Crataegus aperta Sargent; C. patrum Sargent; C. pruinosa (H. L. Wendland) K. Koch var. cognata (Sargent) J. B. Phipps; C. pruinosa var. latisepala (Ashe) Eggleston

Shrubs, 20–40 dm. Stems: ˂main branches often suberect˃; twigs: new growth reddish brown, 1-year old purple-brown, older dark gray; thorns on twigs ˂numerous˃, straight to slightly recurved, 2-years old black, shiny, ± slender, 3–5 cm. Leaves: petiole length 28–36% blade, eglandular or with 1–2 glands distally; blade ovate, 3.5–5.5 cm, subcoriaceous, base broadly cuneate to truncate, lobes 3(or 4) per side, sinuses shallow, lobe apex subacute, margins crenate-serrate, veins 5–7 per side, apex subacute, surfaces glabrous. Inflorescences 4- or 5-flowered; branches glabrous; bracteole margins short-stipitate-glandular. Flowers 17–19 mm diam.; hypanthium glabrous; sepals narrowly triangular, 5 mm, ˂base broad˃, margins subentire, abaxially glabrous; stamens 20, anthers white, 0.6–0.8 mm; styles 3 or 4. Pomes green with pink or purple pruinosity, becoming orange-red or crimson, 8–10 mm diam.; ˂flesh thin˃; sepals on collar, spreading-reflexed; pyrenes 3 or 4. 2n = 51.

Flowering Apr–May; fruiting Sep–Oct. Successional fields, fencerows, brush, open wood margins; 50–300 m; Ont.; Mass., Mich., Mo., N.Y.

Crataegus cognata in the strict sense occurs from Michigan to Massachusetts with the southern limits poorly understood. Specimens from Missouri with large (5–7 cm) leaf blades and no or only weakly developed lobes should be checked against C. pruinosa var. magnifolia.

Crataegus perjucunda Sargent, native to Middlesex County, Ontario, is a distinctive local species similar to C. cognata but with shorter (2–3 cm) and finer thorns as well as relatively wider leaves (length/width = 1.2).