Difference between revisions of "Oak" - New World Encyclopedia
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==Description== | ==Description== | ||
| − | ''Quercus'' is native to the northern hemisphere, and includes [[deciduous]] and [[evergreen]] species extending from cold latitudes to tropical [[Asia]] and the [[Americas]], as well as [[Europe]]. The more southern species tend to be [[tree#Deciduous versus evergreen|evergreen]] and the more northern are [[tree#Deciduous versus evergreen|deciduous]]. Many deciduous species turn bright gold or scarlet in the autumn (Schonbeck and Frey 2005). | + | ''Quercus'' is native to the northern hemisphere, and includes [[deciduous]] and [[evergreen]] species extending from cold latitudes to tropical [[Asia]] and the [[Americas]], as well as [[Europe]]. The more southern species tend to be [[tree#Deciduous versus evergreen|evergreen]], keeping their leaves all year round, and the more northern are [[tree#Deciduous versus evergreen|deciduous]], losing their leaves in autumn. Many deciduous species turn bright gold or scarlet in the autumn (Schonbeck and Frey 2005). |
| + | Oaks have spirally arranged [[leaf|leaves]], with a lobed margin in many species; some have serrated leaves or entire leaves with a smooth margin. Small flowers are produced in spring. The male [[flower]]s hang in [[catkin]]s, and profuse amounts of [[pollen]], while the female flowers are in spikes, both on the same tree (Schonbeck and Frey 2005). The female flowers are wind pollinated by the pollen. | ||
| + | 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. | ||
| − | + | Trees typically are long-lived, with the average life expectancy for most oaks between 200 and 400 years, with some known to be over 800 years old (Schonbeck and Frey 2005). | |
| + | |||
| + | Most oaks are placed into the two categories of red (or black) oaks and the white oaks (Schonbeck and Frey 2005). The red oaks (section Quercus; synonym sect. Erythrobalanus), such as the scarlet oak (''Quercus coccinea'') have lobes that are sharp tipped, acorns that mature in 18 months, and the inside of the acorn shell is woolly. The white oaks (section Lobate; synonym sect. Lepidobalanus), such as the white oak (''Quercus alba''), have leaves that are smooth-lobed, acorns that mature in 6 months, and the inside of the acorn shell is hairless. | ||
| + | |||
| + | The [[live oak|"live oaks"]] (oaks with [[evergreen]] leaves) are not a distinct group, instead with their members scattered among the sections below. | ||
==Classification== | ==Classification== | ||
The genus is divided into a number of sections: | The genus is divided into a number of sections: | ||
| − | *Sect. ''Quercus'' (synonyms ''Lepidobalanus'' and ''Leucobalanus''), the | + | *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 | + | *Sect. ''Mesobalanus'', the Hungarian oak and its relatives of Europe and Asia. Styles long; acorns mature in 6 months, bitter, inside of hairless acorn shell (closely related to sect. ''Quercus'' and sometimes included in it). |
| − | *Sect. ''Cerris'', the | + | *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 | + | *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 | + | *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. |
| − | |||
| − | |||
| − | |||
[[Image:Quercus stellata.jpg|thumb|A hybrid white oak, possibly ''[[Post oak|Quercus stellata]]'' × ''[[Chinkapin oak|Q. muhlenbergii]]'']] | [[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. | [[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 | + | The genus ''[[Cyclobalanopsis]]'', here treated as a distinct genus following the ''Flora of China'' (eFloras), is often included within ''Quercus'' as a distinct subgenus. |
==Uses== | ==Uses== | ||
| Line 104: | Line 107: | ||
==References== | ==References== | ||
| − | + | ||
| + | eFloras. n.d. [http://flora.huh.harvard.edu:8080/flora/browse.do?flora_id=2&taxon_id=108828 Cyclobalanopsis]. ''Flora of China'' 4: 380. Retrieved November 19, 2007. | ||
| + | |||
* Byfield, Liz (1990) ''An oak tree'', Collins book bus, London : Collins Educational, ISBN 0-00-313526-8 | * Byfield, Liz (1990) ''An oak tree'', Collins book bus, London : Collins Educational, ISBN 0-00-313526-8 | ||
* Logan, William B. (2005) ''Oak : the frame of civilization'', New York ; London : W.W. Norton, ISBN 0-393-04773-3 | * Logan, William B. (2005) ''Oak : the frame of civilization'', New York ; London : W.W. Norton, ISBN 0-393-04773-3 | ||
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[[Category:Plants]] | [[Category:Plants]] | ||
| − | {{credit|Oak|172505839}} | + | {{credit|Oak|172505839|List_of_Quercus_species|171707429}} |
Revision as of 00:38, 20 November 2007
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 Foliage and acorns of Quercus robur
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Oak is the common name for any of the deciduous or evergreen trees and shrubs comprising the flowering plant genus Quercus of the beech family Fagaceae, characterized by a fruit that is a nut called an acorn, simple, spirally arranged leaves, and male flowers in the form of catkins. The term also is used for the durable wood. Oak also appears in the common name of some species in related genera, notably the quite similar acorn-producing Cyclobalanopsis and Lithocarpus, both in the Fagaceae family, as well as some species in unrelated taxa, such as the poison oaks, which are shrubs in the genus Toxicodendron of the Anacardiaceae family.
