Xylem vessel

From Wikipedia, the free encyclopedia
Jump to: navigation, search
A cross-section of a stem. The holes with dark red outlines are xylem vessels.

Xylem vessels are long hollow chains of tough long dead xylem cells. Xylem tissue is the water transporter cells of plants. It carries water around a plant. The presence of vessels is a characteristic feature of flowering plants.

Structure[change | change source]

Xylem vessels are a long straight chain made of tough long dead cells known as vessel elements or vessel members. The vessel cells are devoid of protoplasm. The cells are arranged end to end and the cell walls have disappeared. This makes a tube.

They have a lignified cell wall and a large central cavity. Vessel members are interconnected through perforations in their common walls. The secondary walls of vessels are filled with lignin, a kind of hard glue.

Function[change | change source]

Xylem vessels work because of the transpiration stream. It is caused by the evaporation of water from the cells in the leaf to the atmosphere. The resulting surface tension causes pressure in the xylem that pulls the water from the roots and soil. This is called capillary action.