Common Name: Oregon White Oak

General Information

Quercus garryana can be a deciduous shrub with multiple stems and creeping roots, reaching a height of 10 - 300cm when growing in rocky habitats with shallow soils; in more favourable conditions it becomes a tall, usually single-stemmed tree with a spreading crown that can grow 8 - 30 metres tall. The bole of larger trees can be 60 - 100cm in diameter, exceptionally to 250cm[, ].
The seeds were an important food source for the native Americans, and are still eaten to a limited extent. The plant is also harvested from the wild for local use as a medicine and source of materials. The tree is harvested commercially for its wood, and it is also considered to be one of the best fuels for home heating and gathers top prices It is sometiumes grown as an ornamental[].
With a very large range, variety of suitable habitats and minimal threats, Quercus garrynan is classified as 'Least Concern' in the IUCN Red List of Threatened Species(2013)[].

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

Western N. America - British Columbia, Washington, Oregon, California.

Habitat

Found in a variety of inland sites, including upland slopes, exposed ridges and open valley bottoms, in mixed evergreen forests, conifer forests, inland in its own open woodland community, or as a large shrub among pines, firs and junipers[].

Properties

Conservation Status	Least Concern
Edibility Rating
Medicinal Rating
Other Uses Rating
Habit	Deciduous Tree
Height	18.00 m
Growth Rate	Slow
Pollinators	Wind
Cultivation Status	Ornamental, Wild

Cultivation Details

Quercus garryana is a fairly cold-hardy tree, tolerating temperatures down to around -20°c when dormant. It grows in the mild maritime climates of Oregon as well as the more mediterranean climate of California. Summer temperatures usually avereage a bit more than 20°c and mean annual precipitation can range from 250 - 2,500mm[].
Plants generally require a sunny position[], though young plants tolerate reasonable levels of side shade[]. Prefers a good deep fertile loam which can be on the stiff side[, ]. Plants in the wild are found on a variety of soils ranging from dry to very moist and poorly to rapidly draining; gravelly and heavy clay substrates are tolerated[]. Lime tolerant[]. Tolerates moderate exposure, surviving well but being somewhat stunted[]. Often crowded out by species that grow faster and taller, this species has no strict soil preference and can be found on rocky sites as well as heavy clays, and can withstand both lengthy flooding and drought[].
The tree is sometimes grown as an ornamental and shade tree[].
A slow-growing and drought tolerant tree[, ], it can live for 500 years[].
Seed production is cyclic, with a year of high production being followed by 2 - 3 years of lower yields[]. The tree flowers on new growth produced in spring, the seed ripening in its first year[, ].
Trees can resprout from the base if cut back or top-killed by fire[].
Seedlings soon develop a taproot and become intolerant of root disturbance, they should be planted into their permanent positions whilst young[].
Hybridizes freely with other members of the genus[].
Plants in this genus are notably resistant to honey fungus[].

Edible Uses

Seed - raw or cooked[]. The seed can be 12 - 40mm long and 10 - 22mm wide[], with a sweet taste[]. The seed is ground into a powder and used in making bread etc, it is a good thickener for soups and stews[].
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 of many Quercus species has been used as a coffee substitute.

Medicinal

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[, ].

A decoction of the bark has been used in the treatment of tuberculosis[].
The pounded bark has been rubbed on the abdomen and sides of the mother before her first delivery[].

An infusion of the plant has been drunk by a mother before her first baby comes[].

Other Uses

The leaves of most species in this genus are more or less rich in tannins. A mulch of the partially decayed leaves can be placed around vulnerable plants in order to repel slugs, snails, grubs etc, and these will in time break down to add humus and nutrients to the soil. Fresh leaves should be used with caution, however, since as these decay they utilize some of the nitrogen in the soil and thus can 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 and is also used by many cultures to make ink[, ].
The bark of oak trees is also usually rich in tannins and can be used as a dyestuff and for waterproofing rope[, ].

The wood is hard, heavy, strong, tough, close grained, durable, easy to split. A good quality wood, it is ssed for making furniture, cabinet making, Flooring, general construction etc and also for fence posts and fuel[, , , , , ].
The wood is an excellent fuel - burning well and giving off a lot of heat[, ].

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.