254 



NATURE STUDY REVIEW 



[9:8— Nov., 1913 



Under certain conditions white clover and some other 

 plants are useful members of permanent sod. 



There are many other plants in the pasture, considered by 

 us undesirable there, and hence called weeds. They mostly 

 produce abundant seed and have excellent means of giving it 

 wide dispersal. Many seeds find openings among the grasses. 



? 



Fig. 31. Blue grass (a) and timothy (6): flowering spikes and roots; 

 with the two modes of producing new shoots underground shown 

 at {c). 



A few of these plants survive by virtue of the same qualities 

 that save the grasses Some like the thistles and the teasel 

 are spiny, and able to ward off destroyers. Many, like the 

 mullein, the buttercup, the daisy, and the yarrow are un- 

 palatable and are not sought by the cattle. Many grow well 

 underground with only their leaves exposed to danger of 

 trampling. If some leaves are cut off new ones are promptly 

 grow. Then, after a long season of growth, they suddenly 

 shoot up flower stalks into the air, and quickly mature fruit. 

 They do this, too, at the season of abundant grasses, when 

 their exposed shoots are least endangered by close cropping. 

 Some, like the dandelions and the plantains, produce so many 

 flower stalks, they can survive the loss of some of them. 

 Finally there are some, like the speedwells and the chickweeds 

 so small they are inconsequential. They merely fill the 

 chinks between the others. 



