Difference between revisions of "Oak"

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:''This article is about oaks (Quercus). For other uses of "Oak" or "Oak tree", see [[Oak (disambiguation)]]''
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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]].
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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.
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{{Inc|
 
{{Inc|
 
Quercus (ancient Latin name). Fagaceae. Oak. Ornamental trees, rarely shrubs, grown chiefly for their handsome foliage and interesting habit; many species are important timber trees. See Oak.
 
Quercus (ancient Latin name). Fagaceae. Oak. Ornamental trees, rarely shrubs, grown chiefly for their handsome foliage and interesting habit; many species are important timber trees. See Oak.
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Generally the oaks grow best in a moderately moist rich soil, including heavy clay; some, as Q. bicolor, Q. nigra, Q. alba, Q. Phellos, Q. falcata, and Q. virginiana, prefer moister situations and grow naturally in low and often even in swampy ground; while others, especially the red oaks, like Q. rubra, Q. coccinea, Q. imbricaria, Q. marilandica, Q. montana. and Q. stellata, grow well in drier, rocky or sandy soil, and the scrub oaks on dry and barren soil. The black and red oaks especially the pin oak, are usually easily transplanted and large trees are moved successfully, while the white oaks are more particular and only younger nursery- grown trees can be safely transplanted.
 
Generally the oaks grow best in a moderately moist rich soil, including heavy clay; some, as Q. bicolor, Q. nigra, Q. alba, Q. Phellos, Q. falcata, and Q. virginiana, prefer moister situations and grow naturally in low and often even in swampy ground; while others, especially the red oaks, like Q. rubra, Q. coccinea, Q. imbricaria, Q. marilandica, Q. montana. and Q. stellata, grow well in drier, rocky or sandy soil, and the scrub oaks on dry and barren soil. The black and red oaks especially the pin oak, are usually easily transplanted and large trees are moved successfully, while the white oaks are more particular and only younger nursery- grown trees can be safely transplanted.
  
Oaks are propagated usually by seeds sown immediately after gathering in fall; this is especially necessary with Q. alba. Q. virginiana, and some other white oaks which sprout as soon as they are ripe; but only the root is produced in fall, while the stem does not appear until the following spring. The seeds of red and black oaks, and also of Q. Robur, if not sown at once should be stratified and sown early in spring. Acorns should be packed in earth, moss, or sawdust when shipped for a great distance. Varieties are usually grafted on potted stock in the greenhouse in early spring or sometimes in August. As a stock Q. Robur is preferred, but Q. rubra, Q. velutina, and Q. montana are also employed. It is probably safer to graft varieties of white and of red oak each on stock of the same group. The evergreen species are sometimes increased by layers and also by cuttings.
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Oaks are propagated usually by seeds sown immediately after gathering in fall; this is especially necessary with Q. alba. Q. virginiana, and some other white oaks which sprout as soon as they are ripe; but only the root is produced in fall, while the stem does not appear until the following spring. The seeds of red and black oaks, and also of Q. Robur, if not sown at once should be stratified and sown early in spring. Acorns should be packed in earth, moss, or sawdust when shipped for a great distance. Varieties are usually grafted on potted stock in the greenhouse in early spring or sometimes in August. As a stock Q. Robur is preferred, but Q. rubra, Q. velutina, and Q. montana are also employed. It is probably safer to graft varieties of white and of red oak each on stock of the same group. The evergreen species are sometimes increased by layers and also by cuttings.}}
  
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==Cultivation==
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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.
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===Propagation===
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<!--- Type propagation info below this line, then delete this entire line -->
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===Pests and diseases===
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[[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.
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==Species==
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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.
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*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.
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*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. 
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[[List of Quercus species|'''Full list of ''Quercus'' species''']]
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[[Image:Quercus stellata.jpg|thumb|A hybrid white oak, possibly ''[[Post oak|Quercus stellata]]'' × ''[[Chinkapin oak|Q. muhlenbergii]]'']]
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[[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.
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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.
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{{Inc|
 
Index.
 
