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An oak is a
tree In botany, a tree is a perennial plant with an elongated stem, or trunk, usually supporting branches and leaves. In some usages, the definition of a tree may be narrower, including only woody plants with secondary growth, plants that are ...
or
shrub A shrub (often also called a bush) is a small-to-medium-sized perennial woody plant. Unlike herbaceous plants, shrubs have persistent woody stems above the ground. Shrubs can be either deciduous or evergreen. They are distinguished from trees ...
in the
genus Genus ( plural genera ) is a taxonomic rank used in the biological classification of extant taxon, living and fossil organisms as well as Virus classification#ICTV classification, viruses. In the hierarchy of biological classification, genus com ...
''Quercus'' (;
Latin Latin (, or , ) is a classical language belonging to the Italic branch of the Indo-European languages. Latin was originally a dialect spoken in the lower Tiber area (then known as Latium) around present-day Rome, but through the power of the ...
"oak tree") of the
beech Beech (''Fagus'') is a genus of deciduous trees in the family Fagaceae, native to temperate Europe, Asia, and North America. Recent classifications recognize 10 to 13 species in two distinct subgenera, ''Engleriana'' and ''Fagus''. The ''Engle ...
family,
Fagaceae The Fagaceae are a family of flowering plants that includes beeches, chestnuts and oaks, and comprises eight genera with about 927 species. Fagaceae in temperate regions are mostly deciduous, whereas in the tropics, many species occur as evergre ...
. There are approximately 500 extant species of oaks. The common name "oak" also appears in the names of species in related genera, notably ''
Lithocarpus ''Lithocarpus'' is a genus in the beech family, Fagaceae. Trees in this genus are commonly known as the stone oaks and differ from ''Quercus'' primarily because they produce insect-pollinated flowers on erect spikes and the female flowers have ...
'' (stone oaks), as well as in those of unrelated species such as ''
Grevillea robusta ''Grevillea robusta'', commonly known as the southern silky oak, silk oak or silky oak, silver oak or Australian silver oak, is a flowering plant in the family Proteaceae. It is a tree, the largest species in its genus but is not closely rela ...
'' (silky oaks) and the
Casuarinaceae The Casuarinaceae are a family of dicotyledonous flowering plants placed in the order Fagales, consisting of four genera and 91 species of trees and shrubs native to eastern Africa, Australia, Southeast Asia, Malesia, Papuasia, and the Pacifi ...
(she-oaks). The genus ''Quercus'' is native to the Northern Hemisphere, and includes
deciduous In the fields of horticulture and Botany, the term ''deciduous'' () means "falling off at maturity" and "tending to fall off", in reference to trees and shrubs that seasonally shed leaves, usually in the autumn; to the shedding of petals, aft ...
and
evergreen In botany, an evergreen is a plant which has foliage that remains green and functional through more than one growing season. This also pertains to plants that retain their foliage only in warm climates, and contrasts with deciduous plants, which ...
species extending from cool temperate to
tropical The tropics are the regions of Earth surrounding the Equator. They are defined in latitude by the Tropic of Cancer in the Northern Hemisphere at N and the Tropic of Capricorn in the Southern Hemisphere at S. The tropics are also referred to ...
latitudes in the
Americas The Americas, which are sometimes collectively called America, are a landmass comprising the totality of North and South America. The Americas make up most of the land in Earth's Western Hemisphere and comprise the New World. Along with th ...
, Asia, Europe, and North Africa. North America has the largest number of oak species, with approximately 160 species in Mexico of which 109 are endemic and about 90 in the United States. The second greatest area of oak diversity is China, with approximately 100 species.


Description

Oaks have
spiral In mathematics, a spiral is a curve which emanates from a point, moving farther away as it revolves around the point. Helices Two major definitions of "spiral" in the American Heritage Dictionary are:leaves A leaf (plural, : leaves) is any of the principal appendages of a vascular plant plant stem, stem, usually borne laterally aboveground and specialized for photosynthesis. Leaves are collectively called foliage, as in "autumn foliage", wh ...
, with lobate margins in many species; some have
serrated leaves A leaf ( : leaves) is any of the principal appendages of a vascular plant stem, usually borne laterally aboveground and specialized for photosynthesis. Leaves are collectively called foliage, as in "autumn foliage", while the leaves, st ...
or entire leaves with smooth margins. Many deciduous species are
marcescent Marcescence is the withering and persistence of plant organs that normally are shed, and is a term most commonly applied to plant leaves. The underlying physiological mechanism is that trees transfer water and sap from the roots to the leaves t ...
, not dropping dead leaves until spring. In spring, a single oak tree produces both male flowers (in the form of
catkin A catkin or ament is a slim, cylindrical flower cluster (a spike), with inconspicuous or no petals, usually wind-pollinated (anemophilous) but sometimes insect-pollinated (as in ''Salix''). They contain many, usually unisexual flowers, arranged cl ...
s) and small female flowers, meaning that the trees are
monoecious Monoecy (; adj. monoecious ) is a sexual system in seed plants where separate male and female cones or flowers are present on the same plant. It is a monomorphic sexual system alongside gynomonoecy, andromonoecy and trimonoecy. Monoecy is conne ...
. The fruit is a
nut Nut often refers to: * Nut (fruit), fruit composed of a hard shell and a seed, or a collective noun for dry and edible fruits or seeds * Nut (hardware), fastener used with a bolt Nut or Nuts may also refer to: Arts, entertainment, and media Com ...
called an
acorn The acorn, or oaknut, is the nut of the oaks and their close relatives (genera ''Quercus'' and '' Lithocarpus'', in the family Fagaceae). It usually contains one seed (occasionally two seeds), enclosed in a tough, leathery shell, and borne ...
or oak nut borne in a cup-like structure known as a cupule; each acorn contains one seed (rarely two or three) and takes 6–18 months to mature, depending on their species. The acorns and leaves contain
tannic acid Tannic acid is a specific form of tannin, a type of polyphenol. Its weak acidity ( pKa around 6) is due to the numerous phenol groups in the structure. The chemical formula for commercial tannic acid is often given as C76H52O46, which correspon ...
, which helps to guard from fungi and insects. The live oaks are distinguished for being evergreen, but are not actually a distinct group and instead are dispersed across the genus.


Taxonomy

Linnaeus described only five species of oak from eastern
North America North America is a continent in the Northern Hemisphere and almost entirely within the Western Hemisphere. It is bordered to the north by the Arctic Ocean, to the east by the Atlantic Ocean, to the southeast by South America and the Car ...
, based on general leaf form. These were white oak (''
Quercus alba An oak is a tree or shrub in the genus ''Quercus'' (; Latin "oak tree") of the beech family, Fagaceae. There are approximately 500 extant species of oaks. The common name "oak" also appears in the names of species in related genera, notably '' ...
''), chestnut oak ('' Q. montana''), red oak (''
Q. rubra ''Quercus rubra'', the northern red oak, is an oak tree in the red oak group (''Quercus'' section ''Lobatae''). It is a native of North America, in the eastern and central United States and southeast and south-central Canada. It has been introdu ...
''), willow oak ('' Q. phellos''), and water oak (''
Q. nigra Q is the seventeenth letter of the English alphabet. Q may also refer to: People * Q, pseudonym of Sir Arthur Quiller-Couch, the Cornish writer * Q, pseudonym used by the QAnon#Identity_of_Q, originator of QAnon, an American far-right conspirac ...
''). Because he was dealing with confusing leaf forms, the ''Q. montana'' and ''Q. rubra'' specimens actually included mixed foliage of more than one species.


