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:''This article is about oaks (Quercus). For other uses of "Oak" or "Oak tree", see [[Oak (disambiguation)]]''
{{Taxobox
| color = lightgreen
| name = Oaks
| image = Quercus robur.jpg
| image_width = 240px
| image_caption = Foliage and acorns of ''[[Pedunculate oak|Quercus robur]]''
| regnum = [[Plant]]ae
| phylum = [[flowering plant|Magnoliophyta]]
| classis = [[dicotyledon|Magnoliopsida]]
| ordo = [[Fagales]]
| familia = [[Fagaceae]]
| genus = '''''Quercus'''''
| genus_authority = [[Carolus Linnaeus|L.]]
| subdivision_ranks = [[Species]]
| subdivision =
See [[List of Quercus species|List of ''Quercus'' species]]
}}
The term '''oak''' can be used as part of the common name of any of several hundred species of [[tree]]s and [[shrub]]s in the [[genus]] ''Quercus'', and some related genera, notably ''[[Cyclobalanopsis]]'' and ''[[Lithocarpus]]''. The genus is native to the northern hemisphere, and includes [[deciduous]] and [[evergreen]] species extending from cold latitudes to tropical [[Asia]] and the [[Americas]].
Oaks have spirally arranged [[leaf|leaves]], with a lobed margin in many species; some have serrated leaves or entire leaves with a smooth margin. The [[flower]]s are [[catkin]]s, produced in spring. The [[fruit]] is a [[nut (fruit)|nut]] called an [[acorn]], 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 species. The [[live oak|"live oaks"]] (oaks with [[evergreen]] leaves) are not a distinct group, instead with their members scattered among the sections below.
==Classification==
The genus is divided into a number of sections:
*Sect. ''Quercus'' (synonyms ''Lepidobalanus'' and ''Leucobalanus''), the [[List of Quercus species#Section Quercus|oaks]] of [[Europe]], Asia and [[North America]]. Styles short; acorns mature in 6 months, sweet or slightly bitter, inside of acorn shell hairless. Leaves mostly lack a bristle on lobe tips, which are usually rounded.
*Sect. ''Mesobalanus'', the [[List of Quercus species#Section Mesobalanus|Hungarian oak and its relatives]] of Europe and Asia. Styles long; acorns mature in 6 months, bitter, inside of acorn shell hairless (closely related to sect. ''Quercus'' and sometimes included in it).
*Sect. ''Cerris'', the [[List of Quercus species#Section Cerris|Turkey oak and its relatives]] of Europe and Asia. Styles long; acorns mature in 18 months, very bitter, inside of acorn shell hairless. Leaves typically have sharp lobe tips, with bristles at the lobe tip.
*Sect. ''Protobalanus'', the [[List of Quercus species#Section Protobalanus|Canyon live oak and its relatives]], in southwest [[United States]] and northwest [[Mexico]]. Styles short, acorns mature in 18 months, very bitter, inside of acorn shell woolly. Leaves typically have sharp lobe tips, with bristles at the lobe tip.
*Sect. ''Lobatae'' (synonym ''Erythrobalanus''), the [[List of Quercus species#Section Lobatae|red oaks]] of North America, [[Central America]] and northern [[South America]]. Styles long, acorns mature in 18 months, very bitter, inside of acorn shell woolly. Leaves typically have sharp lobe tips, with spiny bristles at the lobe tip.
[[List of Quercus species|'''Full list of ''Quercus'' species''']]
[[Image:Quercus stellata.jpg|thumb|A hybrid white oak, possibly ''[[Post oak|Quercus stellata]]'' × ''[[Chinkapin oak|Q. muhlenbergii]]'']]
[[Hybrid]]s are common in oaks but usually only between species within the same section; no verified inter-section hybrids are known, except between species of sections ''Quercus'' and ''Mesobalanus'', where several occur.
The genus ''[[Cyclobalanopsis]]'', here treated as a distinct genus following the [http://flora.huh.harvard.edu:8080/flora/browse.do?flora_id=2&taxon_id=108828 ''Flora of China''], is often included within ''Quercus'' as a distinct subgenus.
==Uses==
Oaks are [[hardwood]] trees, and the [[wood]] is commonly used in [[furniture]] and flooring. Oak wood has a density of about 0.75 g/cm³.
The bark of ''Quercus suber'', or [[Cork oak]], is use
d to produce [[wine]] [[stopper (plug)|stopper]]s (corks). This species grows in the [[Mediterranean Sea]] region, with [[Portugal]], [[Spain]], [[Algeria]] and [[Morocco]] producing most of the world's supply. Some European and American oak species are used to make [[Barrel (storage)|barrel]]s where wine and other spirits are [[Aging barrel|aged]]; the barrels, which are in some cases charred before use, contribute to the taste, aroma, and color of the contents.
