Perennial, herbaceous. Stems erect, sturdy, quadrangular, leafy, 60-100 cm, above and below with a dense indumentum of glandular and eglandular hairs. Leaves simple, 7-15 x 5-8 cm, regularly triangular-ovate; clearly hastate-sagittate at base, regularly serrate or crenate, pilose below with numerous sessile oil globules; petiole up to 10 cm on lower cauline leaves, less above. Inflorescence simple or with few branches, elongated; verticillasters 2-6-flowered, clearly distant. Bracts up to 10 x 5 mm; bracteoles present. Pedicels c. 3 mm long in flower and fruit, erect-spreading. Calyx tubular-campanulate, c. 10-12 mm long, with a dense indumentum of long and short glandular hairs and numerous sessile glands; upper lip almost unidentate. Corolla pale yellow with prominent brownish markings especially on lower lip; tube curved, ± included in or somewhat exserted from calyx, villous within, squamulate, invaginated; upper lip clearly falcate; lower lip somewhat reflexed. Nutlets ovoid, c. 3.5 x 2 mm.