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B sclereids
Nuts are simple dry fruits and their fruit wall is extremely hard at maturity. Pulp of fruits like pear and guava have grittiness. The tissues that are commonly found in the fruit wall of nuts and pulp of some fruits like guava and pear are called sclereids.
Sclereids or sclerenchymatous cells are simple dead permanent tissue. They have highly thickened walls with narrow cavities (lumen). Their shapes can vary. In the case of pear, these non-living cells are also called stone cells as they form the grit in pear.
Fibres can be xylem or phloem fibres. Xylem fibres are sclerenchymatous. They have highly thickened walls that lack lumen at maturity due to lignin deposition in the cell walls. It provides strength to the tracheids and vessels.
Phloem fibres are sclerenchymatous. It provides mechanical support to sieve elements. Vessels and tracheids are the components of xylem.
Tracheids are unicellular, elongated, tube-like cells with a tapering end. They have thick lignified walls. Their cells lack protoplasm.
Vessels are multicellular, long cylindrical tube-like structures. They are formed of individual units known as vessel members. They have lignified walls with pits and a large central cavity.