Classification

The most recent classification of ''Quercus'' divides the genus into two
subgenera In biology, a subgenus (plural: subgenera) is a taxonomic rank directly below genus. In the International Code of Zoological Nomenclature, a subgeneric name can be used independently or included in a species name, in parentheses, placed between t ...
and eight
sections Section, Sectioning or Sectioned may refer to: Arts, entertainment and media * Section (music), a complete, but not independent, musical idea * Section (typography), a subdivision, especially of a chapter, in books and documents ** Section sig ...
. These divisions support the evolutionary diversification of oaks among two distinct clades: the "
Old World The "Old World" is a term for Afro-Eurasia that originated in Europe , after Europeans became aware of the existence of the Americas. It is used to contrast the continents of Africa, Europe, and Asia, which were previously thought of by the ...
" clade, including oaks that diversified mainly in Eurasia; and the "
New World The term ''New World'' is often used to mean the majority of Earth's Western Hemisphere, specifically the Americas."America." ''The Oxford Companion to the English Language'' (). McArthur, Tom, ed., 1992. New York: Oxford University Press, p. 3 ...
" clade, for oaks that diversified mainly in the Americas.


Subgenus ''Quercus''

* Sect. ''Quercus'' (synonyms ''Lepidobalanus'' and ''Leucobalanus''), the
white oaks The genus ''Quercus'' contains about 500 species, some of which are listed here. The genus, as is the case with many large genera, is divided into subgenera and sections. Traditionally, the genus ''Quercus'' was divided into the two subgenera '' ...
of
Europe Europe is a large peninsula conventionally considered a continent in its own right because of its great physical size and the weight of its history and traditions. Europe is also considered a Continent#Subcontinents, subcontinent of Eurasia ...
,
Asia Asia (, ) is one of the world's most notable geographical regions, which is either considered a continent in its own right or a subcontinent of Eurasia, which shares the continental landmass of Afro-Eurasia with Africa. Asia covers an area ...
and North America. Trees or shrubs that produce nuts, specifically acorns, as fruits. Acorns mature in one year for annual trees and two years for biannual trees. Acorn is encapsulated by a spiny cupule as characterized by the family Fagaceae. Flowers in the Quercus genera produce one flower per node, with three or six styles, as well as three or six ovaries, respectively. The leaves mostly lack a bristle on their lobe tips, which are usually rounded. The
type species In zoological nomenclature, a type species (''species typica'') is the species name with which the name of a genus or subgenus is considered to be permanently taxonomically associated, i.e., the species that contains the biological type specimen ...
is '' Quercus robur''. * Sect. ''Protobalanus'', the canyon live oak and its relatives, in the southwestern
United States The United States of America (U.S.A. or USA), commonly known as the United States (U.S. or US) or America, is a country primarily located in North America. It consists of 50 states, a federal district, five major unincorporated territorie ...
and northwest
Mexico Mexico (Spanish: México), officially the United Mexican States, is a country in the southern portion of North America. It is bordered to the north by the United States; to the south and west by the Pacific Ocean; to the southeast by Guatema ...
. Styles are short; the acorns mature in 18 months and taste very bitter. The inside of the acorn shell appears woolly. The leaves typically have sharp lobe tips, with bristles at the lobe tip. * Sect. ''Ponticae,'' a disjunct including just two species. Styles are short and the acorns mature in 12 months. The leaves have large stipules, high secondary venation, and are highly toothed. * Sect. ''Virentes,'' the southern live oaks of the Americas. Styles are short and the acorns mature in 12 months. The leaves are evergreen or subevergreen. * Sect. ''Lobatae'' (synonym ''Erythrobalanus''), the
red oaks The genus ''Quercus'' contains about 500 species, some of which are listed here. The genus, as is the case with many large genera, is divided into subgenera and sections. Traditionally, the genus ''Quercus'' was divided into the two subgenera ''C ...
of North America,
Central America Central America ( es, América Central or ) is a subregion of the Americas. Its boundaries are defined as bordering the United States to the north, Colombia to the south, the Caribbean Sea to the east, and the Pacific Ocean to the west. ...
and northern
South America South America is a continent entirely in the Western Hemisphere and mostly in the Southern Hemisphere, with a relatively small portion in the Northern Hemisphere at the northern tip of the continent. It can also be described as the southe ...
. Styles are long; the 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. The leaves typically have sharp lobe tips, with spiny bristles at the lobe.


Subgenus ''Cerris''

* Sect. ''Cyclobalanopsis,'' the ring-cupped oaks of eastern and southeastern
Asia Asia (, ) is one of the world's most notable geographical regions, which is either considered a continent in its own right or a subcontinent of Eurasia, which shares the continental landmass of Afro-Eurasia with Africa. Asia covers an area ...
. These are evergreen trees growing 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. Species of ''Cyclobalanopsis'' are common in the evergreen subtropical
laurel forest Laurel forest, also called laurisilva or laurissilva, is a type of subtropical forest found in areas with high humidity and relatively stable, mild temperatures. The forest is characterized by broadleaf tree species with evergreen, glossy and elo ...
s which extend from southern Japan, southern Korea, and Taiwan across southern China and northern Indochina to the eastern Himalayas, in association with trees of the genus '' Castanopsis'' and the laurel family (
Lauraceae Lauraceae, or the laurels, is a plant family that includes the true laurel and its closest relatives. This family comprises about 2850 known species in about 45 genera worldwide (Christenhusz & Byng 2016 ). They are dicotyledons, and occur ma ...
). * Sect. ''Cerris'', the Turkey oak and its relatives of Europe and Asia. Styles are long; acorns mature in 18 months and taste very bitter. The inside of the acorn's shell is hairless. Its leaves typically have sharp lobe tips, with bristles at the lobe tip. * Sect. ''Ilex,'' the Ilex oak and its relatives of Eurasia and northern
Africa Africa is the world's second-largest and second-most populous continent, after Asia in both cases. At about 30.3 million km2 (11.7 million square miles) including adjacent islands, it covers 6% of Earth's total surface area ...
. Styles are medium-long; acorns mature in 12–24 months, appearing hairy on the inside. The leaves are evergreen, with bristle-like extensions on the teeth.


Fossil history

Potential records of ''Quercus'' have been reported from
Late Cretaceous The Late Cretaceous (100.5–66 Ma) is the younger of two epochs into which the Cretaceous Period is divided in the geologic time scale. Rock strata from this epoch form the Upper Cretaceous Series. The Cretaceous is named after ''creta'', the ...
deposits in North America and East Asia, however these are not considered definitive. In a survey of the fossil record of ''Quercus'' it was concluded that "pre-
Paleogene The Paleogene ( ; British English, also spelled Palaeogene or Palæogene; informally Lower Tertiary or Early Tertiary) is a geologic period, geologic period and system that spans 43 million years from the end of the Cretaceous Period million yea ...
, and perhaps pre-
Eocene The Eocene ( ) Epoch is a geological epoch (geology), epoch that lasted from about 56 to 33.9 million years ago (mya). It is the second epoch of the Paleogene Period (geology), Period in the modern Cenozoic Era (geology), Era. The name ''Eocene' ...
occurrences of ''Quercus'' macroremains are generally represented by poorly preserved fossils that lack critical features needed for certain identification and need to be treated with caution." Amongst the oldest unequivocal records of ''Quercus'' are pollen from Austria, dating to the
Paleocene The Paleocene, ( ) or Palaeocene, is a geological epoch (geology), epoch that lasted from about 66 to 56 mya (unit), million years ago (mya). It is the first epoch of the Paleogene Period (geology), Period in the modern Cenozoic Era (geology), E ...
-Eocene boundary, around 55 million years ago. The oldest records of ''Quercus'' in North America are from Oregon, dating to the Middle Eocene, around 44 million years ago, with the oldest records in Asia being from the Middle of Eocene of Japan; both forms have affinites to the ''
Cyclobalanopsis An oak is a tree or shrub in the genus ''Quercus'' (; Latin "oak tree") of the beech family, Fagaceae. There are approximately 500 extant species of oaks. The common name "oak" also appears in the names of species in related genera, notably ...
'' group.


