Japan Flora: Tree with glabrous or thinly pubescent young branchlets; leaves pinnate, 15-20 cm. long, the petioles 3-5 cm. long, glabrous or nearly so, the leaflets 多-15, lanceo­late to narrowly ovate-oblong, 3-7 cm. long, 1-2.5 cm. wide, long-acuminate to acuminate, glabrous or nearly so, pale to whitish and sometimes slightly pubescent on the midrib be­neath, with acuminate teeth, the lateral nerves slender; in­florescence 5-10 cm. across, densely many-flowered, glabrous or loosely brown-pubcscent at anthesis, becoming glabrous in fruit; flowers white, 6-8 mm. across; calyx glabrous, the teeth erect or only slightly incurved in fruit; petals spreading, nearly orbicular, short-clawed, often thinly puberulent inside at base, as long as the stamens; fruit red, 4-5 mm. across, glo­bose. May-July. Mountains.

Hokkaido, Honshu, Shi­koku, Kyushu.

var. rufoferruginea C. K. Schneid. Inflorescence, the calyx­ tube at anthesis, and the leaves beneath along the midrib with long, soft, brown hairs. Mountains; Honshu, Shikoku, Kyushu.

var. sachalinensis Koidz. Leaflets larger, to 8-9 cm. long. Hokkaido. s. Kuriles and Sakhalin.

Sorbus X rikuchuensis Makino. Leaves pinnately divided on lower half, pinnately parted to lobed on upper half, 4-8 cm. wide, glabrous on upper side, irregularly toothed, pubescent beneath, brown-pubescent on nerves be­neath, 6-12 cm. long, the leaflets and lobes chartaceous, spread­ing. Honshu (Rikuchu Prov.); rare; a hybrid involving S. commixta and an unknown second parent. Hybrids of uncertain origin occurring in Honshu 

Korea Flora: Deciduous shrub, 6-8m tall. Winter buds sticky; narrowly ovoid, apex acute, with 3-4 basal scales. Terminal buds larger than lateral buds (10-17mm long); branchlets and winter buds glabrous. Leaf scars remain at the base of petioles, V-shaped or U-shaped. Leaves alternate, pinnate compound leaves with (9)11-13(15) leaflets; leaflets lanceolate, broadly lanceolate, or elliptic-lanceolate, cuneate base, 2.5-4(5)cm × 1-1.5cm; glabrous on both surfaces, upper surface green, lacking luster, lower surface light green, margins sharply doubly serrate or singly serrate. Stipules small (3mm), deciduous early. Petioles 2-3cm long. Inflorescences compound racemose, 8-12cm in diameter, glabrous. Flowers 11mm in diameter, white; styles 3-4, 2.0mm long. Fruits samaras, globose, red, 5mm in diameter.

Flowering: May-July.
Fruiting: September-October.
Distribution: Sakhalin (Russia), throughout Japan; Jirisan Mountain, Deogyusan Mountain, Jeju Island (Korea).
Taxonomic note: This species is characterized by glabrous winter buds and is mainly distributed across the Korean Peninsula (except Baekdusan Mountain and Ulleungdo Island).