Crataegus × grignonensis is a hybrid hawthorn

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,...

 commonly known as "Grignon Hawthorn". The hybrid originated as a seedling of Crataegus mexicana

Crataegus mexicana

Crataegus mexicana is a species of hawthorn known by the common names tejocote, manzanita, tejocotera and Mexican hawthorn. It is native to the mountains of Mexico and parts of Guatemala, and has been introduced elsewhere in the Andes. The fruit of this species is one of the most useful among...

. It is an excellent small ornamental tree up to about 5 meters in height, with deep red fruit that contain 1 or 2 pyrenes

Pyrena

Pyrena or pyrene is the name for a nutlet resembling a seed, or the kernel of a drupe or drupelet....

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Taxonomy

The Latin binomial Crataegus × grignonensis, or the equivalent Crataegus grignonensis appears to have never been validly published under the rules of the International Code of Botanical Nomenclature.