The three theories of transport in the Xylem

Xylem is composed of a number of different types of cell, and may include long, thin, usually dead cells known as tracheids; fibres (schlerenchyma); thin-walled parenchyma cells; and conducting vessels. The xylem vessel has two main functions: * Xylem transports water and dissolved ions from the root system to the stem. * The lignified thick-walled xylem cells strengthen the stem. There are three theories in which the xylem vessel transports water around the plant: Capillarity Spontaneous movement …

…explanation for how water moves in the xylem. This mechanism is called transpiration. As leaves transpire, water evaporates to the dry surroundings outside the plant. Water molecules stick to each other by hyrdogen bonds. This is known as cohesion. So as they leaves transpire the water molecules are all pulled up the plant. Water molecules also stick to the sides of the vessel which helps to speed this mechanism up. This is known as adhesion.