This species is reported in BC from Vancouver Island (BCCDC 2020), while Flora North America (Phipps 2015) describes this species as follows: "Crataegus gaylussacia occurs from north of San Francisco to coastal mainland British Columbia, Vancouver Island, the Queen Charlotte Islands, and coastal Alaska around Anchorage. The species ranges somewhat sporadically to Montana; it is the most northerly occurring Crataegus in North America, reaching 61° N."

Phipps (2015) also distinguishes this species from C. douglasii as follows: "Crataegus gaylussacia differs from C. douglasii by stamen number. Also, the thorns are usually shorter and the fruit is usually smaller and more orbicular than in {i{C. douglasii, as well as being of a different early color."

Hybridizes with Crataegus monogyna (Phipps 2015).

Reference:

James B. Phipps. 2015. Crataegus gaylussacia IN: Flora North America online. Accessed January 10, 2020.