Easy learning with example program codes

Permanent Tissue

Permanent tissue is composed of cells that have lost the meristematic power and do not divide further. They may be living or dead cells, and thin-walled or thick-walled. Based on the composition of cells, permanent tissue is classified into two – Simple and Complex tissues.


Simple permanent tissue

Permanent tissue made of a single type of cells is called a simple permanent tissue. It forms a homogeneous (uniform) mass of cells. There are three types of simple tissues.

  1. Parenchyma



  • Parenchyma is the most common type of unspecialized tissue.
  • They are thin walled cells, more or less isodiametric in shape, with or without intercellular space.
  • They have various shapes – oval, spherical or polygonal.
  • The cell wall is made of cellulose.
  • The main function of parenchyma cells is storage.
  • They are present in the cortex, pith, epidermis and pericycle.
  • Chlorenchyma: When the parenchyma cells contain chlorophyll, they are called chlorenchyma and they carry out photosynthesis.
  • Aerenchyma: When parenchyma cells are arranged with a regular system of intercellular air spaces, it is called parenchyma. These cells are found in aquatic plants, and provide byoyancy to the plants.


  1. Collenchyma


  • Collenchyma consists of living cells with vacuolated protoplasm.
  • They are elongated cells and appear polygonal in cross section.
  • The cell wall thickening is uneven. Walls at the corners are thicker than the rest of the wall, and hence the cells may also sometimes appear circular in cross section.
  • The cell wall is made of cellulose and pectin.
  • Collenchymas cells give strength and flexibility to the growing parts of the plant.
  • They also have the ability to retain meristematic activity.

image2.png sclerenchyma-collenchyma.png

  1. Sclerenchyma
  • Sclerenchyma contains dead cells at maturity.
  • The cell walls are thickened by the presence of lignin.
  • Small pits are seen on the cell wall.
  • Sclerenchyma tissue provides mechanical support to the plants and helps them to withstand various physical pressures.
  • This tissue has 2 types of cells.


    1. Sclereids
      • They are also called sclerotic cells or stone cells.



      • They are thick walled cells with various shapes.
      • The cell walls are strongly lignified and have a very narrow lumen.
      • They occur in the shells of nuts, in hard seeds, stony fruits and in the pulp of fruits like pear, guava and sapota, making them gritty.
    1. Fibres
      • These are elongated sclerenchyma cells with pointed or tapering ends.
      • In cross section, they look angular.
      • The cell walls are hard, uniformely thickened and lignified.
      • They are present widely in xylem tissue, phloem tissue, cortex and pericycle.


Please follow and like us:

Copyright © 2020 CodesJava Protection Status