Ruta graveolens is a small shrub from southern Europe, well known outside its native range as both a herb and a garden ornamental. Typical of many plants from its native region, it is tough and aromatic, able to survive in hot, dry conditions and thin, nutrient-poor soils. It also thrives in the United Kingdom, where it is grown in gardens primarily for its finely cut, bluish-green leaves; it is occasionally found as a garden escape. In summer, its inflorescences of small, bright yellow flowers contrast attractively with the foliage.
As a herb, the uses of Ruta are primarily medicinal rather than culinary, although it is occasionally used (sparingly) to flavour grappa and salads. References in herbal literature date back to at least the sixteenth century, and it has been mentioned by writers including Dioscorides, Pliny, John Gerard and John Evelyn. A common name, 'herb of grace', derives from the fact that bundles of rue were used to sprinkle holy water at Mass; Shakespeare mentions it by this name in Richard III and Hamlet.
Like many plants with long histories of medicinal use, Ruta seems to have been regarded as something of a cure-all, claimed to be effective against a range of human ailments including earache, epilepsy, sciatica, bronchitis, nightmares and colic, and to treat diseases of livestock. It was associated with warding off contagion, and was strewn in courtrooms in an attempt to protect judges and jurors from contracting 'gaol fever' from the prisoners. Another use is as a deterrent against fleas, a common use for aromatic plants and a probable side effect of the defence chemicals produced by them to deter their own insect predators.
Its roles in medicine, household affairs, religion and literature suggest that rue would have been familiar to many people at one time, but as a herb it has largely fallen out of favour. Few people today would be familiar with its medicinal uses, and fewer would practice them, partly because the need for protective herbs has declined due to developments in hygiene and medicine. The use of rue also poses a risk, as like many herbs, rue's therapeutic properties are accompanied by destructive ones. Contact with the skin can result in painful, itchy lesions, while taken internally a sufficient quantity causes vomiting, kidney failure, seizures and death. Despite centuries of medicinal use, perhaps rue's most appropriate role is to be admired from a distance.
Furniss D and Adam T 2007. Herb of Grace: an unusual cause of phytophotodermatitis mimicking burn injury. Journal of Burn Care & Research 28: 767-769.
Eickhorst K et al. 2007. Rue the herb: Ruta graveolens-associated phytophototoxicity. Dermatitis 18: 52-55.