Boneset

Eupatorium perfoliatum is a native North American perennial found naturally in wet meadows, streambanks, swamp margins, and low-lying woodland edges from Nova Scotia to Florida and west to the Great Plains. It grows 2–5 feet tall and produces flat-topped clusters of small white flowers from midsummer into fall. Gardeners with rain gardens, pond margins, or persistently moist low spots will find it one of the most ecologically productive choices for those conditions.

The plant is identified readily by its connate leaf pairs, in which two opposite leaves are fused at the base so the stem appears to pass through a single leaf. It spreads slowly by rhizome and self-seeds modestly, forming stable clumps over time. Late-season native bees, flies, and wasps depend on it as one of the last reliable nectar sources before frost. It tolerates periodic flooding and performs well in average moist garden soil as long as it does not dry out. Thrives in slightly acidic, humus-rich conditions; apply a thick organic mulch to retain moisture in drier garden settings.

Boneset has a well-documented ethnobotanical history. Indigenous peoples of eastern North America used it as a diaphoretic — an agent to induce sweating — to break fevers. Colonists adopted this practice widely, and it remained a common household remedy for influenza and fever through the 19th century. The common name derives from its use in treating dengue fever, then called break-bone fever for the severe joint and bone pain it causes.