PLANTS INFLUENCED BY THEIR SURROUNDINGS 121 



strong wind, they show by their bent forms and curious 

 shapes its strong influence (figure 68). The dying 

 of the branches on the windward side (figure 68) is 

 due to the drying effect ofi the wind, which may in- 

 crease the loss of 

 water as much as 

 twenty times (see 

 page 76). Even 

 moist winds may 

 have a drying effect. 



It is interesting to 

 observe that when 

 for any reason the 

 leaves and branches 

 are developed prin- 

 cipally on one side 

 the stem grows 

 thicker on that |- 

 side. This may 

 often be observed 

 in vines climbing 

 on walls. 



The effect of wind 

 in drying up the blossoms of fruit trees is well known. 

 For this reason, and also because the winds are often 

 cold and do considerable damage to trees laden with 

 ice and snow, the use of wind-breaks is frequently 

 necessary. 



FIG. 68. The effect of wind on the growth 

 of a tree. 



