Crataegus × media, is a hybrid between two species

Species

In biology, a species is one of the basic units of biological classification and a taxonomic rank. A species is often defined as a group of organisms capable of interbreeding and producing fertile offspring. While in many cases this definition is adequate, more precise or differing measures are...

 in the genus

Genus

In biology, a genus is a low-level taxonomic rank used in the biological classification of living and fossil organisms, which is an example of definition by genus and differentia...

 Crataegus

Crataegus

Crataegus , commonly called hawthorn or thornapple, is a large genus of shrubs and trees in the rose family, Rosaceae, native to temperate regions of the Northern Hemisphere in Europe, Asia and North America. The name hawthorn was originally applied to the species native to northern Europe,...

(Hawthorn), C. monogyna and C. laevigata, both in series

Series (botany)

Series is a low-level taxonomic rank below that of section but above that of species.In botany, a series is a subdivision of a genus...

 Crataegus. Under the International Code of Botanical Nomenclature the name C. × media covers all intermediate forms between the two parent species, including backcrosses

Backcrossing

Backcrossing is a crossing of a hybrid with one of its parents or an individual genetically similar to its parent, in order to achieve offspring with a genetic identity which is closer to that of the parent...

.

Horticulturally significant forms of C. × media include some with double pink or red flowers, including 'Paul's scarlet' and 'Rubra Plena'.