Herbs perennial. Stems to 1 m, unbranched, erect, subglabrous or appressed hirtellous to hirsute. Petiole of basal leaf to 7 cm, apex shorter; basal leaf blade ovate to cordate, 4.5-8.5 × 3.5-5 cm, base cordate, apex caudate-acuminate; upper stem leaves ovate-lanceolate, herbaceous, margin incurved dentate-serrate, hirtellous. Verticillasters 4-14-flowered, in upper axils; bracts linear or filiform, 2-3 mm, ciliate. Calyx campanulate, 11-15 × 4-6 mm, subglabrous to sparsely strigose; teeth lanceolate-subulate, 7-10 mm, ciliate. Corolla white or yellowish, ca. 2 cm; tube ca. 2 mm wide near base, saccate, throat to 8 mm wide, partly hairy, hairy annulate near base inside; upper lip obovate or oblong, ca. 1.2 cm, margin ciliate, villous, apex rounded to emarginate; lower lip ca. 6 mm, middle lobe obreniform, 2-lobulate, base abruptly constricted; lateral lobes semicircular, ca. 0.5 mm, each with a needlelike marginal tooth. Anthers dark purple. Nutlets brownish, obovoid, apex truncate, base attenuate, ca. 3 × 1.8 mm. Fl. Apr-Jun, fr. Jul-Aug.