HOW TO KNOW THE GRASSES 



5b. Bristles downwardly-barbed, clinging to objects when the panicle 

 is brushed upward. Fig. 285. 



BRISTLY FOXTAIL Setaria verticillaia (L.) Beauv. 



Annual; tufted; culms up to 1 m. tall. 

 The barbed bristles of the panicles not 

 only cause them to adhere to wool, hair, 

 or clothing, but also to each other. Af- 

 ter windstorms, the plants will often be 

 densely tangled. Sometimes flies or 

 other insects become caught in the 

 bristles. Common in cornfields and on 

 disturbed soil. June — October. Intro- 

 duced from Europe. 



Figure 285 



6a. Margins of sheaths bearing short hairs 7 



6b. Margins of sheaths smooth, thin and translucent; glabrous except 

 for a few long hairs at the apex. Fig. 286. 

 YELLOW FOXTAIL Setaria lutescens (Weigel) Hubb. 



Figure 286 



Annual; tufted; culms spreading or 

 erect, up to 1 m. tall; panicles stiff and 

 compact, with a pronounced golden 

 cast, imparted by the yellow bristles; 

 back of the fertile lemma exposed, trans- 

 versely corrugated. An exceedingly 

 common weed, in cornfields or other 

 disturbed soil. July — October. Intro- 

 duced from Europe. Also known as S. 

 glauca. 



Setaria geniculata (Lam.) Beauv. has 

 similar panicles but is a perennial, and 

 the culms arise singly or in small tufts 

 from knotty, much-branched rhizomes. 

 Atlantic and Gulf Coast states, from 

 Massachusetts to Texas, lower Mississip- 

 pi Valley to Illinois and Iowa. 



151 



