Recent advances in modelling plant stands have emphasised the importance of the structural and functional properties of plant canopies, as distinct from those of the constituent parts. In response to proposals made following the 1984 meeting on the ‘control of leaf growth’, which resulted in Seminar Series Publication 27, the Environmental Physiology Group held a series of sessions on plant canopies during the March 1986 meeting of the Society for Experimental Biology at Nottingham. All the invited speakers at these sessions have contributed chapters to this volume either individually or with collaborators.

Chapters have been included on all the major processes occurring in canopies, although there has been space neither for consideration of the manipulation of canopies by chemical or genetical means, nor for discussion of the canopy as habitat for micro-organisms, insects or vertebrates. A policy decision was made at an early stage of planning to encourage authors to look at a diverse range of canopy types and geographical distribution in order to avoid any bias introduced by, for example, considering only temperate zone cereal crops. The reader can decide how successful this policy has been. Some omissions represent genuine areas of ignorance, but it is a matter of regret that space was not available to allow consideration of stands of mixed species either in agricultural intercropping systems or in natural communities.

It is a pleasure to acknowledge the financial and other support of the Environmental Physiology Group, the Association of Applied Biologists and the British Ecological Society.

I would like to record the contributors’ co-operation during the meeting and to thank them for all the time they and their collaborators devoted to preparing and revising their manuscripts.