The study of the development of flowering plants may be said to be in the throes of a revolution. The literature on the subject is extensive and continues to grow rapidly as new discoveries pile one on top of the other; moreover, these striking advances in our knowledge have put plant developmental biology well ahead of other aspects of the study of plants. This has come about after a period of neglect and stagnation in the field and has been triggered by the power of recombinant DNA technology to analyze genetic information and by a fruitful cross-fertilization between physiology, genetics, and molecular biology. Whereas considerations of developmental phenomena were at one time largely restricted to the structure and physiology of a wide selection of plants, recent molecular and genetic approaches are focused on one or two model systems. Notwithstanding the difficulty of having to relate developmental mechanisms in a few experimentally attractive models to the enormous range of plants, the use of model systems has gained wide accep­ tance. This book is intended to meet the need for a unified account of the general principles of development of flowering plants representing structural, physiolog­ ical, biochemical, genetic, and molecular perspectives. It arose out of the revision and upgrading of an undergraduate course in plant development that I have taught here at The Ohio State University for more than 20 years.