Crataegus subg. Americanae El Gazzar sect. Macracanthae Loudon ser. Macracanthae (Loudon) Rehder; Crataegus macracantha individuals shown to be tetraploid by flow cytometry (Talent & Dickinson 2005).
Folio Media
Project 2523: T. A. Dickinson, B. X. Yan, S. Han, M. Zarrei. 2021. Niche Shifts, Hybridization, Polyploidy and Geographic Parthenogenesis in Western North American Hawthorns (Crataegus subg. Sanguineae, Rosaceae). Agronomy. 11 (11):2133.
Viewing Folio F1028 Crataegus macracantha Lodd. ex Loud. (tetraploid) containing 6 media.