Rue (Ruta graveolens) is a perennial shrub recognized for its powerfully aromatic properties and distinctive appearance. While it has a long history of traditional use, modern understanding emphasizes the need for extreme caution when handling or consuming it. The plant’s potent chemical composition means its use is strictly limited today, particularly in medicinal or culinary applications, due to its inherent toxicity.
Botanical Identity and Characteristics
Rue (Ruta graveolens) is a member of the Rutaceae family, which also includes citrus fruits. This woody, evergreen perennial subshrub typically grows to a mounded height of two to three feet. It is native to the dry, rocky regions of Southern Europe and the Mediterranean, thriving even in poor soil conditions.
The foliage is its most recognizable feature, consisting of delicate, fern-like, blue-green leaves that are compound and often described as glaucous. When bruised, the leaves release a strong, pungent odor, reflected in the specific epithet graveolens, meaning “strongly scented.” In early summer, the plant produces small, dull yellow flowers arranged in flat-topped clusters.
Historical and Traditional Applications
Rue held significant cultural and medicinal importance throughout history, particularly in ancient civilizations. Both the Romans and Greeks valued the herb, using it in folk remedies for ailments such as inflammation, cramps, external ulcers, rheumatism, and as an antidote for venoms.
The herb also acquired a prominent role in folklore and spiritual practices, often referred to as the “herb-of-grace.” It was used as a protective charm against evil spirits, a tradition that persists in some cultures. During the bubonic plague, Rue was included in the purported “four thieves oil,” believed to offer protection.
Rue saw limited culinary use as a bitter flavoring agent, though this practice is rare today due to its toxicity. Historically, it was occasionally used to season cheese or in the production of certain alcoholic beverages and coffee in regions like Ethiopia. Its most controversial historical application was its use in folk medicine as an abortifacient and emmenagogue—used to induce menstruation or terminate a pregnancy.
Safety Profile and Potential Risks
Rue contains potent chemical compounds, most notably furocoumarins, which are responsible for its severe safety warnings. The most immediate hazard is phytophotodermatitis, a severe skin reaction caused by contact with the plant followed by sun exposure. Furocoumarins, such as psoralen, are activated by ultraviolet A light, leading to a photoirritant reaction.
This reaction manifests as intense reddening, a burning sensation, and severe blistering, often resembling a chemical burn. Individuals handling the plant, especially during weeding or pruning, should wear long sleeves and gloves to prevent this phototoxic effect. The risk is highest on sunny days.
Internal consumption of Rue is highly discouraged and carries a significant risk of toxicity. Ingesting the herb can lead to symptoms like severe gastrointestinal irritation, vomiting, and dizziness. High doses are linked to systemic issues, including damage to the kidneys and liver.
Furthermore, its historical use as an abortifacient confirms its ability to stimulate uterine contractions, making it strictly contraindicated for pregnant women. Due to the potent and potentially fatal effects of its chemical constituents, experts advise against the unsupervised internal use of Ruta graveolens.