Describe the structure of the vascular system in higher plants.

The vascular in high plants consists of two types of vascular tissue, the xylem and phloem.

• The xylem contains two types of conducting cells: tracheid and vessel elements. Both types of conducting are hollow, non-living and lack end walls, they are connected end to end to form a continuous pipeline for water and mineral transport. The xylem elements have lignified side walls which are perforated by numerous bordered pits.
• The conducting cells of phloem are the sieve-tubes, each associated with a companion cell. Sieve-tube cells contain cytoplasm no nuclei. Strands of cytoplasm, called plasmodesmata, extend from one cell to another through the sieve plates (perforated cell end walls)
• The vascular system extends from the roots to the leaves and vice versa. In the roots, the vascular tissue is located in the vascular cylinder; in the stem, it forms vascular bundles; and in the leaves. It is found in leaf veins.