Perennial herb, up to 30 cm tall, grey-pubescent and spiny, with rigid, erect stems often branched at the base. Leaves are canescent (2–6 × 0.5–2 cm), lanceolate, coriaceous, with spinulose margins, and arranged in whorls of four at each node. The inflorescence is a dense, strobilate spike (3–30 cm long), with channeled bracts bearing long pilose hairs and marked by 3 to 5 pairs of strong marginal spines. The blue, one-labiate corolla is dark-veined and fades to white, with a three-lobed lower lip and is hairy on the outside. The capsule is narrowly ovate, brown, shiny (6–9 mm long), containing two seeds. Seeds are ovate (4–5 mm), densely covered in hairs.