WEEDS 



467 



conditions and with the farmer and gardener against it, the 

 weed must possess exceptional powers of reproduction or of 



Fig. 352. A, corn cockle, a weed of the Pink family, troublesome in grain- 

 fields. The seeds are poisonous. One third natural size. B, cocklebur, a 

 very troublesome weed of the Composite family, in rich land throughout 

 a large part of the country. Two thirds natural size 



resistance to unfavorable influences. Some of the chief quali- 

 fications wliich distinguish weeds are : 



(1) The power of vegetative reproduction. 



(2) Deep, tough roots, or relatively extensive development 

 of the underground portion. 



(3) The power to produce many seeds. 



