Description from Flora of China
Hydrangea integra Hayata.
Shrubs climbing. Branchlets brown-red, subglabrous. Petiole 1.5-4.5 cm, subglabrous; leaf blade elliptic, oblong-elliptic, or obovate, 7-22 × 3.5-8 cm, leathery, both surfaces glabrous, secondary veins 7-10 on both sides of midvein, curved, abaxially prominent, base subacute to cuneate, margin slightly reflexed, entire, apex acuminate. Inflorescences terminal, corymbose cymes, 8-10 cm wide, to 17 cm wide in fruit, apex subtruncate; peduncle and branches densely yellow-brown stellate hairy and pilose; branches crowded together at apex of peduncle. Sterile flowers with sepals 2-4, suborbicular to broadly orbicular, 1-1.5 × 0.8-2 cm, margin entire to sinuate. Fertile flowers with calyx tube cupular, ca. 1 mm; teeth 4 or 5, broadly ovate, less than 1 mm. Petals oblong, ca. 2.5 mm. Stamens 10, subequal, 3.5-4 mm in fruit; anthers subglobose, ca. 0.5 mm. Ovary inferior. Styles 2(or 3), reflexed, ca. 1.5 mm in fruit; stigmas not enlarged. Capsule campanulate, ca. 2.5 × 2.5-4 mm, apex truncate. Seeds brown, ellipsoid to oblong, ca. 0.5 mm, very shortly and slightly obliquely winged at both ends; seed coat striate veined. Fl. Jul, fr. Oct-Dec.
Dense forests on rocky mountain slopes; 1000-2800 m. Taiwan [Philippines].