Perennial herb, 60–90 cm high; stems erect, branched.. Leaves spiny, lanceolate, 3–10 cm long, 1–1.9 cm wide, base amplexicaul, margins revolute with many short spines (1–2 mm long), apex acute and shortly spiny, spinulose above, glandular and with prominently reticulate venation beneath, with a setulose midrib.. Capitula 12–16 mm long, in dense globose terminal synflorescences 3–4 cm in diameter; phyllaries lanceolate, the outermost spatulate, 6–15 mm long, apex acuminate and spinescent, the innermost acute and shortly laciniate.. Florets dark blue, tube 7–8 mm long, with few minute glands, lobes 8–10 mm long.. Achenes sparsely hairy, ± 3 mm long (immature); pappus of narrow ciliolate scales ± 1 mm long.