Introduction to Pharmacognosy PDF Note Download Free For Pharmacy Students. The use of plants as medicine is as old as human civilization. Men of all ages in both developing and undeveloped countries use plants in an attempt to cure various diseases and to get relief from physical sufferings. India is known as the “Emporium of Medicinal plants” due to the prevalence of several thousands of medicinal plants in different bioclimatic zone (Yoganarasimhan, 2000). The peninsular India probably has the richest and varied flora than other tracks of equal area in India, possible in the world (Gamble, 1967), a phenomenon contributed by its combined effects of its geographical situation and topography. The Western Ghats have been designated as one of the hot spots of global biodiversity. A rich depository of flora with high endemism is found in the Western Ghats. The immense taxonomic diversity of the country throws a challenge to the Indian chemists and biologist to transform the enormous bioresource into economic wealth and intellectual property. The state Tamil Nadu is endowed with a very rich flora due to the various physiographic features and physiognomic factors and different types of vegetation exist in the state. A total o 5640 species of the flowering plants (including 6 gymnosperms) are reported either naturally occurring or cultivated in the state (Nair and Henry, 1983). Among them numerous plants have been reported to be medicinal plants. However, our knowledge of medicinal plants has mostly been inherited traditionally. Our ancestors had a profound knowledge of these medicinal plants and they knew innumerable remedies, a fact indicated in the writings of Siddhars of Tamil Nadu. Had their expertise documented properly it would help the modern man to find more effective prophylactic use of these herbs.