The periderm is the secondary dermal tissue with stem axis and the tertiary boundary tissue in the root.
The complex fabric is constructed from outside to inside of:
- Cork ( phellem ), totes, multi-layer fabric
- Cork cambium ( cork cambium ), single- meristem
- Phelloderm, a partially multilayered parenchyma, often photosynthetically active tissue
Walls of the cork cell are alternately impregnated with suberin and cutin.
Function and development
Through the secondary growth, the epidermis is often torn. Therefore, a second protective tissue (secondary dermal tissue ) must be formed among them. This function takes the periderm.
In the cork cambium ( cork cambium ) ( phellem ) and inward parenchymatous cells in a small amount ( phelloderm ) are formed outward cork cells.
The deported to the outside cork cells die off, because they do not get more water through the medullary rays. They stain brown as they settle beef dyes, which serve as protection against rot.
In some trees, the first cork tissue is permanent, they do not form a scab. It is also called Peridermbäume or bark trees. The most famous local representatives are the beech, hornbeam, common hazel, rowan, and the currants and laburnum species.
In the formation of bark Peridermien also play an important role.