Describe the structure of phloem.
Structure of Phloem. Phloem is a complex permanent tissue of the plant. The phloem consists of four types of elements: sieve tubes, companion cells, phloem fibres and the phloem parenchyma
The main conducting part of the phloem is sieve tube which is formed of elongated cylindrical cells arranged in vertical rows. The terminal walls of each sieve tube member has many minute pores through which food material passes very easily. The entire porous plate is termed as sieve plate. Each sieve tube member is supported by a long parenchymatous cell called the companion cell which helps the sieve tubes in the conduction of food material.
Phloem parenchyma formed of parenchymatous cells. They store the food material. Phloem also contains phloem fibres, also known as Bast Fibres. 
A longitudinal section of phloem.
