DESCRIPTIVE MANUAL 111 



Russian Thistle {Salsala Kali L. var. tenuifoUa G. F. W. Mey). 



Description. — An herbaceous, smooth or slightly pubescent an- 

 nual, diffusely branched from the base, from ly^-S ft. high, spherical 

 in the mature form ; leaves fleshy, alternate, succulent, linear, sub- 

 terete, 1-2 in. long, pointed in the older specimens, upper leaves in 

 the mature plant persistent, each subtending 2 leaf -like bracts and 

 a flower; stem and branches red; apetalous flowers solitary and ses- 

 sile; calyx consisting of 5 persistent lobes, enclosing the dry fruit 

 which is usually rose-colored, about 1-12 in. long; 5 stamens nearly 

 as long as the calyx ; pistils with 2 slender styles producing a single 

 obconical depressed seed, dull gray or green, without albumen ; em- 

 bryo spirally coiled ; on germination cotyledons are subterete. The 

 plant flowers in July or August, the seeds maturing in August. 



Distribution. — Russian thistle is native of Russia and western 

 Asia. Since its introduction into the Dakotas it has been widely 

 scattered in the northern states and is common from Minnesota to 

 the Pacific northwest and in the Rocky mountains from Montana to 

 New Mexico. It is widely scattered in Iowa but abundant only dur- 

 ing dry years, along the right of way of railways, and in the vicinity 

 of stockyards. 



Extermination. — The Russian thistle as said before, is an annual, 

 hence it would seem an easy matter to destroy it ; and as a matter of 

 fact, when taken in time, it is not a difficult weed to remove. Its nox- 

 iousness comes largely from the fact that the plant is so productive. 

 If a Russian thistle is once cut off at the surface of the ground it 

 never grows again ; hence in cultivated fields it is not likely to prove 

 a great pest. The question is, however, a very different one in pas- 

 tures, meadows and roadsides; here the weeds oannot be removed 

 by cultivation and many of the plants mature their seeds unobserved. 

 The removal of the weeds along the roadsides is important, because 

 it is largely from this source that our fields become infested. The 

 removal of such weeds can be best accomplished by running over the 

 patch with a mower. 



Fletcher and Clark recommend as follows : ' ' Hand-pull wherever 

 practicable. Harrowing growing crops is an effective remedy ; it is 

 easily killed by this method when young. The harrow should be ap- 

 plied just before the grain emerges from the ground and again when 

 the crop is three inches high. ' ' 



