Rue is a dainty, attractive perennial native to south Europe with spicy, aromatic foliage. It grows two feet tall, with tiny pinnate blue-green leaves. In mid-summer, clusters of pale yellow flowers top the plants. The lower stems are thick and almost woody, which make it a sub-shrub. In spring,stems can be cut back with old foliage removed, but don't cut them to the base. The plants are hardy, somewhat drought-tolerant and long-lived. The dried leaves are used in herbal medicines, and stems can be used to flavor vinegars, but it is not used directly as food, only as an extract. The fragrance is intriguing, like a combination of pine, thyme and soap; some considering it malodorus. It contains essential oils, rutin (a bitter principle), tannins, and graveoline. It also contains furocoumarin, a substance that is toxic in large doses, causing nausea and tremors.