Description from Flora of China
Shrubs small, 0.7-1.5 m tall. Branchlets brownish, terete or slightly 4-angled, densely crisped pubescent when young, glabrescent; bark peeled off into fragments. Petiole 1-4 cm, crisped pubescent; leaf blade brownish on both surfaces when dry or adaxially darker, elliptic to rhomboid-elliptic, 6-19 × 3-8 cm, thinly papery, both surfaces glabrous, glabrescent, or crisped pubescent only along veins, secondary veins 6-8 on both sides of midvein, arcuate, slender, abaxially plane, base cuneate to broadly so, margin serrate, apex caudate-acuminate. Inflorescences corymbose cymes, 8-14 cm wide, apex slightly arcuate; peduncle and branches short, densely crisped pubescent. Sterile flowers with sepals 3 or 4, bluish, ovate to broadly so, unequal, 1-2 × 1-1.8 cm in fruit, margin entire or apically few denticulate. Fertile flowers with calyx tube campanulate, 1.2-1.5 mm, glabrous; teeth ovate-triangular, ca. 2.5 mm. Petals reflexed after flowering, blue, oblong-ovate, 2.5-3 mm. Stamens 10, 3-5 mm; anthers yellow, broadly oblong, ca. 0.6 mm. Ovary less than 1/2 superior. Styles (2 or)3(or 4), thick, ca. 1 mm in fruit; stigmas slightly enlarged. Capsule oblong-ovoid, ca. 3 mm in diam., projected apical part 1.2-1.5 mm, ca. 1/3 as long as capsule body. Seeds brown, ellipsoid to oblong, compressed, 0.5-0.7 mm, shortly winged at both ends; seed coat net veined. Fl. Jun-Jul, fr. Oct-Nov.
One of the present authors (Bartholomew) believes that this species needs further study. It is close to Hydrangea macrophylla (Thunberg) Seringe and H. stylosa, and may belong to either of these species.
* Sparse forests or thickets along stream banks in valleys or on mountain slopes; 600-1500 m. SE Anhui (She Xian), N Zhejiang.