Herbs 30-100 cm tall, perennial. Roots tuberous, fusiform. Stem solitary, usually branched above; wings undulate, with ca. 5 mm stout rigid spines. Leaves concolorous, green, surface smooth, glabrous. Basal leaves with winged petiole; leaf blade elliptic, to 30 × 4 cm, margin with teeth ending in a 4-9 mm spine. Lower and middle cauline leaves similar but sessile, decurrent, gradually smaller upward. Upper cauline leaves lanceolate to elliptic. Capitula 1 to several, terminal, corymbose to corymbose-paniculate. Involucre ovoid, ca. 1.5 cm in diam., glabrous. Phyllaries in ca. 6 rows, lacking marginal spinules, wings, and scarious appendage; outer phyllaries ovate, ca. 3 × 1.2 mm, apex acute and tipped with a ca. 1.5 mm spinule; middle phyllaries linear-lanceolate, 5-8 × 1.7-2 mm, apex acute and tipped with a ca. 2 mm spinule; inner phyllaries linear, 8-9 × ca. 1.5 mm, apex acuminate and scarious. Florets bisexual. Corolla reddish purple, 1.8-1.9 cm, tube 7-8 mm. Achene yellowish, ca. 3 mm. Pappus bristles white, 1.2-1.3 cm. Fl. and fr. Jul-Aug. 2n = 34.
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