From the biological point of view, L systems have provided a useful theoretical framework within which the nature of cellular behaviour in development can be discussed, computed and compared.
Their study has also provided a number of biologically interesting results.
From the mathematical point of view, L systems have opened a new dimension in formal language theory. Its novelty is reflected in both new types of problems and new techniques for solving them.
For a survey of biological aspects of the theory the reader is referred to the contribution by A. Lindenmayer to the book "Developmental systems and languages" by G.T. Herman and G. Rozenberg (North Holland Publ. Company, 1974). The first paper inthe present volume serves as a survey of the mathematical theory of L systems. It is hoped that the remaining ones give an idea of the current research. In this sense the above mentioned book and this volume should complement each other: the first being more tutorial and the second more research oriented.