Common Name: Sessile Oak

General Information

Quercus petraea is a deciduous tree usually growing 20 - 30 metres tall but sometimes reaching 40 metres[].
The oak is a very important timber tree, being harvested from the wild on a commercial basis. It also provides food, medicine and various materials for local use. One of the most important plant species for wildlife in western Europe, it is often used in reforestation projects and is also grown as an ornamental and shade tree.

Known Hazards

All parts of the plant contain tannins. Whilst tannins are found in many foods, and have a range of medicinal uses. They are usually only present in low concentrations. In some foods made from oaks (particularly the seeds), the tannin content can be quite high unless the food is treated to reduce tannin content.
Tannins are only of low toxicity and, because of their bitter taste and astringency, are unlikely to be eaten in large quantities. However, if they are taken in excess, they can cause stomach pains; constipation followed by bloody diarrhoea: excessive thirst; and excessive urination[].

Botanical References

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Range

Most of Europe except the far north, Portugal and Moldova; W. Asia - Turkey, Caucasus, Syria, Lebanon

Habitat

Woods, especially on acid soils and in the western part of Britain, where it is often dominant[].

Properties

Edibility Rating
Medicinal Rating
Other Uses Rating
Habit	Deciduous Tree
Height	40.00 m
Growth Rate	Slow
Pollinators	Wind
Cultivation Status	Cultivated, Ornamental, Semi-cultivated, Wild

Cultivation Details

Prefers a good deep fertile loam which can be on the stiff side[]. Dislikes heavy clay[]. Young plants tolerate reasonable levels of side shade[]. Found mainly on acid soils in the wild. Thrives in well drained soils but is also tolerant of periodic flooding[]. Tolerates exposure and strong winds if these are not salt-laden[].
A very important timber tree, especially in western Europe, it is also a food plant for the caterpillars of many species of butterfly[], there are 284 insect species associated with this tree[].
The tree flowers on new growth produced in spring, the seed ripening in its first year[, ].
As the trunk is straight and less branched than in Quercus robur, it yields a greater amount of serviceable lumber, with less waste[].
Older trees have a thick corky bark and this can protect them from forest fires, young trees will often regenerate from the base if cut down or killed back by a fire[].
Trees were often coppiced or pollarded in the past for their wood[], though this is best done on a long rotation of perhaps 50 years.
Trees can be managed by coppicing in order to provide material for basket making, fuel, construction etc[].
Trees transplant badly unless moved regularly[].
Hybridizes freely with other members of the genus[].
Immune to attacks by the Tortix moth[]. This species is notably resistant to honey fungus[, ].

Edible Uses

Seed - cooked[, , , ]. The seed is 15 - 25mm long[].
The seed is usually cooked before eating, though it can also be eaten raw. It can be eaten whole, though it is more commonly dried, then ground into a powder and used as a thickening in stews etc or mixed with cereals for making bread.
In some species, especially many of those classified as 'white oaks', the seeds are low in tannins and have a more or less sweet and agreeable flavour. The seed of most species, however, have a very bitter flavour, due especially to the presence of tannins. In these species there are various processes that can remove or at least reduce the amount of these bitter substances (although other water-soluble substances, including some minerals, will also be removed).
Tannins are water-soluble and therefore the easiest way to remove or reduce tannin levels is by soaking in water. A few different methods are listed:-
A traditional method of preparing the seed was to bury it in boggy ground overwinter and allow the wet soil to gradually leach the tannins. The germinating seed was dug up in the spring when it would have lost most of its astringency and bitterness.
Another method was to wrap the seeds in a cloth bag and place them in a stream for several weeks.
Drying the seed and grinding it to a powder before soaking speeds up the process. The fastest method is to use hot water, by cooking the powder and changing the water several times until the cooking water is no longer bitter. Alternatively, you can use cold water (which is reported to produce the best quality flour). In this case, you soak the powdered seed in cold water for 12 - 24 hours then discard the water. Repeat this process for a number of times until the soak water is no longer bitter.

The roasted seed is a coffee substitute[, ].

