We can propound a thermo-mechanical understanding of the ascent of sap
to the top of tall trees thanks to a comparison between experiments associated with the
cohesion-tension theory and the disjoining pressure concept for liquid thin-films. When
a segment of xylem is tight-filled with crude sap, the liquid pressure can be negative
although the pressure in embolized vessels remains positive. Examples are given that
illustrate how embolized vessels can be refilled and why the ascent of sap is possible even
in the tallest trees avoiding the problem due to cavitation. However, the maximum height
of trees is limited by the stability domain of liquid thin-films.