Q.11:- What is periderm? How does periderm formation take place in the dicot stems?
The meristematic tissue which develops to replace the worn out epidermis of dicot stem is called cork cambium or phellogen. The phellogen cuts off cells on both sides. The outer cells differentiate into cork or phellem. The inner cells differentiate into secondary cortex or phelloderm. Cork is impervious to water due to suberin deposition in the cell wall. The cells of secondary cortex are parenchymatous. Phellogen, phellem and phelloderm are collectively called periderm.