Give illustrative account of any type of complex permanent tissues of the plants.

Xylem is a complex vescular tissue which is in all parts such as root, stem and leaf of the plant. It is composed of several types of cells. Xylem consists of tracheids, vessels, xylem parenchyma and xylem fibres.

The cells of this tissue have thick walls and many of them are non-living.

(i) Tracheids: These are long elongated tubular cells. Tracheids cells are dead. These are found in all vascular plants. Its main function is conduction of water and minerals from root to stem.

(ii) Vessels: These are pipe-like structure. Vessels are dead and have lignified cell wall. They also participate conduction of water and minerals.

(iii) Xylem parenchyma: These are simple parenchyma found in the xylem. These are living cells which store food material.

(iv) Xylem fibres: These are dead cells provide mechanical support to the plant.