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the useful and ornamental woods used in a region; the differences in the
color of the heart-wood, the character of the annual layers, and the
size and the distribution of the medullary rays, afford enough
peculiarities to distinguish any one from all others.

BRANCHING.--The regular place from which a branch grows is the _axil_ of
a leaf, from what is called an _axillary bud_; but branches cannot grow
in the axils of all leaves. A tree with opposite leaves occasionally has
opposite branches; while a tree with alternate leaves has all its
branches alternate.

Most branches continue their growth year after year by the development
of a bud at the end, called a _terminal bud_. Many trees form this bud
for the next year's growth so early in the year that it is seldom or
never killed by the winter weather; such trees grow very regularly and
are symmetrical in form. Most evergreens are good examples. Fig. 3
represents a good specimen. The age of such trees, if not too great, can
be readily ascertained by the regularity of each year's growth. The tree
represented is sixteen years old. The branches that started the fifth
year, about the age at which regular growth begins, are shown by their
scars on the trunk.

[Illustration: Fig. 3.]

The terminal buds of many trees are frequently killed by the frosts of
winter; such trees continue their growth by the development of axillary
buds; but as growth from an axillary bud instead of a terminal one will
make a branch crooked, such trees are irregular in their branching and
outline. Just which axillary buds are most apt to grow depends upon the
kind of tree, but trees of the same variety are nearly uniform in this
respect. Most trees are therefore readily recognized by the form of
outline and the characteristic branching. A good example of a tree of
very irregular growth is the Catalpa (Indian Bean), shown in Fig. 4. The
tendency to grow irregularly usually increases with age. The Buttonwood,
for example, grows quite regularly until it reaches the age of thirty to
forty years; then its new branches grow in peculiarly irregular ways.
The twigs of a very old and a young Apple-tree illustrate this change
which age produces.

[Illustration: Fig. 4.]

There are great differences in the color and surface of the bark of the
twigs of different species of trees; some are green (Sassafras), some
red (Peach, on the sunny side), some purple (Cherry). Some are smooth
and dotless, some ma