Abscisic acid was found in the xylem sap of Peach, Salix fragilis, Apple and Tecomaria capensis collected in winter, in the bleeding sap of Actinidia chinensis collected in spring, and in a commercial sample of Acer saccharum syrup. There were wide differences (varying from 9 to >1000 ng/100 ml of sap) between the species. It is suggested that abscisic acid is probably present in the xylem sap of most plants.