Crataegus × grignonensis
Introduction '''''Crataegus''''' × '''''grignonensis''''' sometimes spelled '''''grignoniensis''''', is a hybrid hawthorn commonly known as "Grignon hawthorn". The hybrid originated as a seedling of ''Crataegus mexicana''. It is an excellent small ornamental tree up to about 5 meters in height, with deep red fruit that contain 1 or 2 pyrenes.
Ancestry An atypical seedling from ''C. mexicana'' (which is often referred to by the illegitimate name ''Crataegus pubescens'' Steud.) appeared in 1873 among plants being cultivated at the Arboretum de Grignon, France. The male parent was thought at the time to be ''C. crus-galli'', but that parentage produced ''C.'' x ''lavalleei'', which looks quite different. It is thought to be more likely that the pollen parent was ''C. monogyna''.
Taxonomy The Latin binomial ''Crataegus'' × ''grignonensis'' (or equivalently ''Crataegus grignonensis'') was published in 1890 on the basis of a description written by Pierre Mouillefert, who was the professor of sylviculture at ''l'École nationale d'Agriculture de Grignon''.
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