species both 

 glumes wanting); second glume and sterile lemma subequal, the glume 

 rarely shorter; fruit usually obtuse, the lemma and palea chartaceous- 

 indurated (rarely but slightly so), the margins of the lemma inrolled. 



* For discussion of date of this work see Hitchcock & Chase, Contr. Nat. Herb. 15 : 

 49. 1910. 



+ Owing to a tortion of the short pedicels the crowded, paired spikelets are often 

 turned edgewise to the raehis or even entirely reversed, but in all species examined 

 the spikelet is attached with the back of its fertile lemma toward the raehis. 



