Plant Tissues and Their Types

Overview

• Plant tissues are groups of cells performing specific functions.
• Essential for plant growth, development, and survival.

Main Types of Plant Tissues

1. Meristematic Tissues

   • Undifferentiated, actively dividing cells.
   • Responsible for plant growth.
   • Types:
     • Apical Meristems: Located at root and shoot tips, responsible for primary growth.
     • Lateral Meristems: Found along stems and roots, responsible for secondary growth (e.g., vascular cambium, cork cambium).

2. Permanent Tissues

   • Mature, specialized cells.
   • Lose the ability to divide but perform specific functions.
   • Categories:
     • Simple Permanent Tissues: One type of cell; includes parenchyma, collenchyma, and sclerenchyma.
     • Complex Permanent Tissues: More than one cell type; includes xylem and phloem.

Tissue Systems in Plants

1. Dermal Tissue System

   • Protective outer layer.
   • Structure: Epidermal cells form a continuous layer (like skin). The cuticle is a waxy layer providing protection.
   • Functions:
     • Stomata for gas exchange.
     • Trichomes serve as defense mechanisms.
     • Root hairs increase water absorption surface area.
     • Cork cells replace epidermis in woody plants.
   • Adaptations:
     • Desert plants have thick cuticles to conserve water.
     • Aquatic plants have structures for gas exchange (e.g., aerenchyma).

2. Ground Tissue System

   • Makes up majority of the plant body.
   • Cell Types:
     • Parenchyma Cells: Photosynthesis, storage, wound healing.
     • Collenchyma Cells: Provide flexible support, found in young stems and leaves.
     • Sclerenchyma Cells: Provide rigidity and protection, found in mature plants.
   • Functions:
     • Supports plant structure.
     • Adapts to environmental changes.

3. Vascular Tissue System

   • Responsible for transport of water, nutrients, and sugars.
   • Types:
     • Xylem:
       • Transports water and minerals from roots.
       • Composed of tracheids, vessel elements, xylem parenchyma, xylem fibers.
     • Phloem:
       • Transports organic compounds like sugars.
       • Composed of sieve tube elements, companion cells, phloem parenchyma, phloem fibers.
   • Functions:
     • Xylem provides structural support.
     • Phloem transports nutrients both upward and downward.
     • Vascular bundles (arranged differently in monocots and dicots) assist in primary and secondary growth.

Key Takeaways

• Plant tissues are critical for growth and survival.
• Each tissue type has specialized functions and adaptations.
• Understanding plant tissues is essential for comprehending plant biology and ecology.