An oak is a tree or shrub in the genus Quercus ( /ˈkwɜrkəs/; Latin "oak tree"), of which about 600 species exist. "Oak" may also appear in the names of species in related genera, notably Lithocarpus. The genus is native to the Northern Hemisphere, and includes deciduous and evergreen species extending from cool temperate to tropical latitudes in Asia and the Americas.
Oaks have spirally arranged leaves, with lobed margins in many species; some have serrated leaves or entire leaves with smooth margins. Many deciduous species are marcescent, not dropping dead leaves until spring. The flowers are catkins, produced in spring. The fruit is a nut called an acorn, borne in a cup-like structure known as a cupule; each acorn contains one seed (rarely two or three) and takes 6–18 months to mature, depending on species. The live oaks are distinguished for being evergreen, but are not actually a distinct group and instead are dispersed across the genus.
Read more about Oak: Classification, Hybridization, Uses, Biodiversity and Ecology, Diseases and Pests, Toxicity, Historical Note On Linnaean Species
Famous quotes containing the word oak:
“Where he swings in the wind and rain,
In the sun and in the snow,
Without pleasure, without pain,
On the dead oak tree bough.”
—Edward Thomas (1878–1917)
“Alas for America as I must so often say, the ungirt, the diffuse, the profuse, procumbent, one wide ground juniper, out of which no cedar, no oak will rear up a mast to the clouds! It all runs to leaves, to suckers, to tendrils, to miscellany. The air is loaded with poppy, with imbecility, with dispersion, & sloth.”
—Ralph Waldo Emerson (1803–1882)
“The leaves are all dead on the ground,
Save those that the oak is keeping”
—Robert Frost (1874–1963)