Phylogeny

The advent of molecular techniques for phylogenetic analysis transformed understanding of oak relationships, initially by uncovering molecular support for the diphyletic division of ''Quercus'' into Old World and New World clades. These techniques have proved highly useful in resolving fine-scale relationships among 2–5 oak species, particularly groups known to hybridize, but until recently the larger emphasis on this narrow approach prevented systematists from making large-scale determinations about oak history. As the capacity for sampling across wider swaths of oak species rose, so has resolution at the section and species level across the ''Quercus'' genus. Further advances in oak systematics are expected to arise from
next-generation sequencing Massive parallel sequencing or massively parallel sequencing is any of several high-throughput approaches to DNA sequencing using the concept of massively parallel processing; it is also called next-generation sequencing (NGS) or second-generation s ...
techniques, including a recent project to sequence the entire genome of ''Quercus robur'' (the pedunculate oak). The recent completion of that genome has uncovered an array of mutations that may underlie the evolution of longevity and disease resistance in oaks. In addition, the generation of
RAD-seq Restriction site associated DNA (RAD) markers are a type of genetic marker which are useful for association mapping, Quantitative trait locus, QTL-mapping, population genetics, ecological genetics and evolutionary genetics. The use of RAD markers ...
loci for hundreds of oak species has allowed for the construction of the most highly detailed oak phylogeny to date, although the high signal of
introgression Introgression, also known as introgressive hybridization, in genetics is the transfer of genetic material from one species into the gene pool of another by the repeated backcrossing of an interspecific hybrid with one of its parent species. Intr ...
(by hybridization) across the tree poses difficulties for deriving an unambiguous, unitary history of oaks. The phylogeny from Hipp et al 2019 is:


Ecology

Oaks are
keystone species A keystone species is a species which has a disproportionately large effect on its natural environment relative to its abundance, a concept introduced in 1969 by the zoologist Robert T. Paine. Keystone species play a critical role in maintaini ...
in a wide range of habitats from Mediterranean semi-desert to subtropical rainforest. For example, oak trees are important components of hardwood forests, and certain species are particularly known to grow in associations with members of the Ericaceae in
oak–heath forest An oak–heath forest is a plant community association and type of forest ecology. It is a deciduous forest type of well-drained, acidic soils, characterized by oaks (''Quercus'') and plants of the heath family (Ericaceae). It is commonly found in ...
s. A number of kinds of
truffle A truffle is the fruiting body of a subterranean ascomycete fungus, predominantly one of the many species of the genus ''Tuber''. In addition to ''Tuber'', many other genera of fungi are classified as truffles including ''Geopora'', ''Peziz ...
s, including the two well known varieties, the black Périgord truffle and the white Piedmont truffle, have symbiotic relationships with oak trees. Similarly many other mushrooms such as ''
Ramaria flavosaponaria ''Ramaria flavosaponaria'' is a species of coral fungus in the family Gomphaceae. It is found in the mountains of eastern North America from Georgia and Tennessee to Nova Scotia. Names The specific epithet is from the ('yellow') and ('soapy ...
'' also associate with oaks. The European pied flycatcher is an example of an animal species that often depends upon oak trees. Many species of oaks are under threat of extinction in the wild, largely due to land use changes, livestock grazing and unsustainable harvesting. For example, over the past 200 years, large areas of oak forest in the highlands of Mexico, Central America and the northern Andes have been cleared for coffee plantations and cattle ranching. There is a continuing threat to these forests from exploitation for timber, fuelwood and charcoal. In the US, entire oak ecosystems have declined due to a combination of factors still imperfectly known, but thought to include fire suppression, increased consumption of acorns by growing mammal populations, herbivory of seedlings, and introduced pests. However, it has also been suggested that oaks as generally light-demanding trees with a relatively high tolerance for mechanic disturbances might depend on grazers like
bison Bison are large bovines in the genus ''Bison'' (Greek: "wild ox" (bison)) within the tribe Bovini. Two extant and numerous extinct species are recognised. Of the two surviving species, the American bison, ''B. bison'', found only in North Ame ...
and the clearances they create in order to regenerate successfully, thus missing them since they were extirpated in most regions following the
European colonization The historical phenomenon of colonization is one that stretches around the globe and across time. Ancient and medieval colonialism was practiced by the Phoenicians, the Greeks, the Turks, and the Arabs. Colonialism in the modern sense began ...
. The mature trees shed varying numbers of acorns annually. Scientists suggest that shedding excess numbers allows the oaks to satiate nut gathering species which improves the chances of germination. Every four to ten years, certain oak populations will synchronize to produce almost no acorns at all, only to rain them down excessively the following year, known as a
mast year Mast is the fruit of forest trees and shrubs, such as acorns and other nuts. The term derives from the Old English ''mæst'', meaning the nuts of forest trees that have accumulated on the ground, especially those used historically for fattening ...
. The year preceding the mast year is thought to starve off the mammal populations feeding on the supply, thereby increasing the effectiveness of the overproduction in the mast year that follows. This is necessary to the survival of any given oak species, as only one in 10,000 acorns results in an eventual tree.


Hybridization

Interspecific hybridization In biology, a hybrid is the offspring resulting from combining the qualities of two organisms of different breeds, varieties, species or genera through sexual reproduction. Hybrids are not always intermediates between their parents (such as in ...
is quite common among oaks, but usually between species within the same section only, and most common in the white oak group. White oaks are unable to discriminate against pollination by other species in the same section. Because they are
wind pollinated Anemophily or wind pollination is a form of pollination whereby pollen is distributed by wind. Almost all gymnosperms are anemophilous, as are many plants in the order Poales, including grasses, sedges, and rushes. Other common anemophilous pla ...
and they have weak internal barriers to hybridization, 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 hybridization among oaks has consequences for oak populations around the world; most notably, hybridization has produced large populations of hybrids with copious amounts of
introgression Introgression, also known as introgressive hybridization, in genetics is the transfer of genetic material from one species into the gene pool of another by the repeated backcrossing of an interspecific hybrid with one of its parent species. Intr ...
, and the
evolution Evolution is change in the heritable characteristics of biological populations over successive generations. These characteristics are the expressions of genes, which are passed on from parent to offspring during reproduction. Variation ...
of new species. Frequent hybridization and high levels of introgression have caused different species in the same populations to share up to 50% of their genetic information. Having high rates of hybridization and introgression produces genetic data that often does not differentiate between two clearly morphologically distinct species, but instead differentiates populations. Research suggests that the maintenance of particular loci for adaptation to ecological niches might explain the retention of species identity despite significant gene flow. The
Fagaceae The Fagaceae are a family of flowering plants that includes beeches, chestnuts and oaks, and comprises eight genera with about 927 species. Fagaceae in temperate regions are mostly deciduous, whereas in the tropics, many species occur as evergre ...
, or beech family, to which the oaks belong, is a very slow evolving
clade A clade (), also known as a monophyletic group or natural group, is a group of organisms that are monophyletic – that is, composed of a common ancestor and all its lineal descendants – on a phylogenetic tree. Rather than the English term, ...
compared to other
angiosperm Flowering plants are plants that bear flowers and fruits, and form the clade Angiospermae (), commonly called angiosperms. The term "angiosperm" is derived from the Greek words ('container, vessel') and ('seed'), and refers to those plants th ...
s, and the patterns of hybridization and introgression in ''Quercus'' pose a great challenge to the concept of a species since 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 ''Quercus'' would be lumped together according to their geographic and ecological habitat, despite clear distinctions in morphology and, to a large extent, genetic data.


