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 within 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 robur, the pedunculate oak or English 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 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. It can survive for as long as two centuries. Typically, once it reaches 25 years old, its thick bark can be harvested for cork every 9 to 12 years without causing harm to the tree.
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.
An oak savanna is a type of savanna, where oaks are the dominant trees. It is also generally characterized by an understory that is lush with grass and herb related plants. The terms "oakery" or "woodlands" are also used commonly, though the former is more prevalent when referencing the Mediterranean area. Oak savannas typically exist in areas with low precipitation and feature poor soils. Predominant land uses include rangeland agriculture. Naturally, these savannas depend on natural wildfires to maintain their open vegetation.
Quercus canariensis, the Algerian oak, Mirbeck's oak or zean oak, is an oak native to southern Portugal, Spain, Tunisia, Algeria and Morocco. Despite the scientific name, it does not occur naturally today in the Canary Islands. It is placed in section Quercus.
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.
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.
Quercus × cerrioides is a hybrid oak species in the family Fagaceae. The tree is endemic to Spain. It is a conservation dependent plant threatened by habitat loss. Its parent are Q. canariensis and Q. pubescens subsp. subpyrenaica. Both parents are placed in section Quercus.
Castalagin is an ellagitannin, a type of hydrolyzable tannin, found in oak and chestnut wood and in the stem barks of Terminalia leiocarpa and Terminalia avicennoides.
Quercus ithaburensis, the Mount Tabor oak, is a tree in the beech family Fagaceae. It is found from southeastern Italy to the Levant. It is the national tree of Jordan. Two subspecies are accepted, Quercus ithaburensis subsp. ithaburensis and Quercus ithaburensis subsp. macrolepis. Together with Quercus brantii, it forms a clade of distinct, closely related species within the oak section Cerris.
Quercus porphyrogenita is a species of oak in the family Fagaceae, native to northeastern Mexico.
Quercus urbani, also known as Quercus urbanii, is a species of oak. It is native to western and central Mexico from Sinaloa, Durango, and Zacatecas to Oaxaca. It was previously synonymized with Quercus pennivenia, but this was restored as an independent species in 2020.
Quercus vulcanica is a species of flowering plant in the Fagaceae family. It is referred to by the common name Kasnak oak, and is a rare species of tree native to Lebanon, Syria, and Turkey. It is placed in section Quercus.
Quercus pseudococcifera is a species of flowering plant in the beech family Fagaceae, native to the west and central Mediterranean.
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.
This fossil flora in Turkey stems from at least six Pliocene deposits in Güvem and Beşkonak villages, 80 kilometres (50 mi) north of Ankara, 22 kilometres (14 mi) north of Kızılcahamam and 125 kilometres (78 mi) south of the Black Sea coast. They are 1,000 metres (3,300 ft) to 1,500 metres (4,900 ft) above sea level, extending 15 kilometres (9.3 mi) north-south and 7 kilometres (4.3 mi) east-west. Between six and seven million years ago, a fresh water lake existed there in a forested area with mostly broad leaved deciduous tree species, dominated by sequoia and oak.
Quercus subgenus Quercus is one of the two subgenera into which the genus Quercus was divided in a 2017 classification. It contains about 190 species divided among five sections. It may be called the New World clade or the high-latitude clade; most species are native to the Americas, the others being found in Eurasia and northernmost North Africa.
