A tree 30 ft or more high, with a rounded head of branches; young shoots reddish brown, glabrous; thorns often absent; when present, 3⁄4 to 1 in. long, stout. Leaves obovate to ovate, always tapered at the base, mostly pointed, sometimes rounded at the apex, upper part slightly lobed or double-toothed, or sometimes with two deep lobes near the base; 11⁄2 to 4 in. long, 1 to 3 in. wide; dark glossy green and downy along the midrib above, ultimately quite glabrous below; stalk 1⁄2 to 3⁄4 in. long. Flowers white, 1⁄2 in. diameter, produced during May in corymbs 2 in. across; calyx-tube and flower-stalk quite glabrous; calyx-lobes narrow, glandular-toothed or entire, downy inside; stamens twenty; styles two to five. Fruit black, 1⁄3 in. diameter, falling early.
Native of N. America from Michigan to California and Oregon; introduced about 1828. It is one of the largest, but not, so far as I have seen, one of the most ornamental of thorns, its corymbs being rather small and its fruits ineffective.