St.-John's-wort, any species of the large and widespread herbaceous or shrubby genus Hypericum of the family Hypericaceae (St.-John's-wort family), usually found in moist, open places and often having bright yellow flowers and dotted leaves. A St.-John's-wort is said to have been associated with the sun god Balder, because of its golden flowers, and when Balder's Day became St. John's Day the plant was likewise transferred to St. John. It was supposed to ward off evil spirits and thunderbolts, for which it was worn on St. John's Eve. Long considered to have curative powers, St.-John's-wort was traditionally used for treating wounds and has lately become popular as an herbal remedy in the treatment of mild depression; it is prepared from the dried flowering plant tops of H. perforatum, a European species. Of the North American species a few are cultivated and some are noxious weeds, poisonous to livestock. Several naturalized American plants are Asian species that were introduced by way of Europe. A species of Hypericum is one of several plants called Aaron's-beard, in this case because of the beardlike aspect of its many stamens. See rose of Sharon. St.-John's-wort is classified in the division Magnoliophyta, class Magnoliopsida, order Theales, family Hypericaceae.