Mature sclerenchyma cells have _______.

Sclerenchyma is a simple permanent plant tissue that provides mechanical stiffness and structural support. Unlike parenchyma and collenchyma, which are living at maturity, mature sclerenchyma cells are typically dead and lack protoplasm [1]. These cells are characterized by heavily thickened secondary cell walls that are reinforced with lignin, a complex organic polymer that provides rigidity and makes the walls hard [2]. While primary cell walls are mainly composed of cellulose, the secondary walls of sclerenchyma are strongly lignified, which prevents further elongation and results in the death of the cell at maturity [1]. There are two main types of sclerenchyma: fibers, which are long and narrow, and sclereids (stone cells), which are shorter and provide hardness to seed coats and fruit pericarps. Therefore, mature sclerenchyma cells have lignified walls and are dead.

Sources

1. [1] https://www.sciencedirect.com/topics/agricultural-and-biological-sciences/plant-tissue
2. [2] https://www.britannica.com/science/sclerenchyma