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Quercus
Also called Acorn, Oaks, Oak Tree
Oaks (genus Quercus) are large, long-lived hardwood trees and some shrubs, with about 475 species, both deciduous and evergreen. Most garden and houseplant interest is in young nursery trees or small container-grown oaks, which need full sun and room to grow.
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, with some 475 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.
Ecologically, oaks are keystone species in habitats from Mediterranean semi-desert to subtropical rainforest. They live in association with many kinds of fungi, including truffles. Oaks support more than 950 species of caterpillar, many kinds of gall wasp which form distinctive galls (roundish woody lumps such as the oak apple), and a large number of pests and diseases.
The leaves and acorns of oaks are poisonous to livestock, including cattle and horses, if eaten in large amounts, due to the toxin tannic acid, which causes kidney damage and gastroenteritis. An exception is the domestic pig, which, under the right conditions, may be fed entirely on acorns, and has traditionally been pastured in oak woodlands (such as the Spanish dehesa and the English system of pannage). Humans can eat acorns after leaching out the tannins in water.
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.
Quercus affinis · Coast Live Oak · White Oak · Golden Oak · Scrub oak · Brant's oak · Turkey Oak · Canyon Live Oak · Scarlet Oak · Daimyo oak · Blue oak · Leather oak
Text excerpted from the Wikipedia article Oak by its contributors, under CC BY-SA 4.0; the excerpts and the care summary drawn from them are shared under the same licence.
The care summary was written by AI (Claude, Anthropic) from the sources on this page, with general growing knowledge where they are silent. Check before relying on it.
