Black Hawthorn, Douglas' Hawthorn: Crataegus douglasii (Synonyms: Crataegus columbiana, Crataegus columbiana var. columbiana, Crataegus douglasii var. douglasii) - Native.
Common Hawthorn, English Hawthorn, One-seeded Hawthorn: Crataegus monogyna var. monogyna (Synonyms: Crataegus laevigata, Crataegus monogyna) - Introduced species.
English Hawthorn-Suksdorf's Hawthorn Hybrid: Crataegus gaylussacia x Crataegus monogyna (Synonym: Crataegus monogyna x Crataegus suksdorfii) -
Huckleberry Hawthorn, Suksdorf's Hawthorn: Crataegus gaylussacia (Synonyms: Crataegus douglasii var. suksdorfii, Crataegus suksdorfii) - Native.