Perennial herb, mildly aromatic when bruised; stems ± erect to decumbent, ascending to c. 1 m, dying down almost to the tuberous base after flowering; indumentum of scattered sessile orange glands and ± copious, but not dense, colourless glandular and eglandular hairs, these being mainly retrorse lower down but often spreading towards inflorescence. Petioles to 4 cm long, hairy, broadly channelled above; lamina 3-8 × 2-7 cm, broadly ovate, membranous, ± scabridulous above, puberulent (especially on the veins) and with sessile orange glands beneath, green on both surfaces; margins with up to 10 pairs of prominent rounded or obtuse teeth; base truncate or very broadly cuneate. Inflorescence a terminal, narrow, indeterminate thyrse with 1 or few axes; inflorescence axes 7- 15 cm long, elongating to nearly 40 cm at fruiting; internodes glandular-puberulent and with sessile orange glands; flowers 8-20 per whorl, the lower whorls distant. Bracts broadly ovate, caducous. Calyx strongly 2-lipped; lower lip with 4, triangular, subequal teeth; upper lip suborbicular, mucronate; indumentum of mostly simple hairs and sessile orange glands; fruiting calyx with prominent raised vein net. Corolla 8-11 mm long to apex of lower lip, slightly hairy and glandular outside; tube horizontal or declined, whitish; upper lip 2.4-4 mm long, curving upwards and reflexing, violet except for whitish central band on each lobe; lower lip 4 - 5.5 mm long, naviculate, pale blue or mauve-blue. Stamens lying in lower lip; anthers dark blue; filaments pale bluish. Style included, almost equals longest stamens. Pedicels recurved at fruiting. Nutlets 0.8-1 mm diam., smooth, glossy dark brown, slightly angular or sub-lenticular, or ± rounded. Flowering: January to May.