Quercus robur

''Quercus robur'', commonly known as common oak, pedunculate oak, European oak or English oak, is a species of flowering plant in the beech and oak family, Fagaceae. It is a large tree, native to most of Europe west of the Caucasus. It is widely cultivated in temperate regions elsewhere and has escaped into the wild in scattered parts of China and North America.

Description

''Quercus robur'' is a large deciduous tree, with circumference of grand oaks from to an exceptional . The Majesty Oak with a circumference of is the thickest tree in Great Britain. The Brureika (Bridal Oak) in Norway with a circumference of (2018) and the Kaive Oak in Latvia with a circumference of are among the thickest trees in Northern Europe. The largest historical oak was known as the Imperial Oak from Bosnia and Herzegovina. This specimen was recorded at 17.5 m in circumference at breast height and estimated at over 150 m³ in total volume. It collapsed in 1998. The species has lobed and nearly sessile (very short-stalked) leaves long. Flowering takes place in mid spring, and the fruit, called acorns, ripen by mid autumn. The acorns are long, pedunculate (having a peduncle or acorn-stalk, long) with one to four acorns on each peduncle.

It is a long-lived tree, with a large wide spreading crown of rugged branches. While it may naturally live to an age of a few centuries, many of the oldest trees are pollarded or coppiced, both pruning techniques that extend the tree's potential lifespan, if not its health. Two individuals of notable longevity are the Stelmužė Oak in Lithuania and the Granit Oak in Bulgaria, which are believed to be more than 1500 years old, possibly making them the oldest oaks in Europe; another specimen, called the 'Kongeegen' ('Kings Oak'), estimated to be about 1,200 years old, grows in Jaegerspris, Denmark. Yet another can be found in Kvilleken, Sweden, that is over 1000 years old and around. Of maiden (not pollarded) specimens, one of the oldest is the great oak of Ivenack, Germany. Tree-ring research of this tree and other oaks nearby gives an estimated age of 700 to 800 years. Also the Bowthorpe Oak in Lincolnshire, England is estimated to be 1,000 years old, making it the oldest in the UK, although there is Knightwood Oak in the New Forest that is also said to be as old. The highest density of ''Q. robur'' with a circumference of and more is in Latvia.

Chemistry

Grandinin/ roburin E, castalagin/ vescalagin, gallic acid, monogalloyl glucose (glucogallin) and valoneic acid dilactone, monogalloyl glucose, digalloyl glucose, trigalloyl glucose, rhamnose, quercitrin and ellagic acid are phenolic compounds found in ''Q. robur''. The heartwood contains triterpene saponins.

Taxonomy

''Quercus robur'' (Latin ''quercus'', "oak" + ''robur'' "hardwood, oak wood, oak") is the type species of the genus (the species by which the oak genus ''Quercus'' is defined), and a member of the white oak section (''Quercus'' section ''Quercus''). The populations in Italy, southeast Europe, and Asia Minor and the Caucasus are sometimes treated as separate species, ''Q. brutia'' Tenore, ''Q. pedunculiflora'' K. Koch and ''Q. haas'' Kotschy respectively.

A close relative is the sessile oak ('' Q. petraea''), which shares much of its range. ''Q. robur'' is distinguished from ''Q. petraea'' by its leaves having only a very short stalk ( petiole) long, and by its pedunculate (stalked) acorns. The two often hybridise in the wild, the hybrid being known as '' Quercus × rosacea''.

''Quercus robur'' should not be confused with ''Q. rubra'', the northern red oak, which is in the same subgenus as ''Q. robur'' but is included in a different section.

Ecology

''Quercus robur'' is very tolerant to soil conditions and the continental climate but it prefers fertile and well-watered soils. Mature trees tolerate flooding.

Within its native range, ''Q. robur'' is valued for its importance to insects and other wildlife. Numerous insects live on the leaves, buds, and in the acorns. ''Q. robur'' supports the highest biodiversity of insect herbivores of any British plant (>400 spp) and the quantity of caterpillar species increases with their age. Blue and great tits time their egg hatching to the leaves opening.

The acorns form a valuable food resource for several small mammals and some birds, notably Eurasian jays ''Garrulus glandarius''. Jays were overwhelmingly the primary propagators of oaks before humans began planting them commercially (and still remain the principal propagators for wild oaks), because of their habit of taking acorns from the umbra of its parent tree and burying them undamaged elsewhere. Mammals, notably squirrels who tend to hoard acorns and other nuts, usually leave them too abused to grow in the action of moving or storing them.

Cultivation

A number of cultivars are grown in gardens and parks and in arboreta and botanical gardens. The most common cultivar is ''Quercus robur'' 'Fastigiata', and is the exception among ''Q. robur'' cultivars that are generally smaller than the standard tree, growing to between and exhibit unusual leaf or crown shape characteristics.

