''Quercus suber'', commonly called the cork oak, is a medium-sized,
evergreen
In botany, an evergreen is a plant which has foliage that remains green and functional through more than one growing season. This also pertains to plants that retain their foliage only in warm climates, and contrasts with deciduous plants, whic ...
oak
An oak is a tree or shrub in the genus ''Quercus'' (; Latin "oak tree") of the beech family, Fagaceae. There are approximately 500 extant species of oaks. The common name "oak" also appears in the names of species in related genera, notably ''L ...
tree in the section
''Quercus'' sect. ''Cerris''. It is the primary source of
cork
Cork or CORK may refer to:
Materials
* Cork (material), an impermeable buoyant plant product
** Cork (plug), a cylindrical or conical object used to seal a container
***Wine cork
Places Ireland
* Cork (city)
** Metropolitan Cork, also known as G ...
for wine bottle stoppers and other uses, such as cork flooring and as the cores of
cricket ball
A cricket ball is a hard, solid ball used to play cricket. A cricket ball consists of a cork core wound with string then a leather cover stitched on, and manufacture is regulated by cricket law at first-class level. The trajectory of a crick ...
s. It is native to southwest Europe and northwest
Africa
Africa is the world's second-largest and second-most populous continent, after Asia in both cases. At about 30.3 million km2 (11.7 million square miles) including adjacent islands, it covers 6% of Earth's total surface area ...
. In the
Mediterranean basin the tree is an ancient species with
fossil
A fossil (from Classical Latin , ) is any preserved remains, impression, or trace of any once-living thing from a past geological age. Examples include bones, shells, exoskeletons, stone imprints of animals or microbes, objects preserved ...
remnants dating back to the
Tertiary period
Tertiary ( ) is a widely used but obsolete term for the geologic period from 66 million to 2.6 million years ago.
The period began with the demise of the non-avian dinosaurs in the Cretaceous–Paleogene extinction event, at the start ...
.
It endures drought and makes little demand on the soil quality and is regarded as a defence against desertification. Cork oak forests are home to a multitude of animal and plant species. Since cork is increasingly being displaced by other materials as a bottle cap, these forests are at risk as part of the cultural landscape and animal species such as the
Iberian lynx
The Iberian lynx (''Lynx pardinus'') is a wild cat species endemic to the Iberian Peninsula in southwestern Europe. It is listed as Endangered on the IUCN Red List. In the 20th century, the Iberian lynx population had declined because of overhun ...
are threatened with extinction.
Description
General appearance and bark
![Cork oak trunk section](https://upload.wikimedia.org/wikipedia/commons/7/7f/Cork_oak_trunk_section.jpg)
The cork oak grows as an
evergreen
In botany, an evergreen is a plant which has foliage that remains green and functional through more than one growing season. This also pertains to plants that retain their foliage only in warm climates, and contrasts with deciduous plants, whic ...
tree, reaching an average height of or in rare cases up to 25 m and a trunk diameter (
DBH) of . It forms a dense and asymmetrical crown that starts at a height of and spreads widely in free-standing trees. The crown can be divided into several separate, rounded partial crowns.
The young twigs are densely hairy light gray or whitish. Older branches are strong and knotty. Older trees only form short shoots between in length.
The thick, longitudinally cracked cork layers of the gray-brown trunk bark are characteristic of the cork oak. The
cambium
A cambium (plural cambia or cambiums), in plants, is a tissue layer that provides partially undifferentiated cells for plant growth. It is found in the area between xylem and phloem. A cambium can also be defined as a cellular plant tissue from w ...
of the smooth bark of young trees forms a cork layer very early on, which can be thick. The light and spongy cork fabric shows vertical cracks and is white on the outside and red to red-brown on the inside. After the cork has been harvested, the trunk appears reddish brown, but later it is significantly darker.
The wood is ring-pored, has a brown heartwood and a light reddish sapwood.
The cork oak develops a taproot that reaches a depth of and from which several meters long, horizontally running side roots extend.
The trees can reach over 400 years old, and harvested specimens can be 150 to 200 years old.
Leaves
![Quercus suber - Köhler–s Medizinal-Pflanzen-254](https://upload.wikimedia.org/wikipedia/commons/2/27/Quercus_suber_-_K%C3%B6hler%E2%80%93s_Medizinal-Pflanzen-254.jpg)
The leathery
leaves
A leaf (plural, : leaves) is any of the principal appendages of a vascular plant plant stem, stem, usually borne laterally aboveground and specialized for photosynthesis. Leaves are collectively called foliage, as in "autumn foliage", wh ...
are alternate and are long and wide. The shape varies between round, oval and lanceolate-oval. The leaf blade has five to seven sharp teeth on both edges and a pointed vegetation cone (apex). The midrib stands out clearly on the underside of the leaf, the first-order lateral nerves usually lead to the teeth of the leaf margin. The upper side of the leaf is light green, the underside of the leaf whitish and densely hairy. There is no hair on young trees. The leaf stalks are long and are also hairy. At the base of the petiole are two narrow, lanceolate, long and bright red stipules that fall off in the first year. The new leaves appear in April and May, when older leaves are also shed. They usually stay on the tree for two to three years, less often only one year, the latter especially in severe environmental conditions and on the northern border of the distribution area. Extremely cold winters can also lead to complete defoliation.
