Cork Oak Bark of Tree Branches
Cork Oak Bark of Tree Branches

Cork Oak Tree (Quercus suber), The Famous

The Cork Oak (Quercus suber L.) prior to the Industrial Revolution, did not occupy anyone other than its relatives and friends in the forests.

But with the advent of mass production of bottles, the need for bottling them – much more so when their contents were fine and non-fine wine – brought it dynamically to the forefront.

And the reason that happened something like this was the cork, the product obtained from the bark of the tree, which represented and perhaps still represents the most suitable stopper for bottling – especially wine bottles.

Since then, the Cork Oak has played a very important role as a source of wealth in those countries where, fortunately, among others goods they are happy because they include its forests.

We rejoice with them.

And we are happy because its tree, in addition to being a cork source, is also an excellent ornamental plant.

And with this dimension of the tree, the rich source of "Kalliergeia", which is none other than its sustainable editorial team, will deal with this article.

… Even if slightly – as the cork – sometimes falters.

Quercus suber Origin

Quercus suber (Cork Oak) - Map of Origin
Quercus suber (Cork Oak) - Map of Origin

Cork Oak Tree (Quercus suber)

Cork Oak Tree (Quercus suber) - Brief Description

Scientific name

Quercus suber L.

Common name

Cork Oak

General Characteristics

Type of foliage: Evergreen

Form: Tree

Texture: Fine

Height: 15-25 m (50-82 ft)

Diameter: 10-15 m (33-50 ft)

Growth rate: Slow

Flowering period: Spring

Fruiting period: Autumn – Winter

Shapes and Colors

Leaves shape: Obovate

Foliage colour: Green

Foliage colour in autumn: Green

Flowers: Male: Catkin – Female: Spike

Flowers color: Yellow

Fruit: Acorn

Plantation

Soil type: Excellent drainage, sandy, loamy

Soil pH: 3.5-7

Watering: Moderate

Exposure: Sun

Hardiness: – 10 °C (14 °F – USDA Hardiness Zone 8b)

Uses

Specimen, parks, gardens, landscape restoration 

Cork Oak Tree (Quercus suber)

Cork Oak Old Tree in Parque Anchorena, Uruguay
Cork Oak Old Tree in Parque Anchorena, Uruguay

Cork Oak Tree (Quercus suber) - Etymology

Etymology of the Genus Name

The name Quercus is derived from the Proto-Italic word *kʷerkus, which is derived from the Proto-Indo-European *pérkus or *pr̥kʷéu – and means – what else? – Oak tree.

Etymology of the Species Name

The name of the species suber has Ancient Greek origin and specifically the word σῦφαρ (syphar). The word σῦφαρ literally means a piece of old skin or/and a piece of wrinkled skin, giving as well illustrated the dominant feature of the tree. However, the etymology of the word σῦφαρ is uncertain, if not unknown, being very likely to not have Indo-European derivations.

Cork Oak Tree (Quercus suber)

Cork Oak Tree (Quercus suber) - Origin & Life Span

Origin

The natural populations of the Cork Oak tree are found in that zone of the Mediterranean Basin that includes Algeria and Morocco in the south, Portugal in the west – where the most extensive forests are located – in the north France, and Italy in the east, up to Apulia on the Adriatic coast.

They grow at an altitude that starts almost at sea level and reaches up to 1300 m, although most of the Quercus suber forests are located up to an altitude of 800 m.

Life Span

Cork Oak tree is a very long-lived species since it lives from 200 – 250 to 300 years. Of course, in conditions of agroforestry, its lifespan is only just 150 to 200 years.

Cork Oak Tree (Quercus suber)

Cork Oak Tree (Quercus suber) - Morphological Elements

The Cork Oak is a broad-leaved evergreen tree with a trunk – sometimes with more.

It has a slow growth rate, and its shape is flattened spherical or oval with an upright and spreading appearance.

Its canopy is symmetrical and rather open, has a medium density, is of non-regular outline, and is characterized as of fine texture.

It reaches a height of 23 to 25 m within a very short period of 20 to 50 years from planting.

Cork Oak Tree (Quercus suber)

The Bark of a Quercus suber Tree
The Bark of a Quercus suber Tree

Cork Oak Tree (Quercus suber) - Botanical Description

Roots

Cork Oak tree has a specific root system characterized by dimorphism. It develops a main tap root that reaches a depth of up to 2 m, while at the same time it presents extensive superficial spread.

The superficial root subsystem is located up to a depth of about 40 cm and reaches several meters outside the projection of the tree crown on the ground. The other root subsystem is located in a lower level up to a depth of about 1.20 cm.

The root system dimorphic represents an excellent mechanism for adapting the tree to particular, mostly dry, climatic conditions.

Trunk

The Quercus suber develops a strong and wide trunk, which at chest height reaches a diameter of up to 2 m, while it is surrounded by bark, grayish or grayish-brown in color.

The bark has a large thickness that reaches up to 20 cm, it is porous and grooved, with deep longitudinal fissures. 

