ICSE Class 7 Answered

The xylem is a complex permanent tissue which conducts water and minerals from the roots to the different parts of the plant.

It is also responsible for the mechanical strength of the plant.

It is composed of four elements - tracheids, xylem vessels, xylem fibres and xylem parenchyma.

1. Tracheids:

Tracheids are elongated tube-like structures.

They have thick cells with tapering ends and lignified cell walls.

The cells are dead and without protoplasm.

2. Vessels:

Vessels are cylinder-like structures made of many cells called vessel members.

Cells possess a large cell cavity, and the cell walls are lignified.

They are interconnected to each other through the perforations in their common walls.

3. Xylem Fibres:

They are with highly thickened walls and obliterated lumen.

They are either septate or aseptate.

4. Xylem Parenchyma:

The cells are living and thin walled.

Their cell walls are made of cellulose.

Xylem parenchyma is responsible for the radial conduction of water in plants.

It also stores food in the form of starch or fat and substances such as tannin.