is a tree
in the genus
( ; Latin
"oak tree"), of which about 400
exist. "Oak" may also appear in the names of species in
related genera, notably Lithocarpus
. The genus is native to
hemisphere, and includes deciduous
and evergreen species extending from cold
latitudes to tropical Asia and the Americas.
Oaks have spirally arranged leaves
, with a
lobed margin in many species; some have serrated leaves or entire
leaves with a smooth margin. The flowers
, produced in spring. The fruit
is a nut
, borne in a cup-like structure known as
; each acorn contains one seed
(rarely two or three) and takes 6–18 months to mature, depending on
species. The live oaks
for being evergreen
, but are not actually
a distinct group and instead are dispersed across the genus.
Oak trees are flowering plants
. The genus is divided into
and a number of sections
The Subgenus Quercus
is divided into the following
- Sect. Quercus (synonyms Lepidobalanus and
Leucobalanus), the white oaks of
Europe, Asia and North America. Styles are short; acorns mature in 6 months
and taste sweet or slightly bitter; the inside of acorn shell is
hairless. The leaves mostly lack a bristle on their lobe tips,
which are usually rounded.
- Sect. Mesobalanus, Hungarian oak and
its relatives of Europe and Asia. Styles long; acorns mature in
about 6 months and taste bitter; the inside of acorn shell is
hairless. The section Mesobalanus is closely related to
section Quercus and sometimes included in it.
- Sect. Cerris, the Turkey oak and its
relatives of Europe and Asia. Styles long; acorns mature in 18
months and taste very bitter. The inside of the acorn shell is
hairless. Its leaves typically have sharp lobe tips, with bristles
at the lobe tip.
- Sect. Protobalanus, the Canyon live oak and
its relatives, in southwest United States and northwest Mexico.
Styles short, acorns mature in 18 months and taste very bitter. The
inside of the acorn shell appears woolly. Leaves typically have
sharp lobe tips, with bristles at the lobe tip.
- Sect. Lobatae (synonym Erythrobalanus), the
red oaks of
North America, Central America and
northern South America. Styles long,
acorns mature in 18 months and taste very bitter. The inside of the
acorn shell appears woolly. The actual nut is encased in a thin,
clinging, papery skin. Leaves typically have sharp lobe tips, with
spiny bristles at the lobe.
- The ring-cupped
oaks of eastern and southeastern Asia.
Evergreen trees growing 10–40 m tall. They are distinct from
subgenus Quercus in that they have acorns with distinctive
cups bearing concrescent rings of scales; they commonly also have
densely clustered acorns, though this does not apply to all of the
species. The Flora of China treats
Cyclobalanopsis as a distinct genus,
but most taxonomists consider it a subgenus
of Quercus. It contains about 150 species.
quite common among oaks, but usually only between species within
the same section and most common in the white oak group (subgenus
, section Quercus
; see List of Quercus
). Inter-section hybrids, except between
species of sections Quercus
unknown. Recent systematic studies appear to confirm a high
tendency of Quercus
species to hybridize because of a
combination of factors. White oaks are unable to discriminate
against pollination by other species in the same section because
they are wind pollinated
and they have
weak internal barriers to hybridisation, hybridization produces
functional seeds and fertile hybrid offspring. Ecological stresses,
especially near habitat margins, can also cause a breakdown of mate
recognition as well as a reduction of male function (pollen
quantity and quality) in one parent species.
Frequent hybridisation among oaks has consequences for oak
populations around the world; most notably, hybridization has
produced large populations of hybrids with copious amounts of
, and the evolution
of new species. Frequent
hybridisation and high levels of introgression have caused
different species in the same populations to share up to 50% of
their genetic information. The high rates of hybridisation and
introgression, produces genetic data that often does not
differentiate between two clearly morphologically distinct species,
but instead differentiates populations. Numerous hypotheses have
been proposed to explain how oak species are able to remain
morphologically and ecologically distinct with such high levels of
, but the problem is still
largely a mystery to botanists.
