Fraxinus excelsior

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European ash
Fraxinus excelsior.jpg
Foliage and immature fruit
Scientific classification
Kingdom: Plantae
(unranked): Angiosperms
(unranked): Eudicots
(unranked): Asterids
Order: Lamiales
Family: Oleaceae
Genus: Fraxinus
Species: F. excelsior
Binomial name
Fraxinus excelsior
L.
IKAl 090906 Distribution Fraxinus excelsior.png
Range

Fraxinus excelsior — known as the ash, or European ash or common ash to distinguish it from other types of ash — is a species of Fraxinus native to most of Europe from Spain to Russia, with the exception of northern Scandinavia and southern Iberia. It is also considered native in southwestern Asia from northern Turkey east to the Caucasus and Alborz mountains. The northernmost location is in the Trondheimsfjord region of Norway.[1][2] The species is widely cultivated and reportedly naturalized in New Zealand and in scattered locales in the United States and Canada (Nova Scotia, New Brunswick, Quebec, Massachusetts, Connecticut, New York, New Jersey, Maryland, Ontario, Ohio, Kentucky and British Columbia).[3][4][5]

Description[edit]

Male flowers
Seeds of fraxinus excelsior, popularly known as "keys" or "helicopter seeds", are a type of fruit known as a samara

It is a large deciduous tree growing to 20–35 m (exceptionally to 46 m) tall with a trunk up to 2 m (exceptionally to 3.5 m) diameter, with a tall, domed crown. The bark is smooth and pale grey on young trees, becoming thick and vertically fissured on old trees. The shoots are stout, greenish-grey, with jet black buds (which distinguish it from most other ash species, which have grey or brown buds). The leaves are 20–35 cm long, pinnate compound, with 7-13 leaflets, the leaflets 3–12 cm long and 0.8–3 cm broad, sessile on the leaf rachis, and with a serrated margin. The leaves are often among the last to open in spring, and the first to fall in autumn if an early frost strikes; they have no marked autumn colour, often falling dull green. The flowers open before the leaves, the female flowers being somewhat longer than the male flowers; they are dark purple, and without petals, and are wind-pollinated. Both male and female flowers can occur on the same tree, but it is more common to find all male and all female trees; a tree that is all male one year can produce female flowers the next, and similarly a female tree can become male. The fruit is a samara 2.5-4.5 cm long and 5–8 mm broad, often hanging in bunches through the winter; they are often called 'ash keys'.[1][6][7] If the fruit is gathered and planted when it is still green and not fully ripe, it will germinate straight away, however once the fruit is brown and fully ripe, it will not germinate until 18 months after sowing (i.e. not until two winters have passed).[8]

European Ash rarely exceeds 250 years of age. However there are numerous specimens estimated between 200 and 250 years old and there are a few over 250. The largest is in Clapton Court, England and is 9 m (29 ft) in girth. There are several examples over 4.5 metres (15 feet) in Derbyshire alone.

Ecology[edit]

Ash occurs on a wide range of soil types, but is particularly associated with basic soils on calcareous substrates. The most northerly ashwood in Britain is on limestone at Rassal, Wester Ross, latitude 57.4278 N.

A number of Lepidoptera use the species as a food source. See Lepidoptera which feed on ashes. In the UK, many other invertebrates have also been found to feed on Ash.[9]

Genome[edit]

The genome of Fraxinus excelsior is being sequenced by two groups of scientists in the United Kingdom. A group at Queen Mary University of London led by Richard Buggs are sequencing the self-pollinated offspring of a tree from Worcestershire, held by the Earth Trust.[10] A group at the John Innes Centre and The Genome Analysis Centre led by Allan Downie are sequencing "Tree 35" from Denmark, discovered by Erik Kjær, which has survived 8 years of ash dieback.[11]

Ash dieback[edit]

Ash dieback caused by the fungus Hymenoscyphus pseudoalbidus which was previously known as Chalara fraxinea. Research into the genetics of the resistance of ash (Fraxinus excelsior) has shown that resistance does occur in European populations, but, at least for the samples tested, it is neither common nor strong.[12][13][14][15]

Uses[edit]

Veneer of Common Ash Wood.
Replica of the body frame from the Volvo ÖV 4 car, made primarily from ash wood.

