The cork oak (Quercus suber) is an arboreal species of medium size and evergreen foliage that belongs to the Fagaceae family. Natural of the Mediterranean basin, it usually forms dense and leafy forests, especially in hot and humid environments.
Robust in appearance and slow growing, it is 10-15 m high, sometimes reaching 25 m, it has an abundant and irregular crown. Its main characteristic is a thick cracked and waxy bark that is collected periodically due to its restoration capacity once harvested..
It grows on loose soils, slightly acidic and devoid of lime, in areas with a cool and somewhat humid climate with a certain coastal influence. Unlike other species of the genus Quercus, this species does not tolerate soils of limestone origin and is susceptible to frost.
The cork oak is a very prolific tree from which cork, wood and its acorns are used. Cork is used in the manufacture of stoppers for the wine industry, soles for footwear, ropes and sheets for thermal or acoustic insulation..
On the other hand, the hard and tenacious wood is used in the manufacture of barrels and shipbuilding, as well as fuelwood for combustion. In addition, acorns are the ideal food to fatten Iberian pigs, and in some urban areas it is sown as an ornamental species.
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Quercus suber it is a monoecious species of evergreen foliage that often reaches 20-25 m in height. In its juvenile stage it is an erect tree, which with age tends to stoop and bend.
It is characterized by its thick, rough and cracked bark of dark color that is generally used as cork. This fabric over 15 cm thick is light, fluffy and greyish which, when pulled off, leaves the trunk smooth reddish in color.
Generally a stubby looking tree shorter than the species Quercus blush. Its broad and lower branches present a sinuous and longitudinal growth, crowned by a wide and compact, oval and irregular crown..
The simple, alternate and persistent leaves present a great morphological variation. They are 4-8 cm long and their margins can be lobed or serrated. The leathery leaflets, ovate and curved downwards, are greyish and slightly pubescent on the underside, also green and shiny on the upper surface..
The rib consists of an undulating central rib attached at right angles to 5-7 pairs of secondary ribs. In fact, this characteristic facilitates its differentiation from holm oaks, whose central vein presents a less open joint angle..
On the other hand, despite being a perennial species, the leaves of the cork oak regenerate every two years. However, depending on environmental conditions and cultural management, they tend to remain on the plant for 11 to 23 months..
The cork oak as a monoecious species has female and male flowers on the same trunk. Its flowering occurs between April and June, being the pollination anemophilous, that is, with the intervention of the wind.
The small male flowers of yellowish tones are grouped in hanging inflorescences or catkins 4-8 cm in length. The female ones grow solitary or paired in an axillary position under the leaves..
Its fruit is a 2-3 cm long green acorn sitting in a deep cup with elongated scales and a greyish hue. When ripe, from September to December, or early January, the acorn turns brown.
Acorns with an intense bitter taste, superior to the taste of holm oak acorns, are edible. Indeed, they are used as a nutritional supplement for livestock and constitute the usual sustenance for wildlife.
This species is characterized by its bark composed of a thick layer of cork deeply furrowed at the longitudinal level of greyish-brown color. On Quercus suber, the tissue that forms the cork has the ability to regenerate itself each time the bark is detached.
Cork is an insulating fabric that has a secondary origin from a fabric external to the cambium. In fact, it is made up of dead cells whose cell wall contains a natural polymer made up of fatty acids, epoxides and hydroxides called suberin..
This substance allows the cork to retain air, but makes it waterproof by preventing the passage of water and the retention of moisture. Its main function on the plant is to prevent water loss and protect the trunk from strong changes in temperature..
- Kingdom: Plantae
- Subkingdom: Tracheobionta
- Division: Magnoliophyta
- Class: Magnoliopsida
- Subclass: Hamamelidae
- Order: Fagales
- Family: Fagaceae
- Gender: Quercus
- Subgenre: Quercus
- Section: Cerris
- Species: Quercus suber L.
