This property can obviously be traced directly to hydrogen bonding again. As the highest energy molecules in the liquid achieve what it takes to move away as a gas, their energy is removed from the liquid and it gets cooler. We sometimes refer to this as evaporative cooling . The water is replaced by the transpiration stream in the xylem. Water demonstrates adhesion and cohesion The polarity of the water molecule makes it attractive to polar and less-polar surfaces.
Water adheres to and climbs up materials like glass.
The fact that water molecules attract each other makes them cohesive. Obviously water will climb higher in tubes of smaller radius that those of larger radius. That of course is enough height to explain how water might get to the top of an herb in the xylem. It would fail to explain completely how water gets to the top of a 70 meter tall pine tree. We shall see later that in addition to capillary climb, the water is pulled through the xylem by evaporation.