Index.
  
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The following species of Castanopsis are known to be in cult.: C. ceratacantha, Rehd. & Wilson. Tree, to 50 ft.: branchlets densely villous: lvs. oblong-lanceolate to ovate-lanceolate, acuminate, obscurely toothed above the middle or entire, brownish villous-tomentose beneath, 4-6 in. long: frs. in stout spikes to 8 in. long, 1/4-1 in. across, fulvous-tomentulose, with stout prickles 1/4-1/2in. long and divided at the apex into several spreading spiny points; nuts 2-3, wholly inclosed. W. China.—C. chrysophylla, DC., see Vol. II, p. 682.—C. cuspidata, Schottky (Quercus cuspidata, Thunb. Pasania cuspidata, Oerst.). This species is already mentioned under Pasania, see p. 2479. The ovate pointed involucre is marked with 4 or 5 wavy concentric ridges of small tubercles and includes wholly the solitary nut. There are two varieties in cult.: var. latifolia, Rehd. & Wilson, with larger and broader lvs. to 4 1/2 in. long and to 2 1/2 in. broad; and var. variegata, Rehd. & Wilson, with small lvs. bordered by a broad, irregular, creamy white margin. G.C. II. 12:233.—C. Fargesii, Franch. Tree, to 100 ft.: branchlets glabrous: lvs. elliptic-oblong to lanceolate, acuminate, serrate above the middle, thinly and closely yellowish or grayish tomentulose beneath, finally nearly glabrous, 2-5 in. long: frs. in stout spikes to 6 in. long, about 3/4in. across, with stout, often reflexed fascicled spines, about 1/2in. long; nut usually solitary, wholly inclosed. Cent. China.—C. platyacantha, Rehd. & Wilson. Tree, to 80 ft.: branchlets glabrous: lvs. ovate-oblong to elliptic-oblong, acuminate, slightly toothed above the middle or entire, covered beneath, except the glabrous midrib, with a close fulvous tomentum, becoming paler the second year, 2 1/2-5 in. long: spikes short, 3-6- fruited: frs. about 1 in. across, grayish tomentulose, densely covered with short and stout fascicled prickles; nuts wholly inclosed, 1-3. W. China.—C. sclerophylla, Schottky (Q. sclerophylla, Lindl. Q. chinensis, Abel). Tree, to 60 ft.: lvs. oval to oblong-ovate or oblong, acuminate, serrate above the middle, glabrous, glaucescent beneath, 2 1/2-6 in. long: frs. in dense spikes with the peduncle to 4 in. long; involucre ovoid, with close concentric ridges of small tubercles, not wholly inclosing the solitary nut. E. and Cent.
 
