Rhodora 5: 116. 1903.
Shrubs, spreading into broad thickets, 30–60 dm. Stems numerous; twigs: new growth olive or orange-green, slender, marked by large, oblong, pale lenticels, glabrous, 1-year old light, grayish, or deep reddish-brown, at end of 1d year often deep redbrown, 2-years old gray or light-brown tinged with red, older ashy gray; thorns on twigs numerous, straight, 1-year old shiny, deep redbrown, older dark gray, ultimately ashy gray, stout, 3–6 cm. Leaves: stipules oblong-obovate, to falcate and acuminate on extension shoots, glandular-serrate, acuminate, villous; petiole length 33–40% blade, slightly winged distally, adaxially villous young, glandular, glands minute, dark red; blade ovate-oblong to oblong, (4–) 5–7 (–8) cm (more than 1/2 grown at anthesis), on extension shoots similar, larger, thin to chartaceous, base cuneate to nearly truncate, lobes 5 or 6 per side, sinuses moderately deep (max LII 15%), lobe apex acute, ± triangular, margins serrulate, veins 5–7 per side, apex acute, abaxial surface glabrous, adaxial appressed-scabrous, glabrescent. Inflorescences 9–12-flowered; branches villous; bracteoles linear, small, membranous, margins sessile-glandular. Flowers 13–15 mm diam.; hypanthium glabrous or pubescent; sepals reflexed after flowering, tapering from broad bases, short, margins minutely, bright red glandular, apex acute, abaxially villous; stamens 20, anthers pale-yellow, small; styles 4 or 5. Pomes in broad, multi-fruited clusters, drooping or erect on stout branches; reddish, suborbicular to oblong, 12–14 mm diam., glabrous or pubescent; sepals persistent, sometimes until following spring, prominent, appressed to spreading; pyrenes 4 or 5, full and rounded at ends.
Phenology: Flowering May–Jun; fruiting Sep.
Habitat: Brush, old fields
Elevation: 0–300 m
Nfld. and Labr. (Nfld.), Ont., Que., Conn., N.Y., Wis.
The proven range of Crataegus irrasa is from eastern Ontario and nearby New York to Newfoundland. This species is to be expected in New England.
Crataegus irrasa is readily distinguished from both C. chrysocarpa var. vigintistamina and C. oakesiana by its larger, more oblong, and more venous leaves. Dubious records from Minnesota have more rhombic leaves. The most distinctive form, C. noveboracensis, which flourishes in Muskoka, Ontario, has the largest, most venous, and most oblong leaves; similar plants are known also from Newfoundland. Crataegus irrasa is distinguished from the somewhat similar C. flabellata var. grayana by its wider and thicker leaves, much hairier corymbs and hypanthia, pale yellow anthers, and the color of the flesh of the ripe pomes.