Simple Permanent Tissues: Parenchyma, Collenchyma and Sclerenchyma Tissue (For CBSE, ICSE, IAS, NET, NRA 2022)

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Parenchyma Tissue

Parenchyma is composed of thin-walled living cells. It is present in the softer parts of the plant and performs various functions. These are oval or polygonal cells with cellulose cell wall, cytoplasm, vacuoles, nucleus and intercellular spaces. They store food materials in the form of starch grains. In leaves, these cells contain chloroplasts and thus help in photosynthesis (manufacture of food) . Example: roots, stems, leaves, flowers, fruits and seeds. There are two types.

Chlorenchyma Tissue

It is living tissue and chlorophyll containing photosynthetic parenchyma. It is also called as assimilatory parenchyma found in mesophyll, sepals and phyllodes.

Aerenchyma Tissue

It is living and air storing parenchyma with large air-filled intercellular spaces found in roots stem and leaves of hydrophytes. Function: gaseous exchange and provides buoyancy to plants.

Image Showing Different Types of Parenchyma Tissues

Collenchyma Tissue

Collenchyma has living cells which possess thickenings at the corners. It is found in few layers below the epidermis of dicotyledonous stem. It is generally absent in monocot stem and leaves. These are mechanical tissues, which also consist of living cells. Intercellular spaces are generally absent because in intercellular spaces at the corner of cells thickenings of cellulose and pectin develop due to which the cell wall become rigid and thick at corners. Collenchyma gives strength to the stem. Chloroplast containing collenchyma also manufactures food.

Image Showing Collenchyma Tissue

Sclerenchyma Tissue

  • Sclerenchyma is found in hard parts of the plant body. They are very common in roots, stems, leaves and petioles. They may be present in patches, groups or layers. The cells of the sclerenchyma are dead, they are elongated, narrow, and thick walled and lignified. They are pointed at both ends. It gives strength, rigidity and flexibility to the plant body. This consists of fibers and sclerosis.
  • Fires are long, narrow, thick and liquefied cells usually tapering at both ends.
  • Sclereids cells are normally short with very thick walls, irregular and not tapering at the ends.
Image Showing Sclerenchymatous Fibers and Stone Cells

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