From en.wikipedia.org:
[Tree or shrub in the genus Quercus] [Oak tree] [good article] [date=July
2020] {{Automatic_taxobox | name = Oak | fossil_range = Paleocene - Eocene
boundary – recent [56] possible Paleocene & Late Cretaceous records | image =
Quercus robur.jpg | image_caption = Foliage and acorns of _Quercus robur_ |
taxon = Quercus | authority = L. | subdivision_ranks = Subgenera and sections
| subdivision =
- _Quercus_ subg. _Cerris_
- _Quercus_ sect. _Cerris_
- _Quercus_ sect. _Cyclobalanopsis_
- _Quercus_ sect. _Ilex_
- _Quercus_ subg. _Quercus_
- _Quercus_ sect. _Lobatae_
- _Quercus_ sect. _Ponticae_
- _Quercus_ sect. _Protobalanus_
- _Quercus_ sect. _Quercus_
- _Quercus_ sect. _Virentes_
See also List of _Quercus_ species. }}
An OAK is a hardwood tree or shrub in the genus _QUERCUS_ of the beech family.
They have spirally arranged leaves, often with lobed edges, and a nut called
an acorn, borne within a cup. The genus is widely distributed in the Northern
Hemisphere; it includes some 500 species, both deciduous and evergreen.
Fossil oaks date back to the Middle Eocene. Molecular phylogeny shows that
the genus is divided into Old World and New World clades, but many oak species
hybridise freely, making the genus's history difficult to resolve.<!--Note:
lead summaries cited text in body of article: citations are not repeated up
here.-->
Ecologically, oaks are keystone species in habitats from Mediterranean
semi-desert to subtropical rainforest. They live in association with many
kinds of fungi including truffles. Oaks support more than 950 species of
caterpillar, many kinds of gall wasp which form distinctive galls (roundish
woody lumps such as the oak apple), and a large number of pests and diseases.
Oak leaves and acorns contain enough tannin to be toxic to cattle, but pigs
are able to digest them safely. Oak timber is strong and hard, and has found
many uses in construction and furniture-making. The bark was traditionally
used for tanning leather. Wine barrels are made of oak; these are used for
aging alcoholic beverages such as sherry and whisky, giving them a range of
flavours, colours, and aromas. The spongy bark of the cork oak is used to
make traditional wine bottle corks. Almost a third of oak species are
threatened with extinction due to climate change, invasive pests, and habitat
loss.<!--per MoS, lead summarizes cited claims in body of article but does not
repeat the citations-->
In culture, the oak tree is a symbol of strength and serves as the national
tree of many countries. In Indo-European and related religions, the oak is
associated with thunder gods. Individual oak trees of cultural significance
include the Royal Oak in Britain, the Charter Oak in the United States, and
the Guernica Oak in the Basque Country.<!--per MoS, lead summarizes cited
claims in body of article but does not repeat the citations-->
** Etymology
The generic name _Quercus_ is Latin for "oak", derived from
Proto-Indo-European _*kwerkwu-_, "oak", which is also the origin of the name
"fir", another important or sacred tree in Indo-European culture. The word
"cork", for the bark of the cork oak, similarly derives from _Quercus_.[1] The
common name "oak" is from Old English _ac_ (seen in placenames such as Acton,
from _ac_ + _tun_, "oak village"),[2] which in turn is from Proto-Germanic
_*aiks_, "oak".[3]
** Description
Oaks are hardwood (dicotyledonous) trees, deciduous or evergreen, with
spirally arranged leaves, often with lobate margins; some have serrated leaves
or entire leaves with smooth margins. Many deciduous species are marcescent,
not dropping dead leaves until spring. In spring, a single oak tree produces
both male and female flowers. The staminate (male) flowers are arranged in
catkins, while the small pistillate (female) flowers[4] produce an acorn (a
kind of nut) contained in a cupule. Each acorn usually contains one seed and
takes 6–18 months to mature, depending on the species. The acorns and leaves
contain tannic acid,[5] which helps to guard against fungi and insects.[6]
There are some 500 extant species of oaks.<ref name=powo>[title= _Quercus_ L.
