A thin layer of living cells between the inner bark and the woody part of a tree. This is where nutrients are carried to and from the leaves. The cambium is responsible for diameter growth of trees.

A layer immediately below the bark of a plant from which annual growth occurs. (For all practical purposes it is the green layer beneath the bark.)

A cell layer in the outer part of the tree that produces new wood for the growth of the tree. The cambium encloses the other living parts of the tree. Cambial cells divide to produce wood cells on the inside of the cambium layer and phloam, or bark cells on the outer side of the cambium.