Fraxinus
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, although some subtropical species are evergreen. The genus is widespread throughout much of Europe, Asia, and North America.
The leaves are usually opposite, and mostly pinnately compound. The seeds, known as "keys", are botanically fruits of the type called samara. Some species are dioecious, having male and female flowers on separate plants.
Ash wood is strong and elastic, and used for the handles of tools. Musical instrument makers use it for electric guitars and for drum shells. The Morgan Motor Company makes the frames of sports cars from ash wood. In Greek mythology, the Meliae were the nymphs of ash trees.
Etymology
The tree's common English name, "ash", derives from the Old English æsc, from the Proto-Indo-European name for the tree, while the name of the genus originated in Latin frāxinus, from a Proto-Indo-European word for birch. Both words also meant "spear", as ash wood was used for shafts.Description
The leaves of ash trees are usually opposite, and mostly pinnate. The seeds, known as "keys", are botanically single-winged fruits of the type called samara. Most Fraxinus species are dioecious, having male and female flowers on separate plants. The male flowers have two stamens. If a calyx is present, it has four lobes; if there is a corolla, it has four lobes or four petals, which are white or pale yellow.Evolution
Fossil history
The oldest fossils that are clearly Fraxinus are from the Middle Eocene of southeast North America, including the extinct species F. wilcoxiana. Fossil pollen of F. angustifolia is known from the Upper Miocene of Europe. F. oishii winged fruits have been found in the Middle Miocene of Korea.Taxonomy
The genus Fraxinus was described by Carl Linnaeus in 1753. The name remains accepted by taxonomists. Multiple authors have described other tree genera that are synonymous with Fraxinus: Ornus by the German botanist and physician Georg Rudolf Boehmer in 1760; Fraxinoides by the German physician Friedrich Kasimir Medikus in 1791; Mannaphorus by the French polymath Constantine Samuel Rafinesque in 1818; Calycomelia by the Czech in 1834; Leptalix, Ornanthes,Samarpsea and Samarpses, Apilia and Aplilia by Rafinesque, all in 1838; Meliopsis by the German botanist Ludwig Reichenbach in 1841; and Petlomelia by the Belgian priest Julius Nieuwland in 1914.
External phylogeny
The Angiosperm Phylogeny Group has classified Fraxinus as part of the Oleaceae, within the order Lamiales.Internal phylogeny
Species are arranged into sections identified by phylogenetic analysis of clades within the Fraxinus genus:; Section DipetalaeFraxinus anomala Torr. ex S.Watson – singleleaf ashFraxinus dipetala Hook. & Arn. – California ash or two-petal ashFraxinus parryi Moran – Chaparral ashFraxinus quadrangulata Michx. – blue ashFraxinus trifoliolata
; Section FraxinusFraxinus angustifolia Vahl – narrow-leaved ash
- * Fraxinus angustifolia subsp. oxycarpa – Caucasian ash
- * Fraxinus angustifolia subsp. syriaca Fraxinus excelsior L. – European ashFraxinus mandschurica Rupr. – Manchurian ashFraxinus nigra Marshall – black ashFraxinus pallisiae Wilmott – Pallis' ashFraxinus sogdiana – Tianshan ash
; Section Melioides sensu strictoFraxinus albicans Buckley – Texas ashFraxinus americana L. – white ash or American ashFraxinus berlandieriana DC. – Mexican ashFraxinus caroliniana Mill. – Carolina ashFraxinus latifolia Benth. – Oregon ashFraxinus papillosa Lingelsh. – Chihuahua ashFraxinus pennsylvanica Marshall – green ashFraxinus profunda Bush – pumpkin ashFraxinus uhdei Lingelsh. – Shamel ash or Tropical ashFraxinus velutina Torr. – velvet ash or Arizona ash
; Section OrnusFraxinus apertisquamiferaFraxinus baronianaFraxinus bungeana DC. – Bunge's ashFraxinus chinensis Roxb. – Chinese ash or Korean ashFraxinus floribunda Wall. – Himalayan manna ashFraxinus griffithii C.B.Clarke – Griffith's ashFraxinus insularis Hemsl. – Chinese flowering ashFraxinus japonica – Japanese ashFraxinus lanuginosa – Japanese ashFraxinus longicuspisFraxinus malacophyllaFraxinus micrantha Lingelsh.Fraxinus ornus L. – manna ash or flowering ashFraxinus paxiana Lingelsh.Fraxinus sieboldiana Blume – Japanese flowering ash
; Section PaucifloraeFraxinus dubiaFraxinus gooddingii – Goodding's ashFraxinus greggii A.Gray – Gregg's ashFraxinus purpusiiFraxinus rufescens
; Section SciadanthusFraxinus dimorphaFraxinus hubeiensis Ch'u & Shang & Su – 湖北梣, Hubei qinFraxinus xanthoxyloides Wall. ex DC. – Afghan ash
Ecology and distribution
The genus Fraxinus is widespread throughout much of Europe, Asia, and North America. The genus is primarily temperate or subtropical; 22 of the species occur in China, while for example Italy has 4 species. Both native and introduced Fraxinus species occur in almost every contiguous state of the United States and all the southern provinces of Canada.Ash species provide habitat and food for the larvae of many insects including long-horn beetles, plant bugs, lace bugs, aphids, and caterpillars, as well as birds and mammals.
