St. John's-wort, the popular name for most members of the genus Hypericum, the type of the thalamifloral order Hypericaceae. They may be shrubby or herbaceous, and have opposite and decussate simple leaves, often dotted with glands; yellow, pentamerous, polysymmetric f1owers, with triadelphous or polyadelphous stamens. Originating in branching; and a capsular fruit with distinct styles (generally tricarpellary). Once considered a remedy for epilepsy, St. John's-wort came to be looked upon as a charm agamst evil spirits, and to be used in rustic divination. It is named from the fact that it flowers about the time of the feast of the nativity of St. John the Baptist (June 24th).