2. Crataegus phaenopyrum (L.f.) Medik. (Washington thorn)

C. cordata (Mill.) Aiton

Mespilus phaenopyrum L.f.

Pl. 524 g, h; Map 2413

Plants small trees, 4–10 m tall, the trunks armed with branched thorns, the older bark gray, rough, peeling in small, irregular, checkered flakes,often exposing an orangish brown underlayer. Branchlets with scattered thorns, these mostly 2–5 cm long, dark brown at second year, eventually becoming gray, slender, straight. Twigs glabrous or nearly so, purplish brown by the second year. Petioles 13–25 mm long, glabrous, nonglandular. Leaf blades 2–5(–7) cm long, wider than long to about 3/4 as wide as long, ovate-triangular to broadly ovate-triangular in outline, sometimes slightly asymmetric in outline, broadly rounded to truncate or rarely shallowly cordate at the base, the tip and large lobe tips more or less tapered and sharply pointed, with 2–5 lobes per side (these sometimes appearing palmate or nearly so), the basal pair shallow to more commonly about 50% of the way to the midvein, the remaining lobes much shallower, the sinuses narrow to relatively broad, the margins otherwise sharply and irregularly but often relatively sparsely toothed, nonglandular, the texture somewhat leathery, the surfaces glabrous or nearly so, the upper surface usually at least slightly shiny, the secondary veins extending to the sinuses between the larger lobes and to the tips of the lobes and teeth. Inflorescences 20–30-flowered, the branches glabrous, the bractlets membranous to herbaceous, linear to narrowly oblong-lanceolate, entire to obscurely toothed, with glandular margins, shed early. Flowers 10–12 mm in diameter, the hypanthium glabrous. Sepals 1.5–2.0 mm long, broadly triangular, the margins entire, usually finely and densely hairy, nonglandular, glabrous on the inner and outer surfaces. Petals 4–5 mm long, broadly obovate to circular, white. Stamens 20, the anthers ivory-colored. Styles 3(–5). Fruits 5–8 mm long, 5–8 mm wide, globose, lacking a raised collar at the tip, the surface bright orangish red to red at maturity, glabrous, shiny. Nutlets 3(–5), the lateral faces not pitted. 2n=72; triploid, tetraploid, or higher ploidy (by flow cytometry; see Talent and Dickinson [2005]). Late April–late May.

Scattered in the southern half of the state (except for the Glaciated Plains Division) north locally to Boone and Putnam Counties (eastern U.S. west to Missouri and Louisiana; introduced north to Canada). Bottomland forests, mesic upland forests, banks of streams, margins of sinkhole ponds, marshes, and seeps, ledges of bluffs, and rarely glades; also railroads and roadsides.

Washington thorn is one of the finest ornamentals in the genus. It is often among the latest-flowering members of the genus. In Missouri it is perhaps the most commonly planted species of hawthorn, especially around businesses and along highways in urban areas. The trees are striking and possess beautiful foliage that is remarkably disease-resistant. The bright red fruits are particularly attractive against the glossy bronzed fall foliage.