Scarlet oak acquiring colour in September

Quercus coccinea, the scarlet oak, is an oak in the red oak section Quercus sect. Lobatae. The scarlet oak can be mistaken for the pin oak, the black oak, or occasionally the red oak. On scarlet oak the sinuses between lobes are "C"-shaped in comparison to pin oak (Q. palustris), which has "U"-shaped sinuses and the acorns are half covered by a deep cap.

Scarlet oak is mainly native to the eastern United States, from southern Maine west to eastern Oklahoma, and south to southern Alabama. It is also native in the extreme south of Ontario, Canada. It occurs on dry, sandy, usually acidic soils. It is often an important canopy species in an oak-heath forest.

It is a medium-large deciduous tree growing to 20-30 m tall with an open, rounded crown. The leaves are glossy green, 7-17 cm long and 8-13 cm broad, lobed, with seven lobes, and deep sinuses between the lobes. Each lobe has 3-7 bristle-tipped teeth. The leaf is hairless (unlike the related pin oak, which has tufts of pale orange-brown down where the lobe veins join the central vein). The common English name is derived from the autumn coloration of the foliage, which generally becomes bright scarlet; in contrast, pin oak foliage generally turns bronze in autumn. The acorns are ovoid, 7-13 mm broad and 17-31 mm long, a third to a half covered in a deep cup, green maturing pale brown about 18 months after pollination; the kernel is very bitter.

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 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. 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.

The family Fagaceae, or beech family, comprises about 900 species of both evergreen and deciduous trees and shrubs, which are characterized by alternate simple leaves with pinnate venation, unisexual flowers in the form of catkins, and fruit in the form of cup-like (cupule) nuts. Fagaceous leaves are often lobed and both petioles and stipules are generally present. Fruits lack endosperm and lie in a scaly or spiny husk that may or may not enclose the entire nut, which may consist of one to seven seeds. The best-known group of this family is the oaks, genus Quercus, the fruit of which is a non-valved nut (usually containing one seed) called an acorn. The husk of the acorn in most oaks only forms a cup in which the nut sits.

Several members of the Fagaceae have important economic uses. Many species of oak, chestnut, and beech (genera Quercus, Castanea, and Fagus respectively) are commonly used as timber for floors, furniture, cabinets, and wine barrels. Cork for stopping wine bottles and a myriad of other uses is made from the bark of cork oak, Quercus suber. Chestnuts, a tasty treat enjoyed by many in the winter, are the fruits from species of the genus Castanea. Numerous species from several genera are prominent ornamentals, and wood chips from the genus Fagus are often used in flavoring beers.