The following species of Castanopsis are known to be in cult.: C. ceratacantha, Rehd. & Wilson. Tree, to 50 ft.: branchlets densely villous: lvs. oblong-lanceolate to ovate-lanceolate, acuminate, obscurely toothed above the middle or entire, brownish villous-tomentose beneath, 4-6 in. long: frs. in stout spikes to 8 in. long, 1/4-1 in. across, fulvous-tomentulose, with stout prickles 1/4-1/2in. long and divided at the apex into several spreading spiny points; nuts 2-3, wholly inclosed. W. China.—C. chrysophylla, DC., see Vol. II, p. 682.—C. cuspidata, Schottky (Quercus cuspidata, Thunb. Pasania cuspidata, Oerst.). This species is already mentioned under Pasania, see p. 2479. The ovate pointed involucre is marked with 4 or 5 wavy concentric ridges of small tubercles and includes wholly the solitary nut. There are two varieties in cult.: var. latifolia, Rehd. & Wilson, with larger and broader lvs. to 4 1/2 in. long and to 2 1/2 in. broad; and var. variegata, Rehd. & Wilson, with small lvs. bordered by a broad, irregular, creamy white margin. G.C. II. 12:233.—C. Fargesii, Franch. Tree, to 100 ft.: branchlets glabrous: lvs. elliptic-oblong to lanceolate, acuminate, serrate above the middle, thinly and closely yellowish or grayish tomentulose beneath, finally nearly glabrous, 2-5 in. long: frs. in stout spikes to 6 in. long, about 3/4in. across, with stout, often reflexed fascicled spines, about 1/2in. long; nut usually solitary, wholly inclosed. Cent. China.—C. platyacantha, Rehd. & Wilson. Tree, to 80 ft.: branchlets glabrous: lvs. ovate-oblong to elliptic-oblong, acuminate, slightly toothed above the middle or entire, covered beneath, except the glabrous midrib, with a close fulvous tomentum, becoming paler the second year, 2 1/2-5 in. long: spikes short, 3-6- fruited: frs. about 1 in. across, grayish tomentulose, densely covered with short and stout fascicled prickles; nuts wholly inclosed, 1-3. W. China.—C. sclerophylla, Schottky (Q. sclerophylla, Lindl. Q. chinensis, Abel). Tree, to 60 ft.: lvs. oval to oblong-ovate or oblong, acuminate, serrate above the middle, glabrous, glaucescent beneath, 2 1/2-6 in. long: frs. in dense spikes with the peduncle to 4 in. long; involucre ovoid, with close concentric ridges of small tubercles, not wholly inclosing the solitary nut. E. and Cent.
China.
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China.
 
 
Alfred Rehder.
 
 
 
 
 
 
 
}}
 
 
 
:''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]].
+
==Gallery==
 
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{{photo-sources}}<!-- remove this line if there are already 3 or more photos in the gallery -->
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>
 
<gallery>
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Image:Spanish-moss-tree.jpg|[[Southern live oak]] with [[spanish moss]]
 
Image:Spanish-moss-tree.jpg|[[Southern live oak]] with [[spanish moss]]
 
</gallery>
 
</gallery>
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==References==
 +
*[[Standard Cyclopedia of Horticulture]], by L. H. Bailey, MacMillan Co., 1963
 +
<!--- xxxxx  *Flora: The Gardener's Bible, by Sean Hogan. Global Book Publishing, 2003. ISBN 0881925381  -->
 +
<!--- xxxxx  *American Horticultural Society: A-Z Encyclopedia of Garden Plants, by Christopher Brickell, Judith D. Zuk. 1996. ISBN 0789419432  -->
 +
<!--- xxxxx  *Sunset National Garden Book. Sunset Books, Inc., 1997. ISBN 0376038608  -->
  
 
==External links==
 
==External links==
{{commonscat|Quercus}}
+
*{{wplink}}
* [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'']
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{{stub}}
*[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'']
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__NOTOC__
*[http://www.bcgov.net/bftlib/oaktrees.htm Oak Trees of the Lowcountry (South Carolina) -- Beaufort County Library]
 
[[Category:Fagaceae]]
 

Revision as of 23:44, 11 December 2009


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Plant Characteristics
Cultivation
Scientific Names


This article is about oaks (Quercus). For other uses of "Oak" or "Oak tree", see Oak (disambiguation)

The term oak can be used as part of the common name of any of several hundred species of trees and shrubs 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 leaves, with a lobed margin in many species; some have serrated leaves or entire leaves with a smooth margin. The flowers are catkins, produced in spring. The fruit is a 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 oaks" (oaks with evergreen leaves) are not a distinct group, instead with their members scattered among the sections below.


Read about Oak in the Standard Cyclopedia of Horticulture 

Quercus (ancient Latin name). Fagaceae. Oak. Ornamental trees, rarely shrubs, grown chiefly for their handsome foliage and interesting habit; many species are important timber trees. See Oak.

