Description from Flora of China
Perennials, glabrous or soon glabrescent. Stems creeping, to 30 cm, slender, conspicuously stoloniferous. Basal leaves petiolate; leaf blade spatulate to ovate, 2-5 cm including petiole, thin, margin sparsely serrate. Stem leaves opposite, petiolate; leaf blade obovate-spatulate to subrounded, 1-2.5 cm including petiole, margin crenate to subentire. Racemes usually axillary, rarely terminal, ascending, to 15 cm, lax. Pedicel slen-der, 1-1.5 cm in fruit. Calyx campanulate, 4-7 mm, slightly enlarged in fruit; lobes ovate-lanceolate, as long as tube, apex acute to obtuse. Corolla yellow with purple patches, white, blue-purple, or pale violet, 1.2-1.5 cm; lower lip middle lobe narrowly ovate, narrower, longer than lateral lobes; plaits with sparse glandular hairs; upper lip erect. Ovary glabrous. Capsule globose. Seeds brown-yellow; seed coat smooth. Fl. and fr. Apr-Jul.
* Moist hilly areas, trailsides, beside water; below 800 m. Henan, Hubei, Jiangsu, Jiangxi, Zhejiang.