TOPIC 1CLASSIFICATION KINGDOM FUNGI
Vascular bundle in a stem showing
the position of cambium
Components of the vascular system
Xylem
Xylem tissue is made up of the xylem vessels and
the tracheids. Mature xylem vessels and tracheids are made up of hollow and
dead cells. Their walls are made of cellulose and lignin. Lignin
strengthens the cell walls and makes them rigid. Therefore, xylem has an
additional function of giving support to the plant
The movement of substances in the
xylem is always upward and is by conduction. A xylem vessel is made of
hollow cells without end walls. These cells are joined end to end to form a
pipe-like structure. See above Xylem vessels begin in the roots, go up through
the stem and branch into every leaf of the plant.
Xylem vessels have no cytoplasm and
nuclei. This enables them to transport a larger volume of water and mineral
salts.
