Question

Discuss about the vascular system observed in the cross section of roots, stems and leaves of higher plants.

Answer 1

Part 1: Vascular system
In plants, the vascular system is defined as a network of conducting vessels which help in the transport of water and other necessary organic materials required for the survival of the plant.

Part 2: Vascular tissues
Vascular system is made up of two types of tissues:
1. Xylem
2. Phloem

Part 3:Components of xylem and phloem
Xylem consists of vessels, tracheids, xylem fibres and xylem parenchyma.

Phloem consists of phloem fibres, companion cells, phloem parenchyma and sieve tubes.


Part 4: Xylem
In vascular plants, xylem helps in transporting water absorbed by roots along with some minerals. As it occurs in an upward direction, thus it is a unidirectional transport.

Part 5: Phloem
Phloem helps in transporting the organic molecules in the vascular plants.
It transports photosynthates to the place of its utility.

Leaves act as a source where food (sugar) is generated by the process of photosynthesis and transported to the whole plant. Roots act as a source when they store reserve food material which is transported to the other plant parts like buds of trees in early spring. Thus the movement inside the phloem is bi-directional as the source-sink relationship varies with seasons.