Rhizomes procumbent, with numerous stout fibrous roots. Stems robust, erect, (70-)100-200(-300) cm tall, 8-12 mm in diam. in lower part, striate, glabrous or laxly pubescent. Lower leaves withered by anthesis; petiole 1/3-1/2 as long as blade, with 1.5-2 cm wide wings, basally expanded into an amplexicaul auricle. Median leaf petiole decurrent into a broad wing; median leaves abaxially pale green, adaxially dark green, triangular-hastate, rarely broadly triangular-hastate, 20-30 × 20-50 cm, abaxially glandular puberulent on veins, adaxially sparsely puberulent, 3-veined from base, lateral veins upward divaricate, base truncate or subcordate, margin irregularly triangularly or lanceolate toothed, thin, apex caudate-acute; lateral lobes usually 2-lobed, lobules narrowly lanceolate, apex acute, slightly retuse. Upper leaves smaller, shortly petiolate. Lower leaves 1 or 2, similar to median stem leaves, but rather narrow, triangular-hastate, 2-or 3-fid or lateral lobes with smaller teeth on margins. Capitula quite numerous, 250-350, crowded at apices of stems in 20-50 cm large pyramidal panicles; lower synflorescence branches to 22 cm, ascending; upper branches erect or spreading; peduncles 4-12 mm, slender; rachis and peduncles often densely glandular puberulent. Involucres narrowly cylindric, 9-12 × 2-3 mm; phyllaries 4 or 5, green, linear-lanceolate, 9-12 mm, outside sparsely glandular puberulent or subglabrous, margin scarious, apically acute. Florets 5-7; corolla yellow, 7-8 mm, with 1.5-2 mm tube and campanulate-tubular limb; lobes lanceolate. Anthers ca. 3 mm, basally caudate. Style branches long excurved, apically truncate, papillose. Achenes cylindric, 7-8 mm, glabrous, ribbed. Pappus white, ca. 7 mm. Fl. Jul-Aug, fr. Sep.
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