Water molecules are cohesive. The hydrogen bonds join the molecules together so water molecules move together as one mass.This means plants are able to draw water up the xylem from the roots to the leaves in a continuous stream during transpiration in a similar way to sucking up water through a straw.The cohesion of water molecules causes a skin to be formed on the surface of water when it is in contact with air. The water has a surface tension. Some organisms can inhabit the surface of water as this tension is strong enough to support small organisms such as small insects like pond skaters.Water molecules adhere to materials such as skin or glass. This adhesion causes capillary action - the movement of water within the spaces of a porous material due to the forces of adhesion, cohesion, and surface tension. Adhesion of water to the walls of a vessel will cause an upward force on the liquid at the edges and result in a meniscus which turns upward.