Let's look at the surface of a plant cell A thin layer of water covers the cell wall As water evaporates the cell wall begins to dry out Look at how water sticks to the cell wall This is called adhesion Water molecules also stick to each other This is called cohesion Cohesion and adhesion are the results of hydrogen bonds - the dashed lines Because of cohesion and adhesions transpiration creates a tension from leaf cells through the xylem through the roots that pulls water molecule up the plant