What is peridem ? How does peridem formation take place in the dicot stems ?

Explanation

Phellogem , phellem and phellodem are collectivity known as "Periderm" .
Periderm : Due to the formation secondary vascular tissues inside at stele , a pressure is cortex on the epidermis causing it to rupture . In the mean while , a secondary protective layer is formed called .paridem. from the cortex. The secondary growth in the cortex begins with thee appereiance of a meristematic layer of cells from the cortex. The secondary growth in the cortex begins with the apperiance of a meristematic layer of cells from the middle part of the cortex .This is called "Phellogen or cork cambium ". The cells of the phellon divide periclinally and cuts of new cells on either side . The cells produced towards outside are called cork cells or phellem and the cells produced towards inside are called "secondary cotex cells or phelloderm ." The phellogen ( cork cambium ) ,phellum (cork) and phelloderm (secondary cortex) together constitute "periderm ".