szklerenchyma

Szklerenchyma is a type of supportive plant tissue composed of cells with thickened, lignified secondary cell walls. These cells are typically dead at maturity, providing structural strength and rigidity to plant organs. Szklerenchyma cells are characterized by their thick, often unevenly distributed, secondary walls, which are impregnated with lignin, a complex polymer that makes the cell walls rigid and impermeable. This lignification is a key feature that distinguishes szklerenchyma from collenchyma, another type of supportive tissue.

There are two main types of szklerenchyma cells: fibers and sclereids. Fibers are elongated, slender cells that are usually arranged in strands or bundles. They are commonly found in the vascular tissues of stems and roots, providing support and contributing to the tensile strength of these organs. Fibers can also be found in the leaves and petioles. Sclereids, on the other hand, are more varied in shape and size. They can be spherical, stellate, or irregular. Sclereids are found in various parts of the plant, including the bark, seeds, and fruits, where they contribute to hardness and protection. Examples of sclereids include the stone cells found in the flesh of pears and the hard outer shell of nuts. The presence of szklerenchyma is crucial for the overall structural integrity and mechanical support of plants, allowing them to withstand environmental stresses such as wind and gravity.