Inflorescence and flower
The cork oak is single sexed (
monoecious), with both female and male flowers on one specimen.
The female flowers form upright inflorescences in the leaf axils of young branches. These are formed from a hairy axis long with two to five separate flowers. The female flowers contain a small, hairy, four- to six-lobed
flower envelope and three to four
styles.
The male
catkins also arise on the leaf axils of young branches. They are bright red at the beginning and stand upright, older catkins are yellow and pendulous, long and have a whitish hairy axis. The single flowers are sessile and have a densely hairy flower cover that is colored red when opened. The four to six
stamen
The stamen (plural ''stamina'' or ''stamens'') is the pollen-producing reproductive organ of a flower. Collectively the stamens form the androecium., p. 10
Morphology and terminology
A stamen typically consists of a stalk called the filame ...
s are whitish with yellow, egg-shaped anthers. They are longer than the bracts.
Infructescence, fruit and seed
The
fruit clusters are long and carry two to eight acorns. About half of the fruits are enclosed in the fruit cup (
cupule
A cupule is a small structure shaped like a cup, including:
* In archeology, rock cupules are circular man-made hollows on the surface of a large rock or a rock slab
** On a smaller artifact they are called a cupstone.
* In botany: the base of an ...
); the fruit cups are in diameter. The upper scales of the cupula are gray and hairy, in the subspecies ''Quercus suber occidentalis'' the scales are close together or are fused. The size of the acorns varies between lengths of and diameters of . The fruit casing (
pericarp
Fruit anatomy is the plant anatomy of the internal structure of fruit. Fruits are the mature ovary or ovaries of one or more flowers. They are found in three main anatomical categories: aggregate fruits, multiple fruits, and simple fruits. Aggr ...
) is bare, smooth and shiny brownish red. The
hilum (the starting point of the seed) is convex and has a diameter of .
Quercus fg04.jpg, Leaves
Quercus suber Blatt.jpg, Leaf, front and back
Quercus suber g4.jpg, Acorn with fruit cup
Quercus suber MHNT.BOT.2021.17.19.jpg, Seeds
Quercus suber - San Luis Obispo Botanical Garden - DSC05998.JPG, Unharvested trunk
Denuded cork oak (2874384025).jpg, Denuded trunk
Alcornoques Helechosa 2.jpg, Contrast between old and new cambium
Taxonomy
''Quercus suber'' is a species of the ''
Cerris
The genus ''Quercus'' contains about 500 species, some of which are listed here. The genus, as is the case with many large genera, is divided into subgenera and sections. Traditionally, the genus ''Quercus'' was divided into the two subgenera '' ...
'' section to which, for example, the following species also belong:
*
Valonia oak
''Quercus macrolepis'', the Valonia oak, is a species of oak in the beech family, Fagaceae. Formerly, it was commonly treated as a subspecies of the closely related and sympatric mount Tabor oak. At present, however, it is mostly granted specie ...
(''Quercus macrolepis'')
*
Turkey oak Turkey oak is a common name for several species of oaks and may refer to:
*''Quercus cerris'', native to southeastern Europe and Asia Minor
*''Quercus laevis
''Quercus laevis'', the turkey oak, is a member of the red oak group of oaks. It is n ...
(''Quercus cerris'')
*''
Quercus × crenata
''Quercus'' × ''crenata'', commonly known as Spanish oak, is a tree in the family Fagaceae. It is a hybrid between the European trees Turkey oak (''Quercus cerris'') and cork oak (''Quercus suber''). This hybrid has in the past often been call ...
''
*
Macedonian oak
''Quercus trojana'', the Macedonian oak is an oak in the turkey oak section
( ''Quercus'' sect. ''Cerris'').
It is native to southeast Europe and southwest Asia, from southern Italy east across the southern Balkans (Croatia, Albania, Serbia, N ...
(''Quercus trojana'')
Characteristic for the section are the hairless
pericarp
Fruit anatomy is the plant anatomy of the internal structure of fruit. Fruits are the mature ovary or ovaries of one or more flowers. They are found in three main anatomical categories: aggregate fruits, multiple fruits, and simple fruits. Aggr ...
and the usually two-year ripening time of the fruits. The cork oak is an exception because the fruits can ripen in both the first and the second year.
In the species ''Quercus suber'' two subspecies are distinguished:
*''Quercus suber subsp. suber'': Nominal taxon
*''Quercus suber subsp. occidentalis''
(Gay) Bonnier & Layens: It differs from the nominate form in the shape of the cupula scales, the longer development time of the fruits and the semi-evergreen foliage. The distribution area of the subspecies is the Portuguese Atlantic coast.
