Oak, Quercus

tree of the family Fagaceae
(Spanish chestnut, Oak, Beech)

Etymology: from Latin Quercus, which would come from the Celtic " kaerquez ", " nice tree "; its Greek name, drus, is a generic term to indicate " the tree ". It is also called aigilops or phegos (phagein, "eat", allusion to the eatbable acorn). The Latin robur (allocated in taxonomy in the English Oak) is translated "rouvre" in french. It is a wrong friend because the Sessile oak is not Quercus robur! "robur" gives terms Catalan " roure " and Spanish " roble " (generic names of oaks with deciduous leaves).
Origin : on 400 species, Europe has the English Oak, Quercus pedunculata or Quercus robur (the acorn has a peduncle), the Sessile oak or oak sessile, Quercus sessiliflora or Q. petraea (because the acorn does not have peduncle) or "drill", the Turkey oak, Quercus cerris (so named because its acorn is endowed with hair assimilated with hair!), the variegated Turkey oak (natural in the Doubs and Jura, decorative garden species), the Oak white or Pyrenean, Quercus pyrenaica or Quercus toza (white underside of leaves), the Pubescent oak or the truffle, Quercus pubescens, the Evergreen oak or Holm oak, Quercus ilex ("always green") and the Cork oak, Quercus suber (its bark is exploited), both in persistent leaves. The Oak kermes is a shrub. The oak covers 39 % French forests (see the distribution map of the French forest). There are other species of oaks of America and of Asia.
Habitat: the English Oak is a pioneer species, which means that it is ready to colonize abandoned lands. When a young plant, it supports competition rather badly and to make the quality wood, its crown must be able to develop easily. It prefers cool, deep soils and fed well with water. It is very sensitive to drought but it supports temporary excesses of water. The pH must be close to neutrality (5 - 7,5). The oak sessile is more hardy and tolerant. It can be planted in dense timber while making the wood of high quality. It supports more restrictive conditions: drier, less deep, more acid soils.
the English Oak and the Sessile oak are very hardy (zone 6: they support cold until -23 °C or -9 °F), while the Evergreen oak and the Cork-oak are less resistant to cold (zone 7 ; they support cold until -17 °C or 1° F )
Height: 50 m.
Form (insulated tree):
irregular and broad crown. The low branches are powerful and their tortuous aspect is characteristic in winter. Its foliage is not very dense and branches even in summer are seen. The Sessile oak tightly planted grows straight and high.
Trunk: It can attain 2 m of diameter for the pedunculate oak. It is robust and straight.
Roots: the roots of the oak deeply enter the earth in spindle, to the detriment of the less developed lateral roots.
Bark: smooth and clear on the young tree, it becomes dark at maturity and becomes hollow of deep longitudinal furrows. Grey in the English oak, brown in the sessile oak and the Turkey oak.
Leaves are deciduous (safe to the holm oak and the cork oak) and alternate. They have in general a bigger breadth towards the upper third of the blade (common feature in the deciduous Magnolia leaf). They have a lobbed or deeply toothed margin (holm oak, cork oak, oak chestnut). For difference between oaks, see the next table. The male flower is grouped in rosaries pendulous and discreet in April, at the same time as the appearance of leaves, females are isolated or grouped in small in upright spikes. It has 6 - 8 stamens.
Risk of allergenic pollen : medium.
Its fruit is one akene (the acorn), more or less deeply inserted into a cupule filled with scales sometimes thorny. It falls for itself (leaving its cupule) when it is ripe in September. A grown-up oak produces 50.000. The oak fructifies late (in 50 years).