When it is stripped to use the cork, the underlying trunk reveals a rich red color.

Thanks to the thickness of the dermal system, the Cork Oaks are effectively protected from the natural fires of the Mediterranean forests. 

Twigs

The current year twigs are grayish in color which over time becomes brown or grayish brown.

Leaves

The leaves of Cork Oak are simple, sclerophyllous, glossy and leathery, result in an acute tip, while the base is rounded or almost cordate.

They have 4 to 5 teeth on each side of their margin, on either side of the midrib they develop 5-7 pairs of vines, and are connected by a short petiole 8 to 15 mm long on the shoots, on which they are alternately arranged.

Their shape is obovate or oval-lanceolate to oblong, while their color is dark green on the upper side and white-gray tomentose below.

The size of the leaves varies between 2.5 to 10 cm in length and 1.2 to 6.5 cm in width.

The leaves remain on the plant from 13 to 23 months after their growth.

Flowers

The flowers are monoecious, unisexual (i.e. separate male and female flowers), actinomorphous, and epigynous.

The male flowers are without a peduncle, they have a perianth divided into 5 to 8 lobes, with 5 to 7 stamens, while they are carried on 4 to 7 cm long pedunculated catkins.

The female flowers have a perianth divided into 4 to 6 lobes, and a gynoecium with 3 stylous surrounded by bractrs, and consisting of 3 carpels with an ovary. They are carried 2 to 5 on the pubescent axis of spikes 0.5-3 cm long.

The male flowers are developed by axillary buds located on branches of the previous year. Females arise on the new shoots of the year.

Pollination

Cork Oak is pollinated by wind (anemophilous species).

Fruit

The fruit of Cork Oak is a nut called acorn, which has initially green color and reddish brown during ripening.

The size of the acorns ranges between 2 and 4.5 cm in length, while the width ranges between 1 and 1.8 cm.

Cup of the acorns has a length of 1 to 2 cm and a width of 1.2 to 2.5 cm, and covered with oblong scales.

The acorns are attached to the shoot with a fuzzy, rigid peduncle 0.5 to 4 cm long.

Maturation of the fruits is carried out either the current vegetative period, or that of the following year. An important role for the period of maturation of the acorns play the geography and the climatic factors.

Ecological niches, woodlands, or plantations of Cork Oak located in the South ripen the fruits mainly within the same year, while on the contrary those who are in the North they ripen their fruits mainly in the next year.

Furthermore, the earlier the flowering, the more likely it is that the fruit will ripen within the same year.

In terms of size, the acorns of the tree populations that grow to the south or at low altitude are usually longer, wider and heavier than those developed by the populations of the northern latitude, or of larger elevations.

Cork Oak Tree (Quercus suber)

Trunk and Branch Cork of Quercus suber Trees
Trunk and Branch Cork of Quercus suber Trees

Cork Oak Tree (Quercus suber) - Climate and Soil

Temperature

The Cork Oak tree adapts to a wide temperature range. As for the minimum temperatures the plant withstand up to – 10 °C – under certain conditions it can withstand up to -15 °C.

In relation to the maximum is not experiencing any problems even in those areas where they reach the 40+ °C.

On the other hand, the appropriate average annual temperature range for the for the uninterrupted growth of the Cork Oak, is between 13 and 18 °C.

Rainfall

Cork Oak develops its natural populations within that zone where the average annual lower rainfall is 479 mm (as in the Mamora region of Morocco) and the average annual upper is 2400 mm (as in northwestern Portugal and some parts of the southern Spain).

Soil and pH

The Quercus suber tree grows in a wide range of soils except calcareous and clayey. It also withstands poor soils, while thrives in light to medium textured, which show excellent drainage.

In terms of pH, it could be said that it prefers acidic to slightly acidic soils, ie those that receive values between 5 and 6.5.

Exposure

Cork Oak is a predominantly photophilous species and does not tolerate shade. However, young seedlings tolerate a certain percentage of lateral shading.

Cork Oak Tree (Quercus suber)

Cork Oak Tree (Quercus suber) - Pests & Diseases

We do not know whether it is comforting, but in the past, Cork Oak, in its natural habitats, had almost no problems by pests and diseases – with the exception of sporadic infestations of trees by defoliating insects.

However, in recent years, the changes in the way that forests are managed, the changes in use of the land, wildfires and prolonged droughts that turns its forests into shrubland (where happy ex-forest animals consume its acorns), and problems have begun to increase.

Here, of course, we will not deal with the environmental issue, but we will refer – unfortunately – only to the most important modern pests and diseases of the tree.

Pests

Immediately below are recorded the most important pests of Cork Oak.

Defoliating Insects

  • Phylloxera quercus
  • Curculio elephas
  • Lymantria dispar
  • Tortrix viridana
  • Euproctis chrysorrhoea
  • Malacosoma neustria
  • Periclista andrei

Bark and Wood-Boring Insects

  • Platypus cylindrus
  • Cerambyx cerdo
  • Prinobius myardi
  • Coraebus florentinus
  • Coraebus undatus

Scales

  • Kermes vermilio

With the use of appropriate preparations, the treatment of entomological pests is effective and relatively easy except for wood-boring insects.