; In Australia
English oak is one of the most common park trees in south-eastern Australia, noted for its vigorous, luxuriant growth. In Australia, it grows very quickly to a tree of tall by up to broad, with a low-branching canopy. Its trunk and secondary branches are very thick and solid and covered with deep-fissured blackish-grey bark.
The largest example in Australia is in Donnybrook, Western Australia.

Cultivars

* ''Quercus robur'' 'Fastigiata' ("cypress oak"), probably the most common cultivated form , it grows to a large imposing tree with a narrow columnar habit. The fastigiate oak was originally propagated from an upright tree that was found in central Europe.
* ''Quercus robur'' 'Concordia' ("golden oak"), a small very slow-growing tree, eventually reaching , with bright golden-yellow leaves throughout spring and summer. It was originally raised in Van Geert's nursery at Ghent in 1843.
* ''Quercus robur'' 'Pendula' ("weeping oak"), a small to medium-sized tree with pendulous branches, reaching up to 15 m.
* ''Quercus robur'' 'Purpurea' is another cultivar growing to 10 m, but with purple-coloured leaves.
* ''Quercus robur'' 'Filicifolia' ("cut-leaved oak") is a cultivar where the leaf is pinnately divided into fine forward pointing segments.

Hybrids

Along with the naturally occurring ''Q. × rosacea'', several hybrids with other white oak species have also been produced in cultivation, including Turner's Oak ''Q. × turneri'', Heritage Oak ''Q. × macdanielli'', and Two Worlds Oak ''Q. × bimundorum'', the latter two developed by nurseries in the United States.
* '' Q. × bimundorum'' ( ''Q. alba'' × ''Q. robur'') (two worlds oak)
* '' Q. × macdanielli'' ( ''Q. macrocarpa'' × ''Q. robur'') (heritage oak)
* '' Q. × rosacea'' Bechst. ( ''Q. petraea'' x ''Q. robur''), a hybrid of the sessile oak and English oak. It is usually of intermediate character between its parents, however it does occasionally exhibit more pronounced characteristics of one or the other parent.
* '' Q. × turneri'' Willd. ( ''Q. ilex'' × ''Q. robur'') (Turner's oak), a semi-evergreen tree of small to medium size with a rounded crown; it was originally raised at the Holloway Down Nursery of Spencer Turner, Leyton, Essex, UK, noted by the zoologist Jean-Baptiste Lamarck at Trianon, Versailles in 1783, as the ''chêne de turnère''. (Turner had died in January 1776, and the nursery grounds, on extended lease, returned to the landowner.) An early specimen was planted at the Royal Botanic Gardens, Kew in 1798; it was uprooted in the Great Storm of 1987 but resettled in the ground and then increased its healthy growth.
* ''Q. × warei'' (''Q. robur fastigiata'' x '' Q. bicolor''), a hybrid between upright English oak and the swamp white oak. The selections within this hybrid include 'Long' () and 'Nadler' ().

Diseases

* Acute oak decline
* Powdery mildew caused by ''Erysiphe alphitoides''
* Sudden oak death

Commercial forestry

''Quercus robur'' is planted for forestry, and produces a long-lasting and durable heartwood, much in demand for interior and furniture work. The wood of ''Q. robur'' is identified by a close examination of a cross-section perpendicular to fibres. The wood is characterised by its distinct (often wide) dark and light brown growth rings. The earlywood displays a vast number of large vessels (around in diameter). There are rays of thin (about ) yellow or light brown lines running across the growth rings. The timber is around per cubic meter in density.

Culture

Basque Country

In the Basque Country (Spain and France) the oak symbolises the traditional Basque liberties. This is based on the ' tree of Gernika', an ancient oak tree located in Gernika, below which since at least the 13th century the Lords of Biscay first, and afterwards their successors the Kings of Castile and the Kings of Spain solemnly swore to uphold the charter of Biscay, which secured widespread rights to the inhabitants of Biscay. Since the 14th century, the Juntas Generales (the parliament of Biscay) gathers in a building next to the oak tree, and symbolically passes its laws under the tree as well. Nowadays, the Lehendakari (Basque prime minister) swears his oath of office under the tree.

Bulgaria

The national coat of arms of Bulgaria includes two crossed oak branches with fruits – as shield ( escutcheon) compartment.

Croatia

Oak leaves with acorns are depicted on the reverse of the Croatian 5 lipa coin, minted since 1993. The pedunculate oak of the Croatian region of Slavonia (considered a separate subspecies – ''Slavonian oak'') is a regional symbol of Slavonia and a national symbol of Croatia.

Finland

In traditional Finnish culture, the oak is considered a holy tree. In Finnic mythology, the World tree, which supported the sky, was a great oak, which grew to block the movement of the sky, sunlight and moonlight, and had to be felled, releasing its magic, creating the Milky Way, which guides dead souls to the afterworld. The oak was also considered to have many magical properties, and it was used in traditional Finnish folk medicine as well.

In 1746, all oak trees were legally classified as royal property (at the time Finland was a part of Sweden), and oaks had enjoyed legal protection already from the 17th century.

The oak is also the regional tree of the Southwest Finland region, where it is a common yard tree.

