2 Answers
When secondary growth occurs in the dicot stem and root, the epidermal layer gets broken. There is a need to replace the outer epidermal cells for providing protection to the stem and root from infections. Therefore, the cork cambium develops from the cortical region. It is also known as phellogen and is composed of thin-walled rectangular cells. It cuts off cells toward both sides. The cells on the outer side get differentiated into the cork or phellem, while the cells on the inside give rise to the secondary cortex or phelloderm. The cork is impervious to water, but allows gaseous exchange through the lenticels. Phellogen, phellem, and phelloderm together constitute the periderm.
Cork cambium is a meristematic tissue which develops in the cortex region of mature stem. Cork cambium is formed to replace the broken epidermal layer of stem. The cells cut off on the outer side by cork cambium become cork. Hence, it can be said that the cork cambium is a tissue which forms cork.