THE PLANT 75 



handle (see Fig. 58). If biennials are not cut low enough, 

 they will branch out anew and make many seeds. The 

 most common biennials are the 

 thistle, moth mullein, wild car- 

 rot, wild parsnip, and burdock. 



FIG. 58. A SPUD FIG. 59. HOUND'S TONGUE 



A third group of weeds consists of those that live for 

 more than two years. These weeds are usually most diffi- 

 cult to kill. They propagate by means of running root- 

 stocks as well as by seeds. ' Plants that live more than 

 two seasons are known as perennials and include, for exam- 

 ple, many grasses, dock, Canada thistle, poison ivy, passion, 

 flower, horse nettle, etc. There are many methods of 



