Description from Flora of China
Spiraea japonica Linnaeus f. var. morrisonicola (Hayata) Kitamura.
Shrubs or subshrubs to 50 cm tall. Branchlets brownish or red-brown to gray-brown, slender, terete, pubescent when young, gradually glabrescent; buds ovoid, minute, with 2 brownish scales, puberulous, apex acute or subobtuse. petiole 1–3 mm, glabrous; leaf blade ovate or rhombic-ovate, 10–20 × 8–14 mm, glabrous on both surfaces, lateral veins distinctly raised abaxially, depressed adaxially, base cuneate to broadly so, rarely subrounded, margin entire toward base, grossly sharply serrate distally, apex obtuse or acute. Corymbs terminal on short, lateral branchlets, compound, 1.5–3 × 2–4 cm, densely many flowered; rachis and pedicels glabrous; pedicels 3–6 mm; bracts 8–12 mm, glabrous, apex with a few teeth or entire. Flowers 4–5 mm in diam. Hypanthium campanulate, glabrous abaxially. Sepals broadly triangular or ovate, 1–2 mm, erect in fruit, apex mucronate. Petals white, broadly obovate to suborbicular, longer than sepals, glabrous, base shortly clawed, apex obtuse. Stamens 10–12, nearly equaling to slightly longer than petals. Disk annular, 10-lobed; lobes triangular, apex obtuse. Carpels puberulous basally; styles subequaling stamens. Follicles slightly spreading, puberulous on adaxial suture; styles terminal on abaxial side, divergent, mostly deciduous when ripe. Fl. Jul–Aug. fr. Sep–Oct.
Montane regions; below 4000 m. Taiwan.