Annual to 150 cm high; stems with continuous wings to c. 10 mm wide and spinose lobes to 10 mm wide, cobwebbed. Basal leaves in a sparse rosette, oblanceolate, 5–20 cm long, 2–8 cm wide, deeply pinnatisect, margins spiny, upper surface green and pubescent, lower surface white-cobwebbed; cauline leaves similar but smaller, stem-clasping. Inflorescence of 3–9 capitula in terminal or axillary clusters; capitula cylindric, erect to patent, 6–10 mm diam., sessile; involucral bracts erect, linear-lanceolate, to 20 mm long, green with scarious margins; dorsal surface of intermediate involucral bracts glabrous or very sparsely hairy; inner bracts slightly exceeding florets. Corolla 10–14 mm long, purple. Cypselas 4–5 mm long; pappus bristles subequal, 11–13 mm long. Flowers mainly spring and summer