The resilience and rapid growth made it an important resource for smallholders and farmers. It was probably the most versatile wood in the countryside with wide-ranging uses. Until World War II the trees were often coppiced on a ten-year cycle to provide a sustainable source of timber for fuel and poles for building and woodworking.[16] The colour of the wood ranges from creamy white to light brown, and the heart wood may be a darker olive-brown. Ash timber is hard, tough and very hard-wearing, with a coarse open grain and a density of 710 kg per cubic meter.[17] It lacks oak's natural resistance to decay, and is not as suitable for posts buried in the ground. Because of its high flexibility, shock-resistance and resistance to splitting, ash wood is the traditional material for bows, tool handles, especially for hammers and axes, tennis rackets and snooker cue sticks[citation needed] and it was extensively used in the construction of early aircraft. Ash was commonly used green for making chair frames which would be seated with another timber or with woven rush (e.g. those made by Philip Clissett, see also The English Regional Chair[18]). The parts were turned on a pole lathe or shaped with a drawknife. The practice essentially died out in the early 20th century, but has seen a revival in recent years.

Ash is valuable as firewood because it burns well even when 'green' (freshly cut).[19] Ash was coppiced, often in hedgerows, and evidence in the form of some huge boles with multiple trunks emerging at head height can still be seen in parts of Britain. In Northumberland, crab and lobster pots (traps) sometimes known as 'creeves' by local people are still made from ash sticks.[citation needed] Because of its elasticity European Ash wood was commonly used for walking sticks. Poles were cut from a coppice and the ends heated in steam. The wood could then be bent in a curved vise to form the handle of the walking stick. The light colour and attractive grain of ash wood make it popular in modern furniture such as chairs, dining tables, doors and other architectural features and wood flooring.

Ash is the only wood used for the manufacture of hurleys, referred to as hurls in parts of Leinster and known as a camán in Irish, the timber sticks used in the game of hurling in Ireland. Hurleys are manufactured from the butt log (bottom 1.5-metre of the stem) and from trees ideally of a diameter at breast height of approximately 25-30 centimetres. Only fast grown, straight and knot free ash can be used for this purpose. Due to the lack of available ash in Ireland, over 75% of the timber needed to produce the 350,000 hurleys required for the game annually must be imported, mostly from eastern European countries.[20] The importance of ash timber to the game of hurling is reflected in the fact that the game is referred to all over Ireland as "The Clash of the Ash".

Mythology[edit]

In the 13th century Edda and other writing relating to Norse mythology, a mythological ash tree called Yggdrasil serves as the center of the world. Though traditionally Yggdrasill was often seen as a giant ash tree, many scholars do now agree that in the past an error has been made in the interpretation of the ancient writings, and that the tree is most likely an European yew (Taxus baccata). This mistake would find its origin in an alternative word for the yew tree in the Old Norse, namely Needle Ash (barraskr). In addition, ancient sources, including the Eddas, write about a vetgrønster vida which means "evergreen tree". An ash sheds its leaves in the winter, while yew trees retain their needles.

Yggdrasill's roots were anchored in the abyss of the underworld, and watered by the streams of wisdom and faith. Its trunk was supported by the earth, while its crown touched the arc of heaven.

Folklore[edit]

It is recorded that on the Isle of Bute in Scotland lovers used to eat leaves of an ash tree known at the "Dreamin' Tree" that grew near the church of St Blane and the pleasant dreams they then experienced revealed their actual spouses and intended fates.[21]

Cultivars[edit]

Ash saplings from a mast year.

