Description of the Canada Thistle. 115 



writer; hence they are submitted with a 

 degree of confidence which could not be 

 felt were they based merely on theories, 

 however correct these theories might be. 



An outline sketch is given of each of the 

 weeds dealt with. This' sketch was in 

 every case prepared from living specimens 

 of the weed illustrated. The root develop- 

 ment of each plant is shown, as well as that 

 of the portion above ground. In the work 

 of exterminating weeds, a knowledge of 

 their habits of root growth is frequently 

 of quite as much importance as a knowl- 

 edge of the growth habits of the portions 

 of the plant ordinarily visible to the eye. 



(l) THE CANADA THISTLE. 



The Canada thistle (Carduus arvensis) 

 is a creeping perennial which grows from 

 one to four feet high, according as soils 

 and seasons vary. It is of an upright habit 

 of growth, somewhat branched towards 

 the top, especially when it is not much 

 crowded, but when it is pressed for room 

 it has but a single stem. Its leaves are 

 armed with sharp prickles, which, either 

 when green or dry, but more especially 

 when dry, are exceedingly unpleasant to 

 handle. Its blossoms are of a beautiful 

 crimson, and have a pleasing fragrance. 



