26. MORE ABOUT WEEDS. 



The upper part of a plant of the Canada thistle is shown 

 in Figure 67, i, also a portion of the underground stem 

 with its rootlets (2). 

 At 3, is shown a 

 single flower, with its 

 seed and downy 

 hairs. The seed, also, 

 is shown, in 4, nat- 

 ural size, and, in 5, 

 as it appears under 

 a microscope. 



The root of the 

 Canada thistle is per- 

 ennial. It sends out 

 underground stems 

 o r rootstocks i n 

 every direction. It 

 is because of this fact 

 that it spreads so 

 rapidly and is so dif- 

 ficult to get rid of. 

 These underground FlG - 6 ?- Canada thistle - 



stems develop buds at their joints, which grow upward, 

 forming new plants. Thus a single plant, if left alone 

 for two or three years, may, by means of its rootstocks 



G. & M. Ag. o 129 



