What do you mean by sclereids?

Sclereids (also called stone cells) are one of the two forms of sclerenchyma tissue.

Structural Characteristics:

• Shape:Spherical, oval, or cylindrical
• Cell Wall:Highly thickened with extensive lignin deposition
• Lumen: Very narrow cavity (almost obliterated)
• Pits: Numerous simple or branched pits for former plasmodesmatal connections
• Maturity:Dead cells without protoplasm

Occurrence:

• Fruit walls: Nuts (walnut, coconut shells)
• Fruit pulp: Guava, pear, sapota (gritty texture)
• Seed coats: Legumes (provides hardness)
• Leaves: Tea leaves (structural reinforcement)

Classification of Sclereids:

Type	Shape	Example
Brachysclereids	Short, stone-like	Pear pulp
Macrosclereids	Rod-shaped	Seed coats
Osteosclereids	Bone-shaped	Seed coats
Astrosclereids	Star-shaped	Leaf mesophyll
Trichosclereids	Hair-like	Internal hairs

NEET Application: Identify tissue type from microscopic images showing thick walls and narrow lumen.