Of the North American oaks, the [[Northern red oak]] ''Quercus rubra'' is the most prized of the red oak group for lumber, all of which is marketed as red oak regardless of the species of origin. The standard for the lumber of the white oak group, all of which is marketed as white oak, is the [[White Oak]] ''Quercus alba''. White Oak is often used to make wine barrels. The wood of [[Pedunculate Oak]] ''Quercus robur'' and [[Sessile Oak]] ''Quercus petraea'' are extensively used in [[Europe]].
The [[bark]] of the White Oak is dried and used in medical preparations. Oak bark is also rich in [[tannin]], and is used by tanners for [[tanning]] [[leather]]. Acorns are used for making flour or roasted for acorn coffee. Oak galls were used for centuries as the main ingredient in manuscript ink, harvested at a specific time of year.
Japanese oak is used in the making of professional drums from manufacturer [[Yamaha Drums]]. The rough, hard surface of oak gives the drum a brighter and louder tone compared to traditional drum materials such as [[maple]] and [[birch]].
==Cultivation==
Oak catkins are made up of small, yellowish-green flowers. Acorns appear after the female flowers are fertilized in spring. They are typically brown, tan, yellow, light green, deep green or grayish green. Oaks grow slowly and usually do not bear acorns until they are about 20 years old. Acorns require [[Stratification (botany)|stratification]] to stimulate sprouting. Most [[white oaks]] need immediate stratification; species such as the [[Chestnut oak]] (''Quercus montana'') will sprout a root upon falling and must have a suitable substrate for immediate rooting. Many red oak acorns can be stratified for up to two years before sprouting. The life span of oaks typically ranges from 200 to 600 years, with a few species reaching 1,000 years.
==Diseases and pests==
[[Sudden Oak Death]] (''Phytophthora ramorum'') is a [[water mould]] that can kill oaks within just a few weeks. [[Oak Wilt]], caused by the fungus ''Ceratocystis fagacearum'' (a fungus closely related to [[Dutch Elm Disease]]), 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 [[beetle]]s, as well as root [[rot]] in older trees which may not be apparent on the outside, often only being discovered when the trees come down in a strong [[gale]]. Oaks are used as food plants by the [[larva]]e of [[Lepidoptera]] species.
*''See also [[list of Lepidoptera which feed on Oaks]]''
==Cultural significance==
[[Image:5ec ger.png|right|thumb|An oak twig is depicted on the back of [[German euro coins|German 1-, 2- and 5-cent coins]]]]
The oak is a common [[symbol]] of [[Virtue|strength]] and [[endurance]] and has been chosen as the [[national tree]] of [[England]], [[France]], [[Germany]] and the [[United States]].
[[Thor's Oak]] was a sacred tree of the Germanic [[Chatti]] tribe. Its destruction marked the [[Christianisation]] of the heathen tribes by the [[Franks]]{{Fact|date=April 2007}}.
In the [[Bible]], the oak tree at [[Shechem]] is the site where Jacob buries the foreign gods of his people (Gen. 35.4) . In addition, Joshua erects a stone under an oak tree as the first covenant of the Lord (Josh. 24.25-7). See other [http://www.biblegateway.com/quicksearch/?quicksearch=oak&x=0&y=0 examples] from the Bible.
In [[Classical mythology]] the oak was a symbol of [[Zeus]] and his sacred tree.
Several individual oak trees, such as the [[Royal Oak (tree)|Royal Oak]] in Britain and the [[Charter Oak]] in the United States, are of
great historical or cultural importance; for a list of important oaks, see [[:Category:Individual oak trees|Individual oak trees]].
[[Iowa]] has 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]].
"Ambrosian Oaks" set to the [[Finlandia Hymn]] is the school song of [[St. Ambrose University]] in [[Davenport, Iowa]].
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.
There is a [[proverb]], "Mighty oaks from little [[acorn]]s grow."
Many woods are connected to certain birth months, according to the Irish, and oak is the wood of June/July. However, in some variations, rosewood has been known to be June's wood {{Fact|date=February 2007}}.
[[Raleigh, NC|Raleigh]], [[North Carolina]] has been nicknamed the "City of Oaks."
The [[Romania national rugby union team]] is nicknamed ''The Oaks.''
In [[Celtic mythology]] it is the tree of doors, believed to be a gateway between worlds, or a place where portals could be erected.
