Description from Flora of China
Pyrus aucuparia (Linnaeus) Gaertner var. randaiensis Hayata, J. Coll. Sci. Imp. Univ. Tokyo 30(1): 98. 1911; P. aucuparia var. trilocularis Hayata; Sorbus rufoferrugineus (Shirasawa) Koidzumi var. trilocularis (Hayata) Koidzumi; S. trilocularis (Hayata) Masamune.
Trees 3–8 m tall. Branchlets dark grayish brown, terete, glabrous, with numerous small white lenticels; buds ovoid, 8–10 mm, apex acute or acuminate; scales several, brown, glabrous, slightly viscid. Leaves imparipinnate, together with rachis 12–16 cm; petiole to 3 cm, puberulous, gradually glabrescent; stipules caducous, linear, 6–9 mm; rachis adaxially slightly sulcate, abaxially puberulous, narrowly winged; leaflet blades 8 or 9 pairs, terminal and basal ones smaller than middle ones, at intervals of 1–1.5 cm, oblong-lanceolate or elliptic-oblong, (3–)4–5.5 × (0.8–)1–1.5 cm, abaxially puberulous, adaxially glabrous, base slightly obliquely rounded, margin sharply serrate, with 20–30 teeth per side, apex shortly acuminate. Compound corymbs 7.5–8 × 9–10 cm, many flowered; rachis and pedicels sparsely pubescent or subglabrous, with oblong lenticels; bracts caducous, linear, 5–8 mm. Pedicel 3–5 mm, rarely to 8 mm. Flowers 5–6 mm in diam. Hypanthium campanulate, abaxially glabrous. Sepals triangular, 1.5–2.5 mm, apex acute or shortly acuminate. Petals white, suborbicular, longer than sepals, base shortly and broadly clawed, apex obtuse. Stamens 20, slightly shorter than petals. Styles 3–5, somewhat not exceeding stamens. Fruit reddish, ovoid, 5–7 mm in diam., 4-loculed, rarely 3 or 5-loculed; sepals persistent. Fl. Jun, fr. Oct. 2n = 34*.
Forests; 2100--4200 m. Taiwan.