Quercus suber

The cork oak, *Quercus suber*, is a medium-sized evergreen tree belonging to the *Cerris* section of oaks. It is the main source of natural cork, used for wine bottle stoppers, cork flooring, and the cores of cricket balls. This tree is native to southwestern Europe and northwestern Africa, and it is an ancient species in the Mediterranean region, with fossil evidence from the Tertiary period.

It can live for more than 400 years, though harvested specimens typically reach 150 to 200 years. The tree grows to an average height of 10 to 15 meters, occasionally up to 25 meters, with a trunk diameter of 50 to 100 centimeters. Its dense, asymmetrical crown begins 2 to 3 meters above the ground and spreads widely in open-grown trees. Young twigs are densely hairy and light gray or whitish, while older branches are strong and knotty. The bark is thick, gray-brown, and deeply cracked, with a cork layer 3 to 5 centimeters thick that is light, spongy, grayish-brown on the outside, and red to red-brown inside. After cork is harvested, the trunk appears reddish brown before darkening. The wood is ring-pored with brown heartwood and light reddish sapwood. A taproot reaches 1 to 2 meters deep, with long horizontal side roots.

The leathery leaves are alternate, 2.5 to 10 centimeters long and 1.2 to 6.5 centimeters wide, varying from round to oval to lanceolate-oval. Each leaf has five to seven sharp teeth on both edges and a pointed tip. The upper side is light green, while the underside is whitish and densely hairy, except on young trees. Leaf stalks are 6 to 18 millimeters long and hairy, with two narrow, lanceolate, bright red stipules at the base that fall off in the first year. New leaves appear in April and May as older leaves are shed. Leaves usually stay on the tree for two to three years, but can fall after one year under harsh conditions; extremely cold winters may cause complete defoliation.

The cork oak is monoecious, with both male and female flowers on the same tree. Female flowers grow in upright clusters of two to five in the leaf axils of young branches, on a hairy axis 5 to 30 millimeters long. Each female flower has a small, hairy, four- to six-lobed envelope and three to four styles. Male catkins also arise from leaf axils, starting bright red and upright, then becoming yellow and pendulous, 4 to 7 centimeters long, with a whitish hairy axis.