Description from Flora of China
Shrubs erect or twining. Branches sometimes ascending. Leaves long petiolate, margin dentate. Spikes terminal on short branches, cylindric, composed of crowded verticillasters; bracts persistent, ciliate. Calyx tubular-campanulate, conspicuously 10-veined; teeth 5, subequal, anterior teeth slightly longer; fruiting calyx slightly urceolate, teeth straight. Corolla tube exserted, saccate-swollen in front at middle, puberulent annulate, 2-lipped; upper lip straight, emarginate; lower lip slightly longer, spreading, 3-lobed; middle lobe largest, subcircular; lateral lobes semicircular. Stamens ascending, slightly exserted, involute in bud; anthers 1-celled, longitudinally dehiscent. Ovary with semitransparent, powdery protuberances. Style equally 2-cleft, lobes divergent. Nutlets dark brown, flattened, obovoid, abaxially somewhat wrinkled, adaxially hirsute, with glandular protuberances.
Monotypic: China, India, Malaysia, Myanmar.