In order for water to move upward through the plant, diffusion, transpiration and capillary action must occur together.
For the upward movement of water in plants diffusion, transpiration and capillary action should occur. Water diffuses into the root and the pressure inside pushes the water along the xylem. Due to transpiration water leaves the plant resulting in movement of water up through the xylem. Due to capillary action water flows throughout the plant.