- Quercus suber F. brevicupulata (Batt. & Trab.) F.M. Vazquez 1998
- Quercus suber F. clavata (Cout.) F.M. Vazquez 1998
- Q. suber F. dolichocarpa (A. Camus) F.M. Vazquez 1998
- Q. suber F. longicalyx (A. Camus) F.M. Vazquez 1998
- Quercus go up F. macrocarpa (Willk. & Lange) F.M. Vazquez 1998
- Quercus suber F. microcarpa (Batt. & Trab.) F.M. Vazquez 1998
- Q. suber F. racemosa (Borzí) F.M. Vazquez 1998
- Q. suber F. suboccultata (Cout.) F.M. Vazquez 1998
- Quercus: the name of the genus comes from Latin to designate oak and holm oak in a similar way.
- go up: specific adjective derived from Latin meaning "cork".
- Quercus mitis Banks ex Lowe, Trans. Cambridge Philos. Soc. 4 (1): 15 (1831).
- Quercus corticosa Raf., Alsogr. Amer .: 24 (1838).
- Q. occidentalis Gay, Ann. Sci. Nat., Bot., IV, 6: 243 (1856).
- Q. suberosa Salisb. in A.P. de Candolle, Prodr. 16 (2): 392 (1864).
- Quercus will rise St.-Lag., Ann. Soc. Bot. Lyon 7: 133 (1880).
- Quercus cintrana Welw. ex Nyman, Consp. Fl. Eur .: 662 (1881).
- Q. sardoa Gand, Fl. Eur. 21:58 (1890), opus utique oppr.
- Q. occidentalis F. heterocarp Globa-Mikhailenki, Byull. Glavn. Bot. Sada 80: 29 (1971).
Quercus suber it is a native species of the Mediterranean basin, southwestern Europe and northwestern Africa. It is even found in the wild in Morocco, Algeria, Tunisia, Spain, Portugal, France, Italy and the islands of Sardinia, Corsica and Sicily..
In the Iberian Peninsula it predominates in the southwestern quadrant, being cultivated as an ornamental in parks and gardens, especially in the region of Andalusia. Some references place the origin of the Quercus suber in the Iberian Peninsula, a region where it currently has great phenotypic diversity.
In Portugal and Spain it is widely marketed for its high quality cork used in the wine industry. Likewise, it is found in the wild throughout the Eastern Pyrenees, in the Italian peninsula and the region of the former Yugoslavia.
This species grows on soils of siliceous origin with good drainage, in regions of cold and humid winters, but not very dry warm summers. On hills or slopes with low inclination, between 300-600 meters above sea level and even up to 1,000 meters above sea level.
The optimum temperature range oscillates between 13-18 ºC of annual average, being the winter cold a limitation of growth at continental level. Usually, its vegetative activity is paralyzed at temperatures below 3 ºC and it does not tolerate values below 0 ºC..
It requires full sun exposure as an adult, but during its juvenile phase it requires a certain level of semi-shading. Regarding humidity levels, it adapts to rainfall values greater than 450 mm per year, its optimum being between 600-1,000 mm per year.
On the other hand, it has particular edaphic requirements, since it only develops on acid substrates with good drainage and excellent aeration. It is a calcifugal species, that is, it does not develop on soils rich in calcium or magnesium carbonates, unless they are fully decarbonated.
It is one of the most representative species of Mediterranean forests. Indeed, it requires a greater amount of humidity, is susceptible to low temperatures and does not support limestone soils compared to holm oaks more adapted to continental conditions..
These plants reproduce sexually by seeds, being collected directly from the tree and stored for a short time in humid and cold environments. For its use, the dome that covers the seed must be eliminated through a process of screening, winnowing and flotation..
Cork oak seeds do not require a pregerminative treatment, but it is advisable to soak them for 48 hours before sowing. The seeds collected in autumn can be stratified in sand or humid peat for 30-60 days at 0-2 ºC to favor their rooting..
Sowing is done in autumn with freshly collected seeds or in spring with previously stratified seeds. When the seeds have been stratified, there is a small root of 2-5 cm in length, which is recommended to prune before sowing..
Under nursery conditions, sowing is done in polyethylene bags with fertile and humid substrate. Maintaining the conditions of temperature and humidity, germination begins 4-6 weeks after sowing. The seedlings will be ready for transplanting at 25-40 cm tall.
