Crataegus subg. Sanguineae Ufimov sect. Douglasianae (Rehder) C.K. Schneid. ser. Douglasianae Rehder; Crataegus douglasii individuals shown to be predominantly 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 F1026 Crataegus douglasii Lindley (allopolyploid) containing 15 media.