Crataegus douglasii Lindl.

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.

From the Supplement (Vol. V)

C. rivularis Nutt., given as a synonym, is treated as a variety by some botanists – C. douglasii var. rivularis (Nutt.) Sarg. It is mainly a native of the Rocky Mountains, differing from the more coastal, typical variety in its longer thorns and its longer, relatively narrow leaf-blades.

The only other species of Crataegus in the Pacific north-west of America is C. columbiana Howell, a shrub or small tree with straight or slightly curved thorns up to almost 3 in. long and ovate to obovate, usually doubly serrated, unlobed leaves, permanently downy on both sides and 1 to 21⁄2 in. long. Receptacle clad with curled hairs or greyish wool. Petals white, about 3⁄8 in. long. Stamens ten. Styles woolly. Fruits dark red, ovoid, about 3⁄8 in. long. The oldest example at Kew is from seeds received in 1955, and there are others planted later, raised from wild-collected seed received from the botanic gardens of the Universities of Washington, USA, and of British Columbia.