Tree bark

tree bark

Every tree has its own kind of bark. The bark of a paper birch is smooth and white. The bark of a hickory tree is dark and shaggy. The bark of a sycamore has patches of brown and white. But bark, no matter how it looks, always helps a tree in the same ways.

The outer layer of bark is made of cork, which is waterproof. This layer is a protection against injury from animals and against drying winds. The inner layer of bark can be hurt easily and needs protection. It plays an important part in the life of the tree, for it is made up partly of tubes, called "sieve tubes," that carry food for the tree. Just inside the bark is another región that needs protection. It is the región where new wood is formed. In the new wood water travels up from the roots to the treetop.

Once in a while lightning strikes a tree and peels off all its bark. The tree then has no chance at all of living.
The indians used to make canoes of birchbark. Bark can be used in building other things. too. Several drugs come from bark. One of them is quinine. The spice cinnamon comes from the bark of the cin­namon tree.

Tannin used in making leather comes from the bark of oak trees. Cork comes from the bark of the cork oak. Bark helps people as well as the trees it grows on.