514 COMPOSITAE (COMPOSITE FAMILY) 



Stem two to six feet tall, stout, densely white-woolly, leafy to 

 the top. Leaves oblong lance-shaped in outline but deeply pin- 

 natifid into triangular or lance-shaped segments, armed with long, 

 stiff, yellow spines, white-woolly on the under side, sessile or 

 slightly clasping, the lowest with short, margined petioles. Heads 

 solitary, terminal, about two inches broad, the outer bracts of the 

 involucre lance-shaped and tipped with stout, yellow spines about 

 as long as themselves, the inner ones long-pointed but unarmed ; 

 flowers light purple. 



Another Thistle of the plains, much resembling this one in its 

 dense white-woolliness but smaller and less fiercely armed, is the 

 WAVY-LEAVED THISTLE (Circium undulatum, Spreng), which has 

 a wider range, extending to the Northwest Territory. 



Means of control the same as for C. lanceolatum. 



CANADA THISTLE 



Circium arvense, Scop. 

 (Cdrduus arvensis, Robs.) 



Other English names: Creeping Thistle, Small-flowered Thistle, 



Perennial Thistle, Cursed Thistle. 



Introduced. Perennial. Propagates by seeds and by rootstocks. 

 Time of bloom : June to August. 

 Seed-time: July to September. 

 Range: Newfoundland to the northwest provinces and British 



Columbia, southward to Virginia and Kansas. 

 Habitat: Cultivated fields, meadows, pastures, roadsides, and 



waste places. 



In 1896 the United States Department of Agriculture published 

 a bulletin, "Legislation against Weeds," compiling the acts then 

 on the statute-books of the several states and recommending a 

 general state weed law, sufficiently elastic to fit the varying flora, 

 soils, and climate. Therein it is shown that all but three of the 

 states having laws for the suppression of weeds make it an offense 

 for their citizens to permit the Canada Thistle to mature and 

 scatter its seeds. Penalties are also provided in the case of seeds- 

 men who sell grain, grass, or clover seeds contaminated by its 

 presence but the thistle marches on, bidding defiance in every 



