Perennial herb 40–60 cm high, viscid-pubescent throughout; stems several, simple, ± quadrangular. Leaves linear to narrowly linear-ovate, 3–9 cm long, 5–9(–14) mm wide, sessile, ± cuneate at base, very acute at apex, margins shallowly serrate. Bracts similar to leaves diminishing in size upwards, longer than the pedicels; pedicels 1–2 cm long, curved in fruit. Flowers blue-purple, with white throat, usually 2 in each upper axil. Calyx ± 4 mm long, 5-lobed, lobes ± equal, acuminate. Corolla 2-lipped, ± 1 cm long and 2 cm across, with small glands all over; lobes 5, ± equal; lower lip with a central cavity and thrust forward; style and stigma glabrous. Capsule rotund, ± 5 mm in diameter. Fig. 4, p. 17.