Description of the Russian Thistle. 199 



be so far kept in check that it may not seri- 

 ously injure the crops. It frequently con- 

 tinues to grow and mature seeds until the 

 frosts become severe enough to destroy its 

 vitality. The earlier plants mature much 

 of the seed in the latter part of August 

 and in September, hence all plants cut off 

 or pulled up after that time should be 

 burned. It is claimed that an average sized 

 plant is capable of maturing from 20,000 

 to 30,000 seeds. 



This weed is specially troublesome in 

 grain crops ; the later the crops and the 

 more weakly they are the greater will be 

 the injury done. It grows with sufficient 

 vigor under some conditions to prevent the 

 harvesting of the grain by the ordinary 

 binder, and in all cases on account of its 

 bulk it makes harvesting difficult and 

 expensive. It infests all kinds of crops, 

 but is easily destroyed in such as are culti- 

 vated. This weed grows to some extent on 

 the native prairie, but not so much where 

 grasses are well established in the soil, as 

 where prairie fires, gophers or prairie dogs 

 have prepared a seed bed for it. 



The Russian thistle is propagated solely 

 by means of its seed and its marvelous 



