This book presents a collection of research contributions to tree physiology, mainly from German scientists, who participated in a programme of the German National Science Foundation called ‘Physiology of Trees’. As a final report of this programme on tree physiology it is a valuable contribution of new knowledge of tree physiology. Its content is divided over seven sections. Section 1, structure and function of tree surfaces, contains contributions on the tree leaf surface, chemistry, surface structure and transport properties of the cuticular waxes and functions of lenticels, e.g, in gas transport.