Responsible for growth in thickness and wound healing
Botanists define cambium as a divisible tissue made up of embryonic cells. One of the control centers for the growth of shrubs and trees is hidden behind the sober scientific definition. As the illustration below shows, the cambium is located just below the bark between the bast and wood. The cambium ring fulfills these tasks:
- Intensive cell division in two directions during the growing season
- Formation of new wood on the inside and fresh bast on the outside
- Generation of wound tissue after injuries to trunk or branches
- No wound healing without callus
- Get to the wood: cut the Japanese cherry
- Red dogwood - native wood for dense hedges
The cambium ring is the only layer in the trunk and branch that forms new tissue. The sapwood with elongated vessels develops from the cells released inwards. These channels transport water and nutrients from the roots to the leaves. Over time, tannins are deposited, so that sapwood hardens into heartwood and takes on scaffolding functions. Valuable bast, which also has conduction paths, develops from the cells released to the outside. Here reserve substances flow from the leaves into the roots. The outer, old bast layer turns into the visible bark.
Cambium turns into callus on cuts
As a further key function in the growth of woody plants, cambium takes on the healing of small and large injuries, such as after a cut or storm damage. The process can be recognized by the bead-like tissue that forms along the edges of the wound. A special wound tissue, called callus, gradually develops from the exposed cambium. In the course of time, the newly formed callus tissue overwhelms the open wound in order to protect it from pathogenic agents and the effects of the weather.
The smoother the wound edges, the better the healing process after a cut back. So that cambium tissue can transform into callus and cover the open wound, cuts are smoothed with a sharp, disinfected knife. After a winter cut, coat the wound edges thinly with tree wax (€ 5.99 at Amazon *) to protect the cambium ring from frost damage. No wound treatment is required for the rest of the year.