Diseases and pests

Sudden oak death (''Phytophthora ramorum'') is a water mould that can kill oaks within just a few weeks.
Oak wilt Oak wilt is a fungal disease caused by the organism ''Bretziella fagacearum'' that threatens ''Quercus'' spp. The disease is limited to the Midwestern and Eastern United States; first described in the 1940s in the Upper Mississippi River Val ...
, caused by the fungus ''Bretziella fagacearum'' 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 The term woodboring beetle encompasses many species and families of beetles whose larval or adult forms eat and destroy wood (i.e., are xylophagous). In the woodworking industry, larval stages of some are sometimes referred to as woodworms. The t ...
beetle Beetles are insects that form the order Coleoptera (), in the superorder Endopterygota. Their front pair of wings are hardened into wing-cases, elytra, distinguishing them from most other insects. The Coleoptera, with about 400,000 describ ...
s, as well as root
rot Rot(s) or rotting may refer to: Decay Organic matter * Rot, decomposition of organic matter ** Dry rot, of wood ** Root rot ** Wet rot, of wood * Necrosis, of tissue Technology * Bit rot, data degradation ** Software rot, a form of bit rot * Di ...
in older trees which may not be apparent on the outside, often being discovered only when the trees come down in a strong gale. Oak apples are
gall Galls (from the Latin , 'oak-apple') or ''cecidia'' (from the Greek , anything gushing out) are a kind of swelling growth on the external tissues of plants, fungi, or animals. Plant galls are abnormal outgrowths of plant tissues, similar to be ...
s on oaks made by the
gall wasp Gall wasps, also incorrectly called gallflies, are hymenopterans of the family Cynipidae in the wasp superfamily Cynipoidea. Their common name comes from the galls they induce on plants for larval development. About 1,300 species of this generall ...
. The female kermes
scale Scale or scales may refer to: Mathematics * Scale (descriptive set theory), an object defined on a set of points * Scale (ratio), the ratio of a linear dimension of a model to the corresponding dimension of the original * Scale factor, a number ...
causes galls to grow on kermes oak. Oaks are used as food plants by the
larva A larva (; plural larvae ) is a distinct juvenile form many animals undergo before metamorphosis into adults. Animals with indirect development such as insects, amphibians, or cnidarians typically have a larval phase of their life cycle. The ...
e of
Lepidoptera Lepidoptera ( ) is an order (biology), order of insects that includes butterfly, butterflies and moths (both are called lepidopterans). About 180,000 species of the Lepidoptera are described, in 126 Family (biology), families and 46 Taxonomic r ...
(
butterfly Butterflies are insects in the macrolepidopteran clade Rhopalocera from the Order (biology), order Lepidoptera, which also includes moths. Adult butterflies have large, often brightly coloured wings, and conspicuous, fluttering flight. The ...
and
moth Moths are a paraphyletic group of insects that includes all members of the order Lepidoptera that are not butterflies, with moths making up the vast majority of the order. There are thought to be approximately 160,000 species of moth, many of w ...
) species such as the gypsy moth, ''Lymantria dispar'', which can defoliate oak and other broadleaved tree species in North America. A considerable number of
galls Galls (from the Latin , 'oak-apple') or ''cecidia'' (from the Greek , anything gushing out) are a kind of swelling growth on the external tissues of plants, fungi, or animals. Plant galls are abnormal outgrowths of plant tissues, similar to be ...
are found on oak leaves, buds, flowers, roots, etc. Examples are
oak artichoke gall Andricus foecundatrix (formerly ''Andricus fecundator'') is a parthenogenetic gall wasp which lays a single egg within a leaf bud, using its ovipositor, to produce a gall known as an oak artichoke gall, oak hop gall, larch-cone gall or hop strobi ...
, oak marble gall, oak apple gall, knopper gall, and spangle gall. A number of species of fungus cause powdery mildew on oak species. In Europe the species ''
Erysiphe alphitoides ''Erysiphe alphitoides'' is a species of fungus which causes powdery mildew on oak trees. Discovery and taxonomy Today oak powdery mildew is one of the most common diseases in European forests but it is thought to not always have been present ...
'' is the most common cause. A new and yet little understood disease of mature oaks,
acute oak decline Acute oak decline is a disease that infects oak trees in the UK. It mainly affects mature oak trees of over 50 years old of both Britain's native oak species: the pedunculate oak (''Quercus robur'') and the sessile oak (''Quercus petraea''). The d ...
, has been reported in parts of the UK since 2009. The
oak processionary The oak processionary (''Thaumetopoea processionea'') is a moth whose caterpillars can be found in oak forests, where they feed on oak leaves, causing significant damage. They travel in nose-to-tail processions (hence their name), often arrow-h ...
moth (''Thaumetopoea processionea'') has become a serious threat in the UK since 2006. The caterpillars of this species defoliate the trees, and are hazardous to human health; their bodies are covered with poisonous hairs which can cause rashes and respiratory problems. In California, oaks are affected by the fungal disease
foamy bark canker The foamy bark canker is a disease affecting oak trees in California caused by the fungus ''Geosmithia pallida'' and spread by the Western oak bark beetle ('' Pseudopityopthorus pubipennis''). This disease is only seen through the symbiosis of th ...
. The eastern grey squirrel (''Sciurus carolinensis'') is native in North America and an invasive species across Europe where they are known to strip bark off of a variety of large trees, including oaks. Bark stripping can result in the death of the leading shoot and decreased crown size.


Toxicity

The leaves and acorns of the oak tree are poisonous in large amounts to livestock including
cattle Cattle (''Bos taurus'') are large, domesticated, cloven-hooved, herbivores. They are a prominent modern member of the subfamily Bovinae and the most widespread species of the genus ''Bos''. Adult females are referred to as cows and adult mal ...
,
horse The horse (''Equus ferus caballus'') is a domesticated, one-toed, hoofed mammal. It belongs to the taxonomic family Equidae and is one of two extant subspecies of ''Equus ferus''. The horse has evolved over the past 45 to 55 million y ...
s,
sheep Sheep or domestic sheep (''Ovis aries'') are domesticated, ruminant mammals typically kept as livestock. Although the term ''sheep'' can apply to other species in the genus ''Ovis'', in everyday usage it almost always refers to domesticated s ...
, and
goat The goat or domestic goat (''Capra hircus'') is a domesticated species of goat-antelope typically kept as livestock. It was domesticated from the wild goat (''C. aegagrus'') of Southwest Asia and Eastern Europe. The goat is a member of the a ...
s due to the toxin
tannic acid Tannic acid is a specific form of tannin, a type of polyphenol. Its weak acidity ( pKa around 6) is due to the numerous phenol groups in the structure. The chemical formula for commercial tannic acid is often given as C76H52O46, which correspon ...
, causing kidney damage and
gastroenteritis Gastroenteritis, also known as infectious diarrhea and gastro, is an inflammation of the gastrointestinal tract including the stomach and intestine. Symptoms may include diarrhea, vomiting, and abdominal pain. Fever, lack of energy, and dehydra ...
. Symptoms of poisoning include
lack of appetite Anorexia is a medical term for a loss of appetite. While the term in non-scientific publications is often used interchangeably with anorexia nervosa, many possible causes exist for a loss of appetite, some of which may be harmless, while others i ...
, depression, constipation, diarrhea (which may contain blood), blood in urine, and
colic Colic or cholic () is a form of pain that starts and stops abruptly. It occurs due to muscular contractions of a hollow tube ( small and large intestine, gall bladder, ureter, etc.) in an attempt to relieve an obstruction by forcing content out ...
. The exception is the
domestic pig The pig (''Sus domesticus''), often called swine, hog, or domestic pig when distinguishing from other members of the genus '' Sus'', is an omnivorous, domesticated, even-toed, hoofed mammal. It is variously considered a subspecies of ''Sus s ...
, which may be fed entirely on acorns in the right conditions, and has traditionally been pastured in oak woodlands (such as the Spanish ''
dehesa A ''dehesa'' () is a multifunctional, agrosylvopastoral system (a type of agroforestry) and cultural landscape of southern and central Spain and southern Portugal; in Portugal, it is known as a ''montado''. Its name comes from the Latin 'defens ...
'' and the English system of
pannage Pannage (also referred to as ''Eichelmast'' or ''Eckerich'' in Germany, Switzerland, Liechtenstein, Luxembourg, Austria, Slovenia and Croatia) is the practice of releasing livestock-domestic pig, pigs in a forest, so that they can feed on falle ...
).
Acorn The acorn, or oaknut, is the nut of the oaks and their close relatives (genera ''Quercus'' and '' Lithocarpus'', in the family Fagaceae). It usually contains one seed (occasionally two seeds), enclosed in a tough, leathery shell, and borne ...
s are also edible by humans, after
leaching Leaching is the loss or extraction of certain materials from a carrier into a liquid (usually, but not always a solvent). and may refer to: *Leaching (agriculture), the loss of water-soluble plant nutrients from the soil; or applying a small amoun ...
of the tannins.


