Which of the following statements about cork cambium is incorrect?

Cork cambium or phellogen is a secondary meristem and usually develops in the cortex region. Phellogen is a couple of layers thick. 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. 

 Phellogen, phellem and phelloderm  are collectively known as periderm.

At certain regions, the phellogen cuts off closely arranged parenchymatous cells on the outer side instead of cork cells. These parenchymatous cells soon rupture the epidermis, forming a lens-shaped opening called lenticels.