Eupatorium perfoliatum or (common) boneset is a common North American perennial plant in the sunflower family.
It is native to the Eastern United States and Canada, widespread from Nova Scotia to Florida, west as far as Texas, Nebraska, the Dakotas, and Manitoba.
It is also called “agueweed”, “feverwort” or “sweating-plant”. It was introduced to American colonists by Indians who used the plant for breaking fevers by means of heavy sweating. It is nearly always found in low, wet areas and is often found near Phalaris arundinacea (reed canary grass.)