Collenchyma cell have thicker primary walls than parenchyma cell, though the walls are unevenly thickened. Young stems and petioles often have strands of collenchyma cells just below their epidermis. Collenchyma cells lack secondary walls, and the hardening agent lignin is absent in their primary walls. Therefore, they provide flexible support without restraining growth. At functional maturity, collenchyma cells are living and flexible, elongating with the stems and leaves they support. Grouped in strands or cylinders, collenchyma cells help support young parts of the plant shoot. Different types in collenchyma cells are classified according to the arrangement of the wall thickenings Types:
Angular collencyma is the most common type of collenchyma cell. The cell corners are differentially thickened or the deposition may be restricted to the corner. This type of collenchyma cells can be seen in herbaceous stems and petiole. Lamellar collenchyma
Lamellar collenchyma is very much alike to angular collenchyma but the cells are regularly arranged. Thickening occurs at the inner and outer tangential walls.
Lacunar collenchyma consist thickening around the cell walls facing the cavity lumen or intracellular spaces.
Sclerenchyma tissue is composed of cells with rigid cell walls and they function to support the weight of a plant organ. The main function is as supporting tissues that withstands various strains resulting from stretching and bending which makes the plant elastics. There are two types of sclerenchyma cells which are fibers andsclereids. They comprises a collection of cell types with uniformly and strongly thickened secondary walls that are usually lignified when fully mature. Fibers
Fibers can occur in aggregates forming a continuous cylinder around the stem, they may connect end to end to form multicellular strands acting like strengthening cables exactly like re-bar in concrete, or they sometimes appear as...
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