MANUAL OF THE GRASSES OF THE UNITED STATES 



699 



3. Setaria verticillata (L.) Beauv. Bur bristlegrass. (Fig. 

 1566.) Annual, often much branched at base and geniculate-spread- 

 ing, as much as 1 m long; blades flat, rather thin, scabrous and 

 often more or less pilose, 10 to 20 cm long, 5 to 10 mm wide; panicle 

 erect but not stiff, cylindric or somewhat tapering upward, more or 





Figure 1563.— Distribution of 

 Setaria lutescens. 



Figure 1564.— Setaria geniculata, X ' 1. (Chase 

 2981, Md.) 



Figure 1566.— Setaria verticillata, 

 X 1. (Steele, D.C.) 



less lobed or interrupted, especially toward base, 5 to 15 cm long, 7 

 to 15 mm wide; bristles single below each spikelet, 1 to 3 times as long 

 as the spikelet, retrorsely scabrous; spikelets 2 mm long; fruit finely 

 rugose, o — Cultivated soil and waste places, Massachusetts to 

 North Dakota, south to Alabama and Missouri, occasional west to 



California (fig. 1567); introduced from Europe; 

 tropical America at medium altitudes. 



Setaria verticillata var. ambigua (Guss.) 

 Pari. Differing from S. verticillata in the sca- 

 brous but not pilose axis of the panicle and the 

 antrorsely scabrous bristles, mostly 2 to 3 

 times as long as the spikelets, at maturity 

 spreading and more or less implicate, o — 

 Sparingly introduced in the United States, ballast, and waste places, 

 Albany, N.Y., Philadelphia, District of Columbia, and Mobile, Ala.; 

 Europe. 



4. Setaria macrosperma (Scribn. and Merr.) Schum. (Fig. 1568.) 

 Perennial, often in large tufts, 1 to 1.5 m tall; sheaths keeled; blades 

 elongate, 1 to 2 cm wide, scabrous on upper surf ace ; panicle 15 to 30 cm 

 long, 2 to 4 cm wide, tapering to both ends, rather loose, the secondary 



Figure 1565.— Distribution of 

 Setaria geniculata. 



