Question

What is the complex tissue present in the xylem and phloem? Write its functions.

Answer 1

Depending upon the structure and function of cells in plants; two types of permanent tissues are seen in plants. They are classified as simple permanent tissues and complex permanent tissues. Different types of cells are found in complex permanent tissues with different functions. Xylem and phloem are conducting vessels of plants that form the vascular bundle.

Complete answer:
Complex permanent tissues are composed of different types of cells that are fused together to form and perform a single function. The two main types of complex permanent tissues are xylem and phloem. Vascular tissues are complex tissues found in plants. Both xylem and phloem are conducting tissues of plants which form the vascular bundle. Xylem is a type of vascular tissue which regulates the function of transportation of water from roots to the stem. Xylem tissue is composed of four different types of cells. They are tracheid, vessels, xylem fibres, and xylem parenchyma. The tube-like cells which have tapering end with a thick wall of the lining of lignin are called xylem tracheid. A central cavity is present in long cylindrical cells called xylem vessels. Xylem fibres are called dead fibres and provide mechanical support. Xylem parenchyma is the only living cell and stores fat and starch. Phloem is a vascular tissue that primarily performs the function of conduction of soluble organic compounds from leaves to other parts of the plant. Phloem tissue is composed of four different types of cells. They are sieve tubes, companion cells, phloem fibres, and phloem parenchyma. The elongated living cells called sieve tubes are mainly involved in the conduction of carbohydrates from leaves to other parts of the plants. Phloem parenchyma helps in the transports of food to remote areas of different parts of the plants. On maturation, the phloem fibres die and are mostly used for commercial purposes.

Note: Depending upon the type of plants, the arrangement of these complex permanent tissues varies. The difference in the arrangement of these tissues can be seen in the root and stem of monocot and dicot plants. Xylem vessels are not seen in gymnosperms.