, or oak family, is a very
slowly evolving clade
compared to other
, and the hybridisation
patterns in Quercus
pose a great challenge to the concept of a species
. A species
is often defined as a group of “actually or potentially
interbreeding populations which are reproductively isolated from
other such groups.” By this definition, many species of
would be lumped together according to their
geographic and ecological habitat, despite clear distinctions in
morphology and, to a large extent, genetic data. Thus, although it
may be difficult to place a definition on a species within a genus
, it is trivial and uninformative to apply the
to all forms of life.
Oak wood has a density of about 0.75 g/cm³, great strength and
hardness, and is very resistant to insect and fungal attack because
of its high tannin
content. It also has very
attractive grain markings, particularly when quartersawn
. Wide, quarter-sawn boards of oak have been
prized since the Middle Ages for use in
interior paneling of prestigious buildings such as the debating
chamber of the British House of Commons in London, England, and in the
construction of fine furniture.
Oak wood, from Quercus robur
and Quercus petraea
, was used in Europe for
the construction of ships
, especially naval
men of war
, until the 19th century, and
was the principal timber used in the construction of European
buildings. Today oak
is still commonly used for furniture
making and flooring, timber frame
buildings, and for veneer production. Barrels
in which red wines
and spirits such as Scotch whisky
and Bourbon whiskey
are made from European and American oak.
The use of oak in wine
can add many
different dimensions to wine based on the type and style of the
oak. Oak barrels, which may be charred before use, contribute to
the colour, taste, and aroma, of the contents, imparting a
desirable oaky vanillin
flavour to these
drinks. The great dilemma for wine producers is to choose between
French and American oakwoods. French oaks (Quercus robur
) give the wine greater refinement and are
chosen for best wines since they increase the price compared to
those aged in American oak wood. American oak contributes greater
texture and resistance to ageing, but produces more violent wine
bouquets. Oak wood chips are used for smoking
fish, meat, cheeses
and other foods.
The bark of Quercus suber
, or Cork
, is used to produce wine stoppers
(corks). This species grows in
Sea region, with Portugal, Spain, Algeria and Morocco producing
most of the world's supply.
Of the North American oaks, the
Northern red oak Quercus
is the most prized of the red oak group for lumber, all
of which is marketed as red oak regardless of the species of
origin. It is not good for outdoor use due to the open capillaries.
One can blow air through an end grain piece 10 inches long to
make bubbles come out in a glass of water. These opening give
fungus easy access when the finish deteriorates. The standard for
the lumber of the white oak group, all of which is marketed as
white oak, is the White Oak Quercus
. White Oak is often used to make wine barrels
. The wood of the deciduous Pedunculate
Oak Quercus robur
Oak Quercus petraea
account for most of the European
oak production, but evergreen species
as Holm oak Quercus ilex
Cork oak Quercus suber
produce valuable timber.
of the White Oak is dried and used in
medical preparations. Oak bark is also rich in tannin
, and is used by tanners for tanning leather
are used for making flour or roasted for acorn
coffee. Oak galls were used for centuries as the main ingredient in
manuscript ink, harvested at a specific time of year.
Japanese oak is used in the making of professional drums from
manufacturer Yamaha Drums
. The rough,
hard surface of oak gives the drum a brighter and louder tone
compared to traditional drum materials such as maple
Diseases and pests
Sudden Oak Death
Oak Mildew on Pedunculate Oak.
) is a water mould
kill oaks within just a few weeks. Oak
, caused by the fungus Ceratocystis fagacearum
fungus closely related to Dutch Elm
), is also a lethal disease of some oaks, particularly
the red oaks (the white oaks can be infected but generally live
longer). Other dangers include wood-boring beetles
as well as root rot
in older trees which may not
be apparent on the outside, often only being discovered when the
trees come down in a strong gale
. Oak apples
made by the gall wasp
. The female kermes scale
causes galls to grow on kermes oak
are used as food plants by the larvae
such as the Gypsy Moth
, which can defoliate oak and other broadleaved tree
species in North America.
