The different components of xylem are :
(a) Tracheids : These are elongated annular dead cells with narrow blunt ends. They possess hard lignified walls and wide lumen. They allow rapid movement of sap from one cell to another.
(b) Vessels: They are much elongated tubular channels with wide lumen. The vessels elements are joined end to end and have perforated end walls. Vessels allow quick movement of water or sap and also provides mechanical strength.
(c) Xylem parenchyma : These are parenchymatous
cells associated with xylem. They may be thin walled or thick walled with simple pits. Xylem parenchyma stores food.
(d) Xylem fibres : They are sclerenchymatous fibres.
They may be distinguished from the tracheids by their thick wall and narrow lumen. Xylem fibres provides mechanical support.