An oak is a tree or shrub in the genus Quercus of the beech family, Fagaceae. There are approximately 500 extant species of oaks. The common name "oak" also appears in the names of species in related genera, notably Lithocarpus, as well as in those of unrelated species such as Grevillea robusta and the Casuarinaceae (she-oaks). 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.
The Fagaceae are a family of flowering plants that includes beeches, chestnuts and oaks, and comprises eight genera with about 927 species. Fagaceae in temperate regions are mostly deciduous, whereas in the tropics, many species occur as evergreen trees and shrubs. They are characterized by alternate simple leaves with pinnate venation, unisexual flowers in the form of catkins, and fruit in the form of cup-like (cupule) nuts. Their leaves are often lobed and both petioles and stipules are generally present. Their fruits lack endosperm and lie in a scaly or spiny husk that may or may not enclose the entire nut, which may consist of one to seven seeds. In the oaks, genus Quercus, the fruit is a non-valved nut called an acorn. The husk of the acorn in most oaks only forms a cup in which the nut sits. Other members of the family have fully enclosed nuts. Fagaceae is one of the most ecologically important woody plant families in the Northern Hemisphere, as oaks form the backbone of temperate forest in North America, Europe, and Asia, and are one of the most significant sources of wildlife food.
Quercus robur, the pedunculate oak, is a species of flowering plant in the beech and oak family, Fagaceae. It is a large tree, native to most of Europe and western Asia, and is widely cultivated in other temperate regions. It grows on circumneutral soils in the lowlands and is notable for its value to natural ecosystems, supporting a very wide diversity of herbivorous insects and other pests, predators and pathogens.
Quercus ilex, the evergreen oak, holly oak or holm oak is a large evergreen oak native to the Mediterranean region. It is a member of the Ilex section of the genus, with acorns that mature in a single summer.
Quercus suber, commonly called the cork oak, is a medium-sized, evergreen oak tree in the section Quercus sect. Cerris. It is the primary source of cork for wine bottle stoppers and other uses, such as cork flooring and as the cores of cricket balls. It is native to southwest Europe and northwest Africa. In the Mediterranean basin the tree is an ancient species with fossil remnants dating back to the Tertiary period.
Quercus petraea, commonly known as the sessile oak, Cornish oak, Irish Oak or durmast oak, is a species of oak tree native to most of Europe and into Anatolia and Iran. The sessile oak is the national tree of Ireland, and an unofficial emblem in Wales and Cornwall.
Live oak or evergreen oak is any of a number of oaks in several different sections of the genus Quercus that share the characteristic of evergreen foliage. These oaks are not more closely related to each other than they are to other oaks.
Quercus laevis, the turkey oak, is a member of the red oak group of oaks. It is native to the southeastern United States. The name turkey oak derives from the resemblance of the leaves to a turkey's foot. A Turkish and southern European species Quercus cerris is also commonly referred to as Turkey oak, so Quercus laevis is sometimes referred to as American turkey oak to distinguish it from the European species.
Quercus frainetto, commonly known as the Hungarian oak or Italian oak, is a species of oak, native to southeastern Europe and Turkey; it is classified in Quercus sect. Mesobalanus.
Quercus trojana, the Macedonian oak is an oak in the turkey oak section (Quercus sect. Cerris).
Quercus glauca, commonly called ring-cupped oak or Japanese blue oak, is a tree in the beech family (Fagaceae). It is native to eastern and southern Asia, where it is found in Afghanistan, Bhutan, China, northern and eastern India, southern Japan, Kashmir, Korea, Myanmar, Nepal, and Vietnam.
Quercus acutissima, the sawtooth oak, is an Asian species of oak native to China, Tibet, Korea, Japan, Indochina and the Himalayas. It is widely planted in many lands and has become naturalized in parts of North America.
Quercus faginea, the Portuguese oak, is a species of oak native to the western Mediterranean region in the Iberian Peninsula. Similar trees in the Atlas Mountains of northwest Africa are usually included in this species, or sometimes treated as a distinct species, Quercus tlemcenensis. It occurs in mountains from sea level to 1,900 metres above sea level, and flourishes in a variety of soils and climates. Out of all the oak forests in the Iberian Peninsula, the southern populations of Portuguese oak were found to have the highest diversity and endemism of spider species.
Phyllonorycter roboris is a moth of the family Gracillariidae. It is found in all of Europe.
Phyllonorycter harrisella is a moth of the family Gracillariidae. It is found in all of Europe, except the Balkan Peninsula and the Mediterranean islands.
Urospermum dalechampii, the smooth golden fleece, is a perennial herbaceous plant belonging to the genus Urospermum of the family Asteraceae.
Quercus pyrenaica, commonly known as Pyrenean oak, is a tree native to southwestern Europe and northwestern North Africa. Despite its common name, it is rarely found in the Pyrenees Mountains and is more abundant in northern Portugal and north and northwestern Spain.
Quercus × hispanica, commonly known as Spanish oak, is tree in the family Fagaceae. It is a hybrid between the European trees Turkey oak and cork oak.
Trinia is a genus of flowering plant in the family Apiaceae, native from Europe to Iran and western Siberia. The genus was first described by Georg Franz Hoffmann in 1814.
