白背紫珠 bai bei zi zhu

Trees, 5-8 m tall. Branchlets 4-angled, densely silky-velvety, nodes with a transverse scar. Petiole ca. 1 cm; leaf blade narrowly elliptic to elliptic, 10-13 X 3.5-4.5 cm, abaxially densely gray rusty colored silky, adaxially brown when dry and mealy stellate tomentellous when young, base cuneate, margin serrulate to subundulate, apex acute to acuminate. Cymes ca. 2 cm across; peduncle 4-angled, usually as long as petioles; bracts small. Pedicel ca. 1 mm. Calyx ca. 1 mm, truncate to minutely 4-dentate, gray stellate velvety. Corolla purple, ca. 3 mm, puberulent. Filaments longer than corolla. Ovary glabrous. Fl. May-Jun.

Mixed forests; ca. 200 m. Yunnan (Hekou Xian) [Cambodia, Thailand, Vietnam].