Eupatorium is a genus of perennial herbs, mostly not branched below inflorescence.
Leaves opposite, sometimes whorled, or upper leaves alternate, blade often with 3 major veins; lower leaves smaller than upper and deciduous as plant flowers.
Flowers white to dull purple, very small, all tubular (discoid), petal lobes 5, pointed, no rays; in dense, mostly 5-flowered heads, on a bract covered floral base (involucre) 0.1-0.3 cm wide, bracts in 2-3 rows, usually green, hairy, often with membranous margins; inflorescence branched.
Fruit dry, small, 1-seeded (achene), 5-angled (use lens), plume of bristles in one row (Flora of North America 1993+).
Notes: Fed upon by larvae of the Haploa clymene moths.