Question

Why are xylem and phloem called complex tissues? How are they different from one other?

Answer 1

Both xylem and phloem consist of more than one type of tissue, which coordinate to perform a common function. Hence, called complex tissue.

xylem	phloem
Consists of tracheids, vessels, xylem, parenchyma and xylem fibres.	Consist of sieve tubes, companion cell, phloem parenchyma and phloem fibres.
They transport water and minerals vertically from soil to aerial parts of the plant.	They transport food from leaves to other parts of the plant.
All of the tissues except xylem parenchyma are dead. Conduction is unidirectional from roots to leaves.	Most of the tissues except phloem fibres are living. Conduction is bidirectional, from source to sink.