]
Trees in the genus are often large and slow-growing; _Q. alba_ can reach an
age of 600 years, a diameter of [13] and a height of [145].[7] The Granit oak
in Bulgaria, a _Q. robur_ specimen, has an estimated age of 1,637 years,
making it the oldest oak in Europe.[8] The Wi'aaSal tree, a live oak in the
reservation of the Pechanga Band of Indians, California, is at least 1,000
years old, and might be as much as 2,000 years old, which would make it the
oldest oak in the US.[9] Among the smallest oaks is _Q. acuta_, the Japanese
evergreen oak. It forms a bush or small tree to a height of some [30].[10]
<gallery mode="packed" heights="220px"> File:Brockwell Oak (9).jpg|_Quercus
robur_ habit File:Quercus lusitanica - Köhler–s
Medizinal-Pflanzen-253.jpg|Illustration of _Q. lusitanica_ showing staminate
(left) and pistillate flowers (right) File:2021-04-22 18 54 32 Male flowers
(catkins) on a White Oak within a wooded area in the Franklin Farm section of
Oak Hill, Fairfax County, Virginia.jpg|Catkins of _Q. alba_ containing the
staminate or 'male' flowers File:Летен дъб - цъфтеж, нови листа.JPG|New leaves
and reddish pistillate or 'female' flowers of _Q. robur_ </gallery>
** Evolution
*** Fossil history
Potential records of _Quercus_ have been reported from Late Cretaceous
deposits in North America and East Asia. These are not considered definitive,
as macrofossils older than the Paleogene, and possibly from before the Eocene
are mostly poorly preserved without critical features for certain
identification. Amongst the oldest unequivocal records of _Quercus_ are
pollen from Austria, dating to the Paleocene-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 from the Middle Eocene of Japan; both forms have
affinities to the _Cyclobalanopsis_ group.[11]
<gallery class=center mode=nolines widths=200px heights=200px> File:Quercus
hispanica 20170317.jpg|_Quercus × hispanica_ leaf. Miocene, Lleida, Spain
File:Quercus hiholensis acorn UWBM 56470-3 Pigg & Wehr 2002 Plt2
fig16.png|_Quercus hiholensis_ acorn, Langhian age (Middle Miocene),
Washington State, US (c. 15 mya) File:Quercus kobatakei leaf
(cropped).jpg|_Quercus kobatakei_ leaf. Early Oligocene, Japan File:Early
Oligocene oak acorn from Bridge Creek Flora.jpg|Early Oligocene acorn, Oregon,
US (33 mya) </gallery>
*** External phylogeny
_Quercus_ forms part, or rather two parts, of the Quercoideae subfamily of the
Fagaceae, the beech family. Modern molecular phylogenetics suggests the
following relationships:[12][13]
{{clade |label1=Fagaceae |1={{clade
|label1=Fagoideae
|1=_Fagus_ (beeches)
|label2=Quercoideae
|2={{clade
|1=_Trigonobalanus_ (3 evergreen species)
|2={{clade
|1={{clade
|1=_Lithocarpus_ (stone oaks)
|2=_Chrysolepis_ (chinquapins)
}}
|2={{clade
|1=_QUERCUS pro parte_
|2={{clade
|1=_Notholithocarpus_ (tan oak)
