Crataegus, commonly called hawthorn, quickthorn, thornapple, May-tree, whitethorn, or hawberry, is a genus of several hundred species of shrubs and trees in the family Rosaceae, native to temperate regions of the Northern Hemisphere in Europe, Asia, North Africa, and North America. The name "hawthorn" was originally applied to the species native to northern Europe, especially the common hawthorn C. monogyna, and the unmodified name is often so used in Britain and Ireland. The name is now also applied to the entire genus and to the related Asian genus Rhaphiolepis.
Crataegus mollis, known as downy hawthorn or red hawthorn, occurs in eastern North America from southeastern North Dakota east to Nova Scotia and southwest to eastern Texas. The range of this species is from southern Ontario and Michigan to eastern North Dakota and southward to Denison, Texas, and Arizona. This tree inhabits wooded bottomlands, the prairie border, and the midwest savanna understorey.
Crataegus aestivalis, known as the eastern mayhaw, is a shrub or small tree of the southeastern United States that grows in low-lying or wet areas from eastern Alabama to central Florida and Virginia. It is one of several species of hawthorn with fruits known as "mayhaws", which are harvested for use in making mayhaw jelly, considered a delicacy in many areas of the South. Other species of mayhaws include Crataegus opaca, the western May Hawthorn, which is native from east Texas to Alabama.
Crataegus douglasii is a North American species of hawthorn known by the common names black hawthorn and Douglas' thornapple. It is named after David Douglas, who collected seed from the plant during his botanical explorations.
The name Crataegus columbiana is a source of considerable confusion. The species named by Howell is now considered to be the same as C. douglasii, named earlier, and the earlier name should be used instead. However, some varieties of C. columbiana have also been named that are not related to C. douglasii. C. columbiana has been used by some authors for Crataegus piperi Britton, which is now known as C. chrysocarpa var. piperi.
Crataegus azarolus is a species of hawthorn known by the common names azarole, azerole, and Mediterranean medlar. It is native to the Mediterranean Basin and is a common plant there, growing on sites comparable to those the European common hawthorn grows on. In the Arab countries it is the commonest of the hawthorn species. When growing in the wild the azerole bears plentiful crops of haw fruits, which are similar to the haws of the European common hawthorn, but plumper.
Crataegus chrysocarpa is a species of hawthorn that is native to much of the continental United States and Canada. Common names fireberry hawthorn and goldenberry hawthorn, as well as the scientific name all refer to the colour of the unripe fruit, although the mature fruit is red and in var. vernonensis is "deep claret-colored … nearly black when over-ripe".
Crataegus coccinioides is a species of hawthorn known by the common names Kansas hawthorn and large-flowered cockspurthorn. Crataegus coccinioides is native from Kansas, to New England, and the southernmost parts of Ontario and Quebec. It has large flowers and leaves and fruit that appear pinkish until polished to reveal the red colour underneath the wax bloom. Crataegus coccinioides is a synonym of Crataegus dilatata.
Crataegus crus-galli is a species of hawthorn known by the common names cockspur hawthorn and cockspur thorn. It is native to eastern North America from Ontario to Texas to Florida, and it is widely used in horticulture. It is thought to be the parent, along with Crataegus succulenta, of the tetraploid species Crataegus persimilis.
Crataegus flabellata is a species of hawthorn known by the common name fanleaf hawthorn. It is native to the northeastern United States and adjacent Canada. It is intermediate in appearance between C. macrosperma and C. chrysocarpa. C. macrosperma, which occurs throughout the range of C. flabellata and also in the southeastern U.S., is often misidentified as C. flabellata.
Crataegus hupehensis is an Asian species of hawthorn that can grow to be a substantial tree. It is similar to C. pinnatifida var. major, but with less pronounced lobes on the leaves.
Crataegus macrosperma, the bigfruit hawthorn is a species of hawthorn native to most of the eastern United States and adjacent Canada, though uncommon at lower altitudes in the south. It is sometimes misidentified as C. flabellata. It is one of the earliest hawthorns to bloom in spring.
Crataegus marshallii is a species of hawthorn known by the common name parsley hawthorn. It is native to the southeastern United States.
Crataegus pruinosa is a species of hawthorn known by the common name frosted hawthorn. It is native to a wide area of the eastern United States and southern Canada, and is sometimes considered to be several species, rather than just one.
Crataegus wattiana, the Altai hawthorn, is an Asian species of hawthorn. The original description states that it has yellow fruit with five stones (pyrenes). Crataegus wattiana var. wattiana has become naturalized in Seattle, in the U.S. state of Washington.
Crataegus iracunda, with common name passionate hawthorn, and sometimes called the stolon-bearing hawthorn is a North American species of hawthorn. It was described in 1899 by Chauncey Delos Beadle of the Biltmore Herbarium in North Carolina. Taxonomic opinions have differed about this species, and to complicate matters Crataegus macrosperma and various species of C. series Populneae have frequently been misidentified as C. iracunda, leading to differing statements about its geographic range. The 2015 Flora of North America considers its range to be in the southeastern U.S., restricted to the US states of Alabama, Georgia, Louisiana, Mississippi, North Carolina, South Carolina, and Virginia.
Crataegus phippsii is a species of hawthorn native to south-central British Columbia, Washington state, and Montana. It forms a shrub or small tree to 7 m in height with leaves that have white hair on the underside, and fruit that ripen through red to purplish black. It appears to have potential as an ornamental plant.
Crataegus pennsylvanica, known as the Pennsylvania thorn, is a species of hawthorn native to Delaware, New York, North Carolina, Ontario, Ohio, and Pennsylvania, that grows to about 8 m in height. The mature trees have few thorns.
Series Molles is a series within the genus Crataegus that contains at least six species of hawthorn trees and shrubs, native to Eastern North America. Some of the species are cultivated as ornamental plants. They have relatively large leaves, large flowers, and bloom early for hawthorns. The plant parts are usually hairy, particularly in early growth, and the fruit are generally red and are large for hawthorn fruit.
Series Tenuifoliae is a series within the genus Crataegus that contains at least seven species of hawthorn trees and shrubs, native to Eastern North America, with one disjunct species in the mountains of New Mexico.
