According to this theory:
- evaporation reduces the water potential of cells next to the xylem;
- water enters these cell from the xylem which is at a higher water potential;
- cohesive forces between the water molecules draw other water molecules up the xylem;
- adhesive forces between the water molecules andthe cellulose walls of the xylem vessel prevent the column of water from being pulled down by gravity; and
- the pulling force results in water entering from the roots.