Climbers, deciduous. Young branches, petioles, abaxial surface of leaves and midvein of adaxial surface of leaves, and peduncles densely yellowish gray pubescent, sometimes stiffly hairy. Petiole 5–12 mm; leaf blade ovate to ovate-oblong, 3–10 × 1.5–5 cm, papery, abaxially sometimes powdery-green, with sessile or very shortly stipitate, yellow to orange-red mushroom-like glands, base subrounded or subcordate, apex acuminate or acute. Flower pairs solitary or several clustered on lateral short branches, or clustered into racemes at apices of branchlets; peduncle shorter than or sometimes longer than petioles; bracts linear-lanceolate, subequaling calyx tube, outside stiffly hairy and ciliate; bracteoles orbicular-ovate or ovate, very rarely ovate-lanceolate and apex acuminate, ca. 1/3 as long as calyx tube, ciliate; calyx tube glabrous or sometimes slightly hairy; lobes triangular-lanceolate, 1/2–2/3 as long as calyx tube, ciliate; corolla white, sometimes with reddish hue, later yellow, 3.5–4 cm, bilabiate; tube slightly longer than labia, outside sparsely adpressed pubescent or glabrous, with or without sessile or shortly stipitate glands; stamens and styles slightly exserted, glabrous. Fruit black when mature, subglobose, sometimes pruinose, 7–8 mm in diam.; seeds blackish brown, ellipsoid, ca. 4 mm.

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.