Internal Structure of Dicot Root Notes | Free Biology Notes

Internal Structure of Dicot Root Notes 

This article we will discuss about Internal Structure of dicot Root

The transverse section of a Dicot Root reveals the following structures

Epiblema / rhizoderm / piliferous layer

  • Outermost layer of root & composed of thin, closely packed parenchyma
  • The cuticle and stomata are absent
  • Epidermal cells extend out in form of tubular hairs is called root hairs
  • Epiblema has following functions: uptake of water and mineral salts from the soil and provide maximum surface area for absorption

Cortex

  • It is situated below the epiblema
  • Cortex consists of parenchymatous cells with intercellular spaces
  • Cortex has following functions: store food and
  • Conduct water from epiblema to the inner tissues

Endodermis

  • This layer is barrel shaped cells present between the pericycle and cortex
  • Casparian strips are present on wall of endodermis
  • Casparian strip is made up of suberin & lignin
  • Strip acts as a water dam or check post to prevent the flow of fluids between cortex and phloem
  • Endodermis cells opposite to the protoxylem are without casparian strips is called passage cells
  • These cells help move water and dissolved salts from the cortex to the xylem

Pericycle

  • Pericycle present below the endodermis and made up of single layer of thick walled parenchymatous cells
  • It is very important layer
  • Pericycle has following functions: Lateral roots in dicot arise in this tissue and cork cambium also develops from it

Vascular bundles

  • Vascular bundles are radial and exarch
  • Xylem and phloem are separate and equal in number
  • Tetrarch condition is found ( In some plants diarch to hexarch)
  • Ficus bengalensis root is polyarch
  • Parenchyma which is found between the xylem and phloem is called conjunctive tissue
  • Vascular bundles has following functions: conduction of water and food materials
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Pith

  • Young root contains pith whereas in old root pith is absent.
  • In young root only a small area in the center and consists of few compactly arranged, thin-walled parenchymatous cells

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