Fraxinus (), commonly called ash, is a genus of plants in the olive and lilac family, Oleaceae, and comprises 45–65 species of usually medium-to-large trees, most of which are deciduous trees, although some subtropical species are evergreen trees. The genus is widespread throughout much of Europe, Asia, and North America.
The leaves are opposite (rarely in whorls of three), and mostly pinnately compound, though simple in a few species. The seeds, popularly known as "keys" or "helicopter seeds", are a type of fruit known as a samara. Some Fraxinus species are dioecious, having male and female flowers on separate plants but sex in ash is expressed as a continuum between male and female individuals, dominated by unisexual trees. With age, ash may change their sexual function from predominantly male and hermaphrodite towards femaleness ; if grown as an ornamental and both sexes are present, ashes can cause a considerable litter problem with their seeds. Rowans or mountain ashes have leaves and buds superficially similar to those of true ashes, but belong to the unrelated genus Sorbus in the rose family.
Etymology
The tree's common English name, "ash", traces back to the Old English æsc, which relates to the Proto-Indo-European for the tree, while the generic name originated in Latin from a Proto-Indo-European word for birch. Both words are also used to mean "spear" in their respective languages, as the wood is good for shafts.
Selected species
Species are arranged into sections supported by phylogenetic analysis:
Section Dipetalae
Fraxinus anomala Torr. ex S.Watson – singleleaf ash
Fraxinus dipetala Hook. & Arn. – California ash or two-petal ash
Fraxinus parryi Moran – Chaparral ash
Fraxinus quadrangulata Michx. – blue ash
Fraxinus trifoliolata
Section Fraxinus
Fraxinus angustifolia Vahl – narrow-leaved ash
Fraxinus angustifolia subsp. oxycarpa – Caucasian ash
Fraxinus angustifolia subsp. syriaca
Fraxinus excelsior L. – European ash
Fraxinus holotricha Koehne
Fraxinus mandshurica Rupr. – Manchurian ash
Fraxinus nigra Marshall – black ash
Fraxinus pallisiae Wilmott – Pallis' ash
Fraxinus sogdiana – Tianshan ash
Section Melioides sensu lato
Fraxinus chiisanensis – Jirisan ash
Fraxinus cuspidata Torr. – fragrant ash
Fraxinus platypoda – Chinese red ash
Fraxinus spaethiana Lingelsh. – Späth's ash
Section Melioides sensu stricto
Fraxinus albicans Buckley – Texas ash
Fraxinus americana L. – white ash or American ash
Fraxinus berlandieriana DC. – Mexican ash
Fraxinus caroliniana Mill. – Carolina ash
Fraxinus latifolia Benth. – Oregon ash
Fraxinus papillosa Lingelsh. – Chihuahua ash
Fraxinus pennsylvanica Marshall – green ash
Fraxinus profunda (Bush) Bush – pumpkin ash
Fraxinus uhdei (Wenz.) Lingelsh. – Shamel ash or tropical ash
Fraxinus velutina Torr. – velvet ash or Arizona ash
Section Ornus
Fraxinus apertisquamifera
Fraxinus baroniana
Fraxinus bungeana DC. – Bunge's ash
Fraxinus chinensis Roxb. – Chinese ash or Korean ash
Fraxinus floribunda Wall. – Himalayan manna ash
Fraxinus griffithii C.B.Clarke – Griffith's ash
Fraxinus insularis Hemsl. – Chinese flowering ash
Fraxinus japonica – Japanese ash
Fraxinus lanuginosa – Japanese ash
Fraxinus longicuspis
Fraxinus malacophylla
Fraxinus micrantha Lingelsh. Fraxinus ornus L. – manna ash or flowering ash Fraxinus paxiana Lingelsh. Fraxinus sieboldiana Blume – Japanese flowering ash