Rue was one of the great protective herbs of Mediterranean and European folk practice, hung in the house and worn against witchcraft, the evil eye, plague and poison, and made into the horned amulet, the cimaruta, still worn in southern Italy against the malocchio; it was reputed the enemy of all venom and the plant that even the weasel ate before fighting the serpent. Culpeper placed it under the Sun in Leo. A plain caution belongs with it: rue is an irritant, its sap can burn and blister skin exposed to sunlight, and it is unsafe taken internally, so its old medicinal use is given here only as history. Grace, repentance and protection against evil are its lasting meanings.
The plant gave its name directly to a well-known compound in modern chemistry: rutin, a flavonoid first isolated from rue and named for it, is found more abundantly in a range of other plants, including buckwheat and citrus peel, and is studied today for antioxidant and vein-strengthening properties, a case where a substance discovered in, and named after, this small bitter herb turned out to be far more widespread in the plant kingdom than the herb itself.
Rue is also one of relatively few herbs named directly in Jesus's own teaching, criticised in the Gospel of Luke alongside mint as an example of scrupulous tithing of garden herbs while neglecting justice and the love of God, so that the plant appears in scripture in a context of moral criticism rather than of praise.