There is a small experiment that demonstrates the movement of water in the plant. A twig bearing white flowers is cut at one end and is placed in the colored water for few hours. The white flowers will turn into the color of water and the region in the twig where the mark is present will indicate that the colored water is taken in by the plant. This experiment explains that plant transports water through the vascular bundles and especially the Xylem. The mechanism of movement of water up into the plant from the soil has to be understood now.
The movement of water up into the plant cannot take place just by diffusion as diffusion in general is very slow and it will be beneficial for the movement of molecules for short distances. The molecule moves across the plant cell in about 2.5 seconds. In the large plants, the minerals and water have to move long distances. The site of the availability of the minerals and their storage in the plant parts are very far from each other. So, diffusion or active transport of the molecules will not be sufficient.
The transport of substances to long distances is very essential to make the water and substances to move long distances at fast rate. The food, water and minerals move as a mass flow or bulk flow system. The minerals and water move to long distances as a mass flow from one point to another due to the difference in pressure. Usually in a mass flow, the substances are seen to be passing in the flowing river which is moving at the equal speed. Mass flow is distinct from the diffusion where the substances move individually based on the individual concentration gradients. The positive and negative hydrostatic pressure gradients help the conduction of mass flow.
The movement of substances through the vascular tissues in the bulk manner is known as translocation. There are highly advanced vascular tissues called xylem and phloem that are concerned with the translocation of water, minerals, hormones, and organic nitrogen from the roots of the plant to the top parts of the plant. The organic and inorganic solutes are translocated from the leaves of the plants to other parts of the plant.