Oak leaves are used to symbolize rank in the [[United States Armed Forces]]. A gold oak leaf indicates an O-4 ([[Major]] or [[LCDR|Lt. Commander]]), whereas a silver oak leaf indicates an O-5 ([[Lt. Colonel]] or [[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.
[[Derry]] in [[Northern Ireland]] is named after the [[Irish language|Irish]] word "Doire," meaning oak tree.
==Historical note on Linnaean species==
[[Carolus Linnaeus|Linnaeus]] described only five species of oak from eastern North America, based on general leaf form. These were White oak, ''Q. alba'', Chestnut oak, ''Q. montana'', Red oak, ''Q. rubra'', Willow oak, ''Q. phellos'', and Water oak, ''Q. nigra''. Because he was dealing with confusing leaf forms, the ''Q. prinus'' and ''Q. rubra'' specimens actually included mixed foliage of more than one species. For that reason, some taxonomists in the past proposed different names for these two species (''Q. montana'' and ''Q. borealis'', respectively), but the original Linnaean names have now been lectotypified with only the specimens in Linnaeus' herbarium that refer to the species the names are applied to now.
==References and notes==
<References/>
<gallery>
Image:Raunkiaer.jpg|A [[Pedunculate oak]] in [[Denmark]]
Image:Oak_at_night.JPG|An oak tree at night
Image:Oakbark.jpg|Bark of ''[[Quercus robur]]''
Image:Spanish-moss-tree.jpg|[[Southern live oak]] with [[spanish moss]]
</gallery>
==External links==
{{commonscat|Quercus}}
* [http://flora.huh.harvard.edu:8080/flora/browse.do?flora_id=1&taxon_id=127839 Flora of North America: ''Quercus'']
* [http://flora.huh.harvard.edu:8080/flora/browse.do?flora_id=2&taxon_id=127839 Flora of China: ''Quercus'']
*[http://rbg-web2.rbge.org.uk/cgi-bin/nph-readbtree.pl/feout?FAMILY_XREF=&GENUS_XREF=Quercus&SPECIES_XREF=&TAXON_NAME_XREF=&RANK= Flora Europaea: ''Quercus'']
*[http://www.bcgov.net/bftlib/oaktrees.htm Oak Trees of the Lowcountry (South Carolina) -- Beaufort County Library]
[[Category:Fagaceae]]
{{Taxobox
| color = lightgreen
| name = Oaks
| image = Quercus robur.jpg
| image_width = 240px
| image_caption = Foliage and acorns of ''[[Pedunculate oak|Quercus robur]]''
| regnum = [[Plant]]ae
| phylum = [[flowering plant|Magnoliophyta]]
| classis = [[dicotyledon|Magnoliopsida]]
| ordo = [[Fagales]]
| familia = [[Fagaceae]]
| genus = '''''Quercus'''''
| genus_authority = [[Carolus Linnaeus|L.]]
| subdivision_ranks = [[Species]]
| subdivision =
See [[List of Quercus species|List of ''Quercus'' species]]
}}
The term '''oak''' can be used as part of the common name of any of several hundred species of [[tree]]s and [[shrub]]s in the [[genus]] ''Quercus'', and some related genera, notably ''[[Cyclobalanopsis]]'' and ''[[Lithocarpus]]''. The genus is native to the northern hemisphere, and includes [[deciduous]] and [[evergreen]] species extending from cold latitudes to tropical [[Asia]] and the [[Americas]].
Oaks have spirally arranged [[leaf|leaves]], with a lobed margin in many species; some have serrated leaves or entire leaves with a smooth margin. The [[flower]]s are [[catkin]]s, produced in spring. The [[fruit]] is a [[nut (fruit)|nut]] called an [[acorn]], 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 species. The [[live oak|"live oaks"]] (oaks with [[evergreen]] leaves) are not a distinct group, instead with their members scattered among the sections below.
==Classification==
The genus is divided into a number of sections:
*Sect. ''Quercus'' (synonyms ''Lepidobalanus'' and ''Leucobalanus''), the [[List of Quercus species#Section Quercus|oaks]] of [[Europe]], Asia and [[North America]]. Styles short; acorns mature in 6 months, sweet or slightly bitter, inside of acorn shell hairless. Leaves mostly lack a bristle on lobe tips, which are usually rounded.
*Sect. ''Mesobalanus'', the [[List of Quercus species#Section Mesobalanus|Hungarian oak and its relatives]] of Europe and Asia. Styles long; acorns mature in 6 months, bitter, inside of acorn shell hairless (closely related to sect. ''Quercus'' and sometimes included in it).
