Eupatorium perfoliatum aka Chapman's Thoroughwort

Eupatorium perfoliatum, commonly known as common boneset or just boneset, is a robust, clump-forming perennial plant native to the Eastern United States and Canada. It belongs to the Asteraceae family and can be found in low, wet areas from Nova Scotia to Florida and as far west as Texas, Nebraska, the Dakotas, and Manitoba. Also referred to as agueweed, feverwort, or sweating-plant, this upright and sturdy perennial grows up to 1.2m in height, with erect stems covered in long white hairs. The plant features pairs of long, narrow, lance-shaped leaves that are toothed and reach up to 8" in length. During the summer to early autumn, large terminal clusters of small off-white flowers are produced, forming loose flat-topped corymbs that can measure from 3-8" across. Introduced to American colonists by natives, it was traditionally used for breaking fevers through heavy sweating.