Fraxinus /ˈfræksɨnəs/ is a genus of flowering plants in the olive and lilac family, Oleaceae. It contains 45--65 species of usually medium to large trees, mostly deciduous though a few subtropical species are evergreen. The tree's common English name, ash, goes back to the Old English æsc, while the generic name originated in Latin. Both words also meant "spear" in their respective languages. The leaves are opposite , and mostly pinnately compound, simple in a few species. The seeds, popularly known as keys or helicopter seeds, are a type of fruit known as a samara. Most Fraxinus species are dioecious, having male and female flowers on separate plants; if grown as an ornamental and both sexes are present, ashes can cause a considerable litter problem with their seeds. Rowans or Mountain Ashes are unrelated to true ashes and belong to the Genus Sorbus though the leaves and buds are superficially similar. Selected species Fraxinus americana L. -- White Ash or Autumn Purple Ash Fraxinus caroliniana Mill. -- Carolina Ash Fraxinus nigra Marshall -- Black Ash Fraxinus pennsylvanica Marshall Green Ash Fraxinus profunda (Bush) Bush -- Pumpkin Ash Fraxinus quadrangulata Michx. -- Blue Ash Fraxinus anomala Torr. ex S.Watson -- Singleleaf Ash Fraxinus berlandieriana DC. -- Mexican Ash Fraxinus cuspidata Torr. -- Fragrant Ash Fraxinus dipetala Hook. & Arn. -- California Ash or Two-petal Ash Fraxinus dubia Fraxinus gooddingii -- Goodding's Ash Fraxinus greggii A.Gray -- Gregg's Ash Fraxinus latifolia Benth. -- Oregon Ash Fraxinus lowellii -- Lowell Ash Fraxinus papillosa Lingelsh. -- Chihuahua Ash Fraxinus purpusii Fraxinus rufescens Fraxinus texensis (A.Gray) Sarg. -- Texas Ash Fraxinus uhdei (Wenz.) Lingelsh. -- Shamel Ash or Tropical Ash Fraxinus velutina Torr. -- Velvet Ash or Arizona Ash Fraxinus angustifolia Vahl -- Narrow-leafed Ash Fraxinus angustifolia subsp. oxycarpa -- Caucasian Ash Claret Ash or Raywood Ash Fraxinus angustifolia subsp. oxycarpa -- Caucasian Ash Claret Ash or Raywood Ash Claret Ash or Raywood Ash Fraxinus dimorpha Fraxinus excelsior L. -- European Ash Fraxinus holotricha Koehne Fraxinus ornus L. -- Manna Ash or Flowering Ash Fraxinus syriaca Fraxinus pallisiae Wilmott -- Pallis' Ash Fraxinus apertisquamifera Fraxinus baroniana Fraxinus bungeana DC. -- Bunge's Ash Fraxinus chinensis Roxb. -- Chinese Ash or Korean Ash Fraxinus chiisanensis Fraxinus floribunda Wall. -- Himalayan Manna Ash Fraxinus griffithii C.B.Clarke -- Griffith's Ash Fraxinus hubeiensis Ch'u & Shang & Su -- 湖北梣 hu bei qin Fraxinus japonica -- Japanese Ash Fraxinus lanuginosa Fraxinus longicuspis Fraxinus malacophylla Fraxinus mandschurica Rupr. -- Manchurian Ash Fraxinus mariesii -- Maries' Ash Fraxinus micrantha Lingelsh. Fraxinus paxiana Lingelsh. Fraxinus platypoda Fraxinus raibocarpa Regel Fraxinus sieboldiana Blume -- Japanese Flowering Ash Fraxinus sogdiana Bge Fraxinus spaethiana Lingelsh. -- Späth's Ash Fraxinus trifoliata Fraxinus xanthoxyloides (G.Don) Wall. ex DC. -- Afghan Ash Ecology Ash is used as a food plant by the larvae of some Lepidoptera species (butterflies and moths)—see list of Lepidoptera that feed on ashes. Threats The emerald ash borer (Agrilus planipennis) 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 15 states in the United States and adjacent Ontario in Canada. It threatens some 7 billion ash trees in North America. Research is being conducted to determine if three native Asian wasps, who are natural predators of EAB could be used as a biological control for the management of EAB populations in the United States. The public is being cautioned not to transport unfinished wood products, such as firewood, to slow the spread of this insect pest. The European ash, Fraxinus excelsior, has been affected by the fungus Hymenoscyphus pseudoalbidus, causing 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. At the end of October 2012 in the UK the Food and Environment Research Agency (Fera) reported that ash dieback had been discovered in mature woodland in Suffolk, previous occurrences had been on young trees imported from Europe. Uses Ash is a hardwood and is hard, dense (within 20% of 670 kg/m³ for Fraxinus americana, and higher at 710 kg/m³ for Fraxinus excelsior), tough and very strong but elastic, extensively used for making bows, tool handles, baseball bats, hurleys and other uses demanding high strength and resilience. Attribution: Article text available under CC-BY-SA Public domain image source in video

• published: 19 Nov 2013
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