Hello! This is more about conceptual understanding, concerning cohesion-adhesion-tension theory. In the leaves, the water molecules adhere to the cell walls of the mesophyll cells; and a thin film of water is present over the cell walls. When the water molecules evaporate, the film curves inwards into the gaps between the microfibrils that make up the cell wall, increasing the surface area (and, as a consequence, the rate of evaporation). This increase in surface area apparently increases the surface tension, and so the water molecules forming a chain, via cohesion, are pulled up the plant to counter this curvature and decrease the surface tension. I've looked at a number of sources, but nothing gives a definition than I can apply here. I can understand an object that sits on the water, as the surface water molecules 'hold' togeather and the object can't break the intermolecular bonds. But how does the curvature in the plant example increase the surface tension? If it is energetically more favourable for the water molecules to be in contact with as many other water molecules as possible, and this was sufficiently strong, then I can understand that the flat surface reduces the surface area and therefore the number of water molecules at the surface decreases and the number 'within' (and thus in contact with a larger number of of water moleucles) increases,. Is this the explanation? It seems confusing because the idea of being in contact with as many molecules as possible doesn't sound like it should be called surface tension... I would really appreciate some help. Many thanks.