​RUE (Fr. rue, Lat. ruta, from Gr. ῥυτή, the Peloponnesian word for the plant known as πήγανον), the name of a woody or bushy herb, belonging to the genus Ruta, especially Ruta graveolens, the “ common rue,” a plant with bluish green spotted leaves and greenish yellow flowers. It has a strong pungent smell and the leaves have a bitter taste. The plant was much used in medieval and later medicine as a stimulative and irritant drug. It was commonly supposed to be much used by witches. From its association with “ rue,” sorrow, repentance (O. Eng. hréow, from hréowan, to be sorry for, cf. Ger. reuen), the plant was also known as “ herb of grace,” and was taken as the symbol of repentance.