Sclerenchyma

Sclerenchyma

Single cells or aggregates of cells whose principal function is thought to be mechanical support of plants or plant parts. Sclerenchyma cells have thick secondary walls and may or may not remain alive when mature. They vary greatly in form and are of widespread occurrence in vascular plants. Two general types, sclereids and fibers, are widely recognized, but since these intergrade, the distinction is sometimes arbitrary.

Sclerenchyma

 

in plants, mechanical tissue consisting of two types of thick-walled and usually woody cells: fibers and sclereids.

The fibers are greatly elongated cells, usually ranging in length from fractions of an mm to 1 cm (nettles). Some plants, for example, the ramie, have fibers reaching 4 cm in length. The fibers have sharp ends and porous layered walls. Nonwoody fibers of sclerenchyma having cellulose walls, for example, in flax, are a valuable raw material for the textile industry. Sclerenchyma fibers are as durable as steel and as resilient and elastic as rubber. The amount and distribution of the fibers determine a plant organ’s durability when subjected to stretching, compression, and bending.

In many plants the fibers form a mechanical facing for the vascular bundles. In the stems of dicotyledons they are found mainly in the pericycle and the primary phloem. In the stems and leaves of monocotyledons the fibers often form subepidermal cords, whereas in the roots they are concentrated primarily in the center. In addition to fibers of first derivation formed from the cells of the basic meristem and procambium, the term “sclerenchyma” is also applied to phloem and xylem (libriform) fibers of cambial origin.

For information on sclereids see.

L. I. LOTOVA

sclerenchyma

[sklə′reŋ·kə·mə]

(botany)

A supporting plant tissue composed principally of sclereids whose walls are often mineralized.