Different Types of Sclerenchyma -Fiberes and Sclereids and their Function

Sclerenchyma: (Gk; Sclerous: hard; enchyma: infusion)
       Non-living mechanical tissue
       Thick walled, lignified and pitted cells without protoplasm at maturity
       Distribution: cortex, hypodermis, vascular regions of stem, leaves, fruit wall etc
Types of Sclerenchyma - Fibres and Sclereids
    1. Sclerenchyma Fibres

Sclerenchyma Fibres

  • Thick, elongated, spindle shaped cells with pointed tips.
  • Narrow lumen with simple rounded pits and lignified secondary wall
  • Distribution: cortex, pericycle, xylem and phloem
Types of Fibres:
  • a. Surface fibres: found on fruit wall and seed coat (e.g., coconut)
  • b. Xylary or Wood fibres: associated with xylem
  • c. Extraxylary or Bast fibres: seen associated with cortex, pericycle and phloem
Function of Fibres:
  • Provide mechanical support to the plant parts
  • Surface fibres help in seed and fruit dispersal
      2. Sclereids
       Small sclerenchymatous cells with highly thickened lignified walls and narrow lumen. 
      Distribution: pulp of fruits, fruit walls, cortex, pith etc

  Different types of Sclereids
Different types of Sclereids

       a. Brachysclereids: isodiametric sclerieds called as stone cells
Grit cells: Numerous Stone cells present in the pulp of fruits (guava, sapota)
Distribution: cortex, pith, pericarp of coconut shell
       b. Macrosclereids: rod like sclerieds- present in bark and seed coat of leguminous plants
       c. Osteosclerieds: Bone like sclerieds with lobed ends-seed coat and fruit wall
       d. Astrosclereids: star shaped sclerieds- dicot leaves and gymnosperms

Functions of Scelrenchyma
  • Dead mechanical tissue providing strength and support to the plant
  • Protects from damages
  • Xylem fibres in water conduction
  •  Fibrous sclerenchyma of fruits and seeds helps in seed dispersal.
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