This paper has been written in the hope that it may provoke the interest of physiologists, biochemists, and geneticists in the manifold problems of morphogenesis; for, as this review will show, a sustained cooperative effort is essential if progress is to be assured in this complex and challenging field. A vascular plant presents a striking contrast in its development to that of a vertebrate animal. The latter undergoes gastrulation and in consequence envelopes its digestive and absorbing system, thereby forming a compact adult animal which must ingest elaborated food materials as an energy sub strate. The former grows apically and continuously, extending itself at both its absorbing root tips and its leaf-bearing stem tips. The resulting leaves and associated green parts become the energy-providing organs. Thus the absorbing system is being continuously and further separated from the foliar or photosynthetic system. In the distal region of both shoot and root, an embryonic region, the apical meristem, exists. Under favorable conditions, mitotic activity is pronounced in these meristems. Proximal to each apical meristem, gradual and progressive histological changes become evident as development proceeds. Only once in its development does the vertebrate animal go through its embryological changes; but in the plant, by contrast, growth and developmental change are sustained throughout the vegetative life of each stem and root tip exemplifying what Bower (1, pp. 14-15) has called their continued embryology. Morphogenesis-the inception of form and structure-inevitably in volves an inquiry into the continuing production of new cells and their subsequent growth and differentiation into the functioning tissues of the integrated and harmoniously formed adult organism. In short, it. connotes organized growth. Thus, organogenesis and histogenesis are both included in the term. In all stages of development, gene-controlled biochemical and physiological processes are recognized as fundamentally important. Yet the impact of external environment on genic expression in form and structure must obviously be reckoned with in any consideration of morphogenetic