COMPOSITAE (COMPOSITE FAMILY) 461 



pistil with its cleft style slightly exserted from a hairy and 

 spiny involucre which later becomes a bur about a half- 

 inch long, with two straight beaks at apex and a covering of 

 short, smooth, hooked spines. The burs are two-celled, each cav- 

 ity containing a thick-coated, dark brown, flattened seed. 



Means of control 



In pastures and meadows the plants should be watched for and 

 cut off in May or June with a sharp hoe or spud ; some will be over- 

 looked, to appear conspicuously later, bristling with spines and 

 burs ; these should be cut, piled to dry for a few days, and burned. 

 In cultivated ground tillage should be continued late in order to 

 prevent the development of seed from late-blooming flowers. 



CLOTBUR 



Xdnthium canadense, Mill. 



Other English names: Cocklebur, Sheepbur, Buttonbur, Ditchbur, 



Hedgehog Burweed. 



Native. Annual. Propagates by seeds. 

 Time of bloom: July to September. 

 Seed-time: September to November. 

 Range: Nova Scotia to the Northwest Territory, southward to 



Texas and Mexico. Abundant on the Pacific Coast. 

 Habitat: Rich, moist soil ; cultivated crops, barnyards, roadsides, 



and waste places. 



A huge, coarse plant, one to four feet tall, branched, and widely 

 spreading, its rough, thick, angled stem often reddish and spotted 

 with brown. Leaves also bristly rough on both sides, alternate, 

 large, broadly oval to heart-shaped, with toothed edges, strongly 

 three-nerved and often three-lobed, with long, rigid petioles, often 

 reddish like the stem and contrasting with the dark green of the 

 leaf surface. The sterile heads are clustered at the ends of the 

 branches, small, greenish, and inconspicuous, resembling those 

 of Ragweed; below, in the axils, the fertile heads are densely 

 clustered ; these are thick, green, oblong, densely hairy, and spiny 

 involucres, from which is thrust a style with two-parted stigma ; 

 these involucres develop into burs nearly an inch long, with a 



