Erect rhizomatous perennial herb up to 80 cm. high. Stem usually branched from the base, somewhat swollen below the branches insertions, angular as for the branches with short appressed hairs. Leaves usually sparse; petiole 2–20(25) mm. long, with hair-covering like the branches; lamina 20–50 x 5–20 mm., lanceolate or ovate, with hard short appressed hairs above and on the nerves below, covered with the swollen bases of minute hairs below, rarely roughish on both surfaces, acute to obtuse and sometimes mucronate at apex, acute to obtuse, decurrent on the petiole and often asymmetrical at base, margins usually repand and undulate. Cymes lax, up to 19 cm. long when completely expanded, usually 2, rarely single, terminal; common peduncle 1–4 cm. long. Flowers sessile or subsessile. Calyx minute, callose-strigose or subglabrous outside, subglabrous or glabrous inside; lobes 0.5–1.0(2.0) mm. long, ovate to ovate-triangular, acute, callose-ciliate mainly at the base, thick. Corolla hypocrateriform, white, sparsely strigose outside on the upper part, otherwise glabrous outside and inside; tube 3.5–5.0 mm. long, slightly widened in the upper half; limb 3–5(6) mm. in diam.; lobes 1.2–2.2(2.5) mm. long, triangular-acuminate, usually with undulate and ± crenate margins, bent inwards in bud, spreading. Stamens inserted about the middle of the corolla tube; anthers 1.2–1.5 mm. long, narrowly oblong, emarginate at apex, obtuse to subcordate at base, subsessile. Ovary glabrous. Style 1.0–1.5(2.0) mm. long, filiform, glabrous; stigmatic ring not very well marked; sterile appendix 1.0–1.4 mm. long, narrowly conical, deeply 2-lobed, hirtellous. Fruits c. 4 x 5 x 4 mm., saddle-shaped at apex, tuberculate-crested, glabrous; nutlets connate in pairs, each pair 2-horned, 2-seeded, with the inner surface flat.