The emerald ash borer, is a wood-boring beetle accidentally introduced to North America from eastern Asia via solid wood packing material in the late 1980s to early 1990s. It has killed tens of millions of trees in 22 states in the United States and neighbouring Ontario and Quebec in Canada. It threatens some seven billion ash trees in North America. Three native Asian wasp species, natural predators of the beetle, have been evaluated as possible biological controls. The public was cautioned to avoid transporting unfinished wood products, such as firewood, to slow the spread of the pest. Damage occurs when emerald ash borer larvae feed on the inner bark, phloem of ash trees, preventing nutrient and water transportation.
The European ash, Fraxinus excelsior, has been affected by the fungus Hymenoscyphus fraxineus, causing chalara ash dieback in a large number of trees since the mid-1990s, particularly in eastern and northern Europe. The disease has infected about 90% of Denmark's ash trees. In 2012 in the UK, ash dieback was found in mature woodland. The combination of emerald ash borer and ash dieback has threatened ash populations in Europe, but trees in mixed landscapes appear to have some resistance to the disease.
Uses
Ash is a hardwood and is dense, around 670 kg/m3 for Fraxinus americana, the white ash, and 710 kg/m3 for Fraxinus excelsior, the European ash. The wood of the European ash is strong and elastic, making it suitable for uses such as the handles of tools. It is a good firewood.The Fender musical instrument company has used ash as a tonewood for its electric guitars since 1950. Species used for guitar building include swamp ash. Ash is in addition used for making drum shells. It has been described as resonant, providing a balanced tone for both high and low notes. Ash wood can be used for furniture, agricultural tools, and household objects such as bowls, candlesticks, and spoons. The Morgan Motor Company of Great Britain still manufactures sports cars with frames made from ash.
The green ash is widely planted as a street tree in the United States. The inner bark of the blue ash has been used as a source for blue dye. In Sicily, Italy, a sugary manna is obtained from the resinous sap of the manna ash, extracted by making cuts in the bark. The young seedpods of the European ash, known as "keys", are edible; in Britain, they are traditionally pickled with vinegar, sugar and spices. A range of pharmacologically active compounds exist in Fraxinus species, with for example anti-inflammatory, antihypertensive, and antihyperglycaemic properties which might find practical applications.
Mythology and folklore
In Greek mythology, the Meliae, their name meaning "ash trees", are nymphs associated with the ash, perhaps specifically of the manna ash, as dryads were nymphs associated with the oak. They appear in Hesiod's Theogony, which states that they were born when drops of Ouranos's blood fell on the earth.In Norse mythology, a vast, evergreen ash tree Yggdrasil, watered by three magical springs, serves as axis mundi, sustaining the nine worlds of the cosmos in its roots and branches. Askr, the first man in Norse myth, literally means 'ash'.
In Slavic folklore, an ash stake could be used to kill a vampire.
In the Old English [Latin alphabet], Æ was the letter æsc, "ash tree". This transliterated the Anglo-Saxon futhorc rune ᚫ.
The Welsh folk song Llwyn Onn, "The Ash Grove", sings in the English version by John Oxenford "The ash grove, how graceful, how plainly 'tis speaking; The lark through its branches is gazing on me".