Crataegus subg. Sanguineae Ufimov sect. Salignae T.A.Dickinson & Ufimov ser. Cerrones J.B. Phipps; Crataegus rivularis individuals shown to be tetraploid by flow cytometry (Talent & Dickinson 2005).
Folio Media
Project 2423: 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 F958 Crataegus rivularis Nutt. (tetraploid) containing 13 media.