rue Ruta graveolens, a small shrubby plant of the European parts of the Mediterranean region, now cultivated elsewhere too. The leaves, blue-green and fleshy, have a strong and unattractive aromatic odour, and a bitter taste. They are used, fresh or dried but usually minced and in small quantity, for flavouring bread, meat dishes, and so on; and to impart bitterness to certain alcoholic drinks.
The plant has enjoyed a high reputation for medicinal properties. Another common name, herb of grace, arose because holy water used to be sprinkled from brushes made of rue.