France

The oak tree has had a symbolic value since Ancient times. Some oaks were considered sacred trees by the Gauls. The druids would cut down the mistletoe growing on them. Even after Christianization, oak trees were considered to protect as lightning would strike them rather than on nearby inhabitation. Such struck trees would often be turned into places of worship, like the Chêne chapelle. King Saint Louis has been represented rendering justice under an oak tree. During the French Revolution, oaks were often planted as trees of freedom ( fr). One of such trees, an oak planted during the 1848 Revolution, survived the destruction of Oradour-sur-Glane by the Nazis. The branch of oak is part of the National emblem of France. After the announcement of General Charles de Gaulle's death, caricaturist Jacques Faizant represented him as a fallen oak.

Germany

In Germany, the oak tree (regional known as "German Oak") is used as a typical object and symbol in romanticism. It can be found in several paintings of Caspar David Friedrich and in "Of the life of a Good-For-Nothing" written by Joseph Freiherr von Eichendorff as a symbol of the state protecting every citizen. In those works the oak is shown in different situations, with leaves and flowers or dead without any of its previous beauty. Those conditions are mostly symbols for the conditions Germany is in or going through. Furthermore, the oak's stem is a symbol for Germany's strength and stability. Oak branches were displayed on the reverse of coins of the old Deutsche Mark currency (1 through 10 Pfennigs; the 50 Pfennigs coin showed a woman planting an oak seedling), and are now also displayed on the reverse of German-issue Euro currency coins (1 through 5 cents).

Ireland

In Ireland, at Birr Castle, a specimen over 400 years old has a girth of . It is known as the Carroll Oak, referring to the local Chieftains, Ely O'Carroll who ruled prior to Norman occupation.

Latvia

In Latvia oak is the national symbol. Many Latvian folk songs are about oak tree. Base of the coat of arms is decorated with the branches of an oak tree.

Romania

The Romanian Rugby Union side is known as ''The Oaks.''

Scandinavia

In the Scandinavian countries, oaks were considered the "thunderstorm trees", which representing Thor, the god of thunder.

Serbia

In Serbia the oak is a national symbol, having been part of the historical coat of arms of the Socialist Republic of Serbia, the historical coat of arms and flags of the Principality of Serbia, as well as the current traditional coat of arms and flag of Vojvodina. On the coat of arms, the oak branch at one side symbolized strength and longevity, while the olive branch at the other symbolized peace and fertility. On the socialist coat of arms, the golden oak branch was present next to a golden wreath of wheat. At troublesome times, when there were no churches, people prayed under oak trees where they would carve a cross, '' zapis''; some of these oaks are over 600 years old and are considered sacred. The oak is used in the Serbian Christmas tradition of '' Badnjak''.

United Kingdom

In England, the English oak has assumed the status of a national emblem. This has its origins in the oak tree at Boscobel House, where the future King Charles II hid from his Parliamentarian pursuers in 1650 during the English Civil War; the tree has since been known as the Royal Oak. This event was celebrated nationally on 29 May as Oak Apple Day, which is continued to this day in some communities. 'The Royal Oak' is the third most popular pub name in Britain (with 541 counted in 2007) and has been the name of eight major Royal Navy warships. The naval associations are strengthened by the fact that oak was the main construction material for sailing warships. The Royal Navy was often described as 'The Wooden Walls of Old England' (a paraphrase of the Delphic Oracle) and the Navy’s official quick march is "Heart of Oak". In folklore, the Major Oak is where Robin Hood is purportedly to have taken shelter. Furthermore, the oak is the most common woodland tree in England. An oak tree has been depicted on the reverse of the pound coin (the 1987 and 1992 issues) and a sprig of oak leaves and acorns is the emblem of the National Trust.

Genetics

The genome of ''Q. robur'' has been completely sequenced (GenOak project); a first version was published in 2016. It comprises 12 chromosomes pairs, about  genes and 750 million bp.Oak genome sequencing
/ref> This is roughly a quarter of the size of the human genome, which has about 3 billion base pairs.

See also

* Gernika Oak
* Knopper gall
* Oak marble gall

References

Flora Europaea: ''Quercus robur''
* Bean, W. J. (1976). ''Trees and shrubs hardy in the British Isles'' 8th ed., revised. John Murray.
* Rushforth, K. (1999). ''Trees of Britain and Europe''. HarperCollins .
*

External links

Oaks from Bialowieza Forest in Poland (biggest oak cluster with the monumental sizes in Europe)

Monumental Trees, Photos and location details of large English oak trees

Latvia - the land of oaks

Den virtuella floran - Distribution

''Quercus robur''
- information, genetic conservation units and related resources. European Forest Genetic Resources Programme (EUFORGEN)

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robur
Trees of Asia
Trees of Europe
Trees of humid continental climate
Trees of mild maritime climate
Least concern plants
Least concern biota of Europe
Plants described in 1753
Taxa named by Carl Linnaeus
Garden plants of Europe
Ornamental trees