236 WEEDS OF THE FARM AND GARDEN 



taining two achenes, without pappus ; two large prickles 

 at upper end of involucre ; bur densely prickly and rough ; 

 each bur contains two seeds which generally germinate 



in different seasons. Plant is 

 apt to take possession of 

 worn-out lands, and is fre- 

 quently found on the alluvial 

 bottom of streams; in Iowa 

 it is very troublesome in some 

 corn fields and in many places 

 is a common street weed. 

 Burs are injurious to stock 

 chiefly because of their me- 

 chanical properties, but are 

 said to be poisonous to hogs 

 and many think that the 

 ground where they have 

 grown becomes poisoned. 



Clotbur (Xanthium spino- 

 sum, L.). A pubescent, 

 branched annual herb with 

 slender, yellow three-parted 

 spines in the axils; leaves 

 lanceolate or ovate-lanceo- 

 late, white, downy under- 

 neath ; bur oblong, cylindrical, 

 armed with a single short 

 beak and numerous glabrous 

 prickles. Common in waste 

 Fig. 1483. Young plant of grounds from Ontario to Mis- 

 smaller ragweed. (Am. Steel SOU ri and Texas to Florida, 



but native to the Old World. 



Ox-eye (Heliopsis scabra, Dunal.). A rough, pubes- 

 cent perennial with opposite, petioled, triple-nerved 

 leaves; heads large, peduncled; scales of involucre in 

 two to three rows, nearly equal ; ray-flowers yellow, ten 