|2={{clade
|1=_QUERCUS pro parte_
|2={{clade
|1=_Castanopsis_ (also called chinquapins)
|2=_Castanea_ (chestnuts)
}}
}}
}}
}}
}}
}}
}}
}}
*** Internal phylogeny
Molecular techniques for phylogenetic analysis show that the genus _Quercus_
consisted of Old World and New World clades.<ref name=":0"/>[14][15] The
entire genome of _Quercus robur_ (the pedunculate oak) has been sequenced,[16]
revealing an array of mutations that may underlie the evolution of longevity
and disease resistance in oaks.[17] In addition, hundreds of oak species have
been compared (at RAD-seq loci), allowing a detailed phylogeny to be
constructed. However, the high signal of introgressive hybridization (the
transfer of genetic material by repeated backcrossing with hybrid offspring)
in the genus has made it difficult to resolve an unambiguous, unitary history
of oaks. The phylogeny from Hipp et al. 2019 is:[18]
{{clade |style=font-size:95%; line-height:105%; |label1=_QUERCUS_ |sublabel1=
56 mya |1={{clade
|label1=subgenus _Cerris_
|sublabel1=Old World
|1={{clade
|1={{clade
|label1=section _Cyclobalanopsis_
|sublabel1= 44 mya
|1={{clade
|1={{clade
|1=CTB<!--Compound Trichome Base--> lineage <!--e.g. Quercus chungii--> 60px
|2=Cyclobalanoides <!--Q. corrugata-->
}}
|2={{clade
|1=Glauca 80px
|2={{clade
|1=Acuta 70px
|2=Semiserrata <!--e.g. Quercus macrocalyx-->
}}
}}
}}
}}
|2={{clade
|label1=section _Cerris_
|1={{clade
|1=East Asian Cerris 70px
|2=West Eurasian Cerris 80px
}}
|label2=section _Ilex_
|2={{clade
|1={{clade
|1=Early-diverging Ilex 60px
|2=East Asian Ilex 50px
}}
|2={{clade
|1=Himalaya-Mediterranean 50px
|2=Himalayan subalpine 60px
}}
}}
}}
}}
|label2=subgenus _Quercus_
|sublabel2=New World
|2={{clade
|1={{clade
|label1=section _Lobatae_
|1={{clade
|1=Agrifoliae 40px
|2={{clade
|1=Palustres 60px
|2={{clade
|1={{clade
|1=Coccineae (Rubrae) 35px
|2=Phellos (Laurifoliae) 60px
}}
|2={{clade
|1=Texas red oaks 50px
|2=Erythromexicana 40px
}}
}}
}}
}}
}}
|2={{clade
|1={{clade
|label1=section _Protobalanus_
|1=50px
|label2=section _Ponticae_
|2=55px
|sublabel2=New World, W. Asia
}}
|2={{clade
|label1=section _Virentes_
|1=55px
|label2=section _Quercus_
|sublabel2=New World, Europe
|2={{clade
|1={{clade
|1=Dumosae 33px
|2={{clade
|1={{clade
|1=Prinoids 40px
|2={{clade
|1=Albae 38px
|2=Roburoids 40px
}}
}}
|2={{clade
|1=Stellatae 40px
|2={{clade
|1=Texas white oaks 40px
|2=Leucomexicana 55px
}}
}}
}}
}}
}}
}}
}}
}}
}}
}}
*** Taxonomy
[List of Quercus species]
**** Taxonomic history
The genus _Quercus_ was circumscribed by Carl Linnaeus in the first edition of
his 1753 _Species Plantarum_.[19] He described 15 species within the new
genus, providing type specimens for 10 of these, and giving names but no types
for _Q. cerris_, _Q. coccifera_, _Q. ilex_, _Q. smilax_, and _Q.
