Climbers. Branchlets, petioles, and peduncles densely gray-white puberulous; young branches purple-red, old branches brown. Petiole 4–10(–13) mm; leaf blade abaxially pinkish, adaxially sometimes with purple hue, ovate or ovate-oblong, 2–6(–9) × 2–4 cm, papery, both surfaces glabrous or sparsely pubescent, adaxially gray-white velutinous (on robust branches), base rounded, truncate, or sometimes slightly cordate, those on lower part of stem sometimes irregularly 3–5-pinnatifid, apex obtuse or subrounded, sometimes obtuse-mucronate. Flower pairs axillary at apices of branchlets, congested into racemes, fragrant; peduncle 4–12 mm; bracts triangular, very small, 1–2 mm, much shorter than calyx tube; bracteoles orbicular-ovate, very small, sparsely minutely ciliate; calyx tube 2–2.5 mm, slightly pruinose; lobes broadly triangular or suborbicular to ovate, apex obtuse or rounded; corolla white, tinged with purple-red near base, later yellowish, 2–3.5 cm, bilabiate; tube 1.4–1.7 cm, outside slightly adpressed pubescent or glabrous, inside densely pubescent on upper labium; upper labium subequaling tube; lobes oblong-lanceolate, ca. 5 mm; 2 lateral lobes deep to over 1/3; lower labium narrowly linear, longer than upper labium; stamens subequaling corolla; filaments sparsely pubescent at base; anthers linear; styles exserted, pubescent in lower 1/3 or glabrous. Fruit black.

Flora of China

The flowers are used for epidemic febrile diseases at the early stages, sores, carbuncles, furuncles, and swellings, diarrhea and dysentery with purulent and bloody stools.

Jing-Nuan Wu. An Illustrated Chinese Materia Medica. P: 398, Oxford University Press, Inc.2005.