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 Grayana Eggl. Rhodora 10: 80. May 1908.
A large shrub, sometimes 20° high, with ascending branches, the thorns 3/4'-21/2' long. Leaves ovate, 1-3 1/4' long, 3/4'-3' wide, acuminate at the apex, broadly cuneate to truncate at the base, slightly pubescent above, becoming glabrate, serrate or doubly serrate with 4-6 pairs of acuminate lobes, their tips recurved; corymbs slightly villous; flowers 7"-8" broad; calyx-tube villous below, the lobes slightly villous within, glandular-margined; stamens about 20; styles and nutlets usually 4 or 5; fruit subglobose to short-ellipsoid, angular, dark cherry-red, 6"-8" thick; calyx-lobes reflexed.
Montmorency Falls west to Ottawa, Ontario, western New England and northeastern New York. May; fruit ripe August-September.
Crataegus alnorum Sarg. Rhodora 5: 153. 1903.
Crataegus Edsoni Sarg. Rhodora 7: 205. 1905.
A broad shrub, sometimes 15o high, with ascending branches, the spines 1'-1 1/2' long. Leaves ovate, 1 1/4'-2 3/4' long, l'-2 1/2' wide, acute at the apex, broadly cuneate or truncate at the base, serrate or doubly serrate with acute lobes, dull dark yellow-green above, paler beneath; corymbs glabrous, many-flowered; flowers 7"-10" broad; stamens about 20; styles and nutlets 3-5; fruit subglobose, slightly angular, dark cherry-red, 6" or 7" thick; calyx-lobes erect or spreading; flesh succulent.
C. populnea Ashe, Ann. Carn. Mus. 1: 395. 1902. C. stolonifera Sarg. Bot. Gaz. 35: 109. 1903.
A shrub or small tree, sometimes 20o high, with a flattened round crown. Spines 1'-2' long; leaves membranous, slightly villous above, becoming glabrate, broadly ovate to elliptic-ovate, 1'-2 3/4' long and wide, acute to acuminate at the apex, broadly cuneate to truncate at the base, those of the vegetative shoots usually cordate, serrate or twice serrate, the lobes broad, acute or none; corymbs glabrous; flowers 8"-10" broad; stamens 5-10; anthers pink; styles and nutlets usually 3 or 4; fruit glabrous to short-ellipsoid, scarlet, 5"-7" thick, calyx-lobes appressed or spreading; flesh yellow.
Low grounds, southern Ontario to Pennsylvania and Delaware. May; fruit ripe September.
Crataegus aspera Sarg. Trees & Shrubs 2: 67. pl.131. 1908. C. bracteata Sarg. Rep. Mo. Bot. Gard. 19: 91. July 1908.
A shrub, sometimes 70 high, with slender zigzag branchlets. Spines numerous, curved, 1 1/2-2 1/2' long; leaves ovate, 1V-2Y long, $'-2' wide, acute or acuminate at the apex, rounded or truncate at the base, finely serrate or doubly serrate, with 3 or 4 pairs of acute lobes, yellow-green, membranous, appressed-pubescent, becoming scabrate above, tomentose beneath; petioles tomentose, 1'-1 1/2' long; corymbs few-flowered; pedicels slightly pubescent, becoming glabrous; flowers 8" or 9" broad; calyx-lobes triangular; stamens about 10; styles and nutlets usually 4 or 5; fruit short-ellipsoidal to subglobose, scarlet, very pruinose, 5" or 6" thick; calyx-tube little enlarged, the lobes obtuse, spreading, often deciduous; flesh thin.
Thickets, southern Missouri. April-May; fruit ripe November.