Common Name: Swamp White Oak

General Information

Quercus bicolor is a deciduous tree with a dense, broad, rounded canopy; it can grow up to 30 metres tall[]. The bole can be 60 - 100cm in diameter[]. The tree usually branches from quite low down[].
The plant is harvested from the wild for local use as a food, medicine and source of materials. The wood is commercially important. The tree is planted on highway rights-of-way and is frequently used as a shade tree for lawns, golf courses, parks, and naturalized areas. Its crown shape and bi-coloured leaves are attractive and sought out features[].
It is assumed that this species has a large population size given its widespread distribution along with its abundance throughout. Mapped occurrences reveal an extent large enough to surpass IUCN's criteria for threatened species. Additionally, this species does not face any imminent threat that is known of. 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 N. America - Ontario to Quebec, south to Alabama, Tennessee and North Carolina

Habitat

Found in a variety of soils in swamp forests of river bottoms, stream-sides, depressions, borders of ponds, lakes, and swamps and moist peaty flats; sometimes on moist slopes and poorly drained uplands; at elevations up to 1,000 metress[].

Properties

Conservation Status	Least Concern
Edibility Rating
Medicinal Rating
Other Uses Rating
Habit	Deciduous Tree
Height	20.00 m
Pollinators	Wind
Cultivation Status	Ornamental, Wild

Cultivation Details

Quercus bicolor is very cold tolerant, surviving temperatures down to around -30°c without damage, but requires hot summers if it is to thrive. In areas with cooler summers it will not usually produce much seed, and will also be more liable to winter damage because its wood has not ripened fullyr11, []. This species is one of the best of the white oaks for growing in the maritime zone, though the seed is only likely to be produced after hot summers[].
Prefers a good deep fertile, somewhat acid loam which can be on the stiff side[, , ]. Tolerant of poorly drained sites, it is frequently found in heavy mucky soils in the wild[]. The plant develops severe chlorosis on alkaline soils[]. Young plants tolerate reasonable levels of side shade[]. Tolerates moderate exposure, surviving well but being somewhat stunted[].
A relatively fast-growing tree in the wild, living 300 - 350 years[], though it is relatively shallow-rooted and is considerably more susceptible to forest fires than most other oaks[].
A slow growing but long-lived tree in the wild, living up to 300 years or more[].
The tree flowers on new growth produced in spring, the seed ripening in its first year[, ]. Trees do not commence bearing until about 25 - 30 years old, large crops being produced every 3 - 5 years[].
Seedlings soon develop a taproot and become intolerant of root disturbance, they should be planted into their permanent positions whilst young[].
The seed of this species is attached to the tree by unusually long (by oak tree standards) stems[].
The tree can resprout from the trunk if it is cut down or top-killed by fire[].
Hybridizes freely with other members of the genus[]. Putative hybrids between Quercus bicolor and Quercus macrocarpa are common where their ranges overlap[].
Plants in this genus are notably resistant to honey fungus[].

Edible Uses

Seed - raw or cooked[, , ]. A rather sweet flavour[, ]. The seed is quite large, about 15 - 25mm long and 9 - 20mm wide[, , ], and unlike most other oaks, is attached to the tree by a long stem[]. It matures in its first year[]. The seed can be dried, ground into a powder and used as a thickening in stews etc or mixed with cereals for making bread[].
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[, ].

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[].

The bark has been boiled with hemlock (Tsuga sp.?) and soft maple bark (Acer spp), and the liquid used to remove rust. The mixture was also believed to prevent rust[].

The wood is close-grained, strong, hard, tough, heavy[, , , ]. It weighs 48lb per cubic foot[]. Trees do not self-prune and dead branches remain on the trees for many years. This does mean that the wood is usually quite knotty[]. The wood machines well, though it can check and warp if not dried properly. It is of some importance commercially. And is used for construction, cabinet making, furniture, interior finishes, veneers, fence posts etc[, , , , , ].
The wood makes a good fuel.

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.