Korkkikambium

Korkkikambium, also known as the phellogen, is a secondary meristematic tissue in the stems and roots of vascular plants. It is a layer of actively dividing cells that lies between the epidermis and the cortex, or between the phloem and the periderm. The primary function of korkkikambium is to produce new cells that contribute to the thickening of stems and roots, a process known as secondary growth.

The cells of the korkkikambium divide periclinally, meaning parallel to the surface of the stem or root. This division results in the production of new tissues. On the outer side, it generates cork cells, which are also called phellem. These cork cells are typically dead at maturity and possess suberized cell walls, making them impermeable to water and gases. This outer layer of cork serves as a protective barrier against mechanical injury, dehydration, and pathogen invasion.

On the inner side, the korkkikambium produces phelloderm, which are living parenchyma cells. The phelloderm can be involved in storage of food reserves and may also play a role in gas exchange through lenticels, which are pores that can develop in the cork layer. Collectively, the cork (phellem), the korkkikambium (phellogen), and the phelloderm form the periderm, which replaces the epidermis in woody plants as they undergo secondary growth. The periderm is a significant component of bark.