An Attempt to Explain the Ascent of Sap in Defoliated Trees

The biologist Zimmermann has criticized in his book [12] that the effect of capillarity has been neglected in the past to explain the ascent of sap in trees. We want to propose a method how the sap ascent can be calculated, based on generalized solutions of the capillary equation. Although the theory of such solutions is not simple, the extracted method of calculating the sap storage in given cross sections of xylems can be applied also without having a large mathematical knowledge.