This volume represents the proceedings of a Symposium of the Plant Metabolism Group of the Society for Experimental Biology, held at the University of York in April 1987. I am most grateful to the chairman of this Group, Dr Curt Givan and the Chairman of the Publications Committee of the SEB, Professor Ken Bowler, for their encouragement to publish these proceedings. The generous financial support of the SEB is also gratefully acknowledged. Particular thanks are also due to all contributors who not only provided excellent verbal presentations but also produced manuscripts in good time.

The allocation of a Symposium to this area reflects the current interest in the physiology and biochemistry of herbicide action. Workers in the field of photosynthesis have used herbicides such as monuron and diuron as experimental tools for nearly 40 years, and as a consequence have extended our detailed knowledge of the mechanism of action of these compounds. In recent years the discovery of inhibitors of the shikimic acid pathway, of branched chain amino acid biosynthesis and of fatty acid biosynthesis, for example, has focussed much more attention on these areas of plant metabolism than there might otherwise have been.

In spite of the inevitable time lag between the presentation of papers and the publication of this volume, it is hoped that many undergraduates, research students and workers in academia and industry will find this volume of use and interest.