Shrubs or small trees, erect to slightly climbing. Branchlets green when young, becoming brown. Petiole (0.5-)1-2(-3.5) cm; leaf blade brown when dry, oblong-elliptic, ovate-elliptic, or ovate, 2.5-11 X 1.5-5.5 cm, papery, base cuneate, rounded, or slightly cordate, margin entire, apex caudate to acute, reticulate veins abaxially distinct. Panicles 4-14 X 2-9 cm, subglabrous to puberulent; bracts linear to lanceolate. Calyx cup-shaped, 1.5-2.5 mm, outside pubescent and yellow glandular; teeth 5, minute, triangular, ciliate. Corolla white, yellowish, orange, purple, or brown striate, 5-7 mm, tube 2.5-4 mm, slightly 2-lipped, villous in throat, lower lip 3-lobed; upper lip rounded to emarginate, outside densely glandular. Stamens slightly exserted; filaments glabrous. Ovary glabrous, apically glandular. Style shorter than stamens. Fruit purple-black, obovate. Fl. and fr. May-Sep.
The two Chinese varieties are rather poorly differentiated; however, there does appear to be a good correlation within the material available between flower color and flower size. Plants with white corollas have tubes less than 3 mm, whereas those with yellow corollas or yellow marked with brown have tubes 2.4–4 mm. This distinction merits further investigation.