THE STEM 



237 



shearing stress of wind and storm, it must have a certain amount 

 of strength to withstand such stress or possess some other means 

 to lessen thQ destructive eft'ect of the wind. 



Stems are ordinarily not strong enough to stand against 

 hurricanes; their leaves are torn awaj, branches broken, yea, 

 whole trees uprooted and destroyed. Tlie destructive effect of 

 such a tempest can be specially seen on isolated trees. If they 



Fig. 216.— Trees deformed by the effect of the sea-breeze. 



stand in groups, they help one another and resist the storm-wind 

 with their united strength. Winds also change the mode of the 

 growth of trees and imprint in their very faces signs of the hard 

 battle which they have continually to endure. Such trees 

 follow with their branches the direction of the prevailing winds 

 (fig. 216), or spread out their branches in horizontal sheets in- 

 stead of growing high and increasing the plane of resistance 



