Crataegus × lavallei, sometimes simply known as Crataegus lavallei or Lavallée's hawthorn, is a hybrid that arose between cultivated specimens of 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 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).

The female parent was C. 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...

(sometimes mistakenly called C. pubescens), and the male parent is thought to be C. calpodendron

Crataegus calpodendron

Crataegus calpodendron is a species of hawthorn native to much of the eastern US and to Ontario, Canada. The common name late hawthorn refers to the flowering time, which is later than most North American hawthorns.-References and external links:...

(which is sometimes mistakenly called C. crus-galli).

Carrière's hawthorn, C. × carrieri has the same parentage, and is therefore a synonym, i.e. the same species. There are minor differences between Lavallée's hawthorn and Carrière's hawthorn, and the latter is appropriately considered a separate form

Form (botany)

In botanical nomenclature, a form is one of the "secondary" taxonomic ranks, below that of variety, which in turn is below that of species; it is an infraspecific taxon...

, which is formally written as Crataegus 'carrieri'.

C. × lavallei is an ornamental small tree with glossy dark green unlobed leaves that is used horticulturally.