THE MONTHT.Y BULLETIN. 193 



RUSSIAN THISTLE. 



{Sahola hall L. var. teiiuifolia. G. W. F. May.) 



By O. W. Newman. 



DESCRIPTION. 



The Russian thistle belongs to the Chenopodiacese or goosefoot family, 

 and not to the tliistle tribe, as has commonly been supposed. The term 

 thistle eomes from the short, sharp thistle-like leaves which are char- 

 acteristic of the mature plant. It is an annual of wide distribution, 

 introduced into this country from Asia. It branches ditfusely, is very 

 bushy, and somewhat pubescent. The leaves, especially in the young, 

 Hre very narrow, fleshy, sharp pointed, and about an inch in length; 

 they always alternate and are of a reddish color. The flowers are 

 small, single and sessile, appearing from June to the first part o^ 

 August; seeds verj^ numerous, conical and spirally coiled. 



After blooming, the plants gradually ])leach until nearly white. 

 The stems become very tough and the bristle-like leaves stiffen into 

 thorn-like protuberances along the stems. At maturity the stem breaks 

 close to the ground and the plant is blown and tumbled about by the 

 wind, scattering its seeds over a large territory. Because of its rolling 

 habit it has often been called "tumble weed." 



INJURY. 



The Russian thistle is one of the most persistent pests the farmers 

 of California have to contend with and a constant watch should be 

 kept to prevent its spread. It is found from one end of California 

 to the other and many counties have begun open war against it. 

 In 1910, the county horticultural commissioner of Ventura County 

 made a thorough studj^ of Russian thistle as found in his county and 

 elsewhere and made the following statement : 



"As a pest to cultivated crops, the Russian thistle can not be com- 

 pared to morning-glory. Canada thi.stle, Johnson grass, or white inalva ; 

 but to grain and uncultivated crops it is the worst weed pest known. 

 It not only crowds out all other growths, but takes from the ground 

 a large amount of nourishment, which is always needed in grain fields. 



"In reproduction it is remarkably prolific. The following, worked 

 out by Mr. L. H. Dewey, will give some idea of this: 



" 'A single plant of average size, two to three feet in diameter, 

 and weighing two to three pounds at maturity when dry, is estimated 

 to bear 20,000 to 30,000 seeds. Single plants have been found six 

 feet in diameter, weighing about twenty pounds when thoroughly 

 dry, and estimated to bear 200,000 seeds. At maturity the heaviest 

 and strongest parts of the plant are the seed-bearing twigs. The inner 

 branches receive little of the wear incident to tumbling about and 

 are only strong enough to hold the plant together.' " 



The plant seems to be particularly a railroad weed. It has appeared 

 first along the railroads in sixteen of the twenty-one states and terri- 

 tories in which it has been .'ntroduced. In nearly all the states where 

 it is now found its wide circulation has been chiefly by railroads, in 

 spite of the fact that railroad companies have generally done more 

 than all other parties to combat it. (Yearbook 1896.) This is further 



