A group of secondary tissues forming a protective layer which replaces the epidermis of many plant stems, roots, and other parts. Although periderm may develop in leaves and fruits, its main function is to protects stems and roots.  The periderm consists of three different layers: Phelloderm Phellogen (cork cambium) Phellem (cork)   Its main function is to protect the underlying tissues from: Desiccation Freezing Heat injury Mechanical destruction  Disease Loss of epidermis. Bounding tissue restricting the pathogen & insects. Allowing gaseous exchange through lenticels.

1. Structure, Development & Function of
Periderm
Presented By: Uzma Batool(34)
Subject: Plant Anatomy
Life Sciences, IUB.

2. Periderm:
• A group of secondary tissues forming a protective layer which replaces
the epidermis of many plant stems, roots, and other parts.
• Although periderm may develop in leaves and fruits, its main function is
to protects stems and roots.

3.  Structure & Development:
The periderm consists of three different layers:
1. Phelloderm
2. Phellogen (cork cambium)
3. Phellem (cork)

4. 1. Phelloderm:
• It consists of cells that resemble parenchyma cells in the cortex.
• The phelloderm cells are phellogen derivatives formed inward.
• Phelloderm consists of living cells with photosynthesizing
chloroplasts and cellulosic walls.
• The number of phelloderm layers varies with species, season, and
age of the periderm.

5. 2. Phellogen:
• Secondary meristem and may
form at the same time as vascular
cambium.
• Single or multi layered.
• The function is to produce
the cork, a tough protective
material.
• Synonym is Cork cambium.

6. 3. Phellem:
• The phellem cells are phellogen derivatives formed outward.
• Cells are arranged in tiers with almost no intercellular spaces
except in the lenticel regions.
• After completion of their differentiation, the phellem cells die and
their protoplasts disintegrate.

7.  Function:
Its main function is to protect the underlying tissues from:
• Desiccation
• Freezing
• Heat injury
• Mechanical destruction
• Disease

8. Loss of epidermis.
Bounding tissue restricting the pathogen & insects.
Allowing gaseous exchange through lenticels.