A considerable number of galls
are found on
oak leaves, buds, flowers, roots, ect. Examples are Oak artichoke gall
, Oak Marble gall
gall, Knopper gall
The leaves and acorns of the oak tree are poisonous to horses in
large amounts, due to the toxin tannic
, and cause kidney damage and gastroenteritis
. Additionally, once horses
have a taste for the leaves and acorns, they may seek them out.
Therefore, horse owners are encouraged to fence out oak trees from
their pasture, especially if forage is scarce. Symptoms of
poisoning include lack of
, depression, constipation, diarrhea (which may contain
blood), blood in urine
, and colic
Political or symbolic
The oak is
a common symbol of strength and endurance and
has been chosen as the national tree
of England, Estonia, France, Germany, Moldova, Latvia, Lithuania, Poland, the
States, Basque Country, Wales, Bulgaria and Serbia.
designated the oak as its official state tree in 1961, and the White
Oak is the state tree of Connecticut, Illinois and Maryland. The Northern Red
Oak is the provincial tree of Prince Edward Island, as well as the state tree of New Jersey. The Live Oak is the State Tree of Georgia.
The oak is
the emblem of County Londonderry
Ireland, as a vast amount of the county was covered in
forests of the tree until relatively recently. The name of the
county comes from the city of Derry, which
originally in Irish was known as
Doire meaning oak.
Oak leaves are traditionally an important part of German Army
regalia. They also symbolize rank in the United States Armed Forces
gold oak leaf indicates an O-4 (Major
), whereas a
silver oak leaf indicates an O-5 (Lt.
). Arrangements of oak leaves, acorns and
sprigs indicate different branches of the United States Navy Staff corps
Oak leaves are embroidered onto the covers worn by field grade
officers and flag officers in the United States armed
The oak tree is used as a symbol by a number of political parties.
It is the
symbol of the Conservative
Party in the United
Kingdom, and formerly of the Progressive Democrats in Ireland.
In the cultural arena, the oakleaf is the
symbol of the
(UK) and The
Royal Oak Foundation
In Celtic mythology
, it is the tree
of doors, believed to be a gateway between worlds, or a place where
portals could be erected.
In Norse mythology
, the oak was
sacred to the thunder god, Thor
. Some scholars
speculate that this is because the oak, as the largest tree in
northern Europe, was the one most often struck by lightning.
was a sacred tree
of the Germanic Chatti
tribe. Its destruction marked the Christianisation
of the heathen tribes by
In Classical mythology
, the oak
was a symbol of Zeus
and his sacred tree.
example is the oracle of Dodona, which in
prehistory consisted solely of a holy oak.
tree is traditionally sacred to Serbs and is
widely used throughout Serbia on national
and regional symbols both old and new.
Bible, the oak tree at Shechem is the site where Jacob buries the foreign gods of
his people (Gen.
35:4) . In addition, Joshua erects a stone
under an oak tree as the first covenant of the Lord (Josh.
24.25-7). In Isaiah 61, the prophet refers to the Israelites as
"Oaks of Righteousness".
Several individual oak trees, such as the Royal Oak
in Britain and the Charter Oak
in the United States, are of great
historical or cultural importance; for a list of important oaks,
see Individual oak
"The Proscribed Royalist,
", a famous painting by John Everett Millais
, depicted a
Royalist fleeing from Cromwell
's forces and
hidden in an oak. Millais painted the picture in Hayes, Kent
, from a local oak tree that became
known as the Millais Oak.
N.C. is known as "The City of a Thousand
Historical note on Linnaean species
described only five
species of oak from eastern North America, based on general leaf
form. These were White oak
; Chestnut oak
; Red oak
; Willow oak Q.
