Permanent Tissues

What is Permanent Tissue ?

          The tissues that have lost the capacity of growth and division temporarily or permanently are known as permanent tissue. It is formed as a result of division and differentiation of meristematic tissue.

Types of Permanent Tissue:

1. Simple tissue

2. Complex tissue

3. Special tissue or Secretory tissue

1. Simple tissue:

•Simple tissues called homogenous tissues. A simple tissue may be defined as a group of similar cells that perform a common function.

•These are classified into three groups:

•(a) Parenchyma

•(b) Collenchyma

•(c) Sclerenchyma.

(a) Parenchyma:

•Parenchyma: (Para= Soft, Enchyma = Tissue)

i. These are composed of isodiametric living cells which may be oval or rounded.

ii. Cells have intercellular spaces.

iii. Cell wall is thin and made up of hemicellulose and cellulose.

iv. Vacuole is present and nucleus size is small

v. Cells have dense and living protoplasm.

vi. Cells may show meristematic activity. So these are also called as potential meristematic tissue.

vii. It is found in cortex, pith, mesophyll tissue, and endosperm and also associated with xylem and phloem.

•According to specific function, parenchyma is classified into four groups:

1. Aerenchyma:

Parenchyma having large air spaces is known as aerenchyma. It is found in hydro­phytes and it gives buoyancy to plant.

2. Chlorenchyma:

Parenchyma with large amount of chloroplast is known as chlorenchyma. It is found in mesophyll of leaf and helps in photosynthesis.

3. Prosenchyma:

Parenchymatous cell becoming long and tapper at both ends, without intercellular space is known as prosenchyma. It helps in mechanical support.

4. Idioblast:

Parenchyma that stores unwanted or ergastic substances is known as Idioblast.

Functions of Parenchyma:

1. Parenchyma mainly serves as storage tissue.

2. Being meristematic in nature, parenchyma is associated with regeneration, formation of adventitious root, graft union, wound healing.

3. Aerenchyma renders buoyancy, prosenchyma gives mechanical support, chlorenchyma helps in photosynthesis and idioblast stores ergastic substances.