90 



Fig. 36. 



Perennial Sow Thistle, Field Sow Thistle, or Corn Sow 



Thistle. 

 Son^hus arvensis, (L). 



A perennial weed, 1 to 3 feet high, with large and vigorous root- 

 stocks, full of a milky white juice. The stems are rough, and the 

 growth of the lower part of the plant is rank. The leaves are deeply 

 cut and furnished with small spines, and at their base clasp the stem. 

 The flowers are bright yellow, of fair size, ^ in. across, and quite sim- 

 ilar to those of the Dandelion. They close up in strong sunlight. The 

 <?alyx, or flower cup, is green and covered with yellowish bristles. 

 The seed is brown in color and about 1-8 in. long, with both longitud- 

 inal and transverse markings. To the top, a tuft of silken hair is 

 attached (Fig. 36a.) An average plant produces about 2,000 seeds. 



Time of flowering, June- August. 



Time of seeding, June-August. 



Dispersal — by running rootstocks, and the scattering of seeds by 

 the wind. 



The Sow Thistle draws much water from the soil and is a heavy 

 feeder. It is less troublesome on stiff clays than elsewhere. 



Eradication. The method used for the eradication of the Canada 

 Thistle is recommended for this weed. 



