Crataegus pruinosa

This record is for Crataegus pruinosa following the treatment of FNA (vol. 9, 2014) which includes Crataegus dissona (= C. pruinosa var. dissona) and C. leiophylla (= Crataegus pruinosa var. rugosa) as varieties of C. pruinosa and also recognizes varieties magnifolia and virella. Six varieties are recognized in total (dissona, magnifolia, parvula, pruinosa, rugosa, and virella).

Crataegus pruinosa is a wide-ranging shrub or tree with six varieties found in a variety of open habitat types. It occurs in eastern North America from Ontario and Quebec, Canada and the United States throughout New England, west to Wisconsin, and south to Georgia, Louisiana, and Oklahoma. There are over 300 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 pruinosa is widespread in eastern North America from Ontario and Quebec, Canada and the United States throughout New England, west to Wisconsin, and south to Georgia, Louisiana, and Oklahoma (FNA 2014, Native Plant Trust 2025, and Weakley and the Southeastern Flora Team 2025). Range extent was estimated to be approximately 2.2 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). See individual entries about the varieties.

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 over 300 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).