Spiraea trichocarpa Nakai

Shrubs to 2 m. Branchlets brown or yellow-brown to gray-brown, angled, sterile ones glabrous, flowering ones pubescent; buds long ovoid or cylindric, subequaling petioles, with 2 scales, glabrous or puberulous when young, apex acute or obtuse. Petiole 2–6 mm, glabrous or sparsely puberulous when young; leaf blade oblong, ovate-oblong, or obovate-oblong, 1.5–3 × 0.7–1.5 cm, glabrous on both surfaces, base cuneate, margin entire (leaves on sterile shoots with a few teeth near apex), apex acute or subobtuse. Corymbs terminal on short, lateral branchlets, compound, 4–7 × 3–5.5 cm, many flowered; rachis and pedicels densely pubescent; pedicels 5–9 mm; bracts linear or lanceolate, 4–6 mm, sometimes larger and leaflike at base of pedicels, pubescent. Flowers 5–7 mm in diam. Hypanthium campanulate, pubescent abaxially. Sepals triangular, 1.5–2 mm, usually persistent and erect in fruit, apex acute. Petals white, broadly obovate or suborbicular, 2–3.5 mm, about as broad as long, glabrous, apex emarginate or obtuse. Stamens 18–20, subequaling petals. Disk annular; lobes irregular, apex emarginate. Styles shorter than stamens. Follicles erect, densely pubescent; styles terminal on abaxial side, divergent. Fl. May–Jun, fr. Jul–Sep.

Mixed forests by streams. Jilin, Liaoning, Nei Mongol, Shanxi [Korea].