Together with the Turkey oak (''Quercus cerris'') and the
holm oak (''Quercus ilex''), the cork oak forms
hybrid
Hybrid may refer to:
Science
* Hybrid (biology), an offspring resulting from cross-breeding
** Hybrid grape, grape varieties produced by cross-breeding two ''Vitis'' species
** Hybridity, the property of a hybrid plant which is a union of two dif ...
bastards.
The scientific name ''Quercus suber'' is derived from the Latin word ''quercus'', which the Romans used to describe the
pedunculate oak
''Quercus robur'', commonly known as common oak, pedunculate oak, European oak or English oak, is a species of flowering plant in the beech and oak family, Fagaceae. It is a large tree, native to most of Europe west of the Caucasus. It is widel ...
(''Quercus robur''). The specific epithet ''suber'' means in Latin cork oak and also cork.
Distribution and habitat
![Alcornoques en Grazalema](https://upload.wikimedia.org/wikipedia/commons/e/e4/Alcornoques_en_Grazalema.jpg)
The cork oak occupies the area around the western
Mediterranean basin. In Portugal, natural and cultivated stands cover an area of 750,000 hectares.
There are natural populations of the nominate form at altitudes between above sea level, the subspecies ''occidentalis'' is found along the
Atlantic
The Atlantic Ocean is the second-largest of the world's five oceans, with an area of about . It covers approximately 20% of Earth's surface and about 29% of its water surface area. It is known to separate the " Old World" of Africa, Europe an ...
coast. In Spain the occurrences remain mostly below , but rarely reach heights of . In Spain, cork oaks are common in the southern half of the country, as well as in the western and northeastern areas, but rare in central Spain. In Italy one finds natural occurrences along the
Tyrrhenian Sea
The Tyrrhenian Sea (; it, Mar Tirreno , french: Mer Tyrrhénienne , sc, Mare Tirrenu, co, Mari Tirrenu, scn, Mari Tirrenu, nap, Mare Tirreno) is part of the Mediterranean Sea off the western coast of Italy. It is named for the Tyrrhenian pe ...
and in eastern
Apulia
it, Pugliese
, population_note =
, population_blank1_title =
, population_blank1 =
, demographics_type1 =
, demographics1_footnotes =
, demographics1_title1 =
, demographics1_info1 =
, demographic ...
on the
Adriatic Sea
The Adriatic Sea () is a body of water separating the Italian Peninsula from the Balkan Peninsula. The Adriatic is the northernmost arm of the Mediterranean Sea, extending from the Strait of Otranto (where it connects to the Ionian Sea) to t ...
. Also on the Adriatic is the cork oak on the
Dalmatian coast
Dalmatia (; hr, Dalmacija ; it, Dalmazia; see #Name, names in other languages) is one of the four historical region, historical regions of Croatia, alongside Croatia proper, Slavonia, and Istria. Dalmatia is a narrow belt of the east shore of ...
. It is one of the most common forest trees in
Sardinia
Sardinia ( ; it, Sardegna, label=Italian, Corsican and Tabarchino ; sc, Sardigna , sdc, Sardhigna; french: Sardaigne; sdn, Saldigna; ca, Sardenya, label=Algherese and Catalan) is the second-largest island in the Mediterranean Sea, after ...
. Natural and man-made occurrences exist in Africa on the Mediterranean coast of Tunisia, Algeria and Morocco and at altitudes up to , on the
High Atlas
High Atlas, also called the Grand Atlas ( ar, الأطلس الكبير, Al-Aṭlas al-Kabīr; french: Haut Atlas; shi, ⴰⴷⵔⴰⵔ ⵏ ⴷⵔⵏ ''Adrar n Dern''), is a mountain range in central Morocco, North Africa, the highest part of t ...
up to .
In its native range, cork oak forests cover approximately .
Outside of its natural range, the cork oak is cultivated in the
Crimea
Crimea, crh, Къырым, Qırım, grc, Κιμμερία / Ταυρική, translit=Kimmería / Taurikḗ ( ) is a peninsula in Ukraine, on the northern coast of the Black Sea, that has been occupied by Russia since 2014. It has a pop ...
, the
Caucasus
The Caucasus () or Caucasia (), is a region between the Black Sea and the Caspian Sea, mainly comprising Armenia, Azerbaijan, Georgia, and parts of Southern Russia. The Caucasus Mountains, including the Greater Caucasus range, have historically ...
,
India
India, officially the Republic of India (Hindi: ), is a country in South Asia. It is the seventh-largest country by area, the second-most populous country, and the most populous democracy in the world. Bounded by the Indian Ocean on the so ...
and the
Southwestern United States
The Southwestern United States, also known as the American Southwest or simply the Southwest, is a geographic and cultural region of the United States that generally includes Arizona, New Mexico, and adjacent portions of California, Colorado, Ne ...
. The subspecies ''Quercus suber occidentalis'' also thrives in mild areas of England.
