Glabrous perennial; stems decumbent, lax, ascending to c. 30 cm tall, rooting at lower nodes. Petioles 5-7 mm long. Lamina 3-9 × 1-3 cm, usually ovate- or lanceolate-oblong, serrate; base broad-cuneate to subcordate, often obscuring petiole; apex obtuse to subacute. Racemes axillary, opposite, towards shoot apices, many-flowered; peduncles to c. 20 cm long; pedicels usually 5-10 mm long, slender. Bracts linear, < pedicels at flowering, elongating somewhat after. Calyx 2.5-4 mm long; lobes lanceolate to oblong, obtuse or subobtuse. Corolla 8-11 mm diam., deep blue with white eye; veins purplish. Capsule c. 4 mm diam., orbicular, glabrous. Seeds ± ellipsoid, convex on 1 side, flat on the other.