The Botanical Profile of Rue
Rue, scientifically known as Ruta graveolens, is a perennial, evergreen sub-shrub belonging to the Rutaceae, or citrus family. Native to the Balkan Peninsula and Mediterranean region, it typically grows in a mound shape, reaching heights of 2–3 feet. Its most distinctive feature is its bluish-green, fern-like foliage, which releases a strong, pungent aroma when bruised. The specific epithet graveolens reflects this heavy, or strong, scent. In early summer, the plant produces clusters of small, dull yellow flowers.
Notable Characteristics
- Foliage: The leaves are pinnately divided with rounded, spatulate segments, giving them a delicate, lacy appearance. They are covered in gland-dots that contain the volatile oils responsible for its scent.
- Flowers: The terminal flower in each cluster has five petals, while others have four. Their greenish-yellow hue adds a subtle interest to the garden.
- Growth Habit: A hardy and drought-tolerant plant, rue thrives in full sun and well-drained, even poor, rocky soil. Its longevity is typically around 4–5 years, but it readily self-sows.
A History of Contradictory Uses
For centuries, rue has been woven into various cultures, but its use has always been accompanied by a strong sense of caution due to its toxicity. Its potent properties made it a staple in traditional medicine and folklore, but modern herbalists now recognize the significant risks involved.
Historically, rue was used for a wide range of ailments. Ancient Romans and Greeks employed it for medicinal and culinary purposes, with texts mentioning it as an antidote to poison and for strengthening eyesight. During the Middle Ages, it was famously included in the recipe for Four Thieves Vinegar, a concoction believed to protect against the plague.
Culinary and Medicinal Decline
Despite its historical use, rue is not common in modern cuisine due to its intensely bitter taste and toxic compounds. While it remains a traditional flavoring in some Mediterranean regions, particularly for certain grappas, it is used very sparingly. For instance, a single small branch may be added to a bottle of grappa for flavor. Traditional medicinal applications for conditions like menstrual disorders and inflammation are now considered obsolete or require extreme caution due to the risk of severe side effects, including liver damage and death in large doses.
Modern Applications and Risks
Today, rue is primarily grown as an ornamental garden plant, appreciated for its distinctive foliage and tolerance for challenging growing conditions. It is often used as a low hedge or in rock gardens. Its repellent properties, particularly its scent, can deter some pests, earning it a place in integrated pest management. However, the same compounds that repel insects can pose risks to humans.
Significant Safety Concerns
- Phytophotodermatitis: Contact with the fresh foliage, especially on a sunny day, can cause severe skin irritation, burn-like blisters, and hyperpigmentation. The furocoumarin compounds in the plant react with sunlight, causing this painful reaction.
- Internal Toxicity: Ingesting large quantities of rue, particularly fresh leaves or essential oil, is dangerous and can lead to severe gastrointestinal distress, internal hemorrhaging, and organ damage.
- Pregnancy and Lactation: Rue is a known abortifacient and emmenagogue, meaning it can cause uterine contractions and induce menstruation. It is strictly contraindicated for pregnant and breastfeeding women.
Comparing Rue to Common Garden Herbs
Rue is distinct from many other popular herbs in both its properties and safety profile. Here is a comparison with other common plants that are sometimes confused with or compared to rue.
| Feature | Rue (Ruta graveolens) | Fenugreek (Trigonella foenum-graecum) | Southernwood (Artemisia abrotanum) |
|---|---|---|---|
| Family | Rutaceae (Citrus Family) | Fabaceae (Legume Family) | Asteraceae (Daisy Family) |
| Appearance | Evergreen sub-shrub with blue-green, fern-like leaves | Annual legume with trifoliate green leaves | Woody shrub with fine, silvery-green, feathery leaves |
| Taste | Intensely bitter and pungent | Bitter but edible; nutty flavor | Bitter and aromatic; more lemon-like than rue |
| Toxicity | Highly toxic in large doses, causing skin burns and internal damage | Generally safe to consume, especially cooked seeds | Bitter; low toxicity risk in culinary amounts |
| Primary Use | Ornamental, insect repellent | Culinary (seeds and leaves) | Aromatic foliage, historical use |
How to Safely Handle and Grow Rue
If you choose to cultivate rue for ornamental purposes, careful handling is essential. Due to the risk of phytophotodermatitis, gardeners should always wear gloves and long sleeves when pruning or harvesting, especially on sunny days.
Growing and Care
- Planting: Sow seeds indoors in late winter or early spring, or directly outdoors after the last frost. Seeds need light to germinate and should be pressed into the soil surface.
- Location: Plant in a sunny spot with well-drained, sandy, or rocky soil. Avoid rich, heavy, or waterlogged soils.
- Watering: Water regularly until established, but allow the soil to dry out between waterings. Mature plants are very drought-tolerant.
- Pruning: Prune in early spring to shape the plant and encourage new growth.
Harvesting and Propagation
- Harvesting: For ornamental use, harvest leaves in the early morning for peak essential oil content, wearing protective gloves.
- Propagation: Rue is easily propagated by seeds, cuttings, or division. Cuttings from young, semi-woody stems can be taken in summer or autumn.
Conclusion
Rue is an herb with a truly dual nature. On one hand, its delicate, aromatic foliage and drought-tolerant nature make it a beautiful and low-maintenance addition to the garden, appreciated for its ornamental value and pest-repelling properties. On the other hand, its significant toxicity demands extreme caution, particularly regarding skin contact and internal consumption. Its rich history in traditional medicine is a fascinating story, but one that serves as a powerful reminder of why such practices should not be attempted today without expert medical consultation. By understanding what kind of herb is rue, we can appreciate its beauty and history while respecting its potent and dangerous nature.
For more information on the botanical characteristics of Ruta graveolens, consider consulting resources from trusted botanical gardens and educational institutions.
