Sclerenchyma tissue

Sclerenchyma is dead mechanical tissue made up of sclerenchyma cells were the cells do not have living protoplasm. The cell wall is thick deposited with lignin. Sclerenchyma tissue consists of two different forms of cells accordingly they are classified into two types.

1. Fibers

Structure: Sclerenchyma fibers are elongated sclerenchyma cells with pointed ends. They are compactly arranged without intercellular spaces. They have lignified cell wall. On the cell wall there are non lignified areas called pits.

Occurrence: Sclerenchyma fibers occur in pericycle of dicot stem, hypodermis of monocot stem, mesocarp of coconut fruit, surrounding vascular bundles form bundle sheath in monocot stem and leaf and also occur in vascular tissue xylem and phloem.

Function: Sclerenchyma fibers provide mechanical support. The fibers from fiber yielding plant(Hemp, cotton) are used for making ropes, carpets, mats etc.

2. Sclereids (Sclerotic cell)

Sclereids are the irregular shape sclerenchyma cells. The cells are dead with thick lignified walls. The sclereids cells occur in different forms accordingly. They are as

a) Branchy sclereids(stone shape)

b) Astro sclereids(star shape)

c) Macro sclereids(columnar shape)

d) Osteo sclereids(bone shape)

Sclereids either occur compactly or in isolated forms. Generally occur in fleshy pulpy part of fruits and in some hydrophytic leaves.

Functions: It provide mechanical support to the plant.