Oak
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 is a genus of about 150 species of flowering plant [i]s in the family Fagaceae [i], ...
and
Lithocarpus is a genus in the beech [i] family Fagaceae [i], differing from Quercus [i] in the erect ...
. 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.
Encyclopedia
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 is a genus of about 150 species of flowering plant [i]s in the family Fagaceae [i], ...
and
Lithocarpus is a genus in the beech [i] family Fagaceae [i], differing from Quercus [i] in the erect ...
. 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 and takes 6-18 months to mature, depending on species. The
"live oaks" 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 , the white 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 .
- 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 , 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 bristles at the lobe tip.
Full list of Quercus speciesHybrids 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 is a genus of about 150 species of flowering plant [i]s in the family Fagaceae [i], ...
, here treated as a distinct genus following the , 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/cm
3.
The bark of
Quercus suber, or
Cork oak, is used to produce
wine stoppers . 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
barrels where wine and other spirits are
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 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.
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 to stimulate sprouting. Most white oaks need immediate stratification; species such as the
Chestnut oak 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 is a
water mould that can kill oaks within just a few weeks. Oak Wilt, caused by the fungus
Ceratocystis fagacearum , is also a lethal disease of some oaks, particularly the red oaks . 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.
- See also list of Lepidoptera which feed on Oaks
Cultural significance
The oak is a common
symbol of
strength and endurance, and has been chosen as the national tree of
England,
France,
Germany and the
United States.
In classical mythology the oak was a symbol of
Zeus and his sacred tree.
The name of the
druids, the
Celtic priests, stems from the words for oak and for
knowledge.
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 .
Iowa designated the oak as its official
state tree in 1961, and the White Oak is the state tree of
Connecticut and
Maryland.
There is a proverb, 'Mighty oaks from tiny
acorns grow'.
There are many woods that 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 .
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 , 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
External links
