Perennial, slightly aromatic, clump-forming herb; stems sulcate, hairy, dotted with glands, to a little over 2 m high. Roots fibrous. Petioles 1-2.5 cm long, hairy. Lamina 3.5-10 × 0.7-2 cm, oblong and tapered at both ends, sharply serrate, nearly glabrous above, puberulent beneath on veins and covered with black oil dots; base narrow-cuneate; apex acute. Infl. to c. 30 cm long, branched near base; rachis densely hairy; verticels close, each with 5-10 fls; pedicels very short, tomentose; bracts ovate, subulate, caducous. Calyx 4-6 mm long, campanulate, hairy and dotted with glands; teeth triangular, acuminate, usually c. 1/2 length of tube. Corolla 15-22 mm long; lobes bright blue, hairy and dotted with glands outside; upper lip straight except for ± hooded apex; lower lip bent at right angles to tube, its 2 lateral lobes broader than long. Stamens included or slightly exserted from upper lip; connective of fertile arms c. 2× filaments; sterile arms broad and flat. Nutlets not seen.