Herbs to 2 m tall, biennial. Stem erect, branched, sparsely cobwebby; branches ascending. Leaves abaxially grayish white and densely felted, adaxially green and glabrous. Basal leaves petiolate; leaf blade heart-shaped, 25-50 × 10-30 cm, margin sparsely denticulate, teeth spinulose or mucronulate, apex acute to obtuse and mucronulate. Cauline leaves similar to basal leaves; uppermost cauline leaves sessile, ovate to ovate-elliptic. Capitula few to many, ± corymbose. Involucre ovoid, 1.5-2 cm in diam., ± densely cobwebby. Outer phyllaries subulate, triangular-subulate, or lanceolate, ca. 6 × 1 mm; middle phyllaries linear-subulate, 10-14 × ca. 2 mm, all with a hooked apex; inner phyllaries lanceolate to linear-lanceolate, apex acuminate. Corolla purplish red, 0.9-1.2 cm, tube 4.5-6 mm. Achene pale brown variegated with dark brown, narrowly obovoid, ca. 5.6 mm, multistriate. Pappus bristles pale brown, ca. 3 mm. Fl. and fr. Jul-Sep.
Plants to 250 cm. Basal leaves: petioles hollow or solid, 10–15 cm, glandular-hairy; blades 30–40 × 16–28 cm, coarsely dentate to subentire, abaxially white-tomentose, adaxially green, sparsely short-hairy. Heads usually in corymbiform clusters, long-pedunculate. Peduncles 1.5–12 cm. Involucres 15–25 mm diam., densely cobwebby (rarely glabrate). Phyllaries linear to linear-lanceolate, inner usually purplish, margins with minute spreading or reflexed glandular hairs. Florets 30+; corollas rose-purple, (occasionally white), 9–13 mm. limb minutely glandular. Cypselae light brown, 5–8 mm; pappus bristles 1–3 mm. 2n = 36.
"Resembling no. 3 [Arctium lappa L.] but smaller, seldom over 13 dm; lower petioles mostly hollow; invol mostly 1.5–2.5 cm thick, ± strongly arachnoid-tomentose and the bracts only weakly or scarcely hooked; cor-limb glandular outside; 2n=36. Native of Eurasia, sparingly established in our range. June–Oct."
