Eupatorium ×cordigerum

(Fernald) Fernald

Rhodora 47: 192. 1945.

Basionym: Eupatorium rotundifolium var. cordigerum Fernald Rhodora 45: 477. 1943
Treatment appears in FNA Volume 21. Treatment on page 467. Mentioned on page 463, 464, 472.

Perennials, 40–100+ cm. Stems (from short rhizomes) single, branched distally, densely pilose. Leaves usually opposite (distal sometimes alternate); sessile; blades ± 3-nerved or pinnately nerved, ovate, 3–9.8 × 1.6–5.7 cm, bases clasping or narrowly perfoliate, margins serrate, apices acute, faces (rugose) sparsely pilose (adaxial) or densely pilose (abaxial) and densely gland-dotted. Heads in corymbiform arrays. Phyllaries 7–10 in 2–3 series, 4–12 × 1–4 mm, apices (usually white) acuminate to acute, abaxial faces pilose, gland-dotted. Florets 5–8; corollas 2.5–3 mm. Cypselae 2–3 mm; pappi of 30–40 bristles 3.5–4.5 mm. 2n = 30, 40.

Phenology: Flowering Jul–Aug.
Habitat: Margins of woods, moist areas
Elevation: 10–100+ m



Ark., Miss., N.J., N.C., S.C., Va.


Eupatorium ×cordigerum is an apomictic, polyploid hybrid of E. rotundifolium and E. perfoliatum that occurs in disturbed areas where those two species occur together. It is not uncommonly encountered; it is unclear how long it persists.

Selected References


Lower Taxa