This is the hybrid between the common hawthorn (Crataegus monogyna) and the Midland thorn (C. laevigata). Much more frequent than C. laevigata in hedgerows and occasionally elsewhere such as on the sand dunes of The Umbra, but much less common than C. monogyna. Probably introduced with hedging hawthorns from England, and almost certainly not native to Northern Ireland.
Some forms of this hybrid are very close to C. laevigata and are probably F1 hybrids, others are less distinct because of back-crossing and introgression. Good examples of F1 hybrids are found in lanesides near Crow Glen above Ligoniel.
All names: Crataegus laevigata x monogyna (C. x macrocarpa) Hegetschw.; Crataegus x macrocarpa Hegetschw.; Crataegus laevigata x monogyna; Crataegus x ovalis Kittel; Crataegus x media auct. non Bechst.; Crataegus monogyna x laevigata