An oak is a hardwood tree or shrub in the genus Quercus of the beech family. They have spirally arranged leaves, often with lobed edges, and a nut called an acorn, borne in a cup. The genus is widely distributed in the Northern Hemisphere; it includes some 500 species, both deciduous and evergreen. Fossil oaks date back to the Middle Eocene. Molecular phylogeny shows that the genus is divided into Old World and New World clades, but many oak species hybridise freely, making the genus's history difficult to resolve.
Quercus kelloggii, the California black oak or Kellogg oak, is an oak in the red oak section native to western North America. Although genetically separated from them for more than 20 million years, its leaves are remarkably similar in appearance to several other members of the red oak section including the red oak and the black oak found in eastern and central North America.
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 soils of near neutral acidity 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 bicolor, the swamp white oak, is a North American species of medium-sized trees in the beech family. It is a common element of America's north central and northeastern mixed forests. It can survive in a variety of habitats. It forms hybrids with bur oak where they occur together in the wild.
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.
An oak savanna is a type of savanna—or lightly forested grassland—where oaks are the dominant trees. The terms "oakery" or "woodlands" are also used commonly, though the former is more prevalent when referencing the Mediterranean area. These savannas were maintained historically through wildfires set by lightning, humans, grazing, low precipitation, and/or poor soil.
Quercus pubescens, commonly known as the downy oak, pubescent oak or Italian oak, is a species of white oak native to southern Europe and southwest Asia. It is found from northern Spain (Pyrenees) and France in the West to Turkey and the Caucasus in the East.
The purple hairstreak is a butterfly in the family Lycaenidae distributed throughout much of Europe, North Africa, Anatolia, Caucasia, and Transcaucasia. The larva feeds on Quercus robur, Quercus petraea, Quercus cerris and Quercus ilex.
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 dentata, also called Japanese emperor oak or daimyo oak is a species of oak native to East Asia. The name of the tree is often translated as "sweet oak" in English to distinguish it from Western varieties. It is placed in section Quercus.
The woodlands of the Iberian Peninsula are distinct ecosystems on the Iberian Peninsula. Although the various regions are each characterized by distinct vegetation, the borders between these regions are not clearly defined, and there are some similarities across the peninsula.
Andricus quercuscalicis is a gall wasp species inducing knopper galls.
Lapiș Forest nature reserve IUCN category IV, is located in northwestern Romania, in the west of Sălaj County, near the village of Nușfalău, which is about 9 km from Șimleu Silvaniei.
Polonezköy Nature Park is a nature park in the village of Polonezköy in Istanbul, Turkey.
Quercus serrata, the jolcham oak, is an East Asian species of tree in the beech family. It is native to China, Taiwan, Japan, and Korea.
Quercus hartwissiana, the Strandzha oak, is a species of oak, native to southeastern Bulgaria, northern Asia Minor along the Black Sea, and the Caucasus. It was described by the Finnish-born Russian botanist and entomologist Christian von Steven in 1857.
Avcıkoru Nature Park is a nature park located in Şile district of Istanbul Province, Turkey.
Orchestes pilosus is a beetle of the family Curculionidae found in Europe. It was first described by Johan Christian Fabricius in 1781. The larvae are leaf miners on oak.
Oak regeneration failure is a woodland phenomenon whereby insufficient seedling- and sapling-sized oak (Quercus) trees are recruited into the canopy to replace dead mature oaks. The result is a local population decline in oaks while other more shade-tolerant trees such as maple, lime, and ash may become more prominent. Oak regeneration failure has been observed across Eastern and Midwestern forests in the United States as well as in Europe.
