phelloderm

A limited number of cell layers may form interior to the cork cambium, called the phelloderm.

The phelloderm, which is not always present in all barks, is a layer of cells formed by and interior to the cork cambium.

Cells that grow inwards from the phellogen are termed phelloderm, and cells that develop outwards are termed phellem or cork (note similarity with vascular cambium).

Often a secondary covering called the periderm forms on small woody stems and many non woody plants, which is composed of cork (phellem), the cork cambium (phellogen), and the phelloderm.