Uses

Oak
wood Wood is a porous and fibrous structural tissue found in the stems and roots of trees and other woody plants. It is an organic materiala natural composite of cellulose fibers that are strong in tension and embedded in a matrix of lignin th ...
has a density of about creating great strength and hardness. The wood is very resistant to insect and fungal attack because of its high
tannin Tannins (or tannoids) are a class of astringent, polyphenolic biomolecules that bind to and precipitate proteins and various other organic compounds including amino acids and alkaloids. The term ''tannin'' (from Anglo-Norman ''tanner'', ...
content. It also has very appealing grain markings, particularly when quartersawn. Oak planking was common on high status
Viking Vikings ; non, víkingr is the modern name given to seafaring people originally from Scandinavia (present-day Denmark, Norway and Sweden), who from the late 8th to the late 11th centuries raided, pirated, traded and se ...
longship Longships were a type of specialised Scandinavian warships that have a long history in Scandinavia, with their existence being archaeologically proven and documented from at least the fourth century BC. Originally invented and used by the Nors ...
s in the 9th and 10th centuries. The wood was hewn from green logs, by axe and wedge, to produce radial planks, similar to quarter-sawn timber. Wide, quarter-sawn boards of oak have been prized since the
Middle Ages In the history of Europe, the Middle Ages or medieval period lasted approximately from the late 5th to the late 15th centuries, similar to the post-classical period of global history. It began with the fall of the Western Roman Empire a ...
for use in interior panelling of prestigious buildings such as the debating chamber of the House of Commons in
London London is the capital and largest city of England and the United Kingdom, with a population of just under 9 million. It stands on the River Thames in south-east England at the head of a estuary down to the North Sea, and has been a majo ...
and in the construction of fine furniture. Oak wood, from '' Quercus robur'' and '' Quercus petraea'', was used in Europe for the construction of
ship A ship is a large watercraft that travels the world's oceans and other sufficiently deep waterways, carrying cargo or passengers, or in support of specialized missions, such as defense, research, and fishing. Ships are generally distinguished ...
s, especially naval
men of war ''Men of War'' is a real-time tactics video game franchise, based mainly in World War II. Main series Soldiers: Heroes of World War II ''Soldiers: Heroes of World War II'' is the original game of the 'Men of War' series, and uses an early GEM ...
, until the 19th century, and was the principal timber used in the construction of European
timber-framed Timber framing (german: Holzfachwerk) and "post-and-beam" construction are traditional methods of building with heavy timbers, creating structures using squared-off and carefully fitted and joined timbers with joints secured by large wooden ...
buildings. Today oak wood is still commonly used for
furniture Furniture refers to movable objects intended to support various human activities such as seating (e.g., stools, chairs, and sofas), eating (tables), storing items, eating and/or working with an item, and sleeping (e.g., beds and hammocks). Fu ...
making and flooring, timber-frame buildings, and veneer production. Japanese oak is used for professional drums made by Yamaha Drums. The higher density of oak gives the drum a brighter and louder tone compared to traditional materials such as
maple ''Acer'' () is a genus of trees and shrubs commonly known as maples. The genus is placed in the family Sapindaceae.Stevens, P. F. (2001 onwards). Angiosperm Phylogeny Website. Version 9, June 2008 nd more or less continuously updated since http ...
and
birch A birch is a thin-leaved deciduous hardwood tree of the genus ''Betula'' (), in the family Betulaceae, which also includes alders, hazels, and hornbeams. It is closely related to the beech-oak family Fagaceae. The genus ''Betula'' contains 30 ...
. In hill states of India, besides fuelwood and timber, the locals use oak wood for agricultural implements. The leaves are used as fodder for livestock during lean periods. Of the North American red oaks, the northern red oak is one of the most prized for lumber, and is marketed as red oak regardless of species. This wood has open capillaries, and air blown through an end grain piece 10 inches long can send bubbles out the other end into a glass of water. The openings give fungus easy access when the finish deteriorates, and natural red oak rots easily outdoors. However, if the wood is treated with a preservative compound, the capillaries absorb it deeply, and treated red oak will resist rot better than cured white oak heartwood, which has a closed cell structure.
Shumard oak ''Quercus shumardii'', the Shumard oak, spotted oak, Schneck oak, Shumard red oak, or swamp red oak, is one of the largest of the oak species in the red oak group (''Quercus'' section ''Lobatae''). It is closely related to ''Quercus buckleyi'' (T ...
, a member of the red oak subgenus, provides timber described as "mechanically superior" to northern red oak. Cherrybark oak is another type of red oak that provides excellent timber. The standard lumber tree of the white oak group – all marketed as white oak – is ''
Quercus alba An oak is a tree or shrub in the genus ''Quercus'' (; Latin "oak tree") of the beech family, Fagaceae. There are approximately 500 extant species of oaks. The common name "oak" also appears in the names of species in related genera, notably '' ...
''. White oak is often used to make
wine barrel Oak is used in winemaking to vary the color, flavor, tannin profile and texture of wine. It can be introduced in the form of a barrel during the fermentation or aging periods, or as free-floating chips or staves added to wine fermented in a vess ...
s. The wood of the
deciduous In the fields of horticulture and Botany, the term ''deciduous'' () means "falling off at maturity" and "tending to fall off", in reference to trees and shrubs that seasonally shed leaves, usually in the autumn; to the shedding of petals, aft ...
pedunculate oak and
sessile oak ''Quercus petraea'', commonly known as the sessile oak, Cornish oak, Irish Oak or durmast oak, is a species of oak tree native to most of Europe and into Anatolia and Iran. The sessile oak is the national tree of Ireland, and an unofficial embl ...
accounts for most European oak production, but evergreen species such as
Holm oak Holm oak may refer to: * '' Quercus ilex'', tree native to South and Southeast Europe and parts of France * '' Quercus rotundifolia'', tree native to the Iberian Peninsula and Northwest Africa * ''Quercus agrifolia ''Quercus agrifolia'', the Cal ...
and cork oak also produce valuable timber.
Oak bark Tanbark is the bark of certain species of trees, traditionally used for tanning hides into leather. The words "tannin", "tanning", "tan," and " tawny" are derived from the Medieval Latin ''tannare'', "to convert into leather." Bark mills are ...
is also rich in
tannin Tannins (or tannoids) are a class of astringent, polyphenolic biomolecules that bind to and precipitate proteins and various other organic compounds including amino acids and alkaloids. The term ''tannin'' (from Anglo-Norman ''tanner'', ...
, and is used by tanners for
tanning Tanning may refer to: *Tanning (leather), treating animal skins to produce leather *Sun tanning, using the sun to darken pale skin **Indoor tanning, the use of artificial light in place of the sun **Sunless tanning, application of a stain or dye t ...
leather Leather is a strong, flexible and durable material obtained from the tanning, or chemical treatment, of animal skins and hides to prevent decay. The most common leathers come from cattle, sheep, goats, equine animals, buffalo, pigs and hogs, ...
. Oak
gall Galls (from the Latin , 'oak-apple') or ''cecidia'' (from the Greek , anything gushing out) are a kind of swelling growth on the external tissues of plants, fungi, or animals. Plant galls are abnormal outgrowths of plant tissues, similar to be ...
s were used for centuries as a main ingredient in
iron gall ink Iron gall ink (also known as common ink, standard ink, oak gall ink or iron gall nut ink) is a purple-black or brown-black ink made from iron salts and tannic acids from vegetable sources. It was the standard ink formulation used in Europe for t ...
for manuscripts, harvested at a specific time of year. In Korea, oak bark is used to make
shingles Shingles, also known as zoster or herpes zoster, is a viral disease characterized by a painful skin rash with blisters in a localized area. Typically the rash occurs in a single, wide mark either on the left or right side of the body or face. ...
for traditional roof construction.


