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 
7 
— 
op ha 
auGil = 
F ne 
Fie. 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 
