any of about 40 species of herbaceous plants constituting the genus Eupatorium of the composite family Asteraceae, native primarily to tropical America. The North American plant known as boneset is E. perfoliatum, also known as agueweed and Indian sage. It is common in wet places and is a coarse, rough, hairy perennial about 0.6 to 1.8 metres (2 to 6 feet) high. Its lance-shaped, toothed, and wrinkled leaves are joined together at their bases around the stem. In August the plants bear small, tubular, white flowers in numerous heads that form a flat and branched cluster.

Several species are known as joe-pye-weed, especially E. dubium, native to the eastern coastal plain. Sweet joe-pye-weed (E. purpureum), spotted joe-pye-weed (E. maculatum), and hollow joe-pye-weed (E. fistulosum) are found in wet thickets and meadows of the northern and central United States. Most joe-pye-weeds have clusters of fuzzy pink or purple flowers. white snakeroot, or white sanicle (E. rugosum), contains a toxic alcohol that causes trembles—muscular tremors, weakness, and constipation often leading to death—when eaten by animals; ingestion of the meat or dairy products of livestock so afflicted causes in humans an acute illness known as milk sickness, which is characterized by weakness, vomiting, and constipation. Boneset tea is a folk remedy for fever.