What is a defining feature of sclereids, a type of sclerenchyma?

Sclereids are indeed characterized by their irregular shapes and are typically found scattered within plant tissues. This defining feature distinguishes them from other types of sclerenchyma, which tends to have a more uniform structure. Sclereids play a crucial role in providing mechanical support and protection to various parts of the plant, allowing them to withstand physical stress. Their irregular shapes can vary significantly, contributing further to their specific function within the plant's anatomy.

In contrast, the other attributes listed do not accurately describe sclereids. They do not have a specific longer-than-wide shape; rather, their forms can vary greatly. Sclereids are also not flexible and pliable; in fact, they are known for their rigidity, which contributes to the hard texture of certain plant parts. Furthermore, they do not contain chloroplasts, as they are specialized for structural support rather than photosynthesis, which is a function of softer, living tissues in plants.