Description from Flora of China
Shrubs or small trees, to 8 m tall. Branchlets dark purple or purplish brown when old, terete, slender, tomentose when young; buds dark purple, ovoid, tomentose. Stipules ovate-lanceolate, 4–6 mm, herbaceous, tomentose, margin entire, apex acute; petiole 1.5–3.5 cm, tomentose; leaf blade ovate or broadly ovate, 2.5–5 × 2–4.5 cm, both surfaces tomentose or adaxially subglabrous, base rounded or broadly cuneate, margin irregularly serrate, usually irregularly 3–5-parted; lobes narrowly ovate or narrowly elliptic, apex acute. Corymb umbel-like, 3–5 cm in diam., 3–6-flowered; bracts caducous, linear-lanceolate, membranous, pubescent, margin entire, apex acuminate. Pedicel 1.5–2 cm, tomentose. Flowers 1–2 cm in diam. Hypanthium campanulate, tomentose. Sepals caducous, triangular-ovate, ca. 3 mm, slightly shorter than hypanthium, both surfaces tomentose, margin entire, apex rounded-obtuse or slightly acute. Petals white, ovate, 8–10 mm, base shortly clawed, apex rounded. Stamens 20–25, unequal, slightly shorter than petals. Styles 3–5, slightly longer than or nearly as long as stamens, glabrous. Pome yellowish red, subglobose or oblong-ellipsoid to oblong-ovoid, 6–8 mm in diam., impressed at apex; sepals caducous; fruiting pedicel 1.5–2 cm, tomentose. Fl. May, fr. Sep. 2n = 34*, 51*.
This species is resistant to drought and cold temperatures. It has been used as stock to graft apple trees in NE and NW Shaanxi.
Malus setok Vassilczenko might be an allied species or an ecotype of M. transitoria.
Thickets, slopes, hills of the Loess Plateau, roadsides; 1500--3900 m. Gansu, Nei Mongol, Qinghai, Shaanxi, Sichuan, E Xizang.