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WEED FLORA OF IOWA 



Fig. 72-A. Distribution of Wliite Cockle. 



Exiermination. — This weed can be exterminated by cutting oflf 

 the plants when in bloom or by cutting them off a few inches below 

 the surface of the ground. Since this weed is being spread with 

 European clover seed, care should be used to sow only clean clover 

 seed. 



Catchfly {Silene dichotoma Ehrh.). 



Description. — A tall, more or less hirsute, annual, somewhat viscid, 

 pubescent; leaves lanceolate or oblanceolate ; flowers in branched 

 racemes, short-pediceled in the forks, or solitary at the nodes ; calyx 

 5-ribbed, hirsute ; petals white or pink, bifid. 



Distribution. — Introduced from Europe, spreading occasionally 

 in clover fields from the northeast to Iowa and Texas, also to the 

 Pacific coast. 



Extermination. — A remedy in this case is to sow only clean seed, 

 clean clover or alfalfa seed in clean soil in localities where the weed 

 occurs. Give thorough cultivation. Do not allow any of the plants 

 to go to seed. 



