The secretory activity of plants is a manifestation of the fundamental property of all living organisms: the ability to exchange substances and energy with the environment. This book summarizes today’s knowledge of all such secretory activities of higher plants. It equally considers the cellular aspects, intratissular and external secretion, gas excretion and the excretion of substances under extreme conditions as well as the biological effects of plant excreta. The first edition of the book was published in Russian in Moscow in 1989 (Nauka Publishing House), then the English larger variant – in Heidelberg-Berlin 1993 (Springer-Verlag).