HITCHCOCK AND CHASE — NOETH AMERICAN GRASSES. 35 



adequate description, closely related to P. helopus, and approaches 

 BracMaria in the same way. 



Our species represent nearly the extremes of diversity in the genus, 

 with B. erucaeformis, the type but not the center of the genus, at one 

 end, and B. ciliatissima at the other. The species most nearly related 

 to the latter is B. gilesii (Panicum gilesii Benth.), 1 of Australia, of 

 which a specimen of the type collection by C. Giles at Charlotte 

 Waters is in the National Herbarium. 



In the tropics or subtropics of the eastern hemisphere there are 

 about 70 known species, a single one, B. erucaeformis, reaching south- 

 ern Europe, there probably introduced in ancient times. In America 

 are the six species described herewith. In Africa is a small group in 

 which the spikelets are crowded and almost pectinate on the rachis. 

 This includes B. brizantha (Hochst.) Stapf, the type collection of 

 which (/Schimper, Iter Abyssinicum no. 89, October 3, 1837) is rep- 

 resented in the National Herbarium, B. falcifera (Trin.) Stapf, B. 

 soluta Stapf, and B. decumbens Stapf. 2 



Brachiaria miliif oralis (Panicum milii forme Presl 3 the type of 

 which, collected by Haenke in Luzon, was examined in the National 

 Museum at Prague by Prof. A. S. Hitchcock in 1907) is apparently 

 a common grass in the Philippines and has been distributed thence 

 under various names. It is represented in the National Herbarium 

 by the following : Merrill 332, 352, 9343, in Kneucker Gram. Exs. 610 ; 

 Elmer 10414; Loher 1737; Bur. Science 7624, 12231; Forestry Bur. 

 16661. It was collected in Guam by J. B. Thompson (no. 263). 



Other species referable to Brachiaria, but which, because of the 

 impossibility at present of examining the type specimens in European 

 herbaria and working up the synonymy, are not here transferred, are : 

 Panicum intercedens Domin, P. r ever sum Muell., and P. polyphyllum 

 K. Br., of Australia; P. villosum Lam. and P. distachyon L., of 

 India; and P. ambiguum Trin., of the East Indies. Various species 

 of true Panicum as well as P. ambiguum have been distributed under 

 the last named. In this species the spikelets are paired or solitary, 

 the first glume is nearly as long as the spikelet, and the fruit is awn- 

 tipped. 



DESCRIPTION OF THE GENUS AND SPECIES. 

 BRACHIARIA (Trin.) Griseb. 



Inflorescence of several to many usually dense racemes along a common axis ; 

 spikelets solitary (rarely in pairs), subsessile in 2 rows on one side of 

 a 3-angled, sometimes narrowly winged rachis, the back of the fertile 



l Fl. Austral. 7: 477. 1878. 



2 Stapf (in Prain, Fl. Trop. Africa 9: 505-567. 1919) describes 55 species of 

 Brachiaria, indicating that the species of this genus are chiefly African. 



3 Rel. Haenk. 1 : 300. 1830. 



