Removal of salt from xylem sap by leaves and stems of guttating plants.

Although root pressure and guttation presumably result from a high concentration of salt in the root xylem, the guttation fluid is very dilute. Measurements of the osmotic potential of the guttation liquid and of exudates at various levels in guttating plants indicate that salt is removed from the xylem in the upper part of plants, particularly in the leaves. The concentration of salt solutions forced through individual leaves by an artificial root pressure has no influence on the osmotic potential of the guttation fluid. This suggests that leaves play an important role in removing salt from the xylem of guttating plants.