Relates how the pool of plant genetic resources provides vital raw material for producing new and improved crops, and serves as source material for experimental biologists. The first four sections provide a detailed survey of the role of plants, guidance on the size and structure of plant collections, and, finally, the principles and strategies for evaluation. The last two sections look at wild relatives of crops and the impact of new technology. The volume will be of great use to plant breeders, crop scientists, conservationists and plant biologists.