There are a number of cultivars including;

  • Fraxinus excelsior 'Aurea', the traditional, slow-growing Golden Ash- not to be confused with 'Jaspidea'[22]
  • Fraxinus excelsior 'Aurea Pendula' (Weeping Golden Ash)
  • Fraxinus excelsior 'Autumn Blaze'
  • Fraxinus excelsior 'Autumn Purple'
  • Fraxinus excelsior 'Crispa'
  • Fraxinus excelsior 'Diversifolia' (One-leaved Ash)
  • Fraxinus excelsior 'Erosa'
  • Fraxinus excelsior 'Jaspidea' A modern, vigorous Golden Ash.
  • Fraxinus excelsior 'Monophylla'
  • Fraxinus excelsior 'Nana'
  • Fraxinus excelsior 'Pendula' (Weeping Ash), one of the best known cultivars, widely planted during the Victorian era, it grows vigorously forming an attractive small to medium size tree with mounds of weeping branches.
  • Fraxinus excelsior 'Skyline'.

Gallery[edit]

External links[edit]

References[edit]

  1. ^ a b Rushforth, K. (1999). Trees of Britain and Europe. Collins ISBN 0-00-220013-9.
  2. ^ Den virtuella floran: Fraxinus excelsior distribution
  3. ^ Kew World Checklist of Selected Plant Families, Fraxinus excelsior
  4. ^ Biota of North America Program, Fraxinus excelsior
  5. ^ Altervista Flora of the United States and Canada, Fraxinus excelsior
  6. ^ Mitchell, A. F. (1974). A Field Guide to the Trees of Britain and Northern Europe. Collins ISBN 0-00-212035-6
  7. ^ Mitchell, A. F. (1982). The Trees of Britain and Northern Europe. Collins ISBN 0-00-219037-0
  8. ^ Forestry Commission/ Edlin, H. L. Broadleaves, HMSO, 1985, p36
  9. ^ http://www.buglife.org.uk/Resources/Buglife/Invertebrates%20associated%20with%20Ash%20.pdf
  10. ^ http://www.ashgenome.org
  11. ^ http://www.bbc.co.uk/news/science-environment-22913111
  12. ^ L.G. Stener (2012). "Clonal differences in susceptibility to the dieback of Fraxinus excelsior in southern Sweden". Scandinavian Journal of Forest Research. Retrieved 26 September 2012. 
  13. ^ E.D. Kjær et al. (2012). "Adaptive potential of ash (Fraxinus excelsior) populations against the novel emerging pathogen Hymenoscyphus pseudoalbidus". Evolutionary Applications. Retrieved 9 November 2012. 
  14. ^ L.V. McKinney et al. (2011). "Presence of natural genetic resistance in Fraxinus excelsior (Oleraceae) to Chalara fraxinea (Ascomycota): an emerging infectious disease". Heredity. Retrieved 9 November 2012. 
  15. ^ Pliūra, A.; Lygis, V.; Suchockas, V.; Bartkevičius, E. (2011). "Performance of twenty four European Fraxinus excelsior populations in three Lithuanian progeny trials with a special emphasis on resistance to Chlara fraxinea". Baltic Forestry 17 (1): 17–34. 
  16. ^ Mabey, R. (1996). Flora Britannica. Sinclair-Stevenson Ltd ISBN 1-85619-377-2.
  17. ^ Ash. Niche Timbers. Accessed 19-08-2009.
  18. ^ Cotton, Bernard D. (1990). The English Regional Chair. Woodbridge, Suffolk: Antiques Collectors Club. ISBN 1 85149 023 X. 
  19. ^ http://www.scoutbase.org.uk/library/hqdocs/facts/pdfs/fs315001.pdf
  20. ^ Teagasc Report - Ash For Hurleys.
  21. ^ Downie, R. Angus (1934). Bute and the Cumbraes Glasgow & London : BlacKwood & Son Ltd. Page 83
  22. ^ http://www.kew.org/plants-fungi/Fraxinus-excelsior.htm