Medicinal plants

Medicinal plants, also called medicinal herbs, have been discovered and used in traditional medicine practices since prehistoric times. Plants synthesize hundreds of chemical compounds for various functions, including defense and protection against insects, fungi, diseases, against parasites and herbivorous mammals.

The earliest historical records of herbs are found from the Sumerian civilization, where hundreds of medicinal plants including opium are listed on clay tablets, c. 3000 BC. The Ebers Papyrus from ancient Egypt, c. 1550 BC, describes over 850 plant medicines. The Greek physician Dioscorides, who worked in the Roman army, documented over 1000 recipes for medicines using over 600 medicinal plants in De materia medica, c. 60 AD; this formed the basis of pharmacopoeias for some 1500 years. Drug research sometimes makes use of ethnobotany to search for pharmacologically active substances, and this approach has yielded hundreds of useful compounds. These include the common drugs aspirin, digoxin, quinine, and opium. The compounds found in plants are diverse, with most in four biochemical classes: alkaloids, glycosides, polyphenols, and terpenes. Few of these are scientifically confirmed as medicines or used in conventional medicine.

Medicinal plants are widely used as folk medicine in non-industrialized societies, mainly because they are readily available and cheaper than modern medicines. In many countries, there is little regulation of traditional medicine, but the World Health Organization coordinates a network to encourage safe and rational use. The botanical herbal market has been criticized for being poorly regulated and containing placebo and pseudoscience products with no scientific research to support their medical claims. Medicinal plants face both general threats, such as climate change and habitat destruction, and the specific threat of over-collection to meet market demand.

Plants, including many now used as culinary herbs and spices, have been used as medicines, not necessarily effectively, from prehistoric times. Spices have been used partly to counter food spoilage bacteria, especially in hot climates, and especially in meat dishes that spoil more readily. Angiosperms (flowering plants) were the original source of most plant medicines. Human settlements are often surrounded by weeds used as herbal medicines, such as nettle, dandelion and chickweed. Humans were not alone in using herbs: some animals, such as non-human primates, monarch butterflies and sheep ingest plants when they are ill.

Samples from prehistoric burial sites indicate that Paleolithic peoples consumed plants. For instance, a 60,000-year-old Neanderthal burial site, "Shanidar IV", in northern Iraq yielded pollen from eight plant species. At Taforalt cave, Morocco, 15,000-year-old remains of ephedra were found inside a tomb, indicating its possible role in funeral rites. A mushroom found in the personal effects of Ötzi the Iceman, whose body was frozen in the Ötztal Alps for more than 5,000 years, may have been used against whipworm.

In ancient Sumeria, hundreds of medicinal plants including myrrh and opium are listed on clay tablets from around 3000 BC. The ancient Egyptian Ebers Papyrus lists over 800 plant medicines such as aloe, cannabis, castor bean, garlic, juniper, and mandrake.

In antiquity, various cultures across Europe, including the Romans, Celts, and Nordic peoples, also practiced herbal medicine as a significant component of their healing traditions. The Romans had a rich tradition of herbal medicine, drawing upon knowledge inherited from the Greeks and expanding upon it. Notable works include those of Pedanius Dioscorides, whose "De Materia Medica" served as a comprehensive guide to medicinal plants and remained influential for centuries. Additionally, Pliny the Elder's "Naturalis Historia" contains valuable insights into Roman medical plant practices.

In the Nordic regions, including Scandinavia and parts of Germany, herbal medicine was prevalent in ancient times. The Norse sagas and Eddic poetry often mention the use of herbs for healing purposes. Additionally, archaeological findings, such as the remains of medicinal plants in Viking-age graves, attest to the importance of herbal remedies in Nordic culture.