self-heal or heal-all, weedy perennial (Prunella vulgaris) with the typical angular stems and bluish flowers of the family Labiatae (mint family). Although it probably originated in the Old World, self-heal is now distributed throughout temperate climates and is a common plant of North American pastures and open woods. It was formerly used as a domestic remedy for sore throats and other minor ailments. Prunella is classified in the division Magnoliophyta, class Magnoliopsida, order Lamiales, family Labiatae.