The use of plants / herbs as medicine for the care of diseases goes back to time immemorial and still the plants are the dominant form of medicine in the world. Majority of the population of the world is primarily dependent on raw plant products to meet their health care needs. A number of drugs like atropine, caffeine, digoxin, ephedrine, quinine, theophylline, tubocurarine, warfarin, taxol, vincristine and vinblastin are also derived from plants and used in modern system of medicine. The authors in this book present a comprehensive information about the history of medicinal plants from time immemorial to modern medicine. Beside this the traditional use, biological and phytochemical investigation of genera Phoenix , Castanospermum and Cordia, are described in this book.