An edible gum is obtained from the bark[].

Medicinal

The oak tree has a long history of medicinal use. It is anti-inflammatory, antiseptic, astringent, decongestant, haemostatic and tonic[, , , , , ]. The bark is the part of the plant that is most commonly used[], though other parts such as the galls, seeds and seed cups are also sometimes used[]. A decoction of the bark is useful in the treatment of chronic diarrhoea, dysentery, intermittent fevers, haemorrhages etc[].
Externally, it is used to bathe wounds, skin eruptions, sweaty feet, piles etc[]. It is also used as a vaginal douche for genital inflammations and discharge, and also as a wash for throat and mouth infections[].
The bark is harvested from branches 5 - 12 years old, and is dried for later use[].

Quercus (oak) species are used in the traditional medicine of many cultures, being valued especially for their tannins. Various parts of the plant can be used, most frequently it is the leaves, bark, seeds, seed cups or the galls that are produced as a result of insect damage. A decoction or infusion is astringent, antibacterial, antifungal, antiseptic, styptic and haemostatic. It is taken internally to treat conditions such as acute diarrhea, dysentery and haemorrhages. Externally, it is used as a mouthwash to treat toothache or gum problems and is applied topically as a wash on cuts, burns, various skin problems, haemorrhoids and oral, genital and anal mucosa inflammation[]. Extracts of the plant can be added to ointments and used for the healing of cuts[, ].

The plant is used in Bach flower remedies - the keywords for prescribing it are 'Despondency', 'Despair, but never ceasing effort'[].

A homeopathic remedy is made from the bark. It is used in the treatment of disorders of the spleen and gall bladder[].

Agroforestry Uses:

This is one of several Quercus species which are either cultivated or semi-cultivated in southern France and Italy in order to provide an environment in which to grow various species of truffles[].

Other Uses

The leaves of most species in this genus are more or less rich in tannins. A mulch of the leaves can be placed around vulnerable plants in order to repel slugs, snails, grubs etc. Fresh leaves should be used with caution, since these can utilize some of the nitrogen in the soil and this inhibit plant growth[, ].

Oak galls are excrescences that are sometimes produced in great numbers on the tree and are caused by the activity of the larvae of different insects. The insects live inside these galls, obtaining their nutrient therein. When the insect pupates and leaves, the gall can be used as a rich source of tannin, that can also be used as a dyestuff[].
An ink is made from the oak galls, mixed with salts of iron[, ].

The bark is an ingredient of 'Quick Return' herbal compost activator[]. This is a dried and powdered mixture of several herbs that can be added to a compost heap in order to speed up bacterial activity and thus shorten the time needed to make the compost[]. The bark is very rich in calcium[].

The wood is a source of tar, quaiacol, acetic acid, creosote and tannin[].
Tannin is extracted commercially from the bark and is also found in the leaves[].

The heartwood is a light tan to biscuit-colour. The grain is usually straight, though irregular or cross-grained material can occur. The wood is hard, tough, durable even under water. It dries slowly, with a tendency to split and check; there is medium movement in service. The wood bends well with steam; there is a moderate to severe blunting effect on cutters; it polishes well, holds nails well, though only non-ferrous or galvanized nails should be used or the acidic wood will cause staining and corrosion. Somewhat softer than the wood from Quercus robor, this species is therefore more valued for carpentry[]. The wood is highly valued for a wide range of purposes including furniture, construction, boat building, cooperage, high class joinery etc[, , , ].
The wood is a good fuel, burning well and giving off a lot of heat. It can also be used to make an excellent charcoal[, ].

Propagation

Seed - it quickly loses viability if it is allowed to dry out. It can be stored moist and cool overwinter but is best sown as soon as it is ripe in an outdoor seed bed, though it must be protected from mice, squirrels etc. Small quantities of seed can be sown in deep pots in a cold frame. Plants produce a deep taproot and need to be planted out into their permanent positions as soon as possible, in fact seed sown in situ will produce the best trees[]. Trees should not be left in a nursery bed for more than 2 growing seasons without being moved or they will transplant very badly.