ague weed

(noun) gentian of eastern North America having clusters of bristly blue flowers. Synonyms: agueweed, ague weed, five-flowered gentian, stiff gentian, Gentianella quinquefolia, Gentiana quinquefolia.

(noun) perennial herb of southeastern United States having white-rayed flower heads; formerly used as in folk medicine. Synonyms: boneset, agueweed, thoroughwort, Eupatorium perfoliatum.