452 THE SMALL GRAINS 



rapidly in our northern plains. It is now distributed in 

 all the most important grain-growing districts, and is a 

 common, troublesome weed on the drier lands, and es- 

 pecially on alkaline soils. 



This plant grows from 1 to 3 feet high, but covers an area of 

 several inches to 6 feet in diameter. It is herbaceous when young, 

 glabrous or slightly pubescent, much branched from the base, but at 

 maturity forms a sphere which is readily loosened from the soil and 

 carried long distances by the wind, scattering seed as it goes. The 

 stems become streaked with red as the plant grows older. The 

 leaves are fleshy, linear, alternate, 1 to 2 inches long. The lower 

 leaves soon fall, but the upper leaves persist, each subtending 2 

 leaf -like bracts and a flower; flowers conspicuous, solitary, sessile, 

 without petals ; blooms from July to September, and matures seed 

 in August ; seeds conical, spirally coiled, base of the cone concave, 

 Yjy inch in diameter, and often covered with a thin gray hull. It is 

 estimated that a large plant will produce from 100,000 to 200,000 

 seeds (Fig. 141 6). 



The plants are easily destroyed while small, and can 

 therefore readily be prevented from maturing seed by 

 cultivation. It is recommended to harrow the growing 

 grain in which this thistle occurs. Plants that mature 

 should be gathered and burned before they break loose 

 and scatter seeds. Cultivation to induce late summer or 

 fall germination is effective, as the plants thus resulting 

 will not mature seed before frost. Sheep will eat the 

 young plants. 



493. Other tumble weeds. In addition to the Rus- 

 sian thistle and tumbling mustard, there are other weeds 

 found in grain fields that break from the soil and tumble 

 about and pile along fences, such as the amaranths (Ama- 

 ranthus sp.) and the buffalo bur. Others belong in the 

 genera Chenopodium, Atriplex, Cycloloma, and Coris- 

 permum. 