The species needs very little light and cannot survive in dense populations. It loves warmth, grows at annual mean temperatures of and can withstand maximum temperatures of up to . In the area of distribution, the temperature rarely falls below freezing point, but temperatures down to without damage and down to without major damage can be tolerated. The cork oak is not hardy in
Central Europe
Central Europe is an area of Europe between Western Europe and Eastern Europe, based on a common historical, social and cultural identity. The Thirty Years' War (1618–1648) between Catholicism and Protestantism significantly shaped the area' ...
. It endures drought and survives dry periods in summer by reducing its metabolism. An annual rainfall of is considered optimal, in cooler locations can be sufficient with enough humidity. Cork oaks have low soil demands and also grow in poor, dry or rocky locations. They rarely thrive on
calcareous
Calcareous () is an adjective meaning "mostly or partly composed of calcium carbonate", in other words, containing lime or being chalky. The term is used in a wide variety of scientific disciplines.
In zoology
''Calcareous'' is used as an ad ...
soils, but they are often found on crystalline slates, on gneiss, granite and sands. The
acidity of the soil should be between pH 4.5 and 7.
The cork oak is considered a
pyrophyte
Pyrophytes are plants which have adapted to tolerate fire.
Fire acts favourably for some species. "Passive pyrophytes" resist the effects of fire, particularly when it passes over quickly, and hence can out-compete less resistant plants, which are ...
because it recovers quickly after forest fires as it is protected by the cork.
Ecology
![Linces12](https://upload.wikimedia.org/wikipedia/commons/d/d5/Linces12.jpg)
The cork oak forest is one of the major plant communities of the
Mediterranean woodlands and forests ecoregion
An ecoregion (ecological region) or ecozone (ecological zone) is an ecologically and geographically defined area that is smaller than a bioregion, which in turn is smaller than a biogeographic realm. Ecoregions cover relatively large areas of l ...
. In natural populations, the cork oak grows together with the holm oaks (''
Quercus ilex'', ''
Quercus rotundifolia''), the downy oak (''
Quercus pubescens
''Quercus pubescens'', the downy oak or pubescent oak, is a species of white oak (genus ''Quercus'' sect. ''Quercus'') native to southern Europe and southwest Asia, from northern Spain (Pyrenees) east to the Crimea and the Caucasus. It is also fo ...
''), the maritime pine (''
Pinus pinaster
''Pinus pinaster'', the maritime pine or cluster pine, is a pine native to the south Atlantic Europe region and parts of the western Mediterranean. It is a hard, fast growing pine bearing small seeds with large wings.
Description
''Pinus pina ...
''), the stone pine (''
Pinus pinea''), the strawberry tree (''
Arbutus unedo
''Arbutus unedo'' is an evergreen shrub or small tree in the family Ericaceae, native to the Mediterranean region and western Europe. The tree is well known for its fruits, which bear some resemblance to the strawberry — hence the common na ...
'') and the olive tree (''
Olea europaea''), in cooler locations also with the sweet chestnut (''
Castanea sativa
''Castanea sativa'', the sweet chestnut, Spanish chestnut or just chestnut, is a species of tree in the family Fagaceae, native to Southern Europe and Asia Minor, and widely cultivated throughout the Temperate climate, temperate world. A substa ...
''). In addition to these tree species, the shrub-forming species include the Kermes oak (''
Quercus coccifera
''Quercus coccifera'', the kermes oak, is an oak bush in the ''Ilex'' section of the genus. It is native to the Mediterranean region and Northern African Maghreb, south to north from Morocco to France and west to east from Portugal to Cyprus an ...
''), the holly buckthorn (''
Rhamnus alaternus
''Rhamnus alaternus'' is a species of flowering plant in the buckthorn family Rhamnaceae, known by the common names Italian buckthorn or Mediterranean buckthorn. It is a hardy medium-sized evergreen shrub with fragrant flowers.
Etymology
The s ...
''), species of the genus ''
Phillyrea
''Phillyrea'' is a genus of two species of flowering plants in the family Oleaceae, native to the Mediterranean region, and naturalized in the Canary Islands and Madeira.
They are evergreen shrubs or small trees growing to 3–9 m tall, related ...
'', the myrtle (''
Myrtus communis''), the green heather (''
Erica scoparia
''Erica scoparia'', the green heather, is a shrubby species of heath in the flowering plant family Ericaceae. It is native to the western Mediterranean Basin in the Iberian Peninsula (Spain and Portugal), Northwest Africa (Morocco, Algeria and T ...
''), the common smilax (''
Smilax aspera
''Smilax aspera'', with common names common smilax, rough bindweed, sarsaparille,Cistus monspeliensis
''Cistus monspeliensis'' is a species of rockrose known by the common name Montpellier cistus. It is native to southern Europe and northern Africa, in the Mediterranean forests, woodlands, and scrub ecosystems of matorral—maquis shrublands.
D ...
'') are often found together with the cork oak.