; and Water oak
. Because he was dealing with confusing leaf forms, the
and Q. rubra
included mixed foliage of more than one species. For that reason,
some taxonomists in the past proposed different names for these two
species (Q. montana
and Q. borealis
respectively), but the original Linnaean names have now been
lectotypified by removing some of the specimens in Linnaeus'
Image:Raunkiaer.jpg|A Pedunculate oak in Denmark
Image:Oak_at_night.JPG|An oak tree at
nightImage:Oakbark.jpg|Bark of Quercus
Image:Spanish-moss-tree.jpg|Southern live oak
with spanish mossImage:Quercus mongolica mongolian oak MN
2007.JPG|Quercus mongolica Mongolian Oak in Minnesota
Landscape ArboretumImage:Quercus robur JPG (a).jpg|Old oak in
Liernu, Belgium.Image:Quercus robur JPG (d2).jpg|The
Duke Prosper Oak in Enghien (Belgium).Image:Sivry-Rance AR1aJPG.jpg|Quercus
petraea Sessile Oak in Sivry-Rance (Belgium).
Image:Kindred Spirit® Hybrid Oak.jpg|Form
of Kindred Spirit Hybrid
.Image:Angel Oak Johns Island SC
Oak on Johns Island, South Carolina.Image:Robin Hood
Major Oak.jpg| The Major
Oak is an 800–1000 year old oak in Sherwood
Forest, famed as the alleged principal hideout of Robin Hood.
Lichen.JPG|The Mustard Powder
or Gold Dust lichen is common on old oak bark.
- Sunset Western Garden Book, 1995:606–607
- Williams, Joseph H., William J. Boecklen, and Daniel J. Howard.
2001 Reproductive processes in two oak (Quercus) contact
zones with different levels of hybridisation. Heredity 87:
- Arnold, M. L. 1997. Natural Hybridization and
Evolution. Oxford University Press, New York.
- Conte, L., Cotti, C., and Cristofolini, G. 2007 Molecular
evidence for hybrid origin of Quercus crenata Lam.
(Fagaceae) from Q-cerris L. and Q-suber L.
Plant Biosystems 141 (2): 181–193.
- Gomory, D. and Schmidtova, J. 2007 Extent of nuclear genome
sharing among white oak species (Quercus L. subgen.
Lepidobalanus (Endl.) Oerst.) in Slovakia estimated by
allozymes. Plant Systematics and Evolution 266 (3-4):
- Kelleher, CT., TR Hodkinson, GC Doublas, and DL Kelly. 2005
Species distinction in Irish populations of Quercus
petraea and Q. robur: Morphological versus molecular
analyses. Annals of Botany 96 (7): 1237–1246.
- Frascaria, N., L. Maggia, M. Michaud, and J. Bousquet. 1993 The
RBCL Gene Sequence from Chestnut Indicates a Slow Rate of Evolution
in the Fagaceae. Genome 36 (4): 668–671.
- Manos, PS., AM Stanford. 2001b The historical biogeography of
Fagaceae: Tracking the tertiary history of temperate and subtropical forests of the Northern Hemisphere.
International Journal of Plant Sciences 162: S77-S93
- Raven, Peter H., George B. Johnson, Jonathan B. Losos, Susan R.
Singer. Biology: Seventh Edition. McGraw Hill, New York, NY
- La crianza del vino La Razón
23 de Agosto de 2007
- 200g Oak Smoked Wensleydale – Williams Deli –
tearoom richmond north
- Millais, J.G., Life and Letters of Sir John Everett
Millais, vol. 1, p.166; See also Arborecology, containing a photograph of the Millais
- Byfield, Liz (1990) An oak tree, Collins book bus,
London : Collins Educational, ISBN 0-00-313526-8
- Logan, William B. (2005) Oak : the frame of
civilization, New York ; London : W.W. Norton, ISBN
- Paterson, R.T. (1993) Use of trees by livestock,
5: Quercus, Chatham : Natural Resources
Institute, ISBN 0-85954-365-X
- Royston, Angela (2000) Life cycle of an oak tree,
Heinemann first library, Oxford : Heinemann Library, ISBN
- Savage, Stephen (1994) Oak tree, Observing nature
series, Hove : Wayland, ISBN 0-7502-1196-2
- Tansley, Arthur G., Sir (1952) Oaks and oak woods,
Field study books, London : Methuen, 50 p.