It consists of long, narrow or short, thick walled and lignified cells usually pointed at both the ends. Matured cells become dead due to loss of living protoplast.
They give rigidity and mechanical strength to the plant body. On the basis of variation in form, structure, origin and development, sclerenchyma may be either fibers or sclereids.
The fibers are pointed and needle like. They occur in groups as sheets or cylinders in various parts of the plant body.
The sclereids are very thick walled, hard and strongly lignified. They are mostly isodiametric, polyhedral short and cylindrical with narrow cavity.