Introduction
Man and Animals depend on the plants for their very existence. Our environment is characterized by richly diversified plant life. Plant diversity is composed of more than 500,000 botanical species. The green scum and the duckweed on surface of some ponds, the lichens, fungi, liverworts, mosses, ferns, conifers and the flowering plants are the representatives of the plant diversity.
Worldwide, drugs derived from various organisms continue to be significant for the treatment and prevention of diseases.
Pharmacognosy is the study of medicinal products obtained from our living environment. This includes: plants, animals, insects and microbes of both terrestrial and marine origin. Some medicinal products are also derived from mineral sources.
Pharmacognosy may also be defined as science of nature-derived pharmaceuticals and poisons.
Pharmacognosy is an established basic pharmaceutical science. This subject has changed considerably, from being largely descriptive botanical and mycological field to having more of chemical and biological focus. It has also evolved to include phytotherapy and nutraceuticals.