Cork oak forests are home to several rare species, such as the
Iberian Peninsula
The Iberian Peninsula (),
**
* Aragonese and Occitan: ''Peninsula Iberica''
**
**
* french: Péninsule Ibérique
* mwl, Península Eibérica
* eu, Iberiar penintsula also known as Iberia, is a peninsula in southwestern Europe, defi ...
for the threatened
Iberian lynx
The Iberian lynx (''Lynx pardinus'') is a wild cat species endemic to the Iberian Peninsula in southwestern Europe. It is listed as Endangered on the IUCN Red List. In the 20th century, the Iberian lynx population had declined because of overhun ...
(''Lynx pardinus'')
[Santos Pereira, J., Bugalho, M.N., and Caldeira, M.D. (2008)]
''From the Cork Oak to Cork: A Sustainable Ecosystem''.
APCOR: Portuguese Cork Association. and the endangered
Iberian imperial eagle (''Aquila adalberti''), and a large part of the European
crane population winters here. In the northwestern
Maghreb
The Maghreb (; ar, الْمَغْرِب, al-Maghrib, lit=the west), also known as the Arab Maghreb ( ar, المغرب العربي) and Northwest Africa, is the western part of North Africa and the Arab world. The region includes Algeria, ...
, some cork oak forests are
habitat
In ecology, the term habitat summarises the array of resources, physical and biotic factors that are present in an area, such as to support the survival and reproduction of a particular species. A species habitat can be seen as the physical ...
to the
endangered
An endangered species is a species that is very likely to become extinct in the near future, either worldwide or in a particular political jurisdiction. Endangered species may be at risk due to factors such as habitat loss, poaching and inva ...
Barbary macaque (''Macaca sylvanus''), a species whose habitat is fragmented and whose range was prehistorically much wider.
[Hogan, C. M]
Barbary Macaque, ''Macaca sylvanus''.
GlobalTwitcher.com, Ed. N. Stromberg. The Berber deer (''
Cervus elaphus
The red deer (''Cervus elaphus'') is one of the largest deer species. A male red deer is called a stag or hart, and a female is called a hind. The red deer inhabits most of Europe, the Caucasus Mountains region, Anatolia, Iran, and parts of wes ...
'' subsp. ''Barbarus'') lives in the cork oak forests of Tunisia.
As a
pyrophyte
Pyrophytes are plants which have adapted to tolerate fire.
Fire acts favourably for some species. "Passive pyrophytes" resist the effects of fire, particularly when it passes over quickly, and hence can out-compete less resistant plants, which are ...
, this tree has a thick, insulating bark that makes it well adapted to
forest fires.
After a fire, many tree species regenerate from seeds (as, for example, the
maritime pine
''Pinus pinaster'', the maritime pine or cluster pine, is a pine native to the south Atlantic Europe region and parts of the western Mediterranean. It is a hard, fast growing pine bearing small seeds with large wings.
Description
''Pinus pinast ...
) or resprout from the base of the tree (as, for example, the
holm oak). The bark of the cork oak allows it to survive fires and then simply regrow branches to fill out the canopy. The quick regeneration of this oak makes it successful in the fire-adapted ecosystems of the
Mediterranean biome.
[
]
Symbiosis
The cork oak enters into a mycorrhizal
A mycorrhiza (from Greek μύκης ', "fungus", and ῥίζα ', "root"; pl. mycorrhizae, mycorrhiza or mycorrhizas) is a symbiotic association between a fungus and a plant. The term mycorrhiza refers to the role of the fungus in the pla ...
symbiosis
Symbiosis (from Greek , , "living together", from , , "together", and , bíōsis, "living") is any type of a close and long-term biological interaction between two different biological organisms, be it mutualistic, commensalistic, or parasit ...
with several types of fungus
A fungus ( : fungi or funguses) is any member of the group of eukaryotic organisms that includes microorganisms such as yeasts and molds, as well as the more familiar mushrooms. These organisms are classified as a kingdom, separately from th ...
. The fine root system of the oak is in close contact with the mycelium of the fungus. The oak receives water and nutrient salts from the fungus in exchange for products of photosynthesis. Such a symbiosis exists among others with the following species:
*Caesar's mushroom
''Amanita caesarea'', commonly known as Caesar's mushroom, is a highly regarded edible mushroom in the genus ''Amanita'', native to southern Europe and North Africa. While it was first species description, described by Giovanni Antonio Scopol ...
(''Amanita caesarea'')
* Death cap (''Amanita phalloides'')
*Panther cap
''Amanita pantherina'', also known as the panther cap, false blusher, and the panther amanita due to its similarity to the true blusher ('' Amanita rubescens''), is a species of fungus found in Europe and Western Asia.
Description
*Cap: 5 ...
(''Amanita pantherina'')
* Gilbert's limbed lepidella (''Amanita gilbertii'')
* Cep (''Boletus edulis'')
*'' Russula rubra''
Diseases and predators
Cork oak is relatively resistant to pathogens, but some diseases occur in the species. Leaf spot
A leaf spot is a limited, discoloured, diseased area of a leaf that is caused by fungal, bacterial or viral plant diseases, or by injuries from nematodes, insects, environmental factors, toxicity or herbicides. These discoloured spots or lesions ...
can be caused by the fungus '' Apiognomonia errabunda''. Other fungi can cause leaf scorching, powdery mildew
Powdery mildew is a fungal disease that affects a wide range of plants. Powdery mildew diseases are caused by many different species of ascomycete fungi in the order Erysiphales. Powdery mildew is one of the easier plant diseases to identify, a ...
