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What is periderm? How does periderm formation take place in the dicot stems?

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HARITHA,Subject Matter Expert at Edumarz


Solution:Phellogen,phellem and phelloderm together form periderm.When dicot stems show secondary growth  due to the activity of vascular cambium,the outer cortical and epidermis layers get replaced by new protective cell layers.After this meristematic tissue called cork cambium or phellogen forms in cortex region.Phellogen is formed of thick layered cells.It also cuts off cells present on both sides.The outer cells develop into cork or phellem and the inner cells develop  into secondary cortex or phelloderm.The cork is not permeable  to water due to  presence of deposition of suberin  in the cell wall.

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Characters of dicot stem

  • It contains well developed epidermis with cuticle

  • Anatomy of dicot stem includes structures:     epidermis,hypodermis,pericycle,vascular bundle and pith

  • Hypodermis is formed of collenchyma

  • Vascular bundles are seen as broken rings

  • Presence of well developed pith region

  • Presence of phloem parenchyma

  • Presence of trichomes

  • It also show secondary growth

It lacks bundle sheath on outer region of vascular bundle

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