63 



Looking at some of these weeds, we find Canada Thistle ( Cir- 

 sium arvense ) present on 79 per cent of the farms looked over. This is a 

 perennial of the Thistle Fantiily w^hich spreads by winged seeds and by 

 stout running root-stocks. The root-stocks grow deep down in the soil 

 as far as cultivation penetrates, and branch very freely. 



Red root Pigweed. 



The deeply-cut leaves have very w^avy, crinkled edges, beset -with 

 spines w^hich make the plant a nuisance in shocking-up grain, and a dan- 

 ger to live-stock if fed in hay. The flower-heads are light pink to purple, 

 and smaller than those of Spear or Bull Thistle. The floral involucre is 

 smooth. 



