Question

Why are xylem and phloem called complex tissues?

Answer 1

Xylem and Phloem are the complex permanent tissues of plants that are involved in the transportation of food and water in a plant.

Complete answer:
In plants, the transport of food and water is a very important process for the survival of the plant. If either of the two processes is stopped, the plant will not be able to survive and it will eventually die. So, all plants make special tissues for each of these processes. These tissues are xylem and phloem.
Xylem – The transport of water from the roots of the plant to the shoot system is done through the xylem. Also, the transport of minerals occurs with the transport of water. Xylem is called a complex tissue because it is made of more than one type of cell.
The xylem contains three types of cells –
1. Tracheary elements
2. Xylem parenchyma
3. Xylem vessels
The most distinctive xylem cells are the long tracheary elements that transport water. Tracheids and vessel elements can be easily distinguished by their shape. The vessel elements are shorter and are connected to each other, forming long tubes are called xylem vessels.
Phloem – Phloem is called a complex tissue because it is made up of more than one type of cell.
Phloem consists of
1. Conducting cells called sieve elements
2. Parenchyma cells which include
Specialized companion cells
Albuminous cells
Unspecialized cells
Supportive cells
Phloem fibers
Sclereids

Note: Xylem is generally found in vascular bundles, present in non-woody plants and non-woody parts of woody plants, in secondary xylem, formed by the vascular cambium in woody plants and as a part of a stelar arrangement not divided into bundles, as in many ferns. The xylem and phloem are also known as the vascular system of plants.