Quercus suber
An evergreen oak that produces cork for stoppers and flooring.
The cork oak (*Quercus suber*) is a medium-sized, evergreen tree belonging to the oak section *Cerris*. It is the main source of natural cork, used for wine bottle stoppers, flooring, and the cores of cricket balls. The tree is native to southwestern Europe and northwestern Africa, and it is an ancient species, with fossils dating to the Tertiary period. It can live for over 400 years, though harvested specimens typically reach 150 to 200 years. Once a tree is about 25 years old, its thick bark can be stripped every 9 to 12 years without harming it.
This oak grows to an average height of 10 to 15 meters, occasionally reaching 25 meters, with a trunk diameter of 50 to 100 centimeters. It forms a dense, asymmetrical crown starting 2 to 3 meters above the ground, often splitting into several rounded partial crowns. Young twigs are densely hairy and light gray or whitish; older branches are strong and knotty. The trunk’s most distinctive feature is its thick, cracked cork bark, which is light and spongy, white on the outside and red to red-brown inside. After harvesting, the trunk appears reddish brown but darkens over time. The wood is ring-pored, with brown heartwood and light reddish sapwood. The tree develops a deep taproot, up to 1 to 2 meters, 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; the underside is whitish and densely hairy, though young trees lack this hair. Leaf stalks are 6 to 18 millimeters long and hairy, with two narrow, lance-shaped, bright red stipules at the base that fall off in the first year. New leaves appear in April and May, while older leaves drop. Leaves usually stay on the tree for two to three years, but severe conditions or cold winters can cause earlier shedding or complete defoliation.
The cork oak is monoecious, with both male and female flowers on the same tree. Female flowers grow in upright clusters in the leaf axils of young branches, with a hairy axis 5 to 30 millimeters long bearing two to five separate flowers. Each female flower has a small, hairy, four- to six-lobed envelope and three to four styles. Male catkins also arise from leaf axils; they start bright red and upright, then become
- field
- Botany
- known_for
- Primary source of cork for wine bottle stoppers
- native_range
- Southwest Europe and northwest Africa
- max_height
- Up to 25 m
- max_lifespan
- Over 400 years
Lore & Background
The cork oak grows as an evergreen tree, reaching an average height of 10 to 15 metres, with a trunk diameter of 50 to 100 centimetres. Its thick, longitudinally cracked cork layers are characteristic, and the cambium forms a cork layer 3 to 5 cm thick. The tree develops a taproot reaching 1 to 2 m deep, with horizontal side roots extending several meters. It can live over 400 years, and harvested specimens can be 150 to 200 years old.
The leathery leaves are alternate, 2.5 to 10 cm long, with five to seven sharp teeth on each edge. The upper side is light green, the underside whitish and densely hairy. New leaves appear in April and May, staying on the tree for two to three years. The cork oak is monoecious, with both female and male flowers on one specimen. Female flowers form upright inflorescences in leaf axils, while male catkins are bright red at first, later yellow and pendulous.
The fruit clusters carry two to eight acorns, about half enclosed in a cupule. Acorns vary from 2 to 4.5 cm in length. Two subspecies are distinguished: Quercus suber subsp. suber and Quercus suber subsp. occidentalis, the latter found along the Portuguese Atlantic coast. The cork oak forms hybrids with the Turkey oak and the holm oak.
Reader's Guide
Quercus suber is significant as the primary source of cork for wine bottle stoppers, cork flooring, and cricket ball cores. Its thick bark can be harvested every 9 to 12 years once the tree reaches 25 years old, without causing harm. The tree endures drought and makes little demand on soil quality, and is regarded as a defence against desertification. Cork oak woodlands are home to a multitude of animal and plant species. However, as cork for sealing bottles is increasingly displaced by other materials, these forests are at risk as part of the cultural landscape, threatening animal species such as the Iberian lynx and imperial eagles with extinction. The species needs a lot of light, loves warmth, and can withstand temperatures down to -10 °C without major damage. It is considered a pyrophyte because it recovers quickly after forest fires, protected by its cork. Outside its natural range, it is cultivated in the Crimea, the Caucasus, India, and the Southwestern United States.
Did You Know?
- The cork oak can survive for as long as two centuries, and harvested specimens can be 150 to 200 years old.
- Its thick bark can be harvested every 9 to 12 years without causing harm to the tree.
- The cork oak is considered a pyrophyte because it recovers quickly after forest fires, protected by its cork.
- Cork oak woodlands are home to the Iberian lynx and imperial eagles, which are threatened with extinction due to declining cork use.
More in Flowering Trees & Shrubs 1-20
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