Tejinder Kaur, Academic Content Creator at Edumarz
Plant Tissues:
A tissue is a term given to the group of cells which are similar in structure and function.
Different types of plant tissues present in plants include the meristematic and permanent tissues.
Meristematic Tissues –
These tissues are a group of cells which have dividing capacity. They help in the major growth of the plants.
Depending upon the portion of the plant they are present, the plant tissue are of three types:
Apical Meristem: The meristem tissue present at the apical ends of the stems and roots. It helps in increasing the length of the plant.
Intercalary Meristem: The meristem tissue present at the base of the leaves or at the internodes. It helps in increasing the size of the internode.
Lateral Meristem: The meristem present at the lateral side of the stem or root. It helps in increasing the girth of the plant.
The old meristematic tissues loose their dividing capacity and convert them into permanent tissues. The process by which meristematic tissue loses its capacity and acquires the permanent shape, size and function is called as differentiation.
Permanent Tissues –
The tissues which have lost their dividing capacity and have attained permanent characteristics are called permanent tissues.
They are of two types:
Simple Permanent Tissues: The permanent tissues which are composed of cells of the same type. They are further classified as:
Sclerenchyma
Collenchyma
Parenchyma
Parenchyma –
These are living cells, polygonal in shape, having a big nucleus and having intercellular spaces between them.
The parenchyma which consists of chloroplasts is termed as chlorenchyma. This aids in photosynthesis.
The parenchyma which consists of big air voids is termed as aerenchyma. This aids in providing buoyancy.
Collenchyma –
These are living cells with very less intercellular spaces.
They have thickening at their corners of pectin.
It helps the plant to gain flexibility and provides mechanical support to plants.
Sclerenchyma –
These are elongated, dead cells having lignin deposited in their cell wall.
There are no intercellular spaces in between the cells.
These are found in the hard covering of nuts and seeds and around the vascular tissues in stems and veins of the leaves.
It provides strength to the plants.
Complex Permanent Tissues: The permanent tissues that are composed of cells of varying types. They are of two types:
Xylem
Phloem
Xylem –
The vascular tissue of plants helps in conduction of water.
The transport of water is unidirectional, i.e. in one direction only.
The components of xylem include tracheids, vessels, xylem parenchyma and xylem fibres.
Phloem –
The vascular tissue of plants helps in conduction of food.
The transport of food is bidirectional, i.e. in two directions.
The components of phloem include sieve tubes, companion cells, phloem parenchyma and phloem fibres.