Collenchyma is a cellular tissue that, along with parenchyma, composes the bulk of plant tissues.
Various features of collenchyma are as follows
- Collenchyma is an elastic, living, mechanical tissue.
- Cells of this tissue are called collenchymatous cells which may be oval, spherical or polygonal in shape
- The intercellular spaces are absent because these cells are closely packed with each other. At the corners of these cells, thickenings of cellulose, hemicellulose and pectin develop due to which the cell walls become thick at corners. Cellulose, hemicellulose and pectin are complex carbohydrates which provide the strength to the walls.
- The collenchyma occurs in layers below the epidernmis in dicotyledonous plants. (Epidermis is the outer-most layer of the primary plant body which is in direct contact with the external environment). Collenchyma usually occurs in the form of 3-4 layers below epidermis in dicotyledonous plants. It is found either as homogeneous, (i.e., continuous) layer or in the form of patches discontinuously. Collenchyma is absent in monocotyledonous plants.
- Some of the collenchymatous cells contain chloroplasts and those which contain chloroplasts perform photosynthesis and assimilate the food.
Functions of Collenchyma :
- Collenchyma is a living mechanical tissue which provides the mechanical support to the growing parts of the plant such as young stem and petiole of a leaf. It also resists the bending of stems and pulling out and tearing of young leaves due to action of wind. Hence, collenchyma provides support as well as strength to the growing parts of plants.
- Collenchyma takes part in the synthesis of food, i.e., photosynthesis also, when its cells possess the chloroplasts.