Rhizomes stout, fleshy, up to 5 cm. diam.; stems robust, corymbosely branched above, up to 2 m. tall. Basal lvs up to 1 m. long including petiole up to 20 cm. or more long, 20 cm. wide; lamina about oblong in outline, irregularly pinnatifid to subpinnate; lobes coarsely doubly serrate to dentate, sharply toothed; scabrid above, veins prominent below. Cauline lvs broad and sessile at base. Capitula 2.5-4 cm. diam., pedicels clad in white cottony wool. Phyll. in several series, gradually tapering from broad base to subacute tip; outer with median line of spinulose subfoliaceous processes. Florets ∞, purplish. Achenes large, broad, stout, with 1-2 stout longitudinal ribs and ± 4 slender ones.
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