Cohesion and adhesion theory is otherwise called transpiration pull theory.
Transpiration pull theory
A transpiration pull could be simply defined as a biological process in which the force of pulling is produced inside the xylem tissue. This force helps in the upward movement of water into the xylem vessels. In this process, loss of water in the form of vapours through leaves are observed. This biological process is carried out in all higher plants and trees as their stems are surrounded by bundles of fine tubes, which are made from a woody material known as xylem.
Transpiration pull is also known as suction force, and it is used to draw water from the roots to the leaves in an upward direction. The amount of water obtained by the leaves is used for photosynthesis, and the excess water is released into the atmosphere as vapours through stomata, which are small openings in the leaves.