Description from Flora of China
Hydrangea verticillata W. H. Gao.
Shrubs or small trees, 1-5 m tall. Branchlets dark brown to gray-brown, pilose, glabrescent, with orbicular lenticels. Leaves 2-opposite or 3-verticillate; petiole 1-3 cm; leaf blade ovate to elliptic, 5-14 × 6-6.5 cm, papery, abaxially appressed villous along veins, adaxially glabrous or sparsely strigose, secondary veins 6 or 7 on both sides of midvein, erect proximally, base rounded to broadly cuneate, margin serrulate, apex acute to acuminate. Inflorescences paniculate cymes, pyramidal, to 26 cm; peduncle and branches densely pubescent. Sterile flowers with sepals 4, white, broadly elliptic to suborbicular, unequal, 1-1.8 × 0.8-1.4 cm in fruit, margin entire. Fertile flowers with calyx tube turbinate, ca. 1.1 mm; teeth triangular, ca. 1 mm. Petals white, ovate to ovate-lanceolate, 2.5-3 mm. Stamens unequal, longer ones ca. 4.5 mm, others slightly shorter than petals; anthers subglobose, ca. 0.5 mm. Ovary ca. 1/2 superior. Styles 3, subulate, ca. 1 mm; stigmas capitate, small. Capsule ellipsoid, 3-3.5 mm in diam., projected apical part conical, 2-2.7 mm, equaling calyx tube. Seeds brown, fusiform, compressed, narrowly winged at both ends; wings 2.5-3 mm; seed coat striate veined. Fl. Jul-Aug, fr. Oct-Nov.
Sparse forests or thickets in valleys or on mountain slopes or tops; 300-2100 m. Anhui, Fujian, Gansu, Guangdong, Guangxi, Guizhou, Hubei, Hunan, Jiangxi, Sichuan, Yunnan, Zhejiang [Japan, Russia (Sakhalin)].