Q.Explain sclereids with their types.

Step 1. Define sclereids. Sclereids, also called stone cells, are dead sclerenchyma cells that are usually isodiametric, though some are elongated; their cell wall is very thick due to lignification, so the internal lumen is much reduced, and their pits may be simple or branched. Being dead and mechanically strong, sclereids give a hard texture to structures like seed coats, endosperms and certain fruit flesh, and their function is mechanical rather than conductive.

Step 2. Brachysclereids (stone cells). These are isodiametric sclereids with a hard cell wall, found in bark, pith, cortex, hard endosperm and the fleshy tissue of some fruits, such as the gritty flesh of pear (Pyrus).

Step 3. Macrosclereids. Elongated, rod-shaped sclereids found lining the outer seed coat of leguminous plants, such as Crotalaria and Pisum sativum.

Step 4. Osteosclereids (bone cells). Rod-shaped sclereids with characteristically dilated (swollen) ends, resembling a bone, found in leaves and seed coats, such as those of Pisum and Hakea.

Step 5. Astrosclereids (star cells). Star-shaped sclereids with several lobes or arms diverging from a central body, occurring in petioles and leaves, for example in Tea, Nymphaea and Trochodendron. …

Define sclereids generally (dead, thick-walled, mechanical) and then describe each of the five-to-six named shape …

• Listing the type names without describing what distinguishes each shape (isodiametric vs rod vs star vs hair-like). …