Presented here is an analysis of plant development and plant metabolism using the tools of genetics and molecular biology, such as mutant analysis, mutation tagging, mapping using polymorphic characters and basic molecular biology techniques. Studies with a range of model genetic organisms, most notably maize and Arabidopsis, are included. The reader gains a comprehensive view of the subject which is more and more of both scientific and industrial interest. The value of basic research in plants is highlighted and examples where basic studies have led to applications in agricultural biotechnology are given.