Shrubs or trees, 50 dm. Stems: twigs: new growth reddish, 1-year old dark purple-brown, 2-years old gray-tan, older gray; thorns on twigs recurved, 2-years old dark brown, shiny, older charcoal black, then gray, ± slender, 2.5–5 cm. Leaves: petiole length 30–36% blade, eglandular or slightly glandular; blade deltate (mainly on shoots with terminal inflorescence) to broadly rhombic-elliptic, 4–7 cm, subcoriaceous, base cuneate to nearly truncate, lobes 3 or 4 per side (larger leaves), sinuses moderately deep, lobe apex acute, margins serrate, veins 5 or 6 per side, apex acute, surfaces glabrous. Inflorescences 4–7-flowered; branches glabrous; bracteoles caducous, ˂absent or several˃, margins glandular. Flowers 22–30 mm diam.; sepals triangular, 6 mm, margins subentire, abaxially glabrous; stamens 20, anthers white, 0.6–0.8 mm; styles 4 or 5. Pomes red, ˂often ± angular˃, 10 mm diam., ± pruinose; sepals on collar, spreading; pyrenes 4 or 5.

Flowering May; fruiting Sep–Oct. Brush; of conservation concern; 100–300 m; Ont.; N.Y., Ohio, Wis.

The known distribution of Crataegus formosa is very scattered. The species is one of the most beautiful hawthorns, and one specimen set the Crataegus record for flower size with a diameter of 38 mm (E. P. Kruschke 1965). Crataegus porteri Britton [including C. porteri var. caerulescens (Sargent) E. J. Palmer], from Pennsylvania, is similar but with smaller leaves and may be conspecific.