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Thoroughwort OR''

Thoroughwort OR''

Thoroughwort

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 perennials growing to 0.5–3 m (1.6–9.8 ft) 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.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).

Thoroughwort

Nine white-flowering species of thoroughworts, or bonesets, have been recorded for Missouri. They are in genus Eupatorium (yoo-puh-TOR-ee-um). They are upright, single-stemmed or few-stemmed perennials with fibrous, sometimes fleshy roots. When they branch, it’s usually at the top of the plant. They usually have rounded dome-shaped or flat-topped flower clusters that look rather fuzzy, because each small, composite flowerhead has only disk florets (lacking petal-like ray florets), and the threadlike style branches protrude from the florets. Tall thoroughwort (E. altissimum). Stems and leaves with short white hairs. Leaves are lance shaped or narrowly oval, often sessile, to about 5 inches long and 1 inch wide, usually with teeth along the outer half. Three noticeable main veins extend the length of the leaf, starting from the base of the leaf blade. Flowerheads contain 5 florets. Blooms August–October. Note that late boneset can be as tall or taller than tall thoroughwort. Tall thoroughwort has narrower leaves that are less coarsely toothed and more pubescent (hairier). Also compare to smallflower thoroughwort, which occurs in the Bootheel. Scattered statewide.

Late boneset (E. serotinum). Stems and leaves usually with short hairs. Leaves are lance shaped or ovate, often angled at the base, with definite leaf stalks, tapered to a sharply pointed tip, with sharp, often coarse teeth along the margins. Main veins 3 (sometimes 5), branching from the middle vein at the base of the leaf blade. Flowerheads contain 9–15 florets. Blooms August–October. Note that tall thoroughwort is most similar to late boneset. Late boneset has wider leaves that are more coarsely toothed and less pubescent (less hairy). Scattered statewide.American boneset (or common boneset, or American thoroughwort, E. perfoliatum). Easily identified by its perfoliate leaves: opposite, stalkless leaves that are fused together across the stem, making them look like a single leaf that has been pierced by the stem. Leaves are roughened or felty to the touch and may be up to 8 inches long and 2 inches wide; there is only 1 main vein. Also note its greener color (it’s not as grayish as tall thoroughwort and late boneset); the plant usually has fine, short hairs. Flowerheads contain 9–23 florets. Blooms July–October. Scattered statewide. (Source: mdc.mo.gov)

 

 

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