phellogen
/ˈfɛloʊdʒən/
noun
- The layer of cells in woody plants that produces cork (phellem) on the outside and phelloderm on the inside; also called cork cambium.
- The phellogen is active during the growing season, producing new cork cells.
- In older trees, the phellogen may become inactive or die.
- The phellogen is essential for the formation of protective bark.