Eupatorium rotundifolium
| Roundleaf thoroughwort | |
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| photo by Robert H. Mohlenbrock | |
| Scientific classification | |
| Kingdom: | Plantae |
| (unranked): | Angiosperms |
| (unranked): | Eudicots |
| (unranked): | Asterids |
| Order: | Asterales |
| Family: | Asteraceae |
| Tribe: | Eupatorieae |
| Genus: | Eupatorium |
| Species: | E. rotundifolium |
| Binomial name | |
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Eupatorium rotundifolium L. |
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| Synonyms | |
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Synonymy
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Eupatorium rotundifolium, commonly called Roundleaf thoroughwort, is a North American species of plant in sunflower family. It native to the eastern and central United States, in all the coastal states from Maine to Texas, and inland as far as Missouri and the Ohio Valley.
The stems up to 100 cm (40 inches) tall and are produced from short rhizomes. The inflorescences are composed of a large number of small white flower heads, each with 5 disc florets but no ray florets. Plants can be highly variable due to hybridization, three varieties have been named.
As is common in Eupatorium, E. rotundifolium can form hybrids with other species in the genus. In particular, Eupatorium godfreyanum is a hybrid of E. rotundifolium and Eupatorium sessilifolium.
The plants known as Eupatorium rotundifolium var. saundersii have often been treated as a variety of E. rotundifolium. They can be distinguished based on morphology, and molecular evidence also suggests that these plants may be different enough from E. rotundifolium to recognize them as a species, Eupatorium pilosum.
Eupatorium rotundifolium contains sesquiterpene lactones of the guaianolide type including euparotin acetate and eupachlorin acetate, both of which inhibit tumor growth in vitro when isolated from the plant.
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Wikipedia