Organisation of Plant tissue

1.1

Organisation of Plant Tissue

Plant Tissues

Meristematic Tissues

Permanent Tissues

Epidermal tissues.
Ground tissues:
- Parenchyma tissues.
- Collenchyma tissues.
- Sclerenchyma tissues.
Vascular tissues:
- Xylem tissues.
- Phloem tissues.

Types of Permanent Tissues

Epidermal Tissues

Epidermal tissues layer is at the outermost surface of stems, leaves and roots of young plants.
Epidermal cell walls which are exposed to the air have a waxy and waterproof layer called the cuticle.
The cuticle reduces loss of water through evaporation (transpiration) and protects the leaf from mechanical injuries and pathogens.

Ground Tissues

Parenchyma tissues:
- Paracenchyma tissues are the simplest living cells and do not undergo differentiation.
- They have the thinnest cell walls.
- Parenchyma tissues are always in a turgid state providing support and maintaining the shape of herbaceous plants.
- Involved in photosynthesis, helping in the storage of starch and sugar and involved in gaseous exchange.
- Involved in the repair and regeneration of plant tissue as well as in the vascular system.
Collenchyma tissues:
- Collenchyma tissues are made of living cells which mature into cells that are flexible.
- Have cell walls made of pectin and hemicellulose.
- Their cell walls are thicker than parenchyma tissues.
- Provide mechanical support and elasticity to plants.
Sclerenchyma tissues:
- Sclerenchyma tissues consist of dead cells when they are matured.
- Their cell walls are the thickest among the three ground tissues.
- Provide support and mechanical strength to the parts of matured plants.
- These tissues also help in the transport of water and nutrients in plants.

Vascular Tissues

Xylem:
- The xylem is made up of dead cells without cytoplasm.
- The cell wall of the xylem contains lignin.
- Consists of xylem vessels that are elongated, hollow and connected from its roots to the leaves.
- This enables xylem to transport water and mineral salt to all parts of a plant.
Phloem:
- Phloems are made of companion cells and sieve tubes.
- Made of living cells, which are the sieve tubes with the presence of cytoplasm.
- The sieve tubes do not have organelles such as nucleus and ribosome as they decompose at the maturity stage.
- Phloems consist of sieve tubes arranged from end to end forming elongated and continuous tube structures.
- Phloems transport sugars produced from the photosynthesis from the leaves to storage organs such as roots, fruits and tubers.

1.1

Organisation of Plant Tissue

Plant Tissues

Meristematic Tissues

Permanent Tissues

Epidermal tissues.
Ground tissues:
- Parenchyma tissues.
- Collenchyma tissues.
- Sclerenchyma tissues.
Vascular tissues:
- Xylem tissues.
- Phloem tissues.

Types of Permanent Tissues

Epidermal Tissues

Epidermal tissues layer is at the outermost surface of stems, leaves and roots of young plants.
Epidermal cell walls which are exposed to the air have a waxy and waterproof layer called the cuticle.
The cuticle reduces loss of water through evaporation (transpiration) and protects the leaf from mechanical injuries and pathogens.

Ground Tissues

Parenchyma tissues:
- Paracenchyma tissues are the simplest living cells and do not undergo differentiation.
- They have the thinnest cell walls.
- Parenchyma tissues are always in a turgid state providing support and maintaining the shape of herbaceous plants.
- Involved in photosynthesis, helping in the storage of starch and sugar and involved in gaseous exchange.
- Involved in the repair and regeneration of plant tissue as well as in the vascular system.
Collenchyma tissues:
- Collenchyma tissues are made of living cells which mature into cells that are flexible.
- Have cell walls made of pectin and hemicellulose.
- Their cell walls are thicker than parenchyma tissues.
- Provide mechanical support and elasticity to plants.
Sclerenchyma tissues:
- Sclerenchyma tissues consist of dead cells when they are matured.
- Their cell walls are the thickest among the three ground tissues.
- Provide support and mechanical strength to the parts of matured plants.
- These tissues also help in the transport of water and nutrients in plants.

Vascular Tissues

Xylem:
- The xylem is made up of dead cells without cytoplasm.
- The cell wall of the xylem contains lignin.
- Consists of xylem vessels that are elongated, hollow and connected from its roots to the leaves.
- This enables xylem to transport water and mineral salt to all parts of a plant.
Phloem:
- Phloems are made of companion cells and sieve tubes.
- Made of living cells, which are the sieve tubes with the presence of cytoplasm.
- The sieve tubes do not have organelles such as nucleus and ribosome as they decompose at the maturity stage.
- Phloems consist of sieve tubes arranged from end to end forming elongated and continuous tube structures.
- Phloems transport sugars produced from the photosynthesis from the leaves to storage organs such as roots, fruits and tubers.