Plant Tissues

PLANT TISSUES

 

I. Meristematic tissue:

Characteristics:

1. Cells are small.

2. Cell walls thin.

3. Nuclei large and conspicuous.

4. Cells are without vacuoles.

5. Cells actively dividing.

 

Location:

1. Tip of roots, tips of stem and branches.

2. Between bark and wood of the tree and is responsible for increase in the diameter of the stem.

 

II. Permanent Tissues:

 

A.  Simple Permanent Tissues:

(i) Protective Tissue:

Characteristic: Cell wall thick.

Location: Surface of roots, stems, leaves

Function: Provide protection

Example: Epidermis of leaves, which secretes a waxy water-proof substance.

(ii) Supporting Tissue:

	Parenchyma	Collenchyma	Sclerenchyma
1. Characteristics	a. Spherical. b. Cell wall thin.   c. Large intercellular spaces present between the cells. d. Consists of living cells at maturity.	a. Elongated cells. b. Cell wall thick at the edges. c. Little intercellular spaces present between the cells. d. Consists of living cells at maturity.	a. Long, narrow. b. Cell wall thick.   c. Intercellular spaces absent.     d. Consists of dead cells at maturity.
2. Location	Found throughout the plant, in every soft part.	Found in petioles, veins of leaves and young stems.	Found in mature parts of the plant like in wood, bark, etc.
3. Function	Photosynthesis, respiration, storage of food, buoyancy in aquatic plants.	Provide a flexible mechanical support to plant parts.	Provide rigid mechanical and structural support to the plant.

 

 

B.  Complex Permanent Tissues:

Conducting tissue or Vascular tissue

	Xylem	Phloem
Characteristics	1. Consists mainly of dead cells. 2. Thick walled, tubular.	1. Consists mainly of living cells. 2. Tubular.
Function	2. Transports water and minerals absorbed by roots to other parts of the plant.	2. Conducts food manufactured in leaves to the other parts of the plant.
Direction of conduction	3.Unidirectional, i.e. only upwards from the roots.	3. Bidirectional, i.e. both upwards and downwards from the leaves.