There are several hundred species in the Quercus genus, many of which are commercially important as the source of hardwood lumber. Oaks also are popular shade and ornamental trees and ....
Description
Quercus is native to the northern hemisphere, and includes deciduous and evergreen species extending from cold latitudes to tropical Asia and the Americas, as well as Europe. The more southern species tend to be evergreen, keeping their leaves all year round, and the more northern are deciduous, losing their leaves in autumn. Many deciduous species turn bright gold or scarlet in the autumn (Schonbeck and Frey 2005).
Oaks have spirally arranged leaves, with a lobed margin in many species; some have serrated leaves or entire leaves with a smooth margin. Small flowers are produced in spring. The male flowers hang in catkins, and profuse amounts of pollen, while the female flowers are in spikes, both on the same tree (Schonbeck and Frey 2005). The female flowers are wind pollinated by the pollen.
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.
Trees typically are long-lived, with the average life expectancy for most oaks between 200 and 400 years, with some known to be over 800 years old (Schonbeck and Frey 2005).
Most oaks are placed into the two categories of red (or black) oaks and the white oaks (Schonbeck and Frey 2005). The red oaks (section Quercus; synonym sect. Erythrobalanus), such as the scarlet oak (Quercus coccinea) have lobes that are sharp tipped, acorns that mature in 18 months, and the inside of the acorn shell is woolly. The white oaks (section Lobate; synonym sect. Lepidobalanus), such as the white oak (Quercus alba), have leaves that are smooth-lobed, acorns that mature in 6 months, and the inside of the acorn shell is hairless.
The "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 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 hairless acorn shell (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.
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 (eFloras), is often included within Quercus as a distinct subgenus.
Uses
Oak wood has a density of about 0.75 g/cm³, great strength and hardness, and is very resistant to insect and fungal attack because of its high tannin content. It also has very attractive grain markings, particularly when quarter-sawn. Wide, quarter-sawn boards of oak have been prized since the Middle Ages for use in interior panelling of prestigious buildings such as the debating chamber of the British House of Commons in London, England, and in the construction of fine furniture. Oak wood, from Quercus robur and Q. petraea, was used in Europe for the construction of ships until the 19th century, and was the principal timber used in the construction of European timber-framed buildings. Today oakwood is still commonly used for furniture making and flooring, timber frame buildings, and for veneer production. Barrels in which red wines, sherry, brandy and spirits such as Scotch whisky and Bourbon whiskey are aged are made from European and American oak. The use of oak in wine can add many different dimensions to wine based on the type and style of the oak. Oak barrels, which may be charred before use, contribute to the color taste and aroma, of the contents, imparting a desirable oaky vanillin flavour to these drinks. The great dilemma for wine producers is to choose between French and American oakwoods. French oaks (Quercus robur, Q. petraea) give the wine greater refinement and are chosen for best wines since they increase the price compared to those aged in American oak wood. [1] American oak contributes greater texture and resistance to ageing, but produces more violent wine bouquets.[1] Oak wood chips are used for smoking fish, meat, cheeses[2] [3] and other foods.
The bark of Quercus suber, or Cork oak, is used to produce wine stoppers (corks). This species grows in the Mediterranean Sea region, with Portugal, Spain, Algeria and Morocco producing most of the world's supply. Of the North American oaks, the Northern red oak Quercus 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 the deciduous Pedunculate Oak Quercus robur and Sessile Oak Quercus petraea account for most of the European oak production, but evergreen species, such as Holm oak Quercus ilex, and Cork oak Quercus suber also produce valuable timber.
