How does periderm formation take place in dicot stem

Periderm is a component of secondary growth that is formed towards the surface of stems and roots, having phellem, phellogen and phelloderm. Phellogen or cork cambium develops in a subepidermal layer in the stem and from pericycle in roots, its cells undergo bipolar division. The cells formed on the outer side undergo suberization, deposition of tannins and death of cellular contents. The outer tissue of dead suberised cells is called cork or phellem. At places, it contains lenticels or aerating pores having loosely arranged suberised complementary cells. Cells formed by phellogen on the inner side constitute secondary cortex or phelloderm.