Herbs 1-3 m tall. Stem purplish red, apically long branched, sparsely cobwebby. Leaves papery, abaxially grayish white and densely felted, adaxially green and sparsely strigillose, margin spinulose denticulate. Basal and lower cauline leaves petiolate; petiole long, spinulose, winged, base auriculate and semiamplexicaul; leaf blade undivided, ovate to heart-shaped, 25-50 × 15-30 cm. Middle cauline leaves similar but shortly petiolate or sessile, cordate amplexicaul; upper cauline leaves sessile, smaller. Capitula several, nodding. Involucre 4-5 cm in diam. Outer and middle phyllaries lanceolate to oblanceolate, 8-20 × 3-4 mm, distally with a roundish scarious denticulate appendage apically narrowed into a 1-5 mm spine; inner phyllaries oblanceolate, ca. 3 × 0.3 cm, with a small scarious entire to ± lacerate usually blunt apical appendage. Corolla yellow, ca. 1.6 cm, tube ca. 6 mm. Achene brown, narrowly ovoid to obovoid, ca. 5.5 mm, multistriate. Pappus bristles to 1.5 cm, fragile. Fl. and fr. Jul-Sep. 2n = 26.
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