Herbs perennial, stoloniferous. Stems 50-80 cm tall, glabrous or occasionally sparsely villous near nodes. Petiole 0.8-1.5 cm; leaf blade ovate-oblong to ovate-lanceolate, 5-10 × 1.5-4.5 cm, base cordate to truncate, margin double serrate/crenate, apex acute to short acuminate. Spikes 3-4.5 cm, glabrous; verticillasters close together and 2-flowered; bracts linear-lanceolate. Pedicel ca. 1.5 mm. Calyx campanulate, 4-4.5 × 3-3.5 mm, slightly swollen in front near base, 10-veined; teeth triangular, lower 2 narrower. Corolla white or reddish, 1.2-1.4 cm, tube 1/4 as long as corolla; middle lobe rhombic-obovate, nearly 1/2 as long as limb; lateral lobes ovate-oblong, acute. Style as long as stamens. Nutlets chestnut brown, obovoid, ca. 1.2 mm, smooth, sparsely white bullate, hairy. Fl. Jul-Sep.