Canadensys: University of Alberta Vascular Plant Herbarium (ALTA-VP)
Canadensys, operated from the Université de Montréal Biodiversity Centre
"61903 - Opuntia polyacantha Haw. var. hystericina (Engelm. & J. M. Bigelow) B. D. Parfitt, University of Alberta Vascular Plant Herbarium." University of Alberta Museums Search Site, https://search.museums.ualberta.ca/12-86948. Accessed 27 Feb. 2025.