84 POACEAE 



1-2 dm. long, usually 1.5 cm. ^vule or less: spikelets ovate-lanceolate, acute, 3-3.o mm. 

 long, the silvery white hairs very long and copious, extending much beyond the apex of 

 the spikelet. 



On dry hillsides, Texas to Colorado. Also in Mexico. Summer. 



29. ECHINOCHLOA Beauv. 



Often tall grasses, with flat leaf -blades, the inflorescence composed of several to many 



unilateral more or less spreading spike-like racemes. Spikelets 1-2-flowered, lanceolate to 



ovate or orbicular-ovate, crowded in small clusters or racemes in 2 rows on one side of the 



flat rachis. Scales 4, the .3 outer membranous, spiny-hirsute or hispid externally, the first 



much shorter than the spikelet, often awn-pointed, the second and third awn-pointed or 



awned (rarely awnless), the latter bearing the longer awn and rarely enclosing a palet and 



sometimes also a staminate flower ; fourth scale chartaceous, glabrous and shining, at length 



indurated, acute or acuminate, enclosing a shorter palet of similar texture and a perfect 



flower. Stamens 3. Styles distinct. Stigmas plumose. 



Leaf-sheaths glabrous. 



Awn of the third scale not exceeding 4 times the length of the spikelet, some- 

 times very short or almost wanting. 

 Spikelets 2.5-3 mm. long : lower racemes rarely exceeding the rachis-inter- 



nodes. \. E. colona. 



Spikelets 4 mm. long ; the lower racemes much exceeding the rachis-inter- 



iiodes. 2. E. Onis-galli. 



Awn of the third scale 8-15 times the length of the spikelet. 3. E. longearisiata. 



Leaf-sheaths, at least the lower ones, densely papillose-hispid. 4. E. Walteri. 



1. Echinochloa colona (L. ) Link. Stems tufted, 1-8 dm. tall, often decumbent 

 and rooting at the lower nodes : leaf-sheaths glabrous, compressed ; blades flat, 2-17 cm. 

 long, 2-8 mm. wide : inflorescence composed of 3-18 one-sided more or less spreading ra- 

 cemes, 6-30 mm. long : spikelets single, in pairs, or in 3's in 2 rows, obovate, pointed, his- 

 pid on the nerves, 2.5-3 mm. in length, the fourth scale cuspidate. [Panicum colonum L.] 



In fields and along roadsides, Virginia to Florida, Texas and Mexico. Common in all tropical 

 countries. Spring to fall. Jungle Rice. 



2. Echinochloa Crus-gdlli (L. ) Beauv. Stems 6-12 dm. tall : leaf-sheaths glabrous ; 

 blades 1.5-6 dm. long, 6-25 mm. wide, glabrous, smooth or rough : panicle of 5-15 erect 

 or ascending branches, or the lower ones spreading or reflexed and sometimes 6-8 cm. long : 

 spikelets ovate, densely crowded in 2-4 rows on one side of the rachis, about 4 mm. long, 

 exclusive of the awn, hispidulous, hispid on the nerves, the second and third scales more 

 or less awned, the fourth abruptly pointed. \^Panicuin Crus-gnlU L. ] 



In cultivated and waste places throughout North America, excepting the extreme north, and 

 widely distributed as a weed in all cultivated areas. Introduced from Europe. Summer and fall. 

 Barnyard Grass. 



3. Echinochloa longearistata Nasli. Stems 1-2 m. tall, stout : leaf-sheaths gla- 

 brous ; blades flat, rough on the upper surface, smooth beneath, 6-12 dm. long, 2-4 cm. 

 wide or more : panicle 4-6 dm. long, its branches ascending : spikelets ovate, 3.5-4 mm. 

 long, acuminate, hispidulous, the nerves strongly hispid, the awn of the third scale usually 

 8-15 times as long as the spikelet. 



In wet ground, South Carolina to Louisiana. Summer. 



4. Echinochloa Walteri (Pureh) Nash. Stems 9-18 dm. tall, stout : leaf -sheaths, at 

 least the lower ones, papillose-hispid ; blades 3 dm. long or more, 1-2.5 cm. wide, very 

 rough above : panicle of 10-40 ascending or spreading branches : spikelets ovate-lanceolate, 

 densely crowded in 2-4 rows on one side of the rachis, 3-4 mm. long, exclusive of the awns, 

 hispidulous, hispid on the nerves, the second and third scales very long-awned, the fourth 

 scale ovate-lanceolate, acuminate. 



In marshes and ditches, usually near salt-water. New York to Florida. Summer and fall. 



30. OPLISMENUS Beauv. 



Perennial grasses, often decumbent and l)ranched at the base, with broad flat leaf- 

 blades and inflorescence composed of spike.s, bearing on tlie lower side scattered clusters of 

 a few spikelets. Spikelets 1-flowered. Scales 4, the 3 outer membranous, the first and 

 second empty, awned, the first equalling or somewhat sliorter than the spikelet, the third 

 scale usually awned, empty, or enclosing a small palet, the fourth one shorter than tlie 

 others, obtuse, awnless, chartaceous, finally indurate, enclosing a shorter palet of similar 

 texture and a perfect flower. Stamens 3. Styles distinct to the base. Stigmas plumose. 



Oplismenus setarius ( Lam. ) R. & S. Stems prostrate, rooting at the nodes: leaf- 

 blades ovate tn ovate-lanceolate, acuminate, 1.5-6 cm. long: panicle 2-8 cm. long, its short 



