Common Name: Red Oak

General Information

Quercus rubra is a deciduous tree with a dense, large, rounded crown; it usually grows 20 - 30 metres tall, exceptionally to 49 metres. The straight, cylindrical bole is usually around 60 - 90cm in diameter, occasionally reaching 240cm[, ].
The tree is harvested from the wild for local use as a food, medicine and source of materials. Quercus rubra is the most valuable timber species of all the red oaks in N. America and is harvested from the wild on a commercial basis. This species was first cultivated in 1724, it is sometimes grown as a timber crop and is frequently planted as an ornamental shade tree in eastern North America and in Europe[].
Quercus rubra occurs widely throughout much of eastern North America and is a canopy dominant in many communities across this range. It remains abundant and secure throughout its distribution. The plant 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

Eastern and central N. America - Minnesota to Nova Scotia, south to Oklahoma and Georgia

Habitat

Dry-mesic to mesic sites, including rich woods, dry slopes, rock outcrops, sandy plains and edges of floodplains[]. Found in a variety of soils, preferring deep and fine textured soils, growing largest in protected ravines or on sheltered slopes[].

Properties

Conservation Status	Least Concern
Edibility Rating
Medicinal Rating
Other Uses Rating
Habit	Deciduous Tree
Height	25.00 m
Growth Rate	Fast
Pollinators	Wind
Cultivation Status	Cultivated, Ornamental, Wild

Cultivation Details

Quercus rubra is a very cold-hardy tree, tolerating temperatures down to around -30°c when dormant. It grows best in areas with hot summers but usually still does well in areas with cooler summers[, ]. Mean annual precipitation can range from 760 - 2,030mm[].
Grows best in 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[]. Prefers fertile, sandy, finely-textured soils with good drainage[]. An important attribute of this oak is its ability to flourish on poor, dry soils where other oaks grow less well[]. Tolerant of slightly alkaline soils[, ]. Tolerates moderate exposure, including salt-laden winds, surviving well but being somewhat stunted[, ]. Established plants are fairly drought tolerant[]. Tolerates urban conditions well[].
Quercus rubra is one of several species of eastern red oak that has almost entirely replaced Quercus alba in commerce. Whilst Quercus alba used to be considered the source of the finest and most durable oak lumber in America, these red oaks are more common, have faster growth rates and greater yields. They also lack tyloses and therefore are more suited to pressure treating with preservatives, even though they are less decay-resistant without treatment[].
A fairly fast-growing tree[], it is cultivated for its timber in central Europe[].
Trees normally require 20 - 25 years to reach flowering size, and may take another 20 years before heavy crops of seed are produced[]. Seed production is cyclic, heavy crops being produced every 2 - 5 years in the wild[]. The tree flowers on new growth produced in spring, the seed taking two summers to ripen[].
Trees are able to regenerate from root suckers if the top is killed by a forest 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 - cooked[, , ]. A staple food for several native North American tribes[]. The ovoid to oblong seed can be 15 - 30mm long and 10 - 21mm wide[]. The seed contains bitter tannins[].
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

The bark and inner bark is antiseptic, astringent, emetic, febrifuge and tonic[]. It is used in the treatment of diarrhoea, chronic dysentery, indigestion, asthma, severe coughs, hoarseness, intermittent fevers, bleeding etc[, ].
Externally, it is used as a wash for skin eruptions, rashes, burns etc[, ]. The bark can be chewed as a treatment for mouth sores[].

The bark contains tannins, experimentally these have been shown to be antiviral, antiseptic, anticancer and also carcinogenic[].

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[, ].

Agroforestry Uses:

The tree is well adapted to some types of moderately unproductive environments, including certain acidic sites, and
can be used in various rehabilitation projects. It has been successfully planted onto coal mine spoils in Ohio, Indiana, Illinois, Kentucky, and Pennsylvania[].

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[, ].

Tannin is obtained from the bark[, ]. A reddish-brown dye can be obtained from the bark[].

The wood is coarse-grained, hard, strong, heavy, not very durable[, , , ]. It weighs 41lb per cubic foot[]. When properly dried and treated, the wood glues well, machines very well, and accepts a variety of finishes[]. An important lumber source in America, it is highly valued for flooring, furniture, veneer, construction etc[, , , ].
The wood is a favoured 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.