Plant Tissues

Definition of Tissue

A tissue is a group of similar cells that work together to perform a specific function.

Classification of Plant Tissues

Plant tissues are broadly classified into:

1. Meristematic Tissues: Tissues with actively dividing cells, responsible for growth.
2. Permanent Tissues: Tissues composed of cells that have lost the ability to divide and have taken on a permanent shape, size, and function. These are further divided into Simple and Complex permanent tissues.

Meristematic Tissues

• Characteristics:
  • Cells are small, isodiametric, and compactly arranged without intercellular spaces.
  • Cells have dense cytoplasm, a large nucleus, and thin cell walls.
  • They are actively dividing cells.
• Location: Found in the growing regions of the plant, such as root tips, shoot tips, and cambium.
• Function: Responsible for the growth of the plant in length and girth.
• Examples: Apical meristem, Lateral meristem, Intercalary meristem.

Simple Permanent Tissues

These tissues are made up of only one type of cell.

• Parenchyma:
  • Structure: Thin-walled, isodiametric cells with large central vacuoles and intercellular spaces.
  • Location: Found in the cortex, pith, and mesophyll of leaves.
  • Functions: Storage of food, photosynthesis (chlorenchyma), and providing turgidity to the plant.
• Collenchyma:
  • Structure: Elongated cells with unevenly thickened cell walls, especially at the corners.
  • Location: Found in the leaf stalks, below the epidermis of young stems.
  • Functions: Provides mechanical support and flexibility to young stems and petioles.
• Sclerenchyma:
  • Structure: Long, narrow cells with thick, lignified cell walls. They are dead cells.
  • Location: Found in stems, around vascular bundles, in veins of leaves, and hard coverings of seeds and nuts.
  • Functions: Provides mechanical strength and rigidity to the plant.

Complex Permanent Tissues

These tissues are made up of more than one type of cell, working together as a unit.

• Xylem:
  • Function: Responsible for the transport of water and minerals from the roots to other parts of the plant.
• Phloem:
  • Function: Responsible for the transport of food (sugars) from the leaves to other parts of the plant.