Why is the xylem called water-conducting tissue?

Hint: Xylem is one of the two types of transporting tissue that is present in vascular plants, the other is phloem. The basic function of the xylem is to transport water from roots to stems and leaves, and it also transports nutrients. The word xylem is derived from the Greek word xylon which stands for the meaning wood. The term xylem was introduced by Carl Nageli.

Complete answer:
The most distinctive xylem cells are the long tracheary elements that can transport water. Tracheids and vessel elements are differentiated by their shape. Vessel elements are shorter and are connected together into long tubes which are known as vessels. Xylem also contains two other cell types called parenchyma and fibres.

Xylem is called water-conducting tissue because it is mainly involved in transporting water molecules from the roots to the aerial parts of the plant. Xylem is a tubular-shaped vascular tissue, which is also involved in replacing the total amount of lost water molecules by the process of transpiration and photosynthesis. The movement of the xylem is unidirectional which means that the movement occurs in one direction from roots to the aerial parts of the plant.

Primary xylem is formed during primary growth from procambium which includes protoxylem and metaxylem. Metaxylem develops after the protoxylem but before the development of secondary xylem. Metaxylem has wider vessels and tracheids than protoxylem.Secondary xylem is formed during the process of secondary growth from the vascular cambium

Note: Xylem is found in vascular bundles, present in non-woody plants and non-woody parts of woody plants in the secondary xylem, laid down by a meristem which is known as the vascular cambium in woody plants as part of a stellar arrangement not divided into bundles, as in many ferns. The xylem, vessels and the tracheids of the roots, stems and leaves are interconnected in order to form a continuous system of water-conducting channels reaching all parts of the plants.