Question

The correct option representing the structures forming phellogen, phellem and phelloderm is

• A. Phellogen: Cork cambium, Phellem: Secondary cortex and Phelloderm: Cork
• B. Phellogen: Cork cambium, Phellem: Cork and Phelloderm: Secondary cortex
• C. Phellogen: Cork, Phellem: Secondary cortex and Phelloderm: Cork cambium
• D. Phellogen: Secondary cortex, Phellem: Cork and Phelloderm: cork cambium

Answer 1

Answer: (B)

As the stem continues to increase in girth due to the activity of vascular cambium, the outer cortical and epidermis layers get broken and need to be replaced to provide new protective cell layers. Hence, sooner or later, another meristematic tissue called cork cambium or phellogen develops, usually in the cortex region. Phellogen is a couple of layers thick. It is made of narrow, thin-walled and nearly rectangular cells. Phellogen cuts off cells on both sides. The outer cells differentiate into cork or phellem while the inner cells differentiate into secondary cortex or phelloderm.