Pseudokyrsteniopsis Perpetiolata

''Eupatorium'' is a genus of flowering plants in the family Asteraceae, containing from 36 to 60 species depending on the classification system. Most are herbaceous perennials growing to tall. A few are shrubs. The genus is native to temperate regions of the Northern Hemisphere. Most are commonly called bonesets, thoroughworts or snakeroots in North America. The genus is named for Mithridates Eupator, king of Pontus.

Systematics and taxonomy

''Eupatorium'' has at times been held to contain as many as 800 species, but many of these have been moved (at least by some authors) to other genera, including '' Ageratina'', ''Chromolaena'',
''Condylidium'', ''Conoclinium'', ''Critonia'', ''Cronquistianthus'', '' Eutrochium'', ''Fleischmannia'', ''Flyriella'', ''Hebeclinium'', ''Koanophyllon'', ''Mikania'', and ''Tamaulipa''.

The classification of the tribe Eupatorieae, including species placed in ''Eupatorium'' in the present or past, is an area of ongoing research, so further changes are likely. What seems fairly certain by now is that there is a monophyletic group containing ''Eupatorium'' (about 42 species of white flowered plants in North America, Europe and Asia, but not South America) and the Joe-pye weeds ('' Eutrochium''), and possibly others.

Uses

''Eupatorium'' are grown as ornamental plants, particularly in Asia. A number of popular ornamental plants formerly included in ''Eupatorium'' have been moved to other genera, such as ''Bartlettina''.

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).

Medical use

The common names for the plants are all based on the previous usage of one species, '' Eupatorium perfoliatum'', as an herbal medicine. Despite its name, boneset is not used to treat broken bones, instead the common name apparently derives from the herb's 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 the leaf (i.e. go through, note that in older usage "thorough" was not distinguished from "through", compare for example the word thoroughfare).

Boneset, although poisonous to humans and grazing livestock, has been used in folk medicine, for instance to excrete excess uric acid which causes gout.
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.

Selected species

North America

* '' Eupatorium album'' L.– white thoroughwortSchmidt & Schilling (2000)
* ''Eupatorium altissimum'' L. – tall thoroughwort
*'' Eupatorium anomalum'' Nash – Florida thoroughwort apomictic hybrid derivative of '' Eupatorium mohrii'' and ''Eupatorium rotundifolium''
* ''Eupatorium capillifolium'' (Lamarck) Small – dog-fennel
* '' Eupatorium compositifolium'' Walter – Yankeeweed
* ''Eupatorium godfreyanum'' Cronquist, apomictic hybrid derivative of ''Eupatorium rotundifolium'' and ''Eupatorium sessilifolium''
* '' Eupatorium hyssopifolium'' L. – hyssop-leaved thoroughwort
* ''Eupatorium lancifolium'' (Torrey & A.Gray) Small – lance-leaved thoroughwort
* ''Eupatorium leptophyllum'' DC. – false fennel
* ''Eupatorium leucolepis'' (DC.) Torrey & A.Gray – justiceweed
* ''Eupatorium linearifolium'' Walter – (''Eupatorium cuneifolium'')
* '' Eupatorium maritimum'' E.E.Schill. – apomictic hybrid derivative of '' Eupatorium mohrii'' and '' Eupatorium serotinum''
* '' Eupatorium mikanioides'' Chapman – semaphore thoroughwort
* '' Eupatorium mohrii'' Greene – Mohr's thoroughwort
*''Eupatorium novae-angliae hybrid derivative of '' Eupatorium paludicola'' and '' Eupatorium perfoliatum''
* '' Eupatorium paludicola'' E.E.Schill. & LeBlond – swamp thoroughwort, until 2007 classified as part of ''Eupatorium leucolepis''
* '' Eupatorium perfoliatum'' L. – common boneset
* '' Eupatorium petaloideum'' Britton – showy white thoroughwort, often considered to be part of '' Eupatorium album''
* ''Eupatorium pilosum'' Walter – rough boneset, often considered to be part of ''Eupatorium rotundifolium''
* '' Eupatorium resinosum'' Torrey ex DC. – pine barren boneset
* ''Eupatorium rotundifolium'' L. – round-leaved thoroughwort
* ''Eupatorium semiserratum'' DC. – smallflower thoroughwort
* '' Eupatorium serotinum'' L. – late boneset, late thoroughwort
* ''Eupatorium sessilifolium'' L. – upland boneset
* ''Eupatorium sullivaniae'' E.E.Schill. – apomictic hybrid derivative of '' Eupatorium album'' and ''Eupatorium lancifolium''

Europe

* ''Eupatorium cannabinum'' L. – hemp-agrimony

Asia

* ''Eupatorium amabile'' Kitam.
* '' Eupatorium benguetense'' C.Robinson
* ''Eupatorium camiguinense'' Merr.
* ''Eupatorium chinense'' L.
* ''Eupatorium formosanum'' Hayata
* '' Eupatorium fortunei'' Turcz. – ''fujibakama'', ''pei lan''
* ''Eupatorium japonicum'' Thunb. (often included in ''E. chinense'')
* '' Eupatorium lindleyanum'' DC.
* '' Eupatorium luchuense'' Nakai
* ''Eupatorium makinoi'' T.Kawahara & T.Yahara (see ''E. chinense'')
* '' Eupatorium nodiflorum'' DC.
* '' Eupatorium quaternum'' DC.
* ''Eupatorium sambucifolium'' Elmer
* '' Eupatorium shimadai'' Kitam.
* ''Eupatorium squamosum'' D.Don
* '' Eupatorium tashiroi'' Hayata
* '' Eupatorium toppingianum'' Elmer
* ''Eupatorium variabile'' Makino
* '' Eupatorium yakushimaense'' Masam. & Kitam

Moved to other genera

* ''Eupatorium adamantium'' Gardner (moved to ''Koanophyllon'')
* ''Eupatorium amygdalinum'' (moved to ''Ayapana'')
* ''Eupatorium ayapana'' – aya-pana, water hemp (moved to '' Ayapana triplinervis'')
* ''Eupatorium bracteatum'' Gardn. (moved to ''Stomatanthes, S. pernambucensis'')
* ''Eupatorium coelestinum'' – mistflower (moved to ''Conoclinium'')
* ''Eupatorium collinum'' (moved to ''Chromolaena collina'')
* ''Eupatorium itatiayense'' Georg Hans Emmo Wolfgang Hieronymus, Hieron. (moved to ''Symphyopappus