, rust
Rust is an iron oxide, a usually reddish-brown oxide formed by the reaction of iron and oxygen in the catalytic presence of water or air moisture. Rust consists of hydrous iron(III) oxides (Fe2O3·nH2O) and iron(III) oxide-hydroxide (FeO(OH ...
, and cankers.
The most virulent cork oak pathogen may be ''Diplodia corticola
''Diplodia corticolaa'' is a species of anamorphic fungus in the family Botryosphaeriaceae
The Botryosphaeriaceae are a family of sac fungi (Ascomycetes), which is the type representative of the order Botryosphaeriales. According to a 2008 ...
'', a sac fungus
Ascomycota is a phylum of the kingdom Fungi that, together with the Basidiomycota, forms the subkingdom Dikarya. Its members are commonly known as the sac fungi or ascomycetes. It is the largest phylum of Fungi, with over 64,000 species. The de ...
which causes sap-bleeding sunken canker wounds in the wood, withering of the leaves, and lesions on the acorns. The fungus '' Biscogniauxia mediterranea'' is becoming more common in cork oak forests. Its fruiting bodies appear as charcoal-black cankers. Both of these fungi are transmitted by the oak pinhole borer (''Platypus cylindrus''), a species of weevil.[
The common water mould '']Phytophthora cinnamomi
''Phytophthora cinnamomi'' is a soil-borne water mould that produces an infection which causes a condition in plants variously called " root rot", "dieback", or (in certain ''Castanea'' species), "ink disease". The plant pathogen is one of the wo ...
'' grows in the roots of the tree and has been known to devastate cork oak woodlands.[
Several species of butterflies damage the cork oak, the most important being the ]gypsy moth
''Lymantria dispar'', also known as the gypsy moth or the spongy moth, is a species of moth in the family Erebidae. ''Lymantria dispar'' is subdivided into several subspecies, with subspecies such as ''L. d. dispar'' and ''L. d. japonica'' bei ...
(''Lymantria dispar''). The species lays its eggs in the bark of the branches and trunks, and the caterpillars that hatch in spring are distributed in the crown and eat them bare. The bacterial species '' Bacillus thuringiensis'' is used as a biological plant protection agent against the gypsy moth. Another pest is the green oak tortrix
The green oak tortrix, ''Tortrix viridana'', also known as the European oak leafroller and the green oak moth is a distinctive green moth whose larvae feed on tree leaves, especially oak. The head, forebody and front wings are green, the hind wi ...
(''Tortrix viridana''), whose caterpillars eat flowers and young leaves and roll them up with thread to form typical coils. The lackey moth
The lackey moth (''Malacosoma neustria'') is a moth in the family Lasiocampidae. It was first described by Carl Linnaeus in his 1758 10th edition of ''Systema Naturae''. It is common across southern Britain and central Europe. ''Malacosoma'' sp ...
(''Malacosoma neustria'') also causes damage to the leaves, sticking its eggs to the bark of thin twigs in multiple rows, and also the brown-tail moth
The brown-tail moth (''Euproctis chrysorrhoea'') is a moth of the family Erebidae. It is native to Europe, neighboring countries in Asia, and the north coast of Africa. Descriptions of outbreaks, i.e., large population increases of several year ...
(''Euproctis chrysorrhoea''), whose caterpillars skeletonize the leaves and further damage the tree after overwintering in spring. A special cork pest is the jewel beetle
Buprestidae is a family of beetles known as jewel beetles or metallic wood-boring beetles because of their glossy iridescent colors. Larvae of this family are known as flatheaded borers. The family is among the largest of the beetles, with some ...
''Coraebus undatus
''Coraebus'' is a genus of beetles in the family Buprestidae, containing the following species:
* '' Coraebus aculeatus'' Ganglbauer, 1890
* '' Coraebus acutus'' Thomson, 1879
* '' Coraebus aeneopictus'' (Kerremans, 1895)
* '' Coraebus aequalip ...
'', which lays its eggs in the cork tissue. Another harmful species of beetle is the great capricorn beetle
''Cerambyx cerdo'', commonly known as the great capricorn beetle or cerambyx longicorn, is a species of beetle in family Cerambycidae. It occurs in North Africa (Algeria, Morocco, and Tunisia), Europe (Austria, Belarus, Bulgaria, Croatia, the Cze ...
(''Cerambyx cerdo''), whose larvae eat long corridors in the oak wood.
Unfavorable climatic conditions and fungal attack are made responsible for the weakening of trees and for crown damage. Such fungal parasites of weakness are '' Botryosphaeria stevensii'', ''Biscogniauxia mediterranea'', '' Endothiella gyrosa'' and representatives of the mold genus ''Fusarium
''Fusarium'' is a large genus of filamentous fungi, part of a group often referred to as hyphomycetes, widely distributed in soil and associated with plants. Most species are harmless saprobes, and are relatively abundant members of the soil mi ...
