TREES AS GOOD CITIZENS 
42 
growth is another point for consideration and in this it 
is as necessary to know what to avoid as what to seek. 
The lure of rapid growth has been responsible for the 
planting of numbers of Silver Maples, Carolina Poplars, 
Water Oaks and other species undesirable for the region 
where they were planted. It must be remembered that 
these trees grow rapidly but that they are short lived. 
A Carolina Poplar or Silver Maple will have to be replaced 
at about the time a Red Oak, a Sycamore or a Norway 
Maple has reached its best development. It must be 
remembered also that careful cultivation is a factor in 
tree growth, and that some of the slower growing varieties 
will show more rapid increase, under proper care, than 
the desirable ones would if left to shift for themselves. 
Shade-giving qualities are also an important factor, 
particularly for street trees. Too much shade may be 
as undesirable as too little, and selection should be 
based on the character and width of the street. For 
narrow streets it is best to have trees of slender growth 
or small size, with light foliage, or those in which develop¬ 
ment can be controlled by pruning, in order that the sun¬ 
light may not be entirely shut off from the houses and 
the grass. On thoroughfares of unusual width, the utmost 
in dignity and effectiveness may be obtained by using the 
largest trees and allowing full development of the crown. 
A point to be borne in mind is that beauty is not the 
sole result desired in successful shade tree development. 
If it were, it would be hard to resist the temptation to use 
exclusively trees of the broad spreading type, for the sake 
of the overhanging arch of foliage which would result 
from the meeting of the branches from the two sides of the 
street. Experience has shown that, despite the beauty of 
an archway shade, the dense foliage of the arch may 
prevent the free circulation of air, shut off sunlight from 
