Trees growing in the open
may have branches, leaves and twigs close to the ground, but those
growing under the conditions of the forest tend to have relatively few
lower branches. This can make observation of leaf and twig details
difficult. Although it’s not quite as good as holding a specimen in
your hand, binoculars can definitely help. Otherwise we can rely
partly on what we might call circumstantial evidence.
For deciduous trees—trees
that drop their leaves in winter—there’s a reasonable degree of
certainty that many of the leaves on the ground under a given tree
came from that tree. Likewise, the fruits that litter the ground in
the fall or winter have a comparatively good chance of being from the
individual tree or trees above. Of course this is a bit more reliable
with heavy fruits like acorns and other nuts than with wind-dispersed
seeds like those in maple and ash.
Technical characteristics
aside, in some ways tree identification is like recognizing someone
you know in a crowd. If you were to try to describe what criteria you
use to conclude that the person you see is who you think it is, you
might have some difficulty. You just recognize that person without
thinking about the process. A similar thing begins to happen, with
practice, in tree identification. And the key, of course, is
practice.
Since it would be
impossible to cover the more than 800 species of trees native to North
America in an article like this, the objective will be to touch on
representatives occurring primarily in the northeastern US and leave
others for possible later articles.
Opposites
|
Fig. 1 White Ash treetops
Fig. 2 White Ash twig
Fig. 3 White Ash twigs
with leaves and fruit |
Ash
White ash is one of
several species of ash native to the northeast. All the ashes have an
opposite branching pattern. In other words, at each point where a new
twig grows from a bud on a small branch in the spring, a nearly
identical twig grows from a bud directly, or almost directly, on the
opposite side. This crosswise pattern in the treetops can be evident
even from the ground, and especially when contrasted with neighboring
tops of other trees that have an alternate branching pattern. White
ash has fairly stout twigs, a trait that helps make this feature more
discernible. Ash trees, as a rule, have compound leaves. This
means that each individual leaf is divided into leaflets as shown in
figure 3.