*Sect. ''Cerris'', the [[List of Quercus species#Section Cerris|Turkey oak and its relatives]] of Europe and Asia. Styles long; acorns mature in 18 months, very bitter, inside of acorn shell hairless. Leaves typically have sharp lobe tips, with bristles at the lobe tip.
*Sect. ''Protobalanus'', the [[List of Quercus species#Section Protobalanus|Canyon live oak and its relatives]], in southwest [[United States]] and northwest [[Mexico]]. Styles short, acorns mature in 18 months, very bitter, inside of acorn shell woolly. Leaves typically have sharp lobe tips, with bristles at the lobe tip.
*Sect. ''Lobatae'' (synonym ''Erythrobalanus''), the [[List of Quercus species#Section Lobatae|red oaks]] of North America, [[Central America]] and northern [[South America]]. Styles long, acorns mature in 18 months, very bitter, inside of acorn shell woolly. Leaves typically have sharp lobe tips, with spiny bristles at the lobe tip.
[[List of Quercus species|'''Full list of ''Quercus'' species''']]
[[Image:Quercus stellata.jpg|thumb|A hybrid white oak, possibly ''[[Post oak|Quercus stellata]]'' × ''[[Chinkapin oak|Q. muhlenbergii]]'']]
[[Hybrid]]s are common in oaks but usually only between species within the same section; no verified inter-section hybrids are known, except between species of sections ''Quercus'' and ''Mesobalanus'', where several occur.
The genus ''[[Cyclobalanopsis]]'', here treated as a distinct genus following the [http://flora.huh.harvard.edu:8080/flora/browse.do?flora_id=2&taxon_id=108828 ''Flora of China''], is often included within ''Quercus'' as a distinct subgenus.
==Uses==
Oaks are [[hardwood]] trees, and the [[wood]] is commonly used in [[furniture]] and flooring. Oak wood has a density of about 0.75 g/cm³.
The bark of ''Quercus suber'', or [[Cork oak]], is use
d to produce [[wine]] [[stopper (plug)|stopper]]s (corks). This species grows in the [[Mediterranean Sea]] region, with [[Portugal]], [[Spain]], [[Algeria]] and [[Morocco]] producing most of the world's supply. Some European and American oak species are used to make [[Barrel (storage)|barrel]]s where wine and other spirits are [[Aging barrel|aged]]; the barrels, which are in some cases charred before use, contribute to the taste, aroma, and color of the contents.
Of the North American oaks, the [[Northern red oak]] ''Quercus rubra'' is the most prized of the red oak group for lumber, all of which is marketed as red oak regardless of the species of origin. The standard for the lumber of the white oak group, all of which is marketed as white oak, is the [[White Oak]] ''Quercus alba''. White Oak is often used to make wine barrels. The wood of [[Pedunculate Oak]] ''Quercus robur'' and [[Sessile Oak]] ''Quercus petraea'' are extensively used in [[Europe]].
The [[bark]] of the White Oak is dried and used in medical preparations. Oak bark is also rich in [[tannin]], and is used by tanners for [[tanning]] [[leather]]. Acorns are used for making flour or roasted for acorn coffee. Oak galls were used for centuries as the main ingredient in manuscript ink, harvested at a specific time of year.
Japanese oak is used in the making of professional drums from manufacturer [[Yamaha Drums]]. The rough, hard surface of oak gives the drum a brighter and louder tone compared to traditional drum materials such as [[maple]] and [[birch]].
==Cultivation==
Oak catkins are made up of small, yellowish-green flowers. Acorns appear after the female flowers are fertilized in spring. They are typically brown, tan, yellow, light green, deep green or grayish green. Oaks grow slowly and usually do not bear acorns until they are about 20 years old. Acorns require [[Stratification (botany)|stratification]] to stimulate sprouting. Most [[white oaks]] need immediate stratification; species such as the [[Chestnut oak]] (''Quercus montana'') will sprout a root upon falling and must have a suitable substrate for immediate rooting. Many red oak acorns can be stratified for up to two years before sprouting. The life span of oaks typically ranges from 200 to 600 years, with a few species reaching 1,000 years.
==Diseases and pests==
[[Sudden Oak Death]] (''Phytophthora ramorum'') is a [[water mould]] that can kill oaks within just a few weeks. [[Oak Wilt]], caused by the fungus ''Ceratocystis fagacearum'' (a fungus closely related to [[Dutch Elm Disease]]), 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 [[beetle]]s, as well as root [[rot]] in older trees which may not be apparent on the outside, often only being discovered when the trees come down in a strong [[gale]]. Oaks are used as food plants by the [[larva]]e of [[Lepidoptera]] species.