suber_.[20] He chose _Q. robur_, the pedunculate oak, as the type species for
the genus.[21]
A 2017 classification of _Quercus_, based on multiple molecular phylogenetic
studies, divided the genus into two subgenera and eight sections:<ref
name=DenkGrimManoDeng17>[last1=Denk ]
- Subgenus _Quercus_ – the New World clade (or high-latitude clade), mostly native to North America
- Section _Lobatae_ <small> Loudon </small> – North American red oaks
- Section _Protobalanus_ <small> (Trelease) O.Schwarz </small> – North American intermediate oaks
- Section _Ponticae_ <small> Stef. </small> – with a disjunct distribution between western Eurasia and western North America
- Section _Virentes_ <small> Loudon </small> – American southern live oaks
- Section _Quercus_ – white oaks from North America and Eurasia
- Subgenus _Cerris_ <small> Oerst. </small> – the Old World clade (or mid-latitude clade), exclusively native to Eurasia
- Section _Cyclobalanopsis_ <small> Oerst. </small> – cycle-cup oaks of East Asia
- Section _Cerris_ <small> Dumort. </small> – cerris oaks of subtropical and temperate Eurasia and North Africa
- Section _Ilex_ <small> Loudon </small> – ilex oaks of tropical and subtropical Eurasia and North Africa
<!--note --- these sections are clearly marked on the cladogram below-->
The subgenus division supports the evolutionary diversification of oaks among
two distinct clades: the Old World clade (subgenus _Cerris_), including oaks
that diversified in Eurasia; and the New World clade (subgenus _Quercus_),
oaks that diversified mainly in the Americas.[22][23]
**** Subgenus _Quercus_
[Quercus subg. Quercus]
- Sect. _Lobatae_ ( synonym _Erythrobalanus_ ), the red oaks of North America, Central America and northern South America . Style s 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. <ref name=DenkGrimManoDeng17/>
- Sect. _Protobalanus_ , the canyon live oak and its relatives , in the southwestern United States and northwest Mexico . 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. <ref name=DenkGrimManoDeng17/>
- Sect. _Ponticae,_ a disjunct including just two species. Styles are short, and the acorns mature in 12 months. The leaves have large stipule s, high secondary veins, and are highly toothed. <ref name=DenkGrimManoDeng17/>
- 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. <ref name=DenkGrimManoDeng17/>
- Sect. _Quercus_ (synonyms _Lepidobalanus_ and _Leucobalanus_ ), the white oaks of Europe , Asia 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 is _Quercus robur_ . <ref name=DenkGrimManoDeng17/> [24]
**** Subgenus _Cerris_
[Quercus subg. Cerris]
The type species is _Quercus cerris_.
- Sect. _Cyclobalanopsis_ , the ring-cupped oaks of eastern and southeastern Asia. These are evergreen trees growing [10] 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 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 ). <ref name=DenkGrimManoDeng17/>
- 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. <ref name=DenkGrimManoDeng17/>
- Sect. _Ilex_ , the Ilex oak and its relatives of Eurasia and northern Africa . 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. <ref name=DenkGrimManoDeng17/>
** Distribution
[[File:Quercus Global Distribution.svg|thumb|upright=2| Global distribution of
_Quercus_. The New and Old World parts are mostly separate clades.[The New
World sections are _Protobalanus_ , _Lobatae_ , _Ponticae_ , _Quercus_ , and
_Virentes_ . Old World sections are _Cerris_ , _Ilex_ and _Cyclobalanopsis_
..] Red: North American.[The North American sections are _Protobalanus_ ,
_Lobatae_ , _Ponticae_ , _Quercus_ , and _Virentes_ .] Pink: Central
American.[The Central American sections are _Virentes_ , _Quercus_ and
_Lobatae_] Yellow: European.[The European sections are _Quercus_ , _Cerris_
and _Ilex_ .] Green: West/Central Asian.[The West/Central Asian sections are
_Ponticae_ , _Quercus_ , _Cerris_ and _Ilex_ .] Turquoise: Southeast
Asian.[The Southeast Asian sections are _Quercus_ , _Cyclobalanopsis_ ,
_Cerris_ and _Ilex_ .] Blue: East Asian.[The East Asian sections are _Quercus_
, _Cerris_ , _Ilex_ and _Cyclobalanopsis_ .][25] See Phylogeny chapter/tree
for sections.[reason=Where would one find this?]]]