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.[citation needed]
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 beetles, as well as root rot in older trees which may not be apparent on the outside, often only being discovered when the trees come down in a strong gale. Oak apples are galls on oaks made by the gall wasp. The female kermes scale causes galls to grow on kermes oak. Oaks are used as food plants by the larvae of Lepidoptera species.
- See also list of Lepidoptera which feed on Oaks
Also another pest would be the Gypsy moth. The Gypsy Moth is dominant in North America and there are many concerns of the loss of economically critical and ecologically dominant Oak species.
Toxicity
The leaves and acorns of the Oak tree are poisonous to horses in large amounts, due to the toxin tannic acid, and causes kidney damage and gastroenteritis. Additionally, once horses have a taste for the leaves and acorns, they may seek them out. Therefore, horse owners are encouraged to fence out Oak trees from their pasture, especially if forage is scarce. Symptoms of poisoning include lack of appetite, depression, constipation, diarrhea (which may contain blood), blood in urine, and colic.
Cultural significance
The oak is a common symbol of strength and endurance and has been chosen as the national tree of England, Estonia, France, Germany, Lithuania, Poland, the United States and Wales.
In Celtic mythology it is the tree of doors, believed to be a gateway between worlds, or a place where portals could be erected.
Thor's Oak was a sacred tree of the Germanic Chatti tribe. Its destruction marked the Christianisation of the heathen tribes by the Franks[citation needed].
In Classical mythology the oak was a symbol of Zeus and his sacred tree. An example is the oracle of Dodona, which in prehistory consisted solely of a holy oak.
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 examples from the Bible.
The Oak tree is traditionally sacred to Serbs and is widely used throughout Serbia on national and regional symbols both old and new.
Several individual oak trees, such as the Royal Oak in Britain and the Charter Oak in the United States, are of great historical or cultural importance; for a list of important oaks, see Individual oak trees.
Iowa has designated the oak as its official 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. The name of the county comes from the city of Derry, which originally in Irish was known as Doire meaning oak.
There is a proverb, "Mighty oaks from little acorns grow." Another is: "Every majestic oak tree was once a nut who stood his ground."
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 [citation needed].
Raleigh, North Carolina has been nicknamed the "City of Oaks."
The Romania national rugby union team is nicknamed The Oaks.
Oak leaves symbolize rank in the United States Armed Forces. A gold oak leaf indicates an O-4 (Major or 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 Staff corps officers.
Oak leaves were added to the Iron Cross for added status.
Historical note on Linnaean species
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.
ReferencesISBN links support NWE through referral fees
eFloras. n.d. Cyclobalanopsis. Flora of China 4: 380. Retrieved November 19, 2007.
- Byfield, Liz (1990) An oak tree, Collins book bus, London : Collins Educational, ISBN 0-00-313526-8
- Logan, William B. (2005) Oak : the frame of civilization, New York ; London : W.W. Norton, ISBN 0-393-04773-3
- Paterson, R.T. (1993) Use of trees by livestock, 5: Quercus, Chatham : Natural Resources Institute, ISBN 0-85954-365-X
- Royston, Angela (2000) Life cycle of an oak tree, Heinemann first library, Oxford : Heinemann Library, ISBN 0-431-08391-6
- Savage, Stephen (1994) Oak tree, Observing nature series, Hove : Wayland, ISBN 0-7502-1196-2
- Tansley, Arthur G., Sir (1952) Oaks and oak woods, Field study books, London : Methuen, 50 p.
Gallery
A Pedunculate oak in Denmark
An oak tree at night
Bark of Quercus robur
Southern live oak with spanish moss
Quercus mongolica Mongolian Oak in Minnesota Landscape Arboretum
External links
- Flora of North America: Quercus
- Flora of China: Quercus
- Flora Europaea: Quercus
- Oak Trees of the Lowcountry (South Carolina) — Beaufort County Library
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- ↑ 1.0 1.1 (Spanish) La crianza del vino La Razón 23 de Agosto de 2007
- ↑ http://www.williamsdeli.co.uk/product_info.php?cPath=66&products_id=256&osCsid=6f34dc1a878e28ab056ea5482a70e355
- ↑ http://www.swaledalecheese.co.uk/cheese.htm
