Eupatorium is a genus of flowering plants in the aster family, Asteraceae, containing from 36 to 60 species depending on the classification system. Most are herbaceous perennial plants growing to 0.5–3 m tall. A few are shrubs. The genus is native to temperate regions of the Northern Hemisphere. Most are commonly called bonesets, thoroughworts or snakeroots. The genus is named for Mithridates Eupator, king of Pontus.
Eupatorium is grown as ornamental plants, in particular in Asia. A number of popular ornamental plants formerly included in Eupatorium have been moved to other genera, such as Bartlettina and Conoclinium.
Tobacco leaf curl virus is a pathogen occasionally affecting plants of this genus. The foliage is eaten by some Lepidoptera larvae, including those of Orthonama obstipata (The Gem).
The common names for the plants are all based on the previous usage of one species, Eupatorium perfoliatum, as an herbal medicine. Boneset alludes to the use of the plant to treat broken bones, although it may also come from its use to treat dengue fever, which was also called breakbone fever because of the pain that it caused. The name thoroughwort also comes from Eupatorium perfoliatum, and refers to the perfoliate leaves, in which the stem appears to pierce (i.e. go through, note that in older usage "thorough" was not distinguished from "through", compare for example the word thoroughfare) the leaf. Boneset, although poisonous to humans and grazing livestock, has been used in folk medicine, for instance to excrete excess uric acid which causes gout. Eupatorium has many more presumed beneficial uses, including treatment of dengue fever, arthritis, certain infectious diseases, migraine, intestinal worms, malaria, and diarrhoea. Boneset infusions are also considered an excellent remedy for influenza. Scientific research of these applications is rudimentary at present, however.
Caution is advised when using boneset, since it contains toxic compounds that can cause liver damage. Side effects include muscular tremors, weakness, and constipation; overdoses may be deadly.
See Also: flora, online flowers, flower arrangement