Deciduous or evergreen trees, rarely shrubby: winter buds with usually many imbricate scales: lvs. alternate, short-petioled, with deciduous stipules, pen- ninerved, serrate, lobed or pinnatifid, rarely entire: fls. monoecious; the staminate in slender, pendulous catkins with 4-7-parted calyx and 4-12, usually 6, stamens; pistillate in 1- to many-fld. spikes in the axils of the young lvs., each fl. consisting of an incompletely 3-, or rarely 4-5-celled ovary, surrounded by imbricate bracts; style short or elongated, dilated above and stigmatic on the inner face: fr. a 1-seeded subglobose to oblong nut, surrounded at the base or sometimes almost inclosed by a cup-like involucre.—More than 200 species are known, distributed through the colder and temperate regions of the northern hemisphere and in the mountains of the tropics. The numerous species are usually divided into 3 subgenera. The species of the subgenus Cyclobalanopsis which has the scales of the cup connate into concentric rings are all Asiatic. The American species belong to Lepidobalanus (balanos is Greek for acorn) and to Erythrobalanus. In the former, comprising the white oak tribe, the acorns mature the first year (Fig. 3304). In the latter, comprising the black oaks, the acorns mature the second year (Fig. 3305). Besides the 200 species, about 40 hybrids have been recorded. Pasania, often included under Quercus, is now usually considered a distinct genus, which see. The latest monograph of the whole genus is by A. DeCandolle in "Prodromus," vol. 16, 2, pp. 1-108 (1864-1868). Important illustrated works on American oaks are A. Michaux, "Histoire des Chenes de l'Amerique" (1801), with 36 plates; Kellogg and Greene. "Illustrations of West American Oaks" (1889), with 37 plates; Sargent, "Silva of North America," vol. 8 (1895), with 82 plates, and Liebmann, "Chenes de l'Amerique Tropicale" (1869), with 47 plates. Most of the European and west Asian oaks are figured in Kotschy "Eichen Europas und des Orients" (1862), with 40 colored plates. For comparative illustrations of lvs. see M.D. 1900, p. 32; R.B. 27, p. 61; G.W. 7, pp. 570, 571, 573; for those of frs. see M.D. 1900, p. 40; R.B. 27, p. 109.

The oaks are mostly trees, often tall with massive trunk and stout spreading limbs, with medium-sized, short-petioled leaves, usually more or less lobed, dentate or serrate, rarely entire, with inconspicuous flowers, the staminate ones in slender pendulous catkins and with fruits or "acorns" consisting of a globular to oblong nut inclosed at the base only, rarely wholly or nearly wholly, by a cup-like involucre. The oaks comprise some of the most important forest trees of the northern hemisphere. The wood of most species is strong, tough, hard and durable, and highly valued for many purposes, especially ship-building, construction, for furniture, and in the manufacture of wagons, tools and many other articles. The bark of some species, in America that of Q. velutina and Q. Prinus, is used for tanning leather. Cork is obtained from the bark of Q. Suber and Q. occidentalis in southern Europe. The bark of a few species has also been employed in medicine. The acorns of several species are edible, in America especially those of Q. Prinus, Q. Emoryi and Q. lobata; in Europe those of Q. Ilex var. Ballota and Q. Egilops; in Japan those of Q. glauca; in many European countries the acorns of all species are an important food for hogs. In eastern Asia a silkworm feeds on the leaves of different species. A parasitic insect living on Q. coccifera in southern Europe and northern Africa yields a scarlet dye. Galls caused by the puncture of certain insects are used for tanning and dyeing and are now chiefly obtained from Q. Ilex var. infectoria in western Asia. Some of the above-mentioned species are described only in the supplementary list, page 2890.

The deciduous species are mostly hardy North, while of the evergreen ones none seems to be hardy farther north than Washington, D.C.; some half-evergreen oaks, as Q. Pseudoturneri and Q. macedonica, will probably prove hardy in the vicinity of New York.

