Herb to 0.7 m high. Stems thinly pilose with arachnoid hairs. Leaves green and glabrous above, sparsely arachnoid-hairy below; sessile glands absent; spines 3–12 mm long, yellowish white. Capitula 1–4 in terminal or lateral clusters; involucre broadly ovoid, 15–20 mm diam. at anthesis; median involucral bracts suberect, lanceolate, 8–15 mm long, 2–3 mm wide at base, entire, spinose at apex, glabrous or sparsely arachnoid dorsally. Corolla purple; tube c. 12 mm long; lobes 3–6 mm long. Anthers 6–8 mm long. Achenes 5–6.5 mm long, brown to grey. Pappus bristles 65–80, 13–17 mm long.