THE CANADA THISTLE 



295 



MILKWEED. 



upward stems from one 

 to three feet tall. The 

 leaves are bright green 

 above, white-woolly be- 

 neath ; the edges are 

 curved or wavy, deeply 

 cut, and bear many 

 sharp stiff spines ; the 

 flowers are rose-purple, 

 about an inch long, and 

 are armed with weak 

 prickles. 



The seeds are dis- 

 tributed chiefly by water 

 (creeks, rivers, irrigation 

 canals, etc.) ; by ship- 

 ments of hay, grain, clover, or grass seeds ; and by the 

 wind. They seldom ripen in cultivated fields, because they 



mature late ; but along the road- 

 sides, and in pastures and vacant 

 lots, where they can acquire 

 energy enough, a considerable 

 number of seeds are produced. 

 Moreover, the plant spreads in 

 another way. In cultivation, 

 the implements of tillage tear 

 up the roots and spread them 

 over the field, and then these 

 rootstocks or underground stems 

 reestablish themselves where 

 they have been left to lie. 



The most effective remedies 



FENNEL. 



for the Canada Thistle are as follows : 



(a) On large areas, late plowing in the fall, without 



