INTRODUCTION


A good many popular books on trees have been published in the United
States in recent years. The continually increasing demand for books of
this character indicates the growing public interest not only in the
trees that we pass in our daily walks, but also in the forest considered
as a community of trees, because of its aesthetic and protective value
and its usefulness as a source of important economic products.

As a nation, we are thinking more about trees and woods than we were
wont to do in the years gone by. We are growing to love the trees and
forests as we turn more and more to outdoor life for recreation and
sport. In our ramblings along shady streets, through grassy parks, over
wooded valleys, and in mountain wildernesses we find that much more than
formerly we are asking ourselves what are these trees, what are the
leaf, flower, twig, wood and habit characteristics which distinguish
them from other trees; how large do they grow; under what conditions of
soil and climate do they thrive best; what are their enemies and how can
they be overcome; what is their value for wood and other useful
products; what is their protective value; are they useful for planting
along streets and in parks and in regenerating forests; how can the
trees of our streets and lawns be preserved and repaired as they begin
to fail from old age or other causes? All these questions and many more
relating to the important native and exotic trees commonly found in the
states east of the Great Lakes and north of Maryland Mr. Levison has