Collenchyma is simple living mechanical tissue located in hypodermal region of the plant body provide mechanical support. Collenchyma tissue is made up of collenchyma cells where the cells are oval, spherical, isodiametric and slightly elongated than the parenchyma. The cell wall is unevenly thickened due to the deposition of pectin at intercellular space. Hence, collenchyma cells lack intercellular space.
Position of collenchyma tissue: Occurs in hypodermis of dicot stem, petiole and pedicel and also above the vascular bundle at midrib region in dicot leaf. It is totally absent in roots and monocot.
Depending upon the pectinisation collenchyma are classified into fallowing 3 types
1) Angular
In angular collenchyma the pectinisation is at angles(intercellular space region)
2) Lacunar
In this the pectinisation at angles with small lacuna or spaces
3) Lamellar
In lamellar collenchyma the pectinisation occur in the form of horizontal plates between the cells.
Functions of collenchyma
- Collenchyma provide mechanical support to the plant body as it is located in hypodermal region with pectinized wall.
- In young stems the collenchyma of hypodermis contain chloroplast help in photosynthesis.
- Like parenchyma collenchyma de-differentiate and form secondary meristem during secondary growth.