RIVALRY OF PLANTS 149 



And so, with every plant that grows, we shall 

 see these same tendencies — instincts shall we call 

 them? — to ward off the enemy and make use of 

 the friend. 



So long as plants grow wild, the frosts, the 

 winds, the hailstorms, the droughts, and the ani- 

 mals are principal among the enemies with which 

 they have to reckon. 



So long as they grow in the woods, or 

 on the mountains, or in the deserts, the bees 

 and the birds and the butterflies — the warmth 

 of the sun and moisture and fertility of the soil 

 — these are among the friendly factors in 

 their lives. 



;But when we take plants under cultivation, 

 we upset their whole environment. 



We build fences around our blackberries so 

 that they need no thorns. We save the seeds of 

 our radishes, and the bulbs of our lilies, and 

 through human organization distribute them and 

 plant them wherever they will grow. We cut 

 grafts from our apple trees and ship them from 

 county to coimty, and State to State, and nation 

 to nation, and zone to zone. We select, and im- 

 prove, and plow, and harrow the ground for our 

 plants; we water them when they are dry; we 

 surround them with shade trees if they need 

 shade, we cut down the shade trees if they prefer 



