238 BULLETIN 772, U. S. DEPARTMENT OF AGRICULTURE. 



Freely branching, creeping, shade-loving annuals or perennials, 

 with erect flowering shoots, flat, thin lanceolate or ovate blades, and 

 several one-sided, thickish, short spikes rather distant on a main axis. 

 Species about 10, in the Tropics of both hemispheres, 1 extending 

 into the Southern States. 



Type species: Oplismenus africanus Beauv. 



Oplismenus Beauv., Fl. Owar. 2: 14, pi. 58, f. 1. 1809. A single species is 

 described. 



Orthopogon R. Br., Prodr. Nov. Holl. 194. 1810. Four species are described, 

 O. compositus, O. aemulus, O. flaccidus, and O. imbecillis. Panicum compositum 

 L. is chosen as the type, this being the basis of the first species of Orthopogon. 



The only species in the United States is Oplismenus setarius 

 (Lam.) Roem. and Schult. (fig. 145), found in shady places from 

 Florida to Texas. This is grazed by stock, but is not sufficiently 

 abundant to be of importance. 



122. ECHINOCHLOA Beauv. 



Spikelets plano-convex, often stiffly hispid, subsessile, solitary or 

 in irregular clusters on one side of the panicle branches; first glume 

 about half the length of the spikelet, pointed ; second glume and sterile 

 lemma equal, pointed, mucronate, or the glume short-awned and the 

 lemma long-awned, sometimes conspicuously so, inclosing a mem- 

 branaceous palea and sometimes a staminate flower; fertile lemma 

 plano-convex, smooth and shining, acuminate-pointed, the margins 

 inrolled below, flat above, the apex of the palea not inclosed. 



Coarse, often succulent, annual, or sometimes perennial, grasses, 

 with compressed sheaths, linear flat blades, and rather compact pani- 

 cles composed of short, densely flowered racemes along a main axis. 

 Species about 10, in the warm and temperate regions of both hemi- 

 spheres ; 4 species in the United States. 



Type species : Panicum crusgalli L. 



Echinochloa Beauv., Ess. Agrost. 53, pi. 11, f. 2. 1812. The species figured is 

 selected as the type. 



With the exception of E chmochloa colonum (L.) Link, the species 

 of Echinochloa have distinctly awned or awn-pointed spikelets. In 

 that cosmopolitan species the spikelets are merely apiculate or mucro- 

 nate, and the racemes are simple and rather remote. 



Echinochloa CTUsgdlli (L.) Beauv. (fig. 146), barnyard grass, is 

 a common weedy annual found throughout the country except at 

 higher altitudes. The panicles vary much in the size and length of 

 the awns, and in color vary from green to dark purple. In fields and 

 waste places the plants are usually spreading, but in water or wet 

 places may be stout and erect. An erect short-awned form, with 

 short, ascending racemes, found in the Southwestern States, is the 

 Mexican E. crusgalli zelayensis (H. B. K.) Hitchc. (Oplismenus 

 zelayensis H. B. K.). E. crusgalli edulis (Panicum frumentaceum 

 Koxb., 1820, not Salisb., 1796) is a form that has been cultivated in 