''. Drought and parasite infestation are also considered to be the cause of the weakness syndrome in parts of Spain and Portugal.
Uses
The cork oak is grown for the production of cork in several Mediterranean countries. The centers of cork production are in southern Portugal (accounting for 50% of the total production) and southern Spain, where low trees with large crowns and strong branches are grown in large areas, which provide the highest yield of cork. These mostly extensively managed habitats are called '' montados'' in Portugal and ''dehesa
A ''dehesa'' () is a multifunctional, agrosylvopastoral system (a type of agroforestry) and cultural landscape of southern and central Spain and southern Portugal; in Portugal, it is known as a ''montado''. Its name comes from the Latin 'defens ...
s'' in Spain. They are considered to be extremely valuable from the point of view of biodiversity and cultural heritage.
The cork consists of dead, air-filled, thin-walled cells and contains cellulose
Cellulose is an organic compound with the formula , a polysaccharide consisting of a linear chain of several hundred to many thousands of β(1→4) linked D-glucose units. Cellulose is an important structural component of the primary cell w ...
and suberin
Suberin, cutin and lignins are complex, higher plant epidermis and periderm cell-wall macromolecules, forming a protective barrier. Suberin, a complex polyester biopolymer, is lipophilic, and composed of long chain fatty acids called suberin aci ...
. Cork is heat and sound insulating, the suberine gives it water-repellent properties. The cork layer is replicated by the cork-producing phellogen
Cork cambium (pl. cambia or cambiums) is a tissue found in many vascular plants as a part of the epidermis. It is one of the many layers of bark, between the cork and primary phloem. The cork cambium is a lateral meristem and is responsible fo ...
and can therefore be harvested repeatedly without damaging the tree too much. The first harvest usually takes place after about 25 years with a trunk diameter (DBH) of , though new techniques (such as better irrigation systems) could shorten it to only 8 to 10 years. The first cork layer is called “male cork” or “virgin cork”, is still not very elastic and cracked and is only used for insulating mats. The second harvested cork (known as ''secundeira''), has a more regular structure and is softer, but is still only used for insulation and in decorative objects. Only the following cork harvests deliver a higher quality cork, the "female cork", which can be used commercially in full. The best quality cork is obtained from the third and fourth harvest. Cork harvesting takes place every nine to twelve years when a layer thickness of is reached. Under favorable (warm) conditions, the harvest can take place every eight years, in North Africa
North Africa, or Northern Africa is a region encompassing the northern portion of the African continent. There is no singularly accepted scope for the region, and it is sometimes defined as stretching from the Atlantic shores of Mauritania in ...
every seven years. A cork oak can be harvested five to seventeen times in total. In order to minimize the damage to the trunk surface, harvesting can be carried out every three years, whereby only a third of the usable surface is removed. An important maintenance measure is pruning
Pruning is a horticultural, arboricultural, and silvicultural practice involving the selective removal of certain parts of a plant, such as branches, buds, or roots.
The practice entails the ''targeted'' removal of diseased, damaged, dead, ...
, which begins around the age of ten at a height of about . Some sources say an oak can provide around of cork over its lifespan, and one hectare around per year while others suggest a single tree can produce on average of cork per harvest, a comparatively higher value, as cork oaks can live more than 200 years in good conditions.
The cork is mainly used for the production of stoppers and corks, as well as for heat and sound insulation, cork
paper, badminton shuttlecocks, cricket ball
A cricket ball is a hard, solid ball used to play cricket. A cricket ball consists of a cork core wound with string then a leather cover stitched on, and manufacture is regulated by cricket law at first-class level. The trajectory of a crick ...
s, handles of fishing rods and hand tools, special devices for the space industry
Space industry refers to economic activities related to manufacturing components that go into Earth's orbit or beyond, delivering them to those regions, and related services. Owing to the prominence of the satellite-related activities, some sour ...
and for other technical applications (including composite material
A composite material (also called a composition material or shortened to composite, which is the common name) is a material which is produced from two or more constituent materials. These constituent materials have notably dissimilar chemical or ...
s, shoe soles, floor coverings). Bottle cork production accounts for around 70% of the added value in cork cultivation. Since natural corks are increasingly being replaced by plastic or sheet metal closures, there could be a significant decline in the cork oak population in southwestern Europe, which endangers the biodiversity in these areas.
The bark, which contains around twelve percent extractable tannin
Tannins (or tannoids) are a class of astringent, polyphenolic biomolecules that bind to and precipitate proteins and various other organic compounds including amino acids and alkaloids.
The term ''tannin'' (from Anglo-Norman ''tanner'' ...
, is also used. In addition, the acorns are used as feed in extensive pig fattening (acorn fattening). One tree can provide of acorns per year.