Diseases

After the pests, the recording of the diseases follows.

Various Fungi

  • Discula quercina
  • Cystodendron dryophilum
  • Lembosia quercina
  • Dendrophoma myriadea
  • Diplodia corticola  
  • Biscogniauxia mediterranea
  • Pythium spiculum

Root Fungi

  • Phytophthora cinnamomi
  • Phytophthora quercina
  • Phytophthora gonapodyides
  • Phytophthora psychrophila

Armillarias

  • Armillaria mellea
  • Armillaria gallica
  • Armillaria tabescens

With the timely use of the appropriate preparations, their treatment is considered satisfactory except for the species of Phytophthora and Armillaria.

Cork Oak Tree (Quercus suber)

Cork Oak Tree (Quercus suber) - Toxicity & Allergenicity

Toxicity

Cork Oak is not toxic to humans and pets in its usual uses. However, prolonged exposure in an environment of high density powdered (dust) cork it is possible to cause Pneumoconiosis.

Allergenicity

Although the plant is anemophilous, it does not appear to cause allergic reactions.

Cork Oak Tree (Quercus suber)

Quercus suber Red Tree Trunks After Bark Harvest
Quercus suber Red Tree Trunks After Bark Harvest

Cork Oak Tree (Quercus suber) - Use

The Quercus suber tree is used in both the garden and the landscape, where either the tree alone or in groups creates impressive visual effects. Of course, it is also used as a managed or cultivated species for the production of cork.

Agroforestry

Oak cork is widely used in agroforestry systems. Its cultivation is mostly combined with forage species intended for summer grazing, mainly cattle.

For this purpose, in the plantations of Cork Oak, the density of trees is low, ranging usually between 5o and 30o trees per hectare.

The main use of the plant could not be other than the production of cork. The cork is obtained by peeling the bark and removing it from the trunk, leaving a thin layer of new cork still covering the trunk’s secondary phloem.

The first harvest (or virgin cork as it is called) takes place when the tree reaches the age of about 25 years. Subsequent harvests take place every 9-12 years.

The cork yield of the tree is determined by the circumference of the trunk, the frequency of harvest, as well as the length of the trunk and the main libs that can be removed.

Industrial & Craft Use

The Quercus suber trees utilized industrial by the transformation of cork to stoppers for sealing the bottles.

In addition, the cork used for the production of insulation panels, floor and wall tiles, but also as a sound-proofing raw material in the automotive industry.

It is also – among other things – converted into paper, cork sheets intended for printing and / or book cover, on coasters, and cork boards.

Finally, it has a number of handcraft and art applications.

Use in Garden and Landscape

In areas suitable for its growth, the Cork Oak tree can be planted both in the soil of the garden, and in parks and squares. Of course, due to the extensive development of the surface root system of the tree, it is not recommended to plant it in small gardens, nor on sidewalks or traffic islands.

Also, when the planting area is selected, care must be taken so that the location of the plant is at a distance of more than 15 m from buildings and houses.

With all of the above in mind, it could be said in general that Cork Oak is being exploited:

  • Planted alone as a plant of particular beauty
  • In plantations for preventing soil erosion on steep fields
  • In mass plantings in gardens or parks
  • In combination with other plants, such as Giant Heathers (Erica arborea), Strawberry Trees (Arbutus unedo), Mastic Trees (Pistacia lentiscus) and Mediterranean Cypresses (Cupressus sempervirens)

Section

Cork Oak Tree (Quercus suber) - References

The References of the article which bears the simple title Cork Oak Tree (Quercus suber), The Famous are presented by the very great Spanish master of classical guitar Andrés Segovia with the musical composition Op.47 – No.5: Asturias of the also great – as well as the name of – Spanish Isaac Manuel Francisco Albéniz y Pascual (… whew) from its work Suite española. 

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Andrés Segovia - Asturias
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  1. Aronson, J., Pereira, J. S., & Pausas, J. G. (Eds.). (2009). Cork Oak Woodlands on the Edge: Ecology, Adaptive Management, and Restoration. Washington: Island Press.
  2. Costello, L. R., Hagen, B. W., & Jones, K. S. (2011). Oaks in the Urban Landscape: Selection, Care, and Preservation. UCANR Publications.
  3. Pereira, H. (Ed.). (2011). Cork: Biology, Production and Uses. Elsevier.
  4. Shackleton, C. M., Pandey, A. K., & Ticktin, T. (Eds.). (2015). Ecological Sustainability for Non-Timber Forest Products: Dynamics and Case Studies of Harvesting. Routledge.
  5. Wagstaff, D. J. (2008). International Poisonous Plants Checklist: An Evidence-Based Reference. CRC Press.
  6. Αθανασιάδης, Ν. (1985). Δασική Βοτανική Ι [Forest Botany]. Θεσσαλονίκη: Γιαχούδη Γιαπούλη.

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