APA Dictionary of Psychology

any of a group of plant alkaloids that includes belladonna, the opium alkaloids, mandrake, aconite, and hemlock. The substances have been chewed, smoked, or brewed into potions since ancient times for purposes of healing or intoxication. Medicinal herbs were usually grown and administered by shamans or native healers; some, such as the opiates and anticholinergics, are used in modern medical pharmacology.