Internal Structure of Dicot Stem Notes | Free Biology Notes

Internal Structure of Dicot Stem

Internal Structure of Dicot Stem Notes

This article we will discuss about Internal Structure of Dicot Stem

The transverse section of a dicot stem reveals the following structures

Epidermis

  • Epidermis is a outermost layer and made up of parenchymatous cells
  • Cuticle a protective layer, covers this layer
  • It possesses stomata and large number of multicellular hairs
  • Epidermis has following functions: Minimize the rate of transpiration, protects from mechanical injury, prevents the entry of harmful organisms and helps in the exchange of gases through stomata

Hypodermis

  • Present below the epidermis & multilayered of collenchymatous cells
  • Hypodermis has following functions: provides mechanical strength, perform photosynthesis and storage of food

Middle cortex

  • Present below the hypodermis & made up of oval cells of parenchyma
  • In some plants contains oil ducts & Resin canals
  • Middle cortex has following functions: Storage of food & perform photosynthesis

Endodermis

  • Its separates the cortex from vascular bundles
  • Cells are barrel shaped, compactly arranged, having no intercellular spaces and are parenchymatous.
  • Due to abundant starch grains, this layer is also known as starch sheath
  • Casparian strips are absent in stem
  • Endodermis has following functions: serve for storage of food

Pericycle

  • Pericycle is present below the endodermis and composed of sclerenchymatous and parenchymatous cells
  • Sclerenchyma forming like a cap on the bundle, so called as bundle caps.
  • Parenchymatous present between the two bundles
  • Pericycle has following functions: mechanical support and serves to store food

Vascular bundles

  • These are arranged in a ring and inner to the pericycle
  • Vascular bundle is conjoint, collateral, open type
  • Vascular bundles are made up of: xylem, phloem and cambium
  • Xylem – helps in conduction of sap
  • Phloem – conducts the foods
  • Cambium – lies in between xylem and phloem and responsible for secondary growth

Pith

  • Occupies central portion of the stem
  • Composed of thin walled parenchymatous, rounded or polygonal, with or without intercellular spaces
  • The extension of pith between vascular bundles are called as pith ray or medullary rays.
  • Pith has following functions: food is stored in this region.

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Rajkumar is a lecturer from TamilNadu, India. He holds a master degree in botany. Passionate, Blogger, Video Creator, Photography. He helps the students for advancement and provide Biology Materials. Life Motto: Live while you can! Teach and inspire while you could & smile while you have teeth