Most of the oaks are stately trees of noble and majestic habit with stout, wide-spreading branches; some, as Q. alba, Q. Garryana, Q. vir- giniana, and Q. chrysolepis, often cover a space more than 100 feet in diameter; others, as Q. macrocarpa, Q. montana and Q. velutina, have a more oval, round- topped head, while Q. palustris and Q. imbricaria form symmetrical broad pyramids. A very few hardy species are shrubs, generally called scrub oaks, as Q. prinoides and Q. ilicifolia. Oaks rank among our most valuable park and avenue trees, and are as beautiful when grown as single trees as they are when grouped together and forming groves and woods. As avenue trees, Q. palustris, Q. rubra, Q. coccinea. Q. imbricaria and Q. Phellos are among the best, the last- named when medium-sized trees are desired; in the southern states, Q. laurifolia, Q. nigra, and the evergreen Q. virginiana are preferred. The shrubby species, like Q. prinoides and Q. ilicifolia, may be used for covering rocky hillsides and dry ridges.

Oak leaves are always beautiful. They have many shades of green; especially attractive are some with leaves of contrasting colors, the under side being silvery white, the upper one dark green, as in Q. Muhlenbergii, Q. macrocarpa, Q. Prinus, and some foreign evergreen species. In many oaks the leaves show a handsome pink or crimson color when unfolding, and some species assume brilliant autumnal tints. Especially beautiful in autumn are Q. coccinea and Q. palustris, with the foliage turning brilliant scarlet; Q. rubra, Q. imbricaria, and Q. Prinus, which turn bright or dark red; Q. alba, violet or vinous purple; Q. lyrata, scarlet or orange; Q. Phellos, pale yellow; Q. montana, orange or orange- brown; Q. falcata and Q. ilicifolia, orange-brown or yellow; Q. stellata and Q. nigra, brown or dull orange. Some of the foreign species, like Q. sessiliflora and also Q. Robur, Q. Cerris, Q. lanuginosa, Q. glandulifera, and others, retain the green color until late in fall. Besides our native evergreen species, the Japanese Q. acuta, Q. myrsinaefolia, and Q. glauca are among the best evergreen oaks for cultivation in the South; the European Q. Ilex and Q. Suber are also handsome evergreen trees.

Generally the oaks grow best in a moderately moist rich soil, including heavy clay; some, as Q. bicolor, Q. nigra, Q. alba, Q. Phellos, Q. falcata, and Q. virginiana, prefer moister situations and grow naturally in low and often even in swampy ground; while others, especially the red oaks, like Q. rubra, Q. coccinea, Q. imbricaria, Q. marilandica, Q. montana. and Q. stellata, grow well in drier, rocky or sandy soil, and the scrub oaks on dry and barren soil. The black and red oaks especially the pin oak, are usually easily transplanted and large trees are moved successfully, while the white oaks are more particular and only younger nursery- grown trees can be safely transplanted.

Oaks are propagated usually by seeds sown immediately after gathering in fall; this is especially necessary with Q. alba. Q. virginiana, and some other white oaks which sprout as soon as they are ripe; but only the root is produced in fall, while the stem does not appear until the following spring. The seeds of red and black oaks, and also of Q. Robur, if not sown at once should be stratified and sown early in spring. Acorns should be packed in earth, moss, or sawdust when shipped for a great distance. Varieties are usually grafted on potted stock in the greenhouse in early spring or sometimes in August. As a stock Q. Robur is preferred, but Q. rubra, Q. velutina, and Q. montana are also employed. It is probably safer to graft varieties of white and of red oak each on stock of the same group. The evergreen species are sometimes increased by layers and also by cuttings.

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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 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.

Propagation

Pests and diseases

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 beetles, as well as root rot in older trees which may not be apparent on the outside, often only being discovered when the trees come down in a strong gale. Oaks are used as food plants by the larvae of Lepidoptera species.

Species

The genus is divided into a number of sections:

  • Sect. Quercus (synonyms Lepidobalanus and Leucobalanus), the 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 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 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 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 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.

Full list of Quercus species

A hybrid white oak, possibly Quercus stellata × Q. muhlenbergii

Hybrids 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 Flora of China, is often included within Quercus as a distinct subgenus.


Read about Oak in the Standard Cyclopedia of Horticulture 

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References

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