Herbs 30-80 cm tall. Rhizomes long, woody. Stems erect, apically long virgately branched, glabrous or basally with scattered hairs. Leaves glabrous except at margin, adaxially shiny. Basal leaves petiolate; leaf blade elliptic, undivided, margin toothed. Lower and middle stem leaves lyrately pinnatipartite; lobes toothed, lateral lobes sublinear to linear, terminal lobe ovate to narrowly elliptic. Upper stem leaves pinnatipartite or undivided. Capitula several, solitary at end of a branch. Involucre campanulate, 1.2-1.7 cm in diam. Phyllaries tightly imbricate, in 8 or 9 rows; outer phyllaries triangular, ovate, or ovate-elliptic, 4-7.5 × 1.5-2.5 mm, apex acute and with a (1-)3-5 mm apical spinule; middle phyllaries elliptic-lanceolate or narrowly lanceolate, 11-13 × 1.8-2.5 mm, apex acute and with a (1-)3-5 mm spinule; inner and innermost phyllaries oblanceolate, 20-23 × 1.5-2 mm, apex acuminate. Corolla purple, 1.6-2 cm. Achene brown, ovoid-ellipsoid, ca. 5 mm. Pappus ca. 1 cm. Fl. and fr. Jul-Sep. 2n = 30, 60.
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