This volume is a revised edition of a book first published, under the same title, in 1972 and now several years out of print. In recognition of the impressive body of developmental research that has been reported since the publication of the original volume, this edition has been substantially modified and modestly enlarged. The point of view of the original, however, has been retained. It is, as the title implies, structural and organismal. We have attempted to document the developmental process as the plant undergoes it, beginning with the zygote and the formation of the embryo, continuing with the development of the primary body and completing the picture with a treatment of secondary growth. We have not, therefore, undertaken to analyze phenomena like cell growth, meristematic activity, or polarity as topics in themselves, although certain phenomena, notably differentiation and the potency of differentiated cells, have been given special treatment. It may be argued that this approach could fail to reveal fundamental generalizations about development. Nevertheless, our goal was to show how the plant develops as an organism and we have attempted to adhere to it.

In the more than fifteen years that have elapsed since the original edition was published, there have been phenomenal advances in the fields of cellular and molecular biology, and these discoveries are being applied with ever-increasing intensity to the interpretation of plant development. One may reasonably ask, therefore, whether the structural and organismal approach to development has become obsolete.