Margins of streams and irrigation ditches, swampy places, in shallow water 

 of ponds and in brackish marshes, in Okla. (Murray and Kay cos.) and extreme 

 n. edge of Tex. Rio Grande Plains, s. parts of n.-cen. Tex. and e. Tex., infrequent, 

 summer; Wise, Va., S.C., Ark., La., Okla., Tex. and Coah. 



5. Echinochloa polystachya (H.B.K.) Hitchc. 



Long-creeping perennial, some of the lower internodes 3-6 mm. thick; nodes 

 villous; sheaths smooth; ligule a row of stiff yellowish hairs (use lens); panicles 

 slender and usually nodding; "spikes" 2-5 mm. long, strictly ascending and ap- 

 pressed, the lower ones only slightly overlapping, often with stiflf bristlelike hairs; 

 second glume and sterile lemma with bodies 4—5 mm. long and awns, the awn of 

 the lemma 4-18 mm. long, the nerves (especially the lateral ones) with spinulose 

 cilia but these not conspicuously pilose. Panicum polystachyum H.B.K. 



Infrequent in moist clay loam, in shallow water, swamps and ditches, coastal 

 parts of Tex. Rio Grande Plains and s. part of s.e. Tex., Mar.-Nov.; warm-temp, 

 and trop. parts of Am., n. to Cuba and Tex. 



55. Setaria Beauv. Bristle Grass. Millet 



Panicles with many nodes and short branches, each branch system exhibiting 

 numerous reduced sterile branohlets which are seen as bristles subtending the 

 spikelets; spikelets essentially sessile, each falling as a unit, 2-flowered. the lower 

 floret staminate or completely reduced, the upper perfect; first glume much shorter 

 than the spikelet, several-nerved, membranous; second glume nearly as long as 

 the spikelet, several-nerved, membranous; lower ("sterile") lemma several-nerved, 

 membranous, usually not quite as long as the fertile lemma; sterile palea nearly 

 obsolete to well-developed and as long as the sterile lemma; fertile lemma indurate, 

 strongly convex, the margins revolute and clasping the palea of the same texture, 

 smooth or usually faintly to strongly transversely rugose. 



A genus of about 140 species in the warmer parts of the world; closely related 

 to certain species of Panicum and probably best treated as a subgenus of that 

 genus. 



1. Bristles 4 to 12 below each spikelet; panicles spiciform, not tapering nor inter- 

 rupted (2) 



1. Bristles 1 to 3 below each spikelet; panicles tapering or if spiciform then 



usually interrupted in the lower part (3) 



2(1). Plants perennial, from hard knotty subrhizomatous bases; spikelets mostly 

 1.2-1.6 mm. broad, elliptic 1. S. geniculata. 



2. Plants annual, from bases that are not hard knotty or subrhizomatous; spikelets 



mostly 1.5-1.9 mm. broad, turgid 2. 5. glauca. 



3(1). Bristles retrorsely scabrous 3. S. verticillata. 



3. Bristles antrorsely scabrous only 4. S. magna. 



1. Setaria geniculata (Lam.) Beauv. Fig. 168. 



Perennial from hard knotty subrhizomatous bases; aerial culms 2-10 dm. long, 

 geniculate at the lower nodes, mostly erect; blades 3-8 mm. broad, mostly rather 

 strictly erect; panicles 1-8 cm. long, cylindric. about 15 mm. thick, dense, a I -cm. 

 transection including 13 to 25 spikelets; spikelets subtended by numerous stiflf 

 bristles, mostly 2.5-3 mm. long. 1.2-1.6 mm. broad, elliptic to elliptic-ovate; lower 

 (sterile) floret usually staminiferous with a well-developed palea. 



Most common in disturbed moist areas, in mud along streams, salt and fresh- 

 water marshes, in mud and shallow water about ponds and lakes, in Okla. (Alfalfa. 

 Pittsburg. Mayes and LeFlore cos.), throughout Tex.. N.M. (Hitchcock) and 

 Ariz. (Santa Cruz Co.), spring-fall; in warmer parts of Am. n. to Calif., Ariz., 

 N.M., Kan., la., W.Va. and Mass. 



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