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Herbs 0.4-2 m tall, perennial. Stems erect, branched above, ribbed, unwinged, sparsely cobwebby. Leaves discolorous, surface smooth, abaxially grayish white and densely felted, adaxially green and with multicellular hairs. Basal leaves present at anthesis, long petiolate. Lower and middle cauline leaves sessile, ± narrowly elliptic or lanceolate, 10-30 × 4-6 cm, undivided, semiamplexicaul, margin with numerous obliquely triangular teeth tipped by a 0.5-1 mm spinule and smaller regular spinules in sinuses. Upper cauline leaves similar but gradually smaller upward. Capitula 1 to few, corymbose, erect. Involucre campanulate, ca. 2.5 cm in diam., glabrous or subglabrous. Phyllaries imbricate, in ca. 6 rows, lacking marginal spinules, wings, and scarious appendage; outer and middle phyllaries triangular to lanceolate-elliptic, 6-10 × 1.5-2 mm, apex acute and tipped with a spinule less than 0.2 mm; inner phyllaries elliptic to linear-elliptic, 13-15 × 2-2.5 mm, apex acuminate and scarious. Florets bisexual. Corolla red, ca. 2 cm, tube ca. 8 mm. Achene yellowish, ca. 4.5 mm. Pappus bristles white or dirty white, ca. 2 cm. Fl. and fr. Sep. 2n = 34.
A thistle
