The dependency of the human race on plants as renewable sources of many foodstuffs, drugs, textiles, fuel, and building materials in generally acknowledged. However, the harmful effects produced by certain plant constituents, which result in an increasing incidence of poisoning cases in the United States each year, are not so widely appreciated. This book is not intended to be a comprehensive treatise on all substances from plants that are lethal or otherwise injurious to humans or livestock. Instead, owing to tremendous recent advances in the understanding of the chemical nature of their toxic principles, it reviews selected toxic plants which have been hitherto inadequately documented in previous texts.