The genus _Quercus_ is native to the Northern Hemisphere and includes
deciduous and evergreen species extending from cool temperate to tropical
latitudes in the Americas, 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.[26]
In the Americas, _Quercus_ is widespread from Vancouver and Nova Scotia in the
south of Canada, south to Mexico and across the whole of the eastern United
States. It is present in a small area of the west of Cuba; in Mesoamerica it
occurs mainly above [1,000].[27] The genus crossed the isthmus of Panama when
the northern and southern continents came together[28] and is present as one
species, _Q. humboldtii_, above 1,000 metres in Colombia.<ref name="Nixon
2006" /> The oaks of North America are of many sections (_Protobalanus_,
_Lobatae_, _Ponticae_, _Quercus_, and _Virentes_) along with related genera
such as _Notholithocarpus_.<ref name="Liu Yang Tian Yang 2023" />
In the Old World, oaks of section _Quercus_ extend across the whole of Europe
including European Russia apart from the far north, and north Africa (north of
the Sahara) from Morocco to Libya. In Mediterranean Europe, they are joined
by oaks of the sections _Cerris_ and _Ilex_, which extend across Turkey, the
Middle East, Iran, Afghanistan and Pakistan_,_ while section _Ponticae_ is
endemic to the western Caucasus in Turkey and Georgia. Oaks of section
_Cyclobalanopsis_ extend in a narrow belt along the Himalayas to cover
mainland and island Southeast Asia as far as Sumatra, Java, Borneo, and
Palawan.<ref name="powo" />[29] Finally, oaks of multiple sections
(_Cyclobalanopsis_, _Ilex_, _Cerris_, _Quercus_ and related genera like
_Lithocarpus_ and _Castanopsis_) extend across east Asia including China,
Korea, and Japan.<ref name="Liu Yang Tian Yang 2023" />
** Ecology
Oaks are keystone species in a wide range of habitats from Mediterranean
semi-desert to subtropical rainforest. They are important components of
hardwood forests; some species grow in associations with members of the
Ericaceae in oak–heath forests.[30][31] Several kinds of truffles, including
two well-known varieties – black Périgord truffle[32] and the white Piedmont
truffle<ref
name=r13>[url=http://www.thenibble.com/reviews/main/vegetables/truffle-glossary8.asp#glossary
] – have symbiotic relationships with oak trees. Similarly, many other fungi,
such as _Ramaria flavosaponaria_, associate with oaks.[33][34]
Oaks support more than 950 species of caterpillars, an important food source
for many birds.[35] Mature oak trees shed widely varying numbers of acorns
(known collectively as mast) annually, with large quantities in mast years.
This may be a predator satiation strategy, increasing the chance that some
acorns will survive to germination.[36]
Animals including squirrels[37] and jays – Eurasian jays in the Old World,
blue jays in North America – feed on acorns, and are important agents of seed
dispersal as they carry the acorns away and bury many of them as food
stores.[38][39][40] However, some species of squirrel selectively excise the
embryos from the acorns that they store, meaning that the food store lasts
longer and that the acorns will never germinate.<ref name="Steele Yi 2020"/>
*** Hybridisation
Interspecific hybridization is quite common among oaks, but usually between
species within the same section only,[41] and most common in the white oak
group. White oaks cannot discriminate against pollination by other species in
the same section. Because they are wind pollinated and 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.[42][43]
Frequent hybridization among oaks has consequences for oak populations around
the world; most notably, hybridization has produced large populations of
hybrids with much introgression and the evolution of new species.<ref
name=r2>[last1=Conte ] Introgression has caused different species in the same
populations to share up to 50% of their genetic information.<ref
name=r3>[last1=Gomory ] As a result, genetic data often does not differentiate
between clearly morphologically distinct species, but instead differentiates
populations.<ref name=r4>[last1=Kelleher ] The maintenance of particular loci
for adaptation to ecological niches may explain the retention of species
identity despite significant gene flow.[44]
The Fagaceae, or beech family, to which the oaks belong, is a slowly-evolving
clade compared to other angiosperms,[45][46] and the patterns of hybridization
and introgression in _Quercus_ pose a significant challenge to the concept of
a species as a group of "actually or potentially interbreeding populations
which are reproductively isolated from other such groups."<ref name="Raven
2005"/> By this definition, many species of _Quercus_ would be lumped together
according to their geographic and ecological habitat, despite clear
distinctions in morphology and genetic data.[47]
*** Diseases and pests
Oaks are affected by a large number of pests and diseases. For instance, _Q.
