Crataegus crus-galli

This record for Crataegus crus-galli follows the treatment as recognized in Kartesz (1994, 1999) which includes C. schizophylla and excludes C. limnophila as a distinct species. Phipps in FNA (2014, vol. 9) recognizes C. schizophylla as distinct and includes C. limnophila as indistinct from C. crus-galli var. pyracanthifolia.

Crataegus crus-galli is a wide-ranging shrub or tree found in a variety of habitats and occurring in eastern North America from Ontario and Quebec, Canada south to Florida and Texas in the United States. There are over 1,000 estimated occurrences. This species is moderately and possibly highly threatened across its range due to disease but also the conversion of habitat for other land uses. More information on the distribution, abundance, and threats are needed to better understand the extinction risk of this species. Continued specimen collection for expert identification, and herbarium work is needed to confirm identification of specimens, as well as digitization and georeferencing.

Crataegus crus-galli occurs in eastern North America from Ontario and Quebec, Canada south to Florida and Texas in the United States (FNA 2014). It is introduced and "reported as naturalized in Holland and other parts of Europe" (FNA 2014). Range extent was estimated to be approximately 4 million square kilometers using herbarium specimens, photo-based observations, and NatureServe Network occurrence data documented between 1984 and 2025 (GBIF 2025, iNaturalist 2025, NatureServe 2025, RARECAT 2025, SEINet 2025).

By applying a 1 km separation distance to herbarium specimens, photo-based observations, and NatureServe Network occurrence data documented between 1984 and 2025, it is estimated that there are approximately 1,000 occurrences rangewide (GBIF 2025, iNaturalist 2025, NatureServe 2025, RARECAT 2025, SEINet 2025).

Like most Crataegus, this species is susceptible to blight and fungal rusts which can cause stem cankers and dieback, as well as inhibit seed production. Fungal rusts are especially problematic when the alternate host, Eastern Red Cedar (Juniperus virginiana) is prolific in the vicinity (Lance 2014). Aggressive, invasive woody species, such as Lonicera japonica and Rhamnus cathartica, outcompete hawthorns and other natives, shifting the composition of the habitat such that native biodiversity is reduced, often eliminating hawthorns from these altered communities (e.g., Catling and Mitrow 2012). This species is also threatened by densification/mesophication of open woodland habitat (Nowacki and Abrams 2008) and conversion of natural woodlands to human uses. Plants growing in pastures are tolerant of browsing; while new growth may be consumed by cattle, spines deter further browsing (Lance 2014). The Asian Longhorned Beetle (Coleoptera: Cerambycidae, Anoplophora glabripennis) can use Crataegus for larval hosts, though Acer, Populus, Salix, and Ulmus are preferred (Meng et al. 2015). Modeling changes in range size with habitat shifting due to climate change had mixed results, with some hawthorns expected to have range expansions and other species expected to have no change or range contractions (Naghiloo and Vamosi 2023).