Adhesion is caused by attraction of water molecules to the polar surfaces. Movement of water inside the roots from soil to xylem and then in most of the plant parts takes place by transpiration forces, which provide both energy and necessary pull. Force between tracheary wall and water molecule produces surface tension, which accounts for high capillarity through tracheary elements, which is called as adhesion force. These forces help to ensure the continuity of water column in xylem.