Turkey oak  

sessile oak or sessile

english oak

Legends and traditions: seldom affected by the lightning, the oak was linked to Zeus, God of the thunder in Greek mythology, and Donar, God of the lightning of Germen. The oak of Dodone acted as oracle: a priest interpreted the whisper of leaves in the wind. In Roman mythology, it is of course the Jupiter tree. Its stems in crowns for the valorous warriors were braided (general's kepi of the Army took back this concept). Among the Celts: Druids harvested mistletoe that grew on an oak rarely. The mistletoe was supposed to collect the soul and the powers of the living tree. In deference to these powers, they used a golden sickle. In Celtic astrology, the oak is robust, audacious, strong... The Catholic church recovered these beliefs, building the God home close to the sacred oaks (example: church d'Allouville-Bellefosse, in Normandy, between Yvetot and the Havre).

  1. the oak inspired well the poets, as Joachim Du Bellay, Anatole France, Lamartine, Victor de Laprade, Jean Moréas, Émile Verhaeren, and of many Quotations. A Tale of the Quebec takes the oak as hero.
  2. Fable of Jean de La Fontaine: the Oak and the Reed.
  3. Song on the oak: the big oak of Georges Brassens.
  4. the Oak occupies a broad place in the Encyclopédie ou Dictionnaire raisonné des sciences, des arts et des métiers (written between 1751 and 1772 under the direction of Diderot).
Uses: the oak is very appreciated by the sculptors because it is flexible to work when it is fresh and by getting old, the wood hardens, preventing the worms from finding a place to live there. The oak is the most hardest and most lasting of European woods. It is also very dense and heavy (> 1 ton / m3). It resists well in the water. This quality, alloyed with the curved form of its branches, was put in benefit in shipbuilding. Colbert, who created the Naval, undertook a large programme of planting of Sessile oaks, by the prescription of 1669. There remain nice forests (from Bercéforest, near Jupilles, in the Sarthe : Sessile oaks on 3.000 hectares; forest of Tronçais on 10583 hectares, close to Moulins, Nevers, Montluçon and Bourges). It is also a very good wood for the framework, the railway sleepers, and a firewood (as other Fagaceae). Barrels due to tannin presence are also made. Its bark is used to tan the leather (because it contains the tannin). Finally, its acorn, rich in starch, served for fattening the pigs; roasted, it constituted a coffee substitute. The Pubescent oak is linked to the truffle which develops near its roots. For other properties, see this page.

To keep and use the animal skins and transform skin, leather tanning is normally used.
The skin is immersed in an aqueous solution of tannin, astringent substance contained in the bark including chopped, ground, ground and then the English oak (vegetable tanned). It absorbs gradually and becomes incorruptible.
In France, where the oak tree is abundant, its bark has been used almost exclusively for this purpose. Vegetable tanning take weeks, months or years, depending on the outcome and quality of leather that was desired. It provides a firmer leather, elastic and more resistant to water. Mineral tanning, much steeper shrinks the leather product, but provides a more resistant leather to wear.
The first two operations are called liming and tanning plucking or stripping. The liming was to macerate the skin fresh and washed for three weeks to a month in solutions increasingly rich in lime. This treatment opens the pores to remove hair more easily.
The plucking was then scraping the surface and removing the hairy flesh still adhering until the wash water no longer contains impurities. These two operations have been improved during the nineteenth century, replacing the lime caustic soda. In this way a leather was obtained softer within twice less time.
The third operation, called inflation, was intended to further open the pores to facilitate the absorption of tannin. This was obtained by steeping the skins in solutions more concentrated in bark, tan.
Finally tanning itself was to stack the skins in large vats of wood or masonry waterproof, called pits, between layers of tan nine. It took about 300 kg per 100 kg of tan fresh skin. Water was added throughout the mass. The tannin from the bark was dissolved and absorbed by the skin. The latter operation could be repeated several times, and at the end, the skins became leather.

The common Oak (Quercus pedunculata) and the sessile Oak (Quercus sessiliflora) are susceptible to powdery mildew (Microsphaera alphitoides) which results in whitish powdery spots appear on leaves, then browning and finally weakening of the crown. A sulfur-based treatment is necessary, or if the disease is too developed a treatment based on use of myclobutanil.

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