White birch bark was once used for writing instead of paper
White color is very common among plants while plants with white bark are very rare. The only birch tree has this unusual appearance – the white bark of the tree. The bark that surrounds the birch tree greatly changes its appearance during the life of the birch tree, ie from youth to old age. The tree is only covered with brownish color in young birch up to half a meter high. The middle-aged birch already has a white bark with black transverse lines. During this period, the trees look especially beautiful. An old birch that is at the end of its life has a tree covered with black and white bark with spots. White islands of birch bark are scattered on the general black background. Such a spotted image is obtained because the tree grows in width and deep cracks are created on the bark. These cracks do not heal in the birch bark but in other protective tissues of dark color. Birch bark is preserved only in the spaces between the cracks.
Birch has a white bark because birch cells contain a special substance that acts as a bleach. There will be a trace of chalk if a person in dark clothes touches a birch. This phenomenon is very unusual and rare in the plant world.
The main purpose of birch bark is to protect the inner living tissues of the tree from drying out. This is the basic role of white bark and a vital role for wood. The cells of the birch bark are very densely connected to each other. They look like bricks if we put them together well. There are no gaps between the cells. In addition, the cells are firmly connected and strongly adhered to each other. The cell walls are soaked with a special fatty substance that does not leak water. All this allows moisture to be stored inside the wood. In the 19th century, scientific research first confirmed the beneficial and healing properties of birch bark and birch (for the treatment of minor superficial wounds and burns).
The birch tree grows in width every year. Birch is getting thicker with age. The annual increment, however, is very small — as thick as a plain sheet of writing paper. It is interesting that the growth goes from within. That is why the youngest layers are the deepest, while the oldest layers are on the surface. The outer layers are often partially discarded in the form of a piece of thin white strip torn by the wind. We notice thin layers if we tear off a piece of bark. Each layer is a one-year increment. The separate layers are firmly connected to each other. They form a single whole. Birch bark was once used for writing. The birch bark really resembles a thin book with a lot of connected pages.