Question

Distinguish between Phellem and phelloderm.

Answer 1

Hint: Phellogen is a meristematic cell layer responsible for the development of the periderm. The periderm consists of three different layers which are phelloderm, phellogen, and phellem.

Complete answer:

Phellem	Phelloderm
It is known as cork.	It is commonly called as Secondary cortex
It is present towards the outer side and produced by the phellogen.	It is present towards the inner side and also produced by phellogen.
It is made up of dead cells.	It is made up of living cells.
Cells are closely packed.	Cells are not closely packed.
The cells of phellem are impermeable to water.	The cells are permeable to water.
It provides protection.	It helps in storage of food materials and ergastic substances.
Amount of tannin is high in cells.	No tannin is deposited.
Cells are suberized.	Cells are not suberized.
Pores and lentils occur on phloem	Pores and lenticels are absent.

There are three types of periderm listed below:
- Phelloderm: This layer is present inside the cork cambium, which is composed of living parenchyma cells.
- Phellogen: This layer is also known as cork cambium and is a meristem that gives rise to periderm.
- Phellem: This layer is cork and dead at maturity and is air-filled protective tissue on the outside.

Note: Both phellem and phelloderm are produced by the tissue phellogen and are the types of periderm and found in the cork cambium of the plants. Phelloderm is present toward the inner side whereas phellem is present outside.