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Many types of collenchyma are there ?

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Collenchyma :
Collenchyma (Greek, colla = glue; enchyma an infusion) is the tissue of primary body. The cells of this tissue contain protoplasm and are living. The cell walls show localized thickenings due to presence of approximately 45% pectin, 35 % hemicellulose and 20 % cellulose.

They are never lignified but may possess simple pits. Presence of cellulose and pectic substances in the cell wall accounts for the high water absorbing capacity to the cells. The tissue is plastic, extensible and has capacity to expand and gives a tensile strenth to the organ. Originates from elongated cells that resemble procambium.

Thus, the cells are generally elongated with oblique end walls. Sometimes the ends may be rounded. They occure chiefly in the hvpodermis of dicotyledonous stems (e.g. cucurbita, helianthus) and leaves. They are usually absent in monocots and in roots. However, they may occur in root cortex if the root is exposed to light.

Functions of Collenchyma:

  1. It is the chief supporting tissue in young dicotyledonous stems.
  2. Has capacity to expand and gives a tensile strength to the body.
  3. It is present at the margins of some leaves and resists tearing effect of the wind.
  4. Some cells possess chloroplasts and perform photosynthesis.

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