Perennials, 30-150 cm. Stems (from short rhizomes) single, branched distally, puberulent. Leaves opposite; subsessile or petiolate; blades palmately 3(-5)-lobed (at least larger proximal, lobes relatively broad), blades (or lobes) lanceolate to lance-ovate, 50-100 × 20-40 mm, margins serrate, apices rounded to acute, faces puberulent, gland-dotted. Heads in dense, corymbiform arrays. Phyllaries 8-10 in 2-3 series, oblong, 4.5-6 × 1.5-2 mm, apices rounded, abaxial faces puberulent, gland-dotted. Florets (4-)5(-6); corollas (usually pinkish) 2-2.5 mm. Cypselae 2-3 mm; pappi of 20-30 bristles 3-5 mm. 2n = 20.

Flowering Jul-Sep. Disturbed sites; 10-100 m; introduced; B.C.; N.Y., Pa., Va.; Europe.

Eupatorium cannabinum is a garden escape; it is native to Europe and may be established in British Columbia; it is only casually adventive elsewhere in the flora area.