robur_ and _Q. petraea_ in Britain host 423 insect species.[48] This
diversity includes 106 macro-moths, 83 micro-moths, 67 beetles, 53 cynipoidean
wasps, 38 heteropteran bugs, 21 auchenorrhynchan bugs, 17 sawflies, and 15
aphids.<ref name="Kennedy Southwood 1984"/> The insect numbers are seasonal:
in spring, chewing insects such as caterpillars become numerous, followed by
insects with sucking mouthparts such as aphids, then by leaf miners, and
finally by gall wasps such as _Neuroterus_.[49] Several powdery mildews affect
oak species. In Europe, the species _Erysiphe alphitoides_ is the most
common.[50] It reduces the ability of leaves to photosynthesize, and infected
leaves are shed early.[51] Another significant threat, the oak processionary
moth (_Thaumetopoea processionea_), has emerged 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.<ref name=forestry>[author=unspecified ] A
little-understood disease of mature oaks, acute oak decline, has affected the
UK since 2009.[52] In California, goldspotted oak borer (_Agrilus
auroguttatus_) has destroyed many oak trees,[53] while sudden oak death,
caused by the oomycete pathogen _Phytophthora ramorum_, has devastated oaks in
California and Oregon, and is present in Europe.[54] Japanese oak wilt, caused
by the fungus _Raffaelea quercivora_, has rapidly killed trees across
Japan.[55]
*** Gall communities
[Gall]
Many galls are found on oak leaves, buds, flowers, and roots. Examples are
oak artichoke gall, oak marble gall, oak apple gall, knopper gall, and spangle
gall. These galls are the handiwork of tiny wasps from the Cynipidae. In a
complex ecological relationship, these gall wasps become hosts to parasitoid
wasps—primarily from the order Chalcidoidea—which lay their larvae inside the
gall wasps, ultimately leading to the hosts' demise. Additionally, inquilines
live commensally within the galls without harming the gall wasps.[56]
<gallery mode=packed> File:Gallrazorback.jpg|Oak apple gall on _Quercus
garryana_ File:Oak apples on oak leaf and in cross section.JPG|Oak apples on
oak leaf File:Biorhiza pallida male.jpg|_Biorhiza pallida_ male, the cause of
oak apple galls </gallery>
** Conservation
An estimated 31% of the world's oak species are threatened with extinction,
while 41% of oak species are considered to be of conservation concern. The
countries with the highest numbers of threatened oak species (as of 2020) are
China with 36 species, Mexico with 32 species, Vietnam with 20 species, and
the US with 16 species. Leading causes are climate change and invasive pests
in the US, and deforestation and urbanization in Asia.[57][58][59] In the
Himalayan region of India, oak forests are being invaded by pine trees due to
global warming. The associated pine forest species may cross frontiers and
integrate into the oak forests.[60] 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.[61] In the US, entire oak ecosystems have declined due to a
combination of factors thought to include fire suppression, increased
consumption of acorns by growing mammal populations, herbivory of seedlings,
and introduced pests.[62] However, disturbance-tolerant oaks may have
benefited from grazers like bison, and suffered when the bison were removed
following European colonization.[63][64]
** Toxicity
The leaves and acorns of oaks are poisonous to livestock, including cattle and
horses, if eaten in large amounts, due to the toxin tannic acid, which causes
kidney damage and gastroenteritis.[65][66] An exception is the domestic pig,
which, under the right conditions, may be fed entirely on acorns,[67] and has
traditionally been pastured in oak woodlands (such as the Spanish _dehesa_[68]
and the English system of pannage).[69] Humans can eat acorns after leaching
out the tannins in water.[70]
** Uses
*** Timber
Oak timber is a strong and hard wood with many uses, such as for furniture,
floors, building frames, and veneers.[71] The wood of _Quercus cerris_ (the
Turkey oak) has better mechanical properties than those of the white oaks _Q.
