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OAK
- (Quercus) Oak is a tree or shrub
in the genus Quercus (pronounced /ˈkwɜrkəs/;[1] Latin "oak tree"), of
which about 400 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 cold latitudes to tropical Asia and the Americas.
Oaks have spirally arranged leaves, with a lobed margin in many species;
some have serrated leaves or entire leaves with a smooth margin. 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. |