Plants as Affected by Insufficient Wind. 139 
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 the wind and the 
greater is the leverage upon the trunk; several small 
branches are better able to bear the tempest than a very 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 ex- 
posed to prevailing winds, while others, as the sugar maple,t 
and Norway maple are not thus inclined. 
B—Tue Puant 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 at- 
tacks than those having freer circulation of air between the 
trees. 
247. Insufficient Wind Promotes Damage from 
Frost by permitting the colder 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 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, it is doubtful 
if their fruitfulness is often much restricted by insufficient 
wind. 
* Acer dasycarpum. + Acer saccharinum. { Acer platanoides, 