petraea_ and _Q. robur_; the heartwood and sapwood have similar mechanical
properties.[72] Of the North American red oaks, the northern red oak, _Quercus
rubra_, is highly prized for lumber.[73][74] The wood is resistant to insect
and fungal attack.[75]
Wood from _Q. robur_ and _Q. petraea_ was used in Europe for shipbuilding,
especially of naval men of war, until the 19th century.[76] In hill states of
India such as Uttarakhand, along with being used for fuelwood and timber, oak
wood is used for agricultural implements, while the leaves serve as fodder for
livestock during lean periods.[77][78]
*** Other traditional products
Oak bark, with its high tannin content, was traditionally used in the Old
World for tanning leather.[79] Oak galls were used for centuries as a main
ingredient in iron gall ink for manuscripts, harvested at a specific time of
year.[80] In Korea, sawtooth oak bark is used to make shingles for traditional
roof construction.[81] The dried bark of the white oak was used in traditional
medical preparations; its tannic acid content made it astringent and
antiseptic.[82] Acorns have been ground to make a flour,[83] and roasted for
acorn coffee.[84]
*** Culinary
Barrels for aging wines, sherry, and spirits such as brandy and Scotch whisky
are made from oak, with single barrel malt whiskies fetching a premium.[85]
The use of oak in wine adds a range of flavours. Oak barrels, which may be
charred before use, contribute to their contents' colour, taste, and aroma,
imparting a desirable oaky vanillin 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. American oak contributes greater texture and resistance to
ageing, but produces a more powerful bouquet.[86][87]
Oak wood chips are used for smoking foods such as fish, meat, and
cheese.[88][89] In Japan, Children's Day is celebrated with [ja] rice cakes,
filled with a sweet red bean paste, and wrapped in a [ja] oak leaf.[90] The
bark of the cork oak is used to produce cork stoppers for wine bottles. This
species grows around the Mediterranean Sea; Portugal, Spain, Algeria, and
Morocco produce most of the world's supply.[91]
Acorns of various oak species have been used as food for millennia, in Asia,
Europe, the Middle East, North Africa, and among the native peoples of North
America. In North Africa, acorns have been pressed to make acorn oil: the oil
content can be as high as 30%. Oaks have also been used as fodder, both
leaves and acorns being fed to livestock such as pigs. Given their high
tannin content, acorns have often been leached to remove tannins before use as
fodder.[92]
<gallery class=center mode=nolines widths=200px heights=200px> File:Sherry
cellar, Solera system, 2003.jpg|Sherry maturing in oak barrels File:Cork oak
trunk section.jpg|A cross section of the trunk of a cork oak, _Quercus suber_,
showing the thick spongy bark used for making wine bottle corks
File:Kashiwa-mochi.jpg|Kashiwa-mochi rice cake wrapped in oak leaf, Japan
</gallery>
** Culture
*** Symbols
[[File:Coat of arms of Estonia.svg|thumb|upright|The oak features in many
coats of arms, such as that of Estonia.[93] ]]
The oak is a widely used symbol of strength and endurance.[94] It is the
national tree of many countries,<ref name="Venables 2012"/> including the
US,[95] Bulgaria, Croatia, Cyprus (golden oak), Estonia, France, Germany,
Moldova, Jordan, Latvia, Lithuania, Poland, Romania, Serbia, and Wales.[96]
Ireland's fifth-largest city, Derry, is named for the tree, from [Doire].[97]
Oak branches are displayed on some German coins, both of the former Deutsche
Mark and the euro.[98] Oak leaves symbolize rank in armed forces including
those of the United States. Arrangements of oak leaves, acorns, and sprigs
indicate different branches of the United States Navy staff corps