Culinary

Barrels A barrel or cask is a hollow cylindrical container with a bulging center, longer than it is wide. They are traditionally made of wooden staves and bound by wooden or metal hoops. The word vat is often used for large containers for liquids, u ...
for
aging Ageing ( BE) or aging ( AE) is the process of becoming older. The term refers mainly to humans, many other animals, and fungi, whereas for example, bacteria, perennial plants and some simple animals are potentially biologically immortal. In ...
wine Wine is an alcoholic drink typically made from fermented grapes. Yeast consumes the sugar in the grapes and converts it to ethanol and carbon dioxide, releasing heat in the process. Different varieties of grapes and strains of yeasts are m ...
s, sherry, and spirits such as
brandy Brandy is a liquor produced by distilling wine. Brandy generally contains 35–60% alcohol by volume (70–120 US proof) and is typically consumed as an after-dinner digestif. Some brandies are aged in wooden casks. Others are coloured with ...
, Irish whiskey,
Scotch whisky Scotch whisky (; sco, Scots whisky/whiskie, whusk(e)y; often simply called whisky or Scotch) is malt whisky or grain whisky (or a blend of the two), made in Scotland. All Scotch whisky was originally made from malted barley. Commercial distil ...
and
Bourbon whiskey Bourbon () is a type of barrel-aged American whiskey made primarily from corn. The name derives from the French Bourbon dynasty, although the precise source of inspiration is uncertain; contenders include Bourbon County in Kentucky and Bourbo ...
, are made from European and American oak, with
single barrel whiskey Single barrel whiskey (or single cask whiskey) is a premium class of whiskey in which each bottle comes from an individual aging barrel, instead of coming from blending together the contents of various barrels to provide uniformity of color and ta ...
fetching a premium. The use of oak in wine can add gustatory dimensions depending on the type of oak. Oak barrels, which may be charred before use, contribute to the colour, taste, and aroma of their potable contents, imparting a desirable oaky
vanillin Vanillin is an organic compound with the molecular formula . It is a phenolic aldehyde. Its functional groups include aldehyde, hydroxyl, and ether. It is the primary component of the extract of the vanilla bean. Synthetic vanillin is now used ...
flavour. A dilemma for wine producers is to choose between French and American oakwoods. French oaks (''Quercus robur'', ''Q. petraea'') give greater refinement, and are chosen for the best, most expensive wines; while American oak contributes greater texture and resistance to ageing, but produces a more powerful bouquet. Oak wood chips are also used for
smoking Smoking is a practice in which a substance is burned and the resulting smoke is typically breathed in to be tasted and absorbed into the bloodstream. Most commonly, the substance used is the dried leaves of the tobacco plant, which have bee ...
fish, meat,
cheese Cheese is a dairy product produced in wide ranges of flavors, textures, and forms by coagulation of the milk protein casein. It comprises proteins and fat from milk, usually the milk of cows, buffalo, goats, or sheep. During production, ...
s, and other foods. The bark of the cork oak is used to produce
wine Wine is an alcoholic drink typically made from fermented grapes. Yeast consumes the sugar in the grapes and converts it to ethanol and carbon dioxide, releasing heat in the process. Different varieties of grapes and strains of yeasts are m ...
stoppers (corks). This species grows around the
Mediterranean Sea The Mediterranean Sea is a sea connected to the Atlantic Ocean, surrounded by the Mediterranean Basin and almost completely enclosed by land: on the north by Western and Southern Europe and Anatolia, on the south by North Africa, and on the ea ...
, with
Portugal Portugal, officially the Portuguese Republic ( pt, República Portuguesa, links=yes ), is a country whose mainland is located on the Iberian Peninsula of Southwestern Europe, and whose territory also includes the Atlantic archipelagos of ...
,
Spain , image_flag = Bandera de España.svg , image_coat = Escudo de España (mazonado).svg , national_motto = ''Plus ultra'' (Latin)(English: "Further Beyond") , national_anthem = (English: "Royal March") , i ...
,
Algeria ) , image_map = Algeria (centered orthographic projection).svg , map_caption = , image_map2 = , capital = Algiers , coordinates = , largest_city = capital , relig ...
, and
Morocco Morocco (),, ) officially the Kingdom of Morocco, is the westernmost country in the Maghreb region of North Africa. It overlooks the Mediterranean Sea to the north and the Atlantic Ocean to the west, and has land borders with Algeria to ...
producing most of the world's supply. The
bark Bark may refer to: * Bark (botany), an outer layer of a woody plant such as a tree or stick * Bark (sound), a vocalization of some animals (which is commonly the dog) Places * Bark, Germany * Bark, Warmian-Masurian Voivodeship, Poland Arts, ...
of the white oak is dried and used in medical preparations.
Acorn The acorn, or oaknut, is the nut of the oaks and their close relatives (genera ''Quercus'' and '' Lithocarpus'', in the family Fagaceae). It usually contains one seed (occasionally two seeds), enclosed in a tough, leathery shell, and borne ...
s are used for making flour or roasted for acorn coffee.


Conservation

According to a comprehensive report by
The Morton Arboretum The Morton Arboretum, in Lisle, Illinois, United States, is a public garden, and outdoor museum with a library, herbarium, and program in tree research including the Center for Tree Science. Its grounds, covering 1,700 acres (6.9 square kilometres ...
and the International Union for Conservation of Nature (IUCN) an estimated 31% of the world's estimated 430 oak species are threatened with extinction, while the study found an estimated 41% of oak species to be of conservation concern. The countries with the highest numbers of threatened oak species according to the report are
China China, officially the People's Republic of China (PRC), is a country in East Asia. It is the world's most populous country, with a population exceeding 1.4 billion, slightly ahead of India. China spans the equivalent of five time zones and ...
with 36 species,
Mexico Mexico (Spanish: México), officially the United Mexican States, is a country in the southern portion of North America. It is bordered to the north by the United States; to the south and west by the Pacific Ocean; to the southeast by Guatema ...
with 32 species,
Vietnam Vietnam or Viet Nam ( vi, Việt Nam, ), officially the Socialist Republic of Vietnam,., group="n" is a country in Southeast Asia, at the eastern edge of mainland Southeast Asia, with an area of and population of 96 million, making i ...
with 20 species and the
USA The United States of America (U.S.A. or USA), commonly known as the United States (U.S. or US) or America, is a country Continental United States, primarily located in North America. It consists of 50 U.S. state, states, a Washington, D.C., ...
with 16 species. While the cause of decline is still partly unknown for some species, the main causes the scientists determined were
climate change In common usage, climate change describes global warming—the ongoing increase in global average temperature—and its effects on Earth's climate system. Climate change in a broader sense also includes previous long-term changes to E ...
and invasive pests in the US, and
deforestation Deforestation or forest clearance is the removal of a forest or stand of trees from land that is then converted to non-forest use. Deforestation can involve conversion of forest land to farms, ranches, or urban use. The most concentrated d ...
and
urbanization Urbanization (or urbanisation) refers to the population shift from rural to urban areas, the corresponding decrease in the proportion of people living in rural areas, and the ways in which societies adapt to this change. It is predominantly t ...
in Asia. In the Himalayan region of India, oak forests are being invaded by pine forests due to the increase in temperature. The associated species of pine forest may cross frontiers and become new elements of the oak forests. In eastern North America, rare species of oak trees include scarlet oak ('' Quercus coccinea''), chinquapin oak ('' Quercus muehlenbergii''), and post oak ('' Quercus stellata'').


