Crataegus altaica (Loudon) Lange; C. korolkowii L. Henry; C. purpurea Bosc ex de Candolle var. altaica Loudon

Trees, 30–60 dm. Stems: 1-year old twigs deep red- or purple-brown, older dull or dark gray; thorns on twigs absent or sparse, stout, 1–4 cm. Leaves deciduous; petiole 2–3.5 cm, adaxially glabrous or sparsely pubescent; blade pale green abaxially, dull bluish green adaxially, ± ovate to triangular-ovate, 5–9 cm, base truncate to broadly cuneate, lobes 3–5 per side, evenly spaced, sinuses deep, margins sharply serrate, veins 4 or 5 per side, to lobes and deeper sinuses, apex acute, surfaces glabrous. Inflorescences 20–50-flowered; proximal bracteoles falcate, stipuliform, 2 cm, herbaceous, distal caducous, linear, membranous, margins sparsely sessile-glandular. Flowers 12–15 mm diam.; hypanthium glabrous; sepals triangular-ovate, 2–4 mm, entire or 1- or 2-toothed; styles 4 or 5. Pomes yellow to bright orange or orange-brown, suborbicular, 8–12 mm diam.; sepals persistent, reflexed; pyrenes 4 or 5. 2n = 51, 68.

Flowering Apr–Jun; fruiting Sep–Oct. Scrub; 300–2500 m; introduced; Wash.; c Asia.

Variety wattiana has become naturalized in the Washington Park Arboretum, Seattle. The variety has leaves shallowly incised throughout; those of var. incisa C. K. Schneider are pinnatisect basally.