Common hawthorn is an introduced invasive shrub or small tree that originates in Europe, west Asia and North Africa (Phipps 1998). It was introduced as a garden plant in North America and is now present in western and eastern regions of the continent (USA: AK, AR, CA, CT, DC, DE, IL, KY, MA, ME, MI, MT, NH, NJ, NY, OH, OR, PA, RI, TN, UT, VA, VT, WA, WI, WV, CAN: BC, NB, NS, ON, PE, QC) (USDA 2010
). In BC, common hawthorn is found on southeastern Vancouver Island and the southwestern corner of the mainland, with a few reports from the north coast and the Queen Charlotte Islands. It is frequently encountered in the Fraser delta and is invasive in Garry oak ecosystems on Vancouver Island where it can replace open sites with a dense shrub layer (GOERT 2002). It is locally common at Salmon Arm and Castlegar with sporadic occurrences elsewhere inland (Phipps 1998).
This is generally an easily recognized medium to tall shrub species with distinctive simple lobed leaves, short stout thorns about 1 cm long, white flowers, and red fruit. Morphology can be variable, however, perhaps because of multiple origins and cultivars present in the area (Phipps 1998). The red fruits readily distinguish it from BC's other two species of Crataegus, which are black-fruited, although hybrids with the native black hawthorn (Crataegus douglasii) have been reported (GOERT 2002). The species is readily dispersed by birds.
View a key to the hawthorns of the Pacific Coast (from Alaska to California) (with species notes) by Jim Phipps.