Eupatorium rotundifolium L.
Habitat: Dry to wet siliceous, argillaceous or peaty acid soils, open woods, clearings, savannas, etc. [Hardwood to mixed forest (forest, upland)]
Range: Florida to Louisiana, north to southern Maine, and west to Ohio .
Aids to Identification: As a member of the boneset, or thoroughwort, group, E. rotundifolium has a characteristic broad cluster of white flowers arranged together in multiple heads. The stem is hairy and the opposite sessile leaves are twice as long as they are wide, and pointed at the apex. It is distinguished from the common boneset (E. perfoliatum) by having the opposite leaves seperate at the base rather than fused at the base.
Ecological characteristics: Very little is known about the ecological characteristics of this species in Maine.
Phenology: Flowers July - September.
Synonyms: Represented in Maine by variety ovatum (Bigelow) Torr.; formerly called Eupatorium pubescens Muhl ex Willd.
Known Distribution in Maine: This rare plant has historically been documented from a total of 1 town(s) in the following county(ies): York.
Dates of documented observations are: 1870
Reason(s) for rarity: At northern limit of range.
Conservation considerations: Unknown; no current locations documented.