Herbs to 2 m tall, biennial. Stem purplish, erect, stout, apically branched, sparsely cobwebby; branches ascending. Leaves abaxially grayish white or pale green and thinly felted, adaxially green, sparsely strigose, and yellow gland-dotted. Basal leaves with petiole ca. 32 cm; leaf blade broadly heart-shaped, ca. 30 × 21 cm, margin entire and repand to mucronulate denticulate. Cauline leaves similar to basal leaves or ovate; uppermost cauline leaves ovate to shallowly cordate, smaller. Capitula few to many, ± corymbose. Involucre ovoid, 1.5-2 cm in diam., glabrous except for minute glandular hairs. Phyllaries all with a hooked apex; outer phyllaries triangular to lanceolate-subulate, ca. 15 × 1 mm; middle and inner phyllaries lanceolate to linear-subulate, ca. 15 × 1.5-3 mm. Corolla purplish red, ca. 1.4 cm, tube ca. 8 mm. Achene pale brown variegated with dark brown or concolorous, narrowly sometimes obliquely obovoid, 5-7 mm, multistriate. Pappus bristles to 3.5 mm. Fl. and fr. Jun-Sep. 2n = 18, 34, 36.
Plants to 100–300 cm. Basal leaves: petioles solid, 15–36 cm, glabrous or thinly cobwebby; blades 25–80 × 20–70 cm, coarsely dentate to subentire, abaxially thinly gray-tomentose, adaxially green, sparsely short-hairy to nearly glabrous. Heads usually in corymbiform clusters, long-pedunculate. Peduncles 2.5–6 cm. Involucres 25–45 mm diam. Phyllaries linear to linear-lanceolate, glabrous to loosely cobwebby, inner usually stramineous (sometimes purplish), margins with minute spreading or reflexed hairs. Florets 40+; corollas purple (occasionally white), 9–14 mm, glabrous. Cypselae light brown, often with darker spots, 6–7.5 mm; pappus bristles 2–5 mm. 2n = 32 (Japan), 34 (China), 36 (Japan); (Sweden).
"To 1.5 or even 3 m; lvs petiolate, the petioles mostly solid, progressively shorter upwards, the blade ovate or broader, cordate, to 5 × 3 dm, thinly tomentose beneath, subglabrous above; infl corymbiform, with long, glandular or glandular-hairy peduncles commonly 3–10 cm; heads large, the invol (2.5–)3–4 cm wide, generally equaling or surpassing the fls, glabrous or slightly glandular, and often with a few long cobwebby hairs; achenes 6–7 mm; 2n=32, 36. Native of Eurasia, sparingly established as a weed along roadsides and in waste places over most of the n. U.S. and adj. Can. Aug.–Oct."