Perennial, to 1.2 m high, glabrous or pubescent with short crisped hairs; stem erect, much-branched. Basal leaves petiolate, oblanceolate, 7–30 cm long, 1–12 cm wide, apex acute, margins toothed to pinnatisect; cauline leaves sessile, reduced to scale-leaves at extremities of branches. Capitula 2.5–3 cm diam., 1–3 in axils of reduced leaves; involucre 9–12 mm long; outer bracts lanceolate, straw-coloured at base, green at apex; inner bracts linear-lanceolate, c. twice as long as outer ones, mostly green. Florets 15–30, sky-blue, rarely pink or white; ligule 15–25 mm long. Cypselas 2–3 mm long, striate, pale brown or mottled; pappus of numerous scales 0.2–0.4 mm long. Flowers mainly spring and summer.