Description from Flora of China
Herbs stoloniferous. Stems slender, densely spreading white hirsute. Leaves long petiolate, circular, cordate, or reniform, margin with ovate-deltoid to broadly ovate and apically callose-acute teeth. Verticillasters few flowered, in interrupted terminal racemes; floral leaves similar to cauline leaves. Calyx obconical-campanulate, slightly 2-lipped; teeth ovate-deltoid, 3 of upper lip larger than 2 of lower lip, apex slightly curved. Corolla tubular, dilated at apex, pilose annulate near base inside, 2-lipped; upper lip ovate, galeate; middle lobe of lower lip trapeziform, deeply 2-lobulate, lateral lobes elliptic-obovate. Stamens 4, didynamous, much exserted, anterior 2 longer; filaments complanate; anther cells 2, parallel. Style apex equally 2-cleft. Nutlets triquetrous, ovoid, rounded at apex and on backside, shiny, glabrous.
Two species: China, Japan; both in China.