SHADE TREES. 149 



if pruning is attempted when thej^ are fairh^ well developed, great injury 

 results, and the sj^mmetry of the tree may never be entirely regained. 



The habit of the rock maple is to produce one or two strong vertical 

 leaders, and its ultimate development is such that it seldom gives much 

 trouble so far as pruning is concerned. 



The branches of the pin oak are low and drooping. This objection- 

 able feature detracts from the value of this tree for use on streets, but 

 may be overcome by high pruning. 



The branching habits of the elm, on the other hand, make it one of 

 our most desirable shade trees, the branches invariably forming acute 

 angles with one another. Elms oftentimes develop low, more or less 

 horizontal branches, but these possess no permanent value and may 

 subsequently be removed. The ideal mature elm offers no obstacles to 

 street traffic, and even the wires of public service corporations seldom 

 interfere with the branches. 



On the other hand, evergreens, like the Norway spruce, branch to the 

 ground, and for their best development they should never be placed 

 where it is necessary to prune them, as cutting the lower limbs of the 

 Norway spruce and most other conifers detracts greatly from the beauty 

 of the trees. 



Many trees, including some of the maples, birch, oak, chestnut and 

 elm, and most shrubs, have a habit of suckering or sprouting from the 

 roots. Much of the timber growth such as the chestnut is of this nature, 

 and is termed "sprout growth." This growth is very common in wood- 

 lands and along roadsides which have been cut off. Trees originating 

 from root suckers do not possess the value of those grown from seed, and 

 consequently should not be used for transplanting. Stump growth may 

 develop faster for the first few years than seedlings, but later growth is 

 often slow. As the sprout growth reaches maturity^ it generally becomes 

 involved with the stump, which ultimately decays, leaving an ugly cavit}' 

 at the base of the tree. Most sprout growth shows abnormalities in 

 the foliage the first few j'ears, and it is likewise more susceptible to aphis. 

 The extensive root system of the tree which nourishes it induces malnutri- 

 tion or overfeeding characteristics which are pathological. 



The formation of sprouts on the trunks and branches of trees is of 

 great value in their restoration. Sprouts sometimes originate from the 

 callus of wounds, and are quite serviceable in accelerating healing. 



Soil Conditions, Texture, etc. 



It requires only a glance at the trees of any particular region to observe 

 their natural choice of environment. While this does not always mean 

 that trees will not grow elsewhere with the same degree of vigor as in 

 their natural habitat, — ■ indeed the growth is often more vigorous, — 

 they are very likely to prove less resistant to various troubles. One 

 cannot be always certain, however, that, because a species is restricted 



