In their search for nourishment, primitive humans sampled many kinds of plants. Those that were palatable were used for food, while plants with toxic or unpleasant effects were avoided or used against enemies. Still other plantsÑthose that produced physiological effects such as perspiration, defecation, healing, or hallucinationsÑwere saved for medicinal purposes and divination. Over the course of thousands of years, people have learned to use a wide variety of plants as medicines for different ailments.
More than 4,000 years ago (according to tradition), the Chinese emperor Qien Nong (Chi'en Nung) put together a book, or herbal, of medicinal plants called Ben Zao (Pen Tsao). It contained descriptions of more than 300 plants, several of which are still used in medicine. The Sumerians, at the same time and later, were recording prescriptions on clay tablets, and the Egyptians were writing their medical systems on rolls of papyrus. The most famous of these medical papyri, the so-called Ebers Papyrus, reports voluminously on the pharmaceutical prescriptions of the era. It includes specific information on how plants are to be used.
The Greeks and the Romans derived some of their herbal knowledge from these early civilizations.
Their contributions are recorded in Dioscorides' De Materia Medica and the 37-volume natural history written by Pliny the Elder. Some of these earlier works are known to us through translations into Arabic by Rhazes and Avicenna. The knowledge of medicinal plants was further nurtured by monks in Europe who studied and grew medicinal plants and translated the Arabic works. The first "licensed" apothecary shops opened in Baghdad (now in Iraq) in the 9th century. By the 13th century, London became a major trading center in herbs and spices. Much adulteration occurred in this trade, because proper standards and quality controls had not been established. Poorly identified plants and substitutes for true medicinal herbs were sold everywhere. In 1753, Carolus Linnaeus introduced the binomial system of plant nomenclature, which helped in the identification of plants. With the later publication of pharmacopoeias, the method of identification and the standard of quality for each medicine became clearly defined.