Cambium

„Branch wounds are overgrown (closed) by cambium“, says our wall of senses about these branch pieces. But what is cambium?

Cambium is the „growth layer“ of the tree

The trunk of a tree consists of the wood inside and the protective bark outside. The wood is in turn divided into the so-called core, the innermost part, which serves only as support and for storing nutrients. The wood around the core is called sapwood. In it, the tree transports water and nutrient salts dissolved in it from the roots to the leaves.

The bark consists of the outer shell, which protects against environmental influences, the bark and the inner bast. In the bast, the tree transports the nutrients (sugars, carbohydrates) that it has produced in the leaves by photosynthesis to the places where they are needed.

Between the bark and the wood lies the fine „life layer,“ the cambium. As the tree grows, the cells divide. Some become bast and bark, most become new wood.

If an injury occurs, this open area must be closed. Otherwise, moisture, which favors harmful fungi, and germs, as well as pests can enter the tree. First of all, the wound is closed with resin. Then the tree tries to grow over the spot, this is called „overgrowth„. To do this, the cambium forms a special tissue called callus tissue.

Closing wounds can cost a tree a lot of its produced energy. If the tree does not attempt to close the wound for a while after it has been inflicted, this is a bad sign. The tree has „given up“ and will die.

 

This tree has succeeded well in „covering“ an injury with callus tissue.

Sources: Prof. Michael Hohla, Wikipedia, TIME-LIFE Book Der Planet Erde „Wälder“, Reader´s Digest „Wunderwelt der Pflanzen“.