Perennials, 80-150+ cm. Stems (from tuberous rhizomes) single, densely branched distally (shoots often develop from lateral buds), puberulent throughout (denser distally). Leaves usually opposite (distal sometimes alternate); sessile or subsessile; blades 3-nerved distal to bases, elliptic to oblong, 15-50 × (5-)10-20 mm, bases cuneate, margins entire or serrate (unevenly toothed), apices rounded to acute, faces puberulent (abaxial) or glabrate (adaxial), gland-dotted (both). Heads in corymbiform arrays. Phyllaries 8-12 in 2-3 series, oblong to lanceolate, 2.5-5 × 0.5-0.7 mm, apices rounded to acute, abaxial faces puberulent throughout. Florets 5; corollas 3-3.5 mm. Cypselae 1.8-3 mm; pappi of 20-35 bristles 3.5-4.5 mm. 2n = 20, 30, 40.

Flowering Jul-Aug. Wet, low ground, flatwoods; of conservation concern; 10-100 m; Ala., Fla., Ga., N.C., S.C.

Eupatorium anomalum has been proposed to be intermediate in morphology between E. rotundifolium and E. mohrii and, possibly, a hybrid derivative of that pairing. Molecular data suggest that its derivation is from hybridization between E. serotinum and E. mohrii.