30 PRODUCTIVE FARMING 



and seeds each year. The roots or underground parts live 

 over from year to year, and usually new leaves and stems 

 are sent up from the old roots in the spring. Such weeds 

 are most commonly found in pastures, hay-fields, lawns, 

 roadsides, and fence rows. They grow in places where their 

 roots may live undisturbed in the soil from year to year. 

 Because of this we may conclude that rotation of crops will 

 help destroy them. When a hay-field is plowed and harrowed 

 for corn, nearly all kinds of perennial weeds are killed. 



Examples of perennials are: Canada thistle, quack or 

 couch grass, Johnson grass, curled or yellow dock, smart- 



FIG, 15. Seed samples in wooden case, bottles held in place with shoestring. 

 (Agricultural Education.) 



weed, dandelion (Fig. 136), golden hawkweed, milk-weed, nut 

 sedge, ox-eye daisy, rib-grass plantain, wide-leaved plan- 

 tain, red field sorrel, toad flax, white and purple fall aster, 

 wild garlic, chicory. 



Persistent Weeds. Among the perennial weeds those 

 which are most troublesome are either provided with (1) a 

 rapid means of spreading, or (2) a fleshy root or bulb. Those 

 with runners which take root a-t the joints are seen in some 

 grasses, as Bermuda grass, and the trailing white clover, and 

 the running buttercup. Some have underground running 

 rootstocks that send up new shoots at the joints, as Johnson 



