Eupatorium amoenum Pursh; E. falcatum Michaux; E. fuscorubrum Walter; E. harnedii Steele ex Harned; E. purpureum Linnaeus var. album Barratt; E. purpureum var. amoenum (Pursh) A. Gray; E. purpureum var. falcatum (Michaux) Britton; E. purpureum var. ovatum Alph. Wood;E. purpureum var. verticillatum (Lamarck) Alph. Wood; E. trifoliatum Linnaeus; E. trifoliatum var. amoenum (Pursh) Farwell

Leaves: petioles glabrous; abaxial faces usually glabrous, sometimes sparsely to densely hairy along major veins (hairs fine, simple, 1-cellular). 2n = 20.

Flowering late summer–early fall. Rich, open deciduous woodlands, woodland borders, and thickets, wooded ravines, near bases of slopes bordering wet grounds, partial or deep shade; 10–1200 m; Ont.; Ala., Ark., Conn., Del., Fla., Ga., Ill., Ind., Iowa, Kans., Ky., La., Md., Mass., Mich., Minn., Miss., Mo., Nebr., N.H., N.J., N.Y., N.C., Ohio, Okla., Pa., R.I., S.C., Tenn., Vt., Va., W.Va., Wis.

East of the Mississippi River, abaxial leaf faces of var. purpureum tend to be glabrous and rarely pubescent along the major veins. West of the Mississippi (and in the xeric sandhills of South Carolina), abaxial leaf faces are commonly densely pubescent along the major veins.