Xylem#Transpirational pull

Under transpiration refers to the force that is created by the water output of the leaves of a plant: About the stomata of the leaves, water evaporates and creates a suction, which ensures that the water from the root is pulled through the xylem vessels to the top. And considerable heights can be overcome against the force of gravity, because the strong cohesion forces of the water allows the formation of a negative pressure.