Herbs 70-100 cm tall, perennial. Stems erect, ribbed, unwinged, with sparse multicellular hairs. Leaves concolorous, green, surface smooth, abaxially with scattered multicellular hairs, adaxially glabrous. Middle cauline leaves sessile, elliptic to elliptic-lanceolate, to 20 × 8 cm, pinnately divided, semiamplexicaul; segments 5 or 6 pairs, elliptic, ovate, or triangular-ovate, with 3-5 unequal teeth tipped with a 5-12 mm spine. Upper cauline leaves similar but narrower, gradually smaller upward, undivided but with spiny teeth and apex. Capitula many, paniculate, surrounded by pectinately spiny bracts with long pungent spines. Involucre ovoid, 1.5-2 cm in diam., glabrous or very sparsely cobwebby. Phyllaries imbricate, in ca. 6 rows; outer phyllaries lanceolate, 6-7 × 1-2 mm, basal portion usually with pectinately spinulose margin, narrowed into a ca. 3 mm apical spinule; middle phyllaries triangular-lanceolate to lanceolate, 12-15 × 2-3 mm, above base with loosely and irregularly lacerate scarious wings, apically spine-tipped; inner phyllaries linear-lanceolate, ca. 15 × 2 mm, apically with a spiny-tipped appendage. Florets bisexual. Corolla purplish red, ca. 1.8 cm, tube ca. 9 mm. Achene yellowish with darker striae, ca. 4 mm. Pappus bristles brownish, ca. 1.5 cm. Fl. and fr. Aug-Sep.
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