Culture


Symbols


National

The oak is a common
symbol A symbol is a mark, sign, or word that indicates, signifies, or is understood as representing an idea, object, or relationship. Symbols allow people to go beyond what is known or seen by creating linkages between otherwise very different conc ...
of
strength Strength may refer to: Physical strength *Physical strength, as in people or animals *Hysterical strength, extreme strength occurring when people are in life-and-death situations *Superhuman strength, great physical strength far above human ca ...
and endurance and has been chosen as the national tree of many countries. In England, oaks have been a national symbol since at least the sixteenth century, often used by Shakespeare to convey heritage and power. In England today they remain a symbol of the nation's history, traditions, and the beauty of its countryside. Already an ancient Germanic symbol (in the form of the Donar Oak, for instance), certainly since the early nineteenth century, it stands for the nation of
Germany Germany,, officially the Federal Republic of Germany, is a country in Central Europe. It is the second most populous country in Europe after Russia, and the most populous member state of the European Union. Germany is situated betwe ...
and oak branches are thus displayed on some German coins, both of the former Deutsche Mark and the current
euro The euro ( symbol: €; code: EUR) is the official currency of 19 out of the member states of the European Union (EU). This group of states is known as the eurozone or, officially, the euro area, and includes about 340 million citizens . ...
currency. In 2004 the Arbor Day Foundation held a vote for the official National Tree of the
United States of America The United States of America (U.S.A. or USA), commonly known as the United States (U.S. or US) or America, is a country primarily located in North America. It consists of 50 states, a federal district, five major unincorporated territo ...
. In November 2004, the
United States Congress The United States Congress is the legislature of the federal government of the United States. It is bicameral, composed of a lower body, the House of Representatives, and an upper body, the Senate. It meets in the U.S. Capitol in Washing ...
passed legislation designating the oak as America's National Tree. Other countries have also designated the oak as their national tree including
Bulgaria Bulgaria (; bg, България, Bǎlgariya), officially the Republic of Bulgaria,, ) is a country in Southeast Europe. It is situated on the eastern flank of the Balkans, and is bordered by Romania to the north, Serbia and North Macedon ...
,
Croatia , image_flag = Flag of Croatia.svg , image_coat = Coat of arms of Croatia.svg , anthem = "Lijepa naša domovino"("Our Beautiful Homeland") , image_map = , map_caption = , capit ...
,
Cyprus Cyprus ; tr, Kıbrıs (), officially the Republic of Cyprus,, , lit: Republic of Cyprus is an island country located south of the Anatolian Peninsula in the eastern Mediterranean Sea. Its continental position is disputed; while it is geo ...
(
golden oak ''Quercus alnifolia'', commonly known as the golden oak, is an evergreen oak species of Cyprus. Its common English name refers to the golden coloured lower surface of its leaves. ''Quercus alnifolia'' belongs to the endemic flora of the island a ...
),
Estonia Estonia, formally the Republic of Estonia, is a country by the Baltic Sea in Northern Europe. It is bordered to the north by the Gulf of Finland across from Finland, to the west by the sea across from Sweden, to the south by Latvia, a ...
,
France France (), officially the French Republic ( ), is a country primarily located in Western Europe. It also comprises of Overseas France, overseas regions and territories in the Americas and the Atlantic Ocean, Atlantic, Pacific Ocean, Pac ...
,
Germany Germany,, officially the Federal Republic of Germany, is a country in Central Europe. It is the second most populous country in Europe after Russia, and the most populous member state of the European Union. Germany is situated betwe ...
,
Moldova Moldova ( , ; ), officially the Republic of Moldova ( ro, Republica Moldova), is a Landlocked country, landlocked country in Eastern Europe. It is bordered by Romania to the west and Ukraine to the north, east, and south. The List of states ...
,
Jordan Jordan ( ar, الأردن; tr. ' ), officially the Hashemite Kingdom of Jordan,; tr. ' is a country in Western Asia. It is situated at the crossroads of Asia, Africa, and Europe, within the Levant region, on the East Bank of the Jordan Rive ...
,
Latvia Latvia ( or ; lv, Latvija ; ltg, Latveja; liv, Leţmō), officially the Republic of Latvia ( lv, Latvijas Republika, links=no, ltg, Latvejas Republika, links=no, liv, Leţmō Vabāmō, links=no), is a country in the Baltic region of ...
,
Lithuania Lithuania (; lt, Lietuva ), officially the Republic of Lithuania ( lt, Lietuvos Respublika, links=no ), is a country in the Baltic region of Europe. It is one of three Baltic states and lies on the eastern shore of the Baltic Sea. Lithuania ...
,
Poland Poland, officially the Republic of Poland, is a country in Central Europe. It is divided into 16 administrative provinces called voivodeships, covering an area of . Poland has a population of over 38 million and is the fifth-most populous ...
, Romania, Serbia, and Wales.


Regional and state

The oak is the emblem of County Londonderry in Northern 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 language, Irish was known as ''Doire'' meaning "oak". The Irish County Kildare derives its name from the town of Kildare which originally in Irish language, Irish was ''Cill Dara'' meaning the Church of the Oak or Oak Church. In the United States, Iowa designated the oak as its official list of U.S. state trees, 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 the US state of Georgia (U.S. state), Georgia. The oak is a national symbol from the Basque Country (autonomous community), Basque Country, especially in the province of Biscay. In Colombia, the oak tree is an insignia of the Boyacá Department, Department of Boyacá. In 2008, the Flag of Boyacá Department was amended to include five oak leaves. The oak is a symbol of the East Bay (San Francisco Bay Area), East Bay of the San Francisco Bay Area; the coat-of-arms and flag of Oakland, California feature the oak and the logo of the East Bay Regional Park District is an oak leaf. The coats-of-arms of Vest-Agder, Norway, and Blekinge, Sweden, feature oak trees. The coat-of-arms of the municipality Eigersund, Norway features an oak leaf.


Military

Oak leaves are traditionally an important part of German Army regalia. The Nazi party used the traditional German eagle, standing atop of a swastika inside a wreath of oak leaves. It is also known as the Iron Eagle. During the Third Reich of Nazi Germany, oak leaves were used for military valor decoration on the Knights Cross of the Iron Cross. They also symbolize rank in the United States Armed Forces. A gold oak leaf indicates an O-4 (Major (United States), major or Lieutenant commander (United States), lieutenant commander), whereas a silver oak leaf indicates an O-5 (Lieutenant colonel (United States), lieutenant colonel or Commander (United States), commander). Arrangements of oak leaves, acorns and sprigs indicate different branches of the United States Navy List of United States Navy staff corps, staff corps officers. Oak leaves are embroidered onto the covers (hats) worn by field grade officers and flag officers in the United States armed services. If a member of the United States Army or Air Force earns multiple awards of the same medal, then instead of wearing a ribbon or medal for each award, he or she wears one metal representation of an "oak leaf cluster" attached to the appropriate ribbon for each subsequent award.


Political

The oak tree is used as a symbol by a number of political parties. It is the symbol of Toryism (on account of the Royal Oak) and the Conservative Party (UK), Conservative Party in the United Kingdom, and formerly of the Progressive Democrats in Republic of Ireland, Ireland and the Democrats of the Left in Italy. In the cultural arena, the oakleaf is the symbol of the National Trust for Places of Historic Interest or Natural Beauty, National Trust (UK), The Woodland Trust, and The Royal Oak Foundation.


