This book deals with arid and semi-arid environments and their classification, and the physiological restraints and adaptations of plants to the environment. Further, it discusses economic botany and the needs and methods of conserving economic plants. A broad view is taken regarding the definition of economic plants, taking into account their value to the environment as well as to man and to livestock. The individual deserts and associated semi-arid regions are described in separate chapters, providing background information on the regional environments in terms of climate and major plant formations. The economic plants within these formations, their usages, geographical distribution together with their morphological and physiological adaptations are treated in detail.