Description from Flora of China
Shrubs 2-4 m tall. Branchlets of previous year gray-brown or gray, those of current year purple-brown, glaucous, glabrous or villous. Petiole 3-5 mm; leaf blade oblong- or ovate-lanceolate, 4.5-6 × 3-8 cm, abaxially densely gray villous, adaxially strigose, veins 3-5, slightly basifugal, base rounded or cuneate, margin serrulate or subentire, apex acuminate, rarely acute. Racemes 5-9(-21)-flowered, lowest pairs 3-5-flowered; rachis 5-9 cm, glabrous; pedicels 5-10(-13) mm, glabrous. Calyx purple, black-purple, or brown; tube glaucous, glabrous; lobes ovate, 5-6 × 3-4 mm, apex acute. Corolla discoid or cruciform; petals white, oblong, ovate-oblong, or broadly obovate, 1.2-1.5 × 1-1.2 cm, margin subcrisped, apex rounded, sometimes 2-lobed. Stamens 30-35, longest ones ca. 9 mm; anthers oblong, ca. 1.5 mm. Disc and style glabrous. Style slightly divided or entire, 7-8 mm; stigmas clavate, 1.8-2 mm, longer than anthers. Capsule obovoid, 8-10 × 7-7.5 mm. Seeds ca. 4 mm, shortly tailed. Fl. Jun-Aug, fr. Sep-Nov.
Three varieties occur in China. In FRPS, a fourth variety was recognized: var. cruciflorus S. Y. Hu. However, that name was actually published as a form by Hu (J. Arnold Arbor. 36: 329. 1955) and has never been validly published at varietal rank. It is treated in the present account as a synonym of var. melanocalyx.
Mixed forests, thickets, mountain slopes; 700-3800 m. Sichuan, Xizang, Yunnan [Myanmar].