Plants as Affected by Unfavorable Wind. 145 



or elevations of land. Orchards may be in part pro- 

 tected by planting a wind-break on the windward side 

 (204). 



b Shade trees in exposed situations should be headed 

 low, and the head should be formed of numerous branches. 

 The higher the head, the more it is exposed to wind and 

 the greater is the leverage upon the trunk. Several 

 small branches are better able to bear the tempest than 

 a few larger ones. 



Shade trees for exposed situations should be of species 

 not likely to be deformed by wind. Certain trees, as the 

 white maple,* often develop one-sided if planted where 

 exposed to prevailing winds, while others, as the sugar 

 maple f and Norway maple J are not thus affected. 



B PLANTS AS AFFECTED BY INSUFFICIENT WIND 



246. Insufficient Wind Promotes the development of 

 certain Fungous Parasites (321) by favoring an exces- 

 sively moist atmosphere. Orchards too closely planted 

 or surrounded by wind barriers suffer more from fungous 

 attacks than those having freer circulation of air between 

 the trees. 



247. Insufficient Wind Promotes Damage from Frost by 

 permitting cold air to settle in the lower places (210). 



On these accounts, gardens and fruit plantations should 

 not be entirely surrounded by wind barriers. 



248. Pollination (151) is Dependent upon Wind in many 

 plants, as the coniferous trees, oaks, elms, birches and 

 sedges; but as the pollen of such plants is very light, 

 their fruitfulness is not often much restricted by insuf- 

 ficient wind. 



* Acer dasyearpum. f Acer saccharinum. J A cer platanoides. 