Cork oaks cannot legally be cut down in Portugal, except for forest management Forest management is a branch of forestry concerned with overall administrative, legal, economic, and social aspects, as well as scientific and technical aspects, such as silviculture, protection, and forest regulation. This includes management fo ...
felling of old, unproductive trees, and, even in those cases, farmers need special permission from the Ministry of Agriculture.
Cork harvesting is done entirely without machinery, being dependent solely on human labour. Usually five people are required to harvest the tree's bark, using a small axe. The process mandates specialized training due to the skill required to harvest bark without inflicting too much damage to the tree.
The European cork industry produces 300,000 tonne
The tonne ( or ; symbol: t) is a unit of mass equal to 1000 kilograms. It is a non-SI unit accepted for use with SI. It is also referred to as a metric ton to distinguish it from the non-metric units of the short ton ( United State ...
s of cork a year, with a value of €
The euro sign () is the currency sign used for the euro, the official currency of the eurozone and unilaterally adopted by Kosovo and Montenegro. The design was presented to the public by the European Commission on 12 December 1996. It consists ...
1.5 billion
Billion is a word for a large number, and it has two distinct definitions:
*1,000,000,000, i.e. one thousand million, or (ten to the ninth power), as defined on the short scale. This is its only current meaning in English.
* 1,000,000,000,000, i. ...
and employing 30,000 people. Wine
Wine is an alcoholic drink typically made from fermented grapes. Yeast consumes the sugar in the grapes and converts it to ethanol and carbon dioxide, releasing heat in the process. Different varieties of grapes and strains of yeasts are m ...
corks represent 15% of cork usage by weight but 66% of revenues.
Cork oaks are sometimes planted as individual trees, providing a minor income to their owners. The tree is also sometimes cultivated for ornament. Hybrids with Turkey oak (''Quercus cerris
''Quercus cerris'', the Turkey oak or Austrian oak, is an oak native to south-eastern Europe and Asia Minor. It is the type species of ''Quercus'' sect. ''Cerris'', a section of the genus characterised by shoot buds surrounded by soft bristle ...
'') are not uncommon, both where their ranges overlap in the wild in southwest Europe and in cultivation; the hybrid ''Quercus'' × ''hispanica'' is known as Lucombe oak, for William Lucombe
William Lucombe (before 1720 – after 1785) was a horticulturalist and nurseryman, who discovered and gave his name to the natural hybrid Lucombe Oak ('' Quercus × hispanica'' 'Lucombeana'), a semi-deciduous oak tree.
The Lucombe nursery
William ...
, who first identified it.
Some cork is also produced in eastern Asia
Asia (, ) is one of the world's most notable geographical regions, which is either considered a continent in its own right or a subcontinent of Eurasia, which shares the continental landmass of Afro-Eurasia with Africa. Asia covers an area ...
from the related Chinese cork oak (''Quercus variabilis
''Quercus variabilis'', the Chinese cork oak, is a species of oak in the section ''Quercus'' sect. ''Cerris'', native to a wide area of eastern Asia in southern, central, and eastern China, Taiwan, Japan, and Korea.
Description
''Quercus varia ...
'').
Culture
The cork oak is featured in the city arms of several cities in Portugal, such as the city of Reguengos de Monsaraz
Reguengos de Monsaraz () is a municipality in Évora District in Portugal. The population in 2011 was 10,828, in an area of 464.00 km2. The City of Reguengos de Monsaraz proper has a population of 7,308.
The present Mayor is José Calixto, el ...
, which shows a freshly harvested cork tree.
In 2007, a 2 euro commemorative coin with the motif of a cork oak was issued in Portugal in memory of the Portuguese Presidency of the European Union.
Notable trees
In the Portuguese town of Águas de Moura lies the Sobreiro Monumental (''Monumental Cork Oak''), also known as 'The Whistler Tree', a tree 236 years old (planted in 1783/1784), over tall and with a trunk that requires at least three people to embrace it. It has been considered a National Monument since 1988, and Guinness World Records
''Guinness World Records'', known from its inception in 1955 until 1999 as ''The Guinness Book of Records'' and in previous United States editions as ''The Guinness Book of World Records'', is a reference book published annually, listing world ...
lists it as the largest cork tree in the world.
References
Further reading
* Aronson J., Pereira J. S., Pausas J. G. (eds.). (2009).
Cork Oak Woodlands on the Edge: Conservation, Adaptive Management, and Restoration
'. Washington, D.C.: Island Press, 315 pp.
External links
''Quercus suber''
Plants of the World Online. Kew Science.
Cork Oak
World Wildlife Foundation Priority Species.
Cork Industry Federation
2014.
PlanetCork.org
Educating primary school children in sustainable development. Cork Industry Federation. 2009.
Cork Oak (''Quercus suber'')
European Forest Genetic Resources Programme (EUFORGEN).
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suber
Flora of North Africa
Trees of Morocco
Trees of Europe
Flora of Portugal
Trees of Mediterranean climate
Garden plants of Europe
Drought-tolerant trees
Ornamental trees
Plants described in 1753
Taxa named by Carl Linnaeus
Flora of the Mediterranean Basin