Religion

The prehistoric Proto-Indo-Europeans, Indo-European tribes worshiped the oak and connected it with a thunder or lightning god, and this tradition descended to many classical cultures. In Greek mythology, the oak is the tree sacred to Zeus, king of the gods. In Zeus's oracle in Dodona, Epirus, the sacred oak was the centerpiece of the precinct, and the priests would divine the pronouncements of the god by interpreting the rustling of the oak's leaves. Mortals who destroyed such trees were said to be punished by the gods since the ancient Greeks believed beings called hamadryads inhabit them. In Celtic polytheism, the name of the oak tree was part of the Proto-Celtic word for 'druid': ''*derwo-weyd-'' > ''*-''; however, Proto-Celtic ''*derwo-'' (and ''*dru-'') can also be adjectives for 'strong' and 'firm', so Ranko Matasovic interprets that ''*-'' may mean 'strong knowledge'. As in other Indo-European faiths, Taranis, being a thunder god, was associated with the oak tree. "Tree" and ''drus'' may also be cognate with "Druid," the Celtic priest to whom the oak was sacred. There has even been a study that shows that oaks are more likely to be struck by lightning than any other tree of the same height. In Norse mythology, the oak was sacred to the thunder god, Thor. Thor's Oak was a sacred tree of the Germanic Chatti tribe. In Baltic mythology, Baltic and Slavic mythology, the oak was the sacred tree of Latvian mythology, Latvian god Pērkons, Lithuanian mythology, Lithuanian Perkūnas, Prussian mythology, Prussian Perkūns and Slavic Perun, the god of thunder and one of the most important deities. The oak also appears in the Hebrew tradition. In the Bible, the oak tree at Shechem is the site where Jacob buries the foreign gods of his people (Gen. 35:4). Also, Joshua erects a stone under an oak tree as the first covenant of Yahweh, the god of Israel (Josh. 24.25–7). In Isaiah 61, the prophet refers to the Israelites as "Oaks of Righteousness". Absalom's long hair (2 Samuel 18:9) gets caught in an oak tree, and allows Joab to kill him. Veneration of the oak survives in Serbian Orthodox Church tradition. Christmas celebrations include the Badnjak (Serbian), ''badnjak'', a branch taken from a young and straight oak ceremonially felled early on Christmas Eve morning, similar to a yule log. In recent times, only the branches are collected, brought home, and ceremoniously thrown into a stove or church bonfire. In another tradition, a Zapis, z''apis'' (lit. "inscription") is an old, isolated oak on a hilltop or promontory, often inscribed with a cross by a parish priest. Reverence for ' probably originated in pre-Christian times, and they long remained places of public gathering and even of Christian worship where churches were not available. For example, in 1815, at a ''zapis'' assembly in Takovo, ''knez'' Miloš Obrenović declared the start of the Second Serbian Uprising. Even in modern times, cutting down ''zapis'' oaks can result in public outcry, even for projects like road building.


History

Several oak trees, such as the Royal Oak (tree), Royal Oak in Britain, the Charter Oak in the United States, and the Guernica oak in the Basque Country (greater region), Basque Country are of great historical or cultural importance. "The Proscribed Royalist, 1651", a famous painting by John Everett Millais, depicted a Royalist fleeing from Oliver Cromwell, 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. Approximately 50 km west of Toronto, Canada is the town of Oakville, Ontario, famous for its history as a shipbuilding port on Lake Ontario. The city of Raleigh, N.C., is known as the "City of Oaks". The Jurupa Oak tree – a clonal colony of ''Quercus palmeri'' or Palmer's oak found in Riverside County, California – is an estimated 13,000 years old. Large groups of very old oak trees are rare. One venerable group found in Poland, is about 480 years old, as assessed by dendrochronology. In the Roman Republic, a crown of oak leaves was given to those who had saved the life of a citizen in battle; it was called the "Civic Crown, civic oak crown".


Famous specimens

: :Individual oak trees, ''Individual oak trees'' * The Emancipation Oak is designated one of the 10 Great Trees of the World by the National Geographic Society and is part of the National Historic Landmark district of Hampton University in Virginia. * The Ivenack Oak which is one of the largest trees in Europe is located in Mecklenburg-Vorpommern, Germany, and is approximately 800 years old. * The Bowthorpe Oak, located in Bourne, Lincolnshire, is thought to be 1,000 years old. It was featured in the Guinness Book of World Records and was filmed for a TV documentary for its astonishing longevity. * The Minchenden Oak Garden#Minchenden Oak, Minchenden (or Chandos) Oak, in Southgate, London, is said to be the largest oak tree in England (already in girth in the nineteenth century), and is perhaps 800 years old. * The Seven Sisters Oak is the largest certified southern live oak tree. Located in Mandeville, Louisiana, it is estimated to be up to 1,500 years old with a trunk that measures . * The Major Oak is an 800- to 1000-year-old tree located in Sherwood Forest, Nottinghamshire. According to folklore, it was used by Robin Hood for shelter. * Friendship Oak (Long Beach, Mississippi), Friendship Oak is a 500-year-old southern live oak located in Long Beach, Mississippi. * The Crouch Oak is believed to have originated in the 11th Century and is located in Addlestone, Addlestone, Surrey. It is an important symbol of the town with many local businesses adopting its name. It used to mark the boundary of Windsor Great Park. Legend says that Queen Elizabeth I stopped by it and had a picnic. * The Angel Oak is a southern live oak located in Angel Oak Park on John's Island near Charleston, South Carolina. The Angel Oak is estimated to be in excess of 400–500 years old, stands tall, and measures in circumference. * The Kaiser's Oak, located at the village of Gommecourt, Pas-de-Calais, Gommecourt in Artois, France, named in honour of Kaiser Wilhelm II, symbolically marked from late 1914 to April 1917 the furthest point in the West of the German Imperial Army during World War I. * The Wye Oak in Maryland was the United States' largest white oak tree before it blew down in a storm in 2002, at an estimated age of 460 years. * The Bland Oak in Sydney, Australia, planted in the 1840s, was the largest tree in Australia until it was split in a storm early on New Year Day 1941. * The Treaty Oak (Austin, Texas), Treaty Oak in Austin, Texas, is a Texas live oak, and the last surviving member of the Council Oaks, a grove of 14 trees that served as a sacred meeting place for Comanche and Tonkawa tribes prior to European settlement of the area. * The Holwood House#Wilberforce Oak, Wilberforce Oak was a pollard pedunculate oak in Keston, Kent, under which William Wilberforce resolved to propose the Abolitionism in the United Kingdom, abolition of the slave trade to the House of Commons of the United Kingdom, House of Commons in 1787. The original was a hollow shell by 1969; its young replacement then blew down in the Great Storm of 1987, and the third generation oak now stands in its place. File:Tamme-Lauri Tamm suvel.jpg, Tamme-Lauri oak is the thickest and oldest tree in Estonia. File:Gustave Courbet - Le Gros Chêne (1843).jpg, ''The Big Oak'', by Gustave Courbet (1843). File:Dąb Blaszak (Blaszany) w Henrykowie Gm. Szprotawa.jpg, ''Tin Oak'' in Henryków, Lubusz Voivodeship, Henryków
Poland Poland, officially the Republic of Poland, is a country in Central Europe. It is divided into 16 administrative provinces called voivodeships, covering an area of . Poland has a population of over 38 million and is the fifth-most populous ...
; the name refers to the steel fittings that fasten the damage to the tree.


References


Bibliography

* Byfield, Liz (1990) ''An Oak Tree'', Collins book bus, London: Collins Educational, * Philips, Roger. ''Trees of North America and Europe'', Random House, New York , 1979. * Logan, William B. (2005) ''Oak: The Frame of Civilization'', New York; London: W. W. Norton, * Paterson, R.T . (1993) ''Use of Trees by Livestock'', 5: ''Quercus'', Chatham: Natural Resources Institute, * Royston, Angela (2000) ''Life Cycle of an Oak Tree'', Heinemann first library, Oxford : Heinemann Library, * Savage, Stephen (1994) ''Oak Tree'', Observing nature series, Hove: Wayland, * Tansley, Arthur G., Sir (1952) ''Oaks and Oak Woods'', Field study books, London: Methuen. * Marek Żukow-Karczewski, Żukow-Karczewski, Marek (1988) "Dąb – król polskich drzew" ("Oak – the king of the Polish trees"), ''AURA: A Monthly for the Protection and Shaping of Human Environment'', 9, 20–21.


External links


''Flora of China'' – ''Cyclobalanopsis''

Oak diseases

Flora Europaea: ''Quercus''

Oaks from Bialowieza Forest

Common Oaks of Florida

Oaks of the world

The Global Trees Campaign
The Red List of Oaks and Global Survey of Threatened Quercus
Latvia – the land of oaks
* {{authority control Quercus, Quercus taxa by common names, 01 Wood