116 



CHEMICAL WEED -KILLERS OR HERBICIDES 



Fig. 162. Harrow-leaved 

 dock IBumex crispus). 



Fig. 163. 

 Fig. 161. Broad-leared dodc 



Canada thistle iSumex ottusifoUm). 



{Cnicus arvensia). 



Fie. 167. Water hemlock (Oscuto maoMJuta). A similar spe- 

 cies, also poisonous, grows from Mahn westward. 



Fig. 164. 



Toad-flax {Idnaria 



vulgaris). 



Fig. 165. Yarrow 



