320 Field, Forest, and Wayside Flowers 



to produce offspring inheriting the habits of their 

 parents, and of these offspring the more tender 

 and defenceless will be eaten, while the thorniest, 

 stringiest, or bitterest individuals will be spared, 

 to produce offspring thorny, stringy, and bitter, 

 like themselves. So, in the course of generations, 

 Nature brings into being a number of plant-fam- 

 ilies, each protected from browsing animals by 

 some well-marked peculiarity." 



The common mullein, a plant of the roadsides 

 and pastures, is rendered unappetizing by the down 

 which covers its leaves, and which, it seems, is 

 doubly useful. For "hairs," says Vines, " often 

 serve to diminish transpiration and radiation, and 

 to screen chlorophyll from too intense light, and 

 a clothing of hairs is characteristic of plants which 

 habitually grow in dry soils and in sunny situa- 

 tions." But in this case the fuzz which clothes 

 the mullein-leaves makes them as " dry eating" as 

 so much flannel. 



The great cool leaves of the burdock are bitter 

 and sour exceedingly (Fig. 90). So efficient are 

 these devices of Nature for the protection of this- 

 tles, mullein, and burdock, that they are generally 

 spared, even in close-cropped pastures. The dan- 

 delion and wild lettuce-leaves contain a bitter juice. 