*''See also [[list of Lepidoptera which feed on Oaks]]''
==Cultural significance==
[[Image:5ec ger.png|right|thumb|An oak twig is depicted on the back of [[German euro coins|German 1-, 2- and 5-cent coins]]]]
The oak is a common [[symbol]] of [[Virtue|strength]] and [[endurance]] and has been chosen as the [[national tree]] of [[England]], [[France]], [[Germany]] and the [[United States]].
[[Thor's Oak]] was a sacred tree of the Germanic [[Chatti]] tribe. Its destruction marked the [[Christianisation]] of the heathen tribes by the [[Franks]]{{Fact|date=April 2007}}.
In the [[Bible]], the oak tree at [[Shechem]] is the site where Jacob buries the foreign gods of his people (Gen. 35.4) . In addition, Joshua erects a stone under an oak tree as the first covenant of the Lord (Josh. 24.25-7). See other [http://www.biblegateway.com/quicksearch/?quicksearch=oak&x=0&y=0 examples] from the Bible.
In [[Classical mythology]] the oak was a symbol of [[Zeus]] and his sacred tree.
Several individual oak trees, such as the [[Royal Oak (tree)|Royal Oak]] in Britain and the [[Charter Oak]] in the United States, are of
great historical or cultural importance; for a list of important oaks, see [[:Category:Individual oak trees|Individual oak trees]].
[[Iowa]] has 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]].
"Ambrosian Oaks" set to the [[Finlandia Hymn]] is the school song of [[St. Ambrose University]] in [[Davenport, Iowa]].
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.
There is a [[proverb]], "Mighty oaks from little [[acorn]]s grow."
Many woods are connected to certain birth months, according to the Irish, and oak is the wood of June/July. However, in some variations, rosewood has been known to be June's wood {{Fact|date=February 2007}}.
[[Raleigh, NC|Raleigh]], [[North Carolina]] has been nicknamed the "City of Oaks."
The [[Romania national rugby union team]] is nicknamed ''The Oaks.''
In [[Celtic mythology]] it is the tree of doors, believed to be a gateway between worlds, or a place where portals could be erected.
Oak leaves are used to symbolize rank in the [[United States Armed Forces]]. A gold oak leaf indicates an O-4 ([[Major]] or [[LCDR|Lt. Commander]]), whereas a silver oak leaf indicates an O-5 ([[Lt. Colonel]] or [[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.
[[Derry]] in [[Northern Ireland]] is named after the [[Irish language|Irish]] word "Doire," meaning oak tree.
==Historical note on Linnaean species==
[[Carolus Linnaeus|Linnaeus]] described only five species of oak from eastern North America, based on general leaf form. These were White oak, ''Q. alba'', Chestnut oak, ''Q. montana'', Red oak, ''Q. rubra'', Willow oak, ''Q. phellos'', and Water oak, ''Q. nigra''. Because he was dealing with confusing leaf forms, the ''Q. prinus'' and ''Q. rubra'' specimens actually included mixed foliage of more than one species. For that reason, some taxonomists in the past proposed different names for these two species (''Q. montana'' and ''Q. borealis'', respectively), but the original Linnaean names have now been lectotypified with only the specimens in Linnaeus' herbarium that refer to the species the names are applied to now.
==References and notes==
<References/>
<gallery>
Image:Raunkiaer.jpg|A [[Pedunculate oak]] in [[Denmark]]
Image:Oak_at_night.JPG|An oak tree at night
Image:Oakbark.jpg|Bark of ''[[Quercus robur]]''
Image:Spanish-moss-tree.jpg|[[Southern live oak]] with [[spanish moss]]
</gallery>
==External links==
{{commonscat|Quercus}}
* [http://flora.huh.harvard.edu:8080/flora/browse.do?flora_id=1&taxon_id=127839 Flora of North America: ''Quercus'']
* [http://flora.huh.harvard.edu:8080/flora/browse.do?flora_id=2&taxon_id=127839 Flora of China: ''Quercus'']
*[http://rbg-web2.rbge.org.uk/cgi-bin/nph-readbtree.pl/feout?FAMILY_XREF=&GENUS_XREF=Quercus&SPECIES_XREF=&TAXON_NAME_XREF=&RANK= Flora Europaea: ''Quercus'']
*[http://www.bcgov.net/bftlib/oaktrees.htm Oak Trees of the Lowcountry (South Carolina) -- Beaufort County Library]
[[Category:Fagaceae]]