Cork is formed from:

Explanation

In hypodermis or outer cortical cells, a layer becomes meristematic which is known as cork cambium or phellogen. This phellogen also cuts off cells both on its outer side and inner side. The cells cut off on the outer side are phellem or cork cells and cells cut off on the inner side are phelloderms or secondary cortex. The phellem or cork cells are dead and have deposition of a fatty substance called suberin (i.e., cork cells are suberized). Suberin is impervious to water and these cork cells are buoyant (i.e., float on water). Phellem, phellogen, and phelloderm collectively constitute periderm.