The genus Quercus, in the family Fagaceae, is commonly referred to as oak. The group comprises more than 500 species and several hybrids and includes deciduous and evergreen species. The genus is native of the Northern Hemisphere and is therefore a genus that migrated during the Pleistocene, from the cool northern temperature zone to the tropics in the south.
Although the geological history of this genus could be traced back to the early Paleocene, the earliest reliable Quercus fossil in North America is from the Middle Eocene Oregon flora.
The leaves are spirally arranged and have various shapes, colors and textures with the margins entire, lobed, or toothed. The fruit is a nut called an acorn. The leaves and acorns of the oak posses a toxicity risk due the presence of tannic acid and may cause kidney damage and gastroenteritis. The pollen grain, Quercoidites, is tricolporate.
Oak wood was used in the construction of European timber-framed buildings and for the construction of ships until the 19th century.
In Greek mythology, the oak is the tree sacred to Zeus, while in the Norse mythology, the oak was sacred to the thunder god, Thor. Today, the oak is still a symbol of strength and endurance and has been chosen as the national tree of many countries.
Edith L. Taylor,Thomas N. Taylor,Michael Krings, 2009, Paleobotany: The Biology and Evolution of Fossil Plants, Academic Press.
Xing et al, 2013, A new Quercus species from the upper Miocene of southwestern China and its ecological significance, Review of Palaeobotany and Palynology, Elsevier.