Collenchyma is a simple living permanent tissue with the deposition of cellulose and pectin in specific areas of their walls. It has a high refractive index. Cells of collenchyma are generally elongated, circular, oval, or angular in the transverse section. Each cell in collenchyma has a large central vacuole and a peripheral cytoplasm along with a nucleus. There is also the presence of chloroplasts in Collenchyma. Depending on the thickness of the wall Collenchyma is categorized into three types.
TYpes of Plant Collenchyma
1. Angular Collenchyma
The wall thickenings are present at the angles (angular thickening) e.g. stem of tomato, Datura, Salanun, Tagetes,etc.
2. Lamellate Collenchyma
Lamellate collenchyma is also called tangential collenchyma. The wall thickenings occur on tangential walls ( plate-like thickenings) e.g. stem of sunflower, Rhombus, etc.
3. Lacunate Collenchyma
The wall thickenings is found in the intercellular spaces but there is the presence of small hollow cylinder (lacuna) in intercellular spaces e.g. stem of Cucurbita, petiole of Salvia, etc.
Collenchyma is found in the hypodermis of the petiole, pedicel, leaf and stem of some herbaceous dicot plants in the region of ridges. It is absent in woody dicot stem, monocot stem and roots.
Function of Collenchyma
1. It provides mechanical strength to young stems, leaves and petioles of herbaceous plant.
2. It helps in cell elasticity and supports the growing organs.
3. It provides support to delicate leaf margins and prevents tearing of leaves.
4. It provides flexibility to organs and allows their belding. So, it prevents the lodging of an herbaceous dicot plant.
5. it takes part in photosynthesis due to the presence of chloroplasts.
6. It helps in storage of small amount of food.
7. It allows the growth and elongation of organs.
8. The cells of the collenchyma can undergo dedifferentiation and can form cork cambium or phellogen.