hich the problem of identifying trees may be
approached. The majority attempt to recognize trees by their leaf
characters. Leaf characters, however, do not differentiate the trees
during the other half of the year when they are bare. In this chapter
the characterizations are based, as far as possible, on peculiarities
that are evident all year round. In almost every tree there is some one
trait that marks its individuality and separates it, at a glance, from
all other trees. It may be the general form of the tree, its mode of
branching, bark, bud or fruit. It may be some variation in color, or, in
case of the evergreen trees, it may be the number and position of the
needles or leaves. The species included in the following pages have thus
been arranged in groups based on these permanent characters. The
individual species are further described by a distinguishing paragraph
in which the main character of the tree is emphasized in heavy type.

The last paragraph under each species is also important because it
classifies all related species and distinguishes those that are liable
to be confused with the particular tree under consideration.

GROUP I. THE PINES

[Illustration: FIG. 1.--Twig of the Austrian Pine.]

How to tell them from other trees: The pines belong to the _coniferous_
class of trees; that is, trees which bear cones. The pines may be
told from the other coniferous trees by their leaves, which are in
the form of _needles_ two inches or more in length. These needles
keep green throughout the entire year. This is characteristic of all
coniferous trees, except the larch and cypress, which shed their
leaves in winter.

[Illustration: FIG. 2.--Twig of the White Pine.]

The pines are widely distributed throughout the Northern Hemisphere,
and include about 80 distinct species with over 600 varieties. The
species enumerated here are especially common in the eastern part of
the United states, growing either native in the forest or under
cultivation in the parks. The pines form a very important class of
timber trees, and produce beautiful effects when planted in groups
in the parks.

How to tell them from each other: The pine needles are arranged in
_clusters_; see Fig. 1. Each species has a certain characteristic
number of needles to the cluster and this fact generally provides
the simplest and most direct way of distinguishing the different