This section is from the book "An Illustrated Flora Of The Northern United States, Canada And The British Possessions Vol2", by Nathaniel Lord Britton, Addison Brown. Also available from Amazon: An Illustrated Flora of the Northern United States, Canada and the British Possessions. 3 Volume Set..
Crataegus Crus-galli L. Sp. Pl. 476. 1753. Crataegus lucida Mill. Dict. Ed. 8, no. 6. 1768.
A small tree, sometimes 300 high, with spreading branches; spines very numerous, straight, 1'-7' long. Leaves obovate to elliptic, 3/4'-4' long, 1/4'-1 1/2' wide (sometimes 2 3/4' wide), sharply serrate, except toward the base, acute or rounded at the apex, cuneate, dark green and shining above, coriaceous, glabrous, or occasionally slightly pubescent, glandless; corymbs glabrous, or occasionally pubescent; flowers about 8" broad; stamens 10-20; anthers usually pink; calyx-lobes lanceolate; acuminate, entire; styles and nutlets usually 2; fruit ellipsoid-ovoid to subglobose, about 5" thick, greenish to red; flesh hard and dry.
Sandy soil; northern New York to Ontario, eastern Kansas, south through western Connecticut to Georgia. Introduced near Montreal, about Lake Champlain and on Nantucket Island. An extremely variable species for which many names have been proposed. May-June; fruit ripe October. Red haw. Thorn-apple, -bush or -plum. Pin-thorn. Hawthorn. ,
Crataegus berberifolia T. & G. Fl. N. Am. 1: 469. 1840. Crataegus Engelmannii Sarg. Bot. Gaz. 31: 2. 1901.
A small tree, sometimes 300 high, with spreading branches and a broad crown, the spines occasional; twigs pubescent, becoming glabrous. Leaves oblong-cuneiform, spatulate or obovate, rounded or acute at the apex, cuneate, serrate towards the apex, 3/4'-2 1/2' long, ¥-\¥ wide, rough-pubescent above, white-pubescent or tomentose beneath (in northern forms less pubescent than in southern); corymbs densely villous; flowers about 8" broad; stamens 10-20; anthers yellow or pink; styles and nutlets 2 or 3; calyx-lobes entire, slightly pubescent, fruit subglobose to short-ellipsoid, about 5" thick; yellow, orange or red, slightly pubescent.
Western Kentucky to Missouri and the Gulf states. May; fruit ripe October.
Crataegus schizophylla Eggl. Bull. Torr. Club 38: 243. 1911.
A small tree, sometimes 12° high, with ascending irregular branches. Spines numerous, 1' - 3' long; leaves oblong-obovate to ovate, 3/4'-2 1/2' long, 1/4'-1 3/4'wide, acute or obtuse at the apex, cuneate at the base, coarsely serrate with short acute lobes towards the apex, glabrous, slightly impressed-veined; petioles 1/4'-3/4' long; corymbs glabrous; flowers about 6" broad; calyx-lobes lanceolate, acute; stamens about 10, anthers pale purple; styles and nutlets usually 2; fruit pyriform-ellipsoid, dark red, about 5" thick; calyx persistent, its lobes reflexed; flesh hard at maturity; nutlets ridged on the back.
Common on Martha's Vineyard, Massachusetts. June; fruit ripe October.