27. Give one basic functional difference between phellogen and phelloderm.
Phellogen is a meristematic tissue, while phelloderm is a permanent tissue. Phellogen (cork cambium) develops from the cortical ceils, sometimes from pericycle cells. These cells actively divide and forms phellem on outerside and phelloderm (cortex cells) innerside on so phelloderm takes its origin from phellogen.