officers.[99][100] The oak tree is used as a symbol by several political
parties and organisations. It is the symbol of the Conservative Party in the
United Kingdom,[101] and formerly of the Progressive Democrats in Ireland.<ref
name=r9>Coalition Government 1989 To 1992 (see
https://web.archive.org/web/20071119201140/http://www.progressivedemocrats.ie/about_us/coalition_government_1989_to_1992/)
.. progressivedemocrats.ie
*** Religion
The prehistoric Indo-European tribes worshipped the oak and connected it with
a thunder 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.[102] Mortals who destroyed such
trees were said to be punished by the gods since the ancient Greeks believed
beings called hamadryads inhabited them.[103] In Norse and Baltic mythology,
the oak was sacred to the thunder gods Thor and Perkūnas
respectively.[104][105] In Celtic polytheism, the name druid, Celtic priest,
is connected to Proto-Indo-European _*deru_, meaning oak or tree.<ref
name=Credo>[last=Ferber ] Veneration of the oak survives in Serbian Orthodox
Church tradition. Christmas celebrations include the _badnjak_, a branch
taken from a young and straight oak ceremonially felled early on Christmas Eve
morning, similar to a yule log.[106]
*** History
[List of individual trees]
Category: _Individual oak trees_
Several oak trees hold cultural importance; such as the Royal Oak in
Britain,[107] the Charter Oak in the United States,[108] and the Guernica oak
in the Basque Country.[109] "The Proscribed Royalist, 1651", a famous painting
by John Everett Millais, depicts a Royalist hiding in an oak tree while
fleeing from Cromwell's forces.[110][111]
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".<ref
name="Credo"/> In his 17th century poem _The Garden_, Andrew Marvell critiqued
the desire to be awarded such a leafy crown: "How vainly men themselves amaze
/ To win the palm, the oak, or bays; And their uncessant labors see / Crowned
from some single herb or tree, ..."[112][113]
** Notes
[notelist]
** References
[30em]
** Further reading
- Byfield, Liz (1990) _An Oak Tree_ , Collins Book Bus, London: Collins Educational, [0-00-313526-8]
- Phillips, Roger (1979). _Trees of North America and Europe_ , Random House, New York [0-394-50259-0] .
- Logan, William B. (2005) _Oak: The Frame of Civilization_ , New York; London: W. W. Norton, [0-393-04773-3]
- Paterson, R. T. (1993). _Use of Trees by Livestock_ , 5 : _Quercus_ , Chatham: Natural Resources Institute, [0-85954-365-X]
- Royston, Angela (2000). _Life Cycle of an Oak Tree_ , Heinemann first library, Oxford: Heinemann Library, [0-431-08391-6]
- Savage, Stephen (1994). _Oak Tree_ , Observing nature series, Hove: Wayland, [0-7502-1196-2]
- Tansley, Arthur G. (1952). _Oaks and Oak Woods_ , Field study books, London: Methuen. [3196286] .
- 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
[Quercus] [Quercus]
- _Flora of China_ – _Cyclobalanopsis_ (see http://www.efloras.org/florataxon.aspx?flora_id=2&taxon_id=108828)
- Oak diseases (see http://extension.uga.edu/publications/detail.cfm?number=B1286)
- Flora Europaea: _Quercus_ (see http://rbg-web2.rbge.org.uk/cgi-bin/nph-readbtree.pl/feout?FAMILY_XREF=&GENUS_XREF=Quercus&SPECIES_XREF=&TAXON_NAME_XREF=&RANK=)
- Common Oaks of Florida (see http://ufdc.ufl.edu/IR00001806/00001)
- Oaks of the world (see http://oaksoftheworld.fr/)
- The Global Trees Campaign (see https://web.archive.org/web/20120606034357/http://www.bgci.org/ourwork/oaksmain/) The Red List of Oaks and Global Survey of Threatened Quercus
- [wstitle=Oak ]
[Culinary wrappings] [Tannin source] [Woodworking] [from=Q12004] [authority
control]
01 Category:Pseudocereals Category:Wood Category:Botanical taxa named by Carl
Linnaeus