Sclerenchyma is one of the three ground tissues found in vascular plants that provide strength and support, especially in the stem and roots. Upon maturity, the sclerenchyma cells have usually lost their protoplasts and are dead cells. The name of the tissue and cells derives from the Greek word skleros meaning hard.

This supporting tissue is composed of two main types of cells. The first type is the fiber cell, which is elongated and has tapering ends that can interlock with other fiber cells. These elastic, interconnected cells have great tensile strength and provide flexibility in the stem and roots. The second type, sclereid cells, are shorter and more diverse in shape, and may be found in the cortex, pith, xylem, and phloem, providing a degree of internal support for various plant organs. Sclereids are also common components in the hard coats of many seeds and the shells of nuts.