Flora of North America species comparison

Varieties 2 (1 in the flora).

Crataegus monogyna was introduced early to North America to be used for agricultural hedges, a practice now discontinued on this continent.

Cultivar 'Crimson Cloud,' often under an incorrect species name, is widely cultivated as an ornamental.

(Discussion copyrighted by Flora of North America; reprinted with permission.)

Crataegus macracantha is the most widespread North American hawthorn and one of the more variable. Variation is particularly great in Quebec and Montana. Attempts to package the variation into named taxa have hitherto run into the problems that the type is an illustration of inadequate quality and that authors have been insufficiently aware of the total variation. Two common eastern forms are similar white-anthered and pink-anthered with abaxially glabrous, broadly elliptic-ovate leaves, shallowly and sharply lobed, and fruit ripening directly from green to red; these have the longest thorns in the species, and both have been treated as if typical.

Crataegus occidentalis, a white-anthered, intermontane form with leaves similar to the foregoing usually has shorter thorns and fruit ripening to red through a characteristic orange or salmon stage. Pink-anthered C. pertomentosa, with leaves of a similar shape but abaxially pubescent to tomentose grows on the Great Plains. The last two forms have been treated as varieties. Other striking variants have brilliant red bracteoles or strongly convex leaves (both from Montana) and entire-margined sepals (C. integriloba Sargent from Quebec). Some rare forms have glabrous inflorescences. Some populations in northwestern Montana, otherwise much like a common pink-anthered sympatric form, have glandular petioles and may represent introgression from another species.

Crataegus macracantha often forms suckering thickets in the east.

(Discussion copyrighted by Flora of North America; reprinted with permission.)