It is not the easiest thing in the world to learn to know trees by the bark alone. To the beginner, so many trees with dark, furrowed bark look strangely alike, although the trees are not even related to each other. The foresters began with trees that have peculiar and easily recognised bark. So we shall begin here, and hope that the hard cases will gradually become easier.
Every tree wears a garment of bark from the ground up to the utmost twigs. The thinnest bark is on the youngest branches. The thickest is on the trunk.
Begin with the white birch upon the lawn. The bark of this tree is made of thin layers; the outer one shining like white satin. It breaks and tatters, and peels off around the trunk. Three-cornered patches of black are found under each branch, and others on the trunk show where branches once came out, but were broken or cut off.
Do you notice narrow, horizontal slits of different lengths on the birch bark? These are breathing holes that let the air in to the layer under the bark. Spongy, porous substance fills these slits, but allows the air to pass through. At the lower part of the trunk the satiny outer bark is shed, leaving dark under layers, rough and checked into irregular blocks. As the tree grows older, the trunk becomes rougher and darker, but the branches always show the kind of bark that the little tree wore.
In the Northern woods the white bark of the canoe birch is stripped from the trees in layers as thick as sole leather. Out of these the Indians once made their bark canoes. Now the same material is used for making all manner of trifling souvenirs to sell to tourists. A square of this thick bark, cut on the smooth side of a trunk, may be split into a great number of thin sheets. This the camper uses to write letters upon, and it is a beautiful and fitting substitute for note paper, when one is camping out.
We recognize birches by their silky, tattered bark
The beech trunk is clothed in smooth, pale grey bark
It is a great pity that so many beautiful trees are girdled and killed to supply the needs of camping parties. If the bark were stripped but part way around it would not kill the tree.