Description from Flora of China
Hydrangea angustipetala Hayata; H. angustipetala var. major W. T. Wang & M. X. Nie; H. chloroleuca Diels; H. jiangxiensis W. T. Wang & M. X. Nie; H. macrosepala Hayata; H. obovatifolia Hayata; H. scandens (Linnaeus f.) Seringe subsp chinensis (Maximowicz) E. M. McClintock; H. umbellata Rehder.
Shrubs 0.5-4 m tall. First and 2nd years' branchlets red-brown to brown, pubescent when young, glabrescent. Petiole 0.5-2 cm, glabrous or pubescent; leaf blade lanceolate, narrowly elliptic, or obovate, 5-12 × 1.5-4 cm, papery to thinly so, both surfaces sparsely pubescent or glabrous except along veins, abaxially usually barbate at vein axils, secondary veins 4-7 on both sides of midvein, abaxially slightly elevated, base cuneate to subacute, margin subentire to roughly serrate, apex caudate-acuminate to acute. Inflorescences umbellate or subcorymbose, 3-7 cm, 10-14 cm wide in fruit, apex flat or slightly arcuate; branches 3 or 5, equal or central one longer and thicker, pubescent. Sterile flowers with sepals 3 or 4, elliptic, obovate, ovate-orbicular, or broadly orbicular, 1.1-3 × 1-3 cm in fruit, margin entire, undulate, or few denticulate. Fertile flowers with calyx tube cupular to campanulate, 0.5-1.5 × 1.5-2 mm; teeth lanceolate to triangular-ovate, 0.5-2 mm. Petals yellow, elliptic to oblanceolate, 2.5-3.5 × 1-1.2 mm, base with a claw ca. 0.5 mm, apex subacute. Stamens 8-11, subequal, 2-4.5 mm; anthers oblong, 0.6-1 mm. Ovary ca. 1/2 or more superior. Styles 3 or 4, erect or slightly spreading, 1-2 mm in fruit; stigmas usually enlarged, decurrent along both sides of style. Capsule fusiform to ovoid-globose, 3.5-5 × 2.4-3.5 mm, projected apical part 1.5-2.5 mm, equaling or slightly longer than calyx tube. Seeds brownish, ellipsoid, ovoid, or subglobose, slightly compressed, 0.5-1 × 0.4-0.5 mm, wingless; seed coat net veined. Fl. Mar-Aug, fr. May-Oct.
Hydrangea chinensis is a very common and widespread taxon that forms a species complex out of which a number of segregate species have been recognized. One of the present authors (Bartholomew) feels that species nos. 2-4 below all fall within the pattern of variation found in H. chinensis, in the synonymy of which they would be better treated.
Sparse to dense forests on mountain slopes, mountain tops, or in valleys; 300-2000 m. Anhui, Fujian, Guangxi, Hunan, Jiangxi, Taiwan, Zhejiang [Japan].