338 



INTRODUCTION TO BOTANY 



farther westward. A few weeds, like the buffalo bur (fig. 244), 

 have made their way eastward from the Great Plains. 



315. How to avoid and 

 destroy weeds. It is often 

 easier to keep weeds out 

 of cultivated ground than 

 to destroy them after they 

 get a foothold there. The 

 principal means of avoid- 

 ing weeds are to plant as 

 few weed seeds as possi- 

 ble and to allow few to be 

 planted by natural agen- 

 cies. This means that the 

 seeds used for the farm 

 and garden shall be as 

 free as possible from 

 weed seeds, that all ma- 

 nure used shall contain 

 as few weed seeds as pos- 

 sible, and that all spots 

 which might serve as 

 breeding places for weeds 

 must be carefully watched 

 and prevented from seed- 

 ing the adjacent ground. 

 Neglected fence rows and 

 other bits of uncultivated 

 land may grow enough 



FIG. 245. Couch grass, one of the worst weeds of the northeastern states 



It is rapidly propagated by its long rootstocks (rh). Note the manner in which 

 young shoots (a, b, c) are shown arising from the nodes of the rootstock 



