Perennial with hairy stems, to c. 50 cm tall, usually much-branched. Lvs shortly petiolate; lamina 2.5-5 × 0.7-2.5 cm, lanceolate, ovate or elliptic, not rugose, serrate or crenate-serrate, hairy, sometimes minutely so, dotted with oil glands; lamina of uppermost lvs smaller; base cuneate, apex ± subacute. Verticels of many fls, in distant axillary whorls; pedicels short. Calyx 3-3.5 mm long, campanulate, hairy and with oil globules outside, glabrous inside; teeth equal, much < tube at anthesis, acuminate. Corolla 5-6 mm long, hairy outside, mauve, exserted. Stamens usually exserted from corolla, sometimes scarcely exceeding calyx. Nutlets 8-9 mm long, oblong, minutely reticulate.