This study of the "dioscorea" genus or yam, consisting of 600 species, is a synthesis of new information. In this world of famine, the yam must play a leading role in the regions it is grown. Its cultivation may even increase once the problems which this book highlights have been resolved. The text fills a critical gap, summarizing what is known about the yam; it is also significant because it asks many questions, and encourages further experimentation.