Tissues

Tissue

Groups of cells associated together and performing a common function are called tissues.

Plant Tissues

Types

1.       Simple tissues

• 2.       Compound Tissues
•          i.            Simple Tissues

When single types of cells perform similar function then they form a simple tissue. These are further divided into two groups.......

(i)                  Meristematic Tissues   (ii)  Permanent Tissues

Meristematic Tissues

These are composed of cells, Which have power of division.

Properties

(i)                  They the ability of division.

(ii)                They have dense cytoplasm, large nuclei in the center with small or no vacuoles.

(iii)               They have thin and delicate cell walls, composed of cellulose.

(iv)              They are alike.

(v)                They do not have inter-cellular spaces among them.

Location

On the basis of location, meristematic cells are divided into three groups.

(i)                  Apical Meristems

It means the dividing cells are present at the shoot or root tip (apices).

These are also called growing points. These result in the increase in length of these shoots and roots. Such a growth is called primary growth.

(ii)                Lateral Meristems

It means the dividing cells are present on the lateral sides of shoot and roots. These results in the increase in diameter of these shoot and root.

Such a growth is called secondary growth.

There are two types of lateral Meristems

• a.       Vascular Cambium: This is present in between the center and phloem. This gives rise to new xylem cells towards xylem and new phloem cells towards on side.
• b.      Cork Cambium: This is present in the outer lateral sides and gives rise to a corky layer.

(iii)               Intercalary Meristems

Patches of this type of Meristems are present among the mature tissues. This helps in the regeneration of removed parts removed by herbivores. Mostly it is present in grasses.