1.1 - Organisation of Plant Tissues

Figure 1 - Do you still remember organisation of plant tissues from Form 4 Chapter 2? You have learnt about the organisation of tissues in humans. Now, we will be focusing on tissues and their respective functions present in plants only.

Permanent tissues are matured tissues that have already undergone differentiation or are currently undergoing differentiation process. Permanent tissues can be divided into 3 types – epidermis tissues, ground tissues and vascular tissues.

Figure 2 - Locations of the permanent tissues in different parts of the plant are different.

Types of plant tissues and their respective functions

Epidermis tissues

• Found on the outer surface of stems, leaves and roots of young plants.
• Epidermal wall exposed to outer environment has a layer of waxy and waterproof cuticle.
• Cuticle helps to minimize water loss through evaporation (transpiration), provide protection dan prevent entry of pathogens.
• Modified epidermal cells include guard cells dan root hair cells.
• Guard cells control the opening and closing of stoma for photosynthesis.
• Root hair cells help to increase the surface area for absorption of water and mineral salts.

Ground tissues

• Parenchyma tissues

  • Simplest living cells that are not differentiated yet.
  • Cell walls are thin.
  • Parenchyma tissues are arranged in a turgid state to provide support and maintain the shape of herbaceous plants.
  • Carry out photosynthesis and store starch and glucose.
  • Involved in gaseous exchange.
  • Involved in the repair and regeneration of plant tissues as well as transport of vascular system.

• Collenchyma tissues

  • Living cells which become flexible upon maturation.
  • Cell walls are made up of pectin and hemicellulose.
  • Cell wall is thicker than the cell wall of parenchyma cell.
  • Give mechanical support and elasticity to the plants.

• Sclerenchyma tissues

  • Made up of matured deade cells.
  • Cell walls are the thickest.
  • Support and strengthen matured parts of the plant.
  • Help in the transport of water and nutrients.

Vascular tissues

• Xylem

  • Made up of dead cells without cytoplasm.
  • Cell walls contain lignin.
  • Made up of hollow xylem vessels that extend from the roots to the leaves.
  • Transport water and mineral salts from the roots to other parts of the plant.

• Phloem

  • Made up companion cells and sieve tubes (living cells that contain cytoplasm).
  • Sieve tubes do not have nucleus and ribosomes due to decomposition after maturation.
  • Sieve tubes are continuous arranged from end to end.
  • Phloem transports glucose formed from photosynthesis from the leaves to the roots, fruits and tubers to be stored.