Evaporation from the leaves of a tall tree keeps a continuous column of water moving up its xylem. What is that movement called?

الشرح

Water leaving the leaves lowers the water content at the top of the column and draws the water beneath it upwards, and it is that loss by transpiration which gives the whole flow its name. Explaining the movement as a push from below cannot account for the height a tall tree reaches, because the pull created where the water escapes is what keeps the column climbing.