Book excerpt: Most conventional gardening books concentrate on how and when to carry out horticultural tasks such as pruning, seed sowing and taking cuttings. This book is unique in explaining in straightforward terms some of the science that underlies these practices. It is principally a book of 'Why' - Why are plants green? Why should one cut beneath a leaf node when taking cuttings? Why do plants need so much water? But it also goes on to deal with the 'How', providing rationale behind the practical advice. The coverage is wide-ranging and comprehensive and includes the basic structure and functioning of garden plants, nomenclature, genetics and plant breeding, environmental factors affecting growth, methods of propagation and production, pest and disease control, and post harvest management and storage. Published on behalf of the Royal Horticultural Society, this book will be a most valuable text for those sitting the RHS general examination, and horticultural students at certificate and diploma levels; it will also appeal to gardeners, growers and scientists.