It adapts to various types of soils, whether they are loose, deep, well drained and slightly acidic, never of calcareous origin. In addition, it requires full sun exposure to develop properly.
During its juvenile phase, it needs regular watering during summer and spring, with less intensity during autumn and winter. Adult plants, already established and well rooted, are more resistant to drought and require occasional watering..
It grows effectively in Mediterranean conditions with a mild climate and less intense frosts, where the sea breeze softens the temperature and the environment is more humid. On the contrary, the ripening of the fruits would be delayed if the plant is grown in cold and temperate climates..
In the growth phase, it is recommended to carry out maintenance pruning during the spring, in order to structure a rounded crown. Likewise, it is necessary to perform sanitation pruning frequently during autumn and winter to eliminate damaged, dry or diseased branches..
The cork oak is a rustic, undemanding and low-maintenance species that is not exempt from the attack of certain pests or diseases. Among these, the beetle stands out Coraebus undatus that feed on cork and phytopathogenic fungi such as Phytophthora sp. Y Botryosphaeria sp.
The beetle Coraebus undatus It is a monophagous species that feeds exclusively on the cork of the cork oak, causing serious damage. In turn, the larvae of some Lepidopterans of the Noctuidae family feed on the foliage causing great losses. If the attacks are severe, chemical control is required.
The soil phytopathogenic fungus Phytophthora cinnamomi It is the causal agent of root rot that occurs during the establishment of the crop. The symptoms are manifested as chlorosis, leaf spots, defoliation and the progressive death of branches and apical shoots. The best control is the elimination of infected plants.
The chanco is caused by the pathogen Botryosphaeria dothidea manifested as cortical lesions at the level of branches and bark. Once the disease is detected, the tree must be isolated. Control measures are usually of the preventive type since curative techniques are inefficient.
Quercus suber it is one of the species of the genus Quercus of greatest economic importance in the region of influence of the Mediterranean basin. From the bark of this tree, a high quality cork is obtained every 8-10 years used at an industrial level as buoys, floats, plugs or shoe soles..
In addition, its firm and hard wood is made of handles for tools and musical instruments, as well as for cooperage. On the other hand, the fruits of high nutritional content are used as a nutritional supplement for pigs..
The main use of the cork obtained from the bark of the cork oak is in the production of stoppers for wine bottles. It is also used for the manufacture of insulating material, shoe inserts, floats, washers, gaskets, handles for fishing rods and sheets or planks..
Cork has been used as an insulator to protect homes from the severe cold during the winter or to cool down during the summer. It is obtained by separating it from the trunk, leaving only a thin layer that constitutes the secondary phloem that is regenerated into new cork.
The first cork is separated when the plant is 22-25 years old, from there every 9-12 years a new harvest can be made. Due to its regenerative capacity, the cork of the cork oak can be harvested 12-15 times during its useful life.
Cork is considered a renewable resource, since its harvest does not damage the tree and is renewed each time it is cut. Its harvest does not damage the tissues of the stem, obtaining a better quality cork from the third.
The cork industry is generally considered environmentally friendly. In fact, cork production is a sustainable process and cork waste is easily recyclable..
Large plantations of cork oaks, either alone or in association with other species, prevent the desertification of intervened areas. In addition, they are home to various wild and endangered species such as the imperial eagle and the Iberian lynx..
On the other hand, cork oak forests provide an economic value associated with livestock, grazing, hunting, cultivation and mushroom gathering. Indeed, these forests present a social importance related to traditional forestry and agricultural practices.
Acorns have a high content of carbohydrates, fats and proteins that favors their use as forage or food supplement for livestock. Indeed, the cork oak acorns, together with other species, form the food base of the Iberian pig, resulting in a ham with an excellent aroma.
The species Quercus suber It has a wide and dense crown, being of adequate size to plant as an ornamental in parks, squares and large gardens..
The bark of the cork oak has certain chemical elements such as tannins that provide it with astringent properties. In addition, it has anti-inflammatory and analgesic properties useful for the treatment of gingivitis or inflammation of the gums..
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