Japan Flora: Shrub; young branches angled, glabrous or nearly so; leaves con color ous, broadly lanceolate to narrowly ovate, 3-7 cm. long, 1-3 cm. wide, acuminate, cuneate at base, doubly toothed on margin with acute incised teeth, loosely white- pilose on midrib beneath near base and on margin when young, the petioles 4-6 mm. long, glabrous; inflorescence terminal on short young branchlets from last year’s branches, many-flowered, short-pubescent; flowers white, about 8 mm. across; calyx glabrous, the teeth reflexed, deltoid, acute; petals orbicular, about half as long as the stamens; fruiting carpels with short spreading-hairs. Apr.

Hokkaido (sw. distr.), Honshu (n. distr.); rare

Korea Flora: Deciduous shrub, 1-1.5m tall. Branchlets yellowish, ridged, pubescent when young; older branches grayish-white. Leaves alternate, broadly lanceolate, thin, acuminate apex, broadly cuneate base, 4-7cm × 2-4cm; glabrous on the upper surface, lower surface grayish-green, veins pubescent, margins doubly serrate. Petioles 2-5mm long. Inflorescences compound racemose, 5-8(10)cm in diameter, narrower than Spiraea prunifolia ; pedicels densely pubescent. Flowers 7-8mm in diameter, white; calyx lobes spreading; stamens 2-3 times longer than obovate petals. Fruits follicles, sparsely pubescent; styles attached slightly below the apex.

Flowering: Late July to mid-August.
Fruiting: Late September to October.
Distribution: Hokkaido to northern Honshu (Japan); South and North Pyeongan s, South Hamgyeong to Gangwon and northward (Korea).
Taxonomic note: This species is distinguished from Spirea frischiana and S. betulifolia by the dense pubescence on its inflorescences. Its flowering period (late July to mid-August) also differs from related species, which typically flower in May-July.