Common Name: Willow Oak

General Information

Quercus phellos is a deciduous tree with a dense, pyramidal canopy when young becoming more rounded with age; it can grow up to 40 metres tall. The slender bole is straight and cylindrical, and can be more than 100cm in diameter[, ].
The tree is harvested from the wild for local use as a food, medicine and source of materials. It is a good source of low-quality lumber and pulpwood and is sometimes grown in plantations as a source of pulp[]. Additionally, this species is widely planted as an ornamental and shade tree[]
Quercus phellos is a common lowland species throughout its wide range and there are no reports of significant population declines. 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

South-eastern N. America - eastern Oklahoma to New Jersey, south to eastern Texas and Georgia

Habitat

Low wet borders of swamps and streams, bottom lands and sandy uplands on rich soils[, ]. Moist alluvial soils of bottomland flood plains and stream banks, occasionally on poorly drained uplands; at elevations up to 400 metres[].

Properties

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

Cultivation Details

Quercus phellos is a moderately cold-hardy tree, tolerating temperatures down to around -20°c when dormant. Although it grows best in areas with hot summers, it will usually also succeed in areas with cool summers but will then often fail to set seed[, , ].
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[, ]. Somewhat lime tolerant accordong to one report[], whilst another says it dislikes a soil pH higher than 7[]. Plants are often found in constantly wet to moist soils, but are also highly tolerant of drought once established[]. Tolerates moderate exposure, including salt-laden winds, surviving well but being somewhat stunted[]. Generally tolerant of urban conditions[].
A long-lived tree, it commences to bear seeds when about 20 years old in the wild and good crops are usually produced annually[]. The tree flowers on new growth produced in spring, the seed taking two summers to ripen[].
A very ornamental plant[]. It is widely planted as an ornamental and shade tree, particularly because its shallow root system allows it to be transplanted easily[].
Hybridizes freely with other members of the genus[].
Willow Oak is susceptible to pests and pathogens that affect many members of the Red Oak group in the eastern US. However, no reports of widespread population decline are available, suggesting this does not currently pose a major threat to the species[].
This species is notably resistant to honey fungus[, ].

Edible Uses

Seed - cooked[, , ]. The ovoid to hemispheric seed is 8 - 12mm long and 6 - 10mm wide[]. The seeds have 5.9% total protein and 19.6% crude fat[].
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

A decoction of the wood chips or bark has been applied externally as an analgesic and as a bath for aches, pains, sores, cuts and haemorrhoids[].

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 used for restoration of the wetter sites of bottomland hardwood forests and for rehabilitation of disturbed areas. It is also a good species to plant along margins of fluctuating-level reservoirs[].

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 contains about 10% tannin and is a commercial source of that material[]. Tannin is also found in the leaves and wood[].

The seedcups are used as buttons[].

The wood is close-grained, strong, not hard, heavy, not durable[, , , , ]. It weighs 46lb per cubic foot[]. Of rather low quality for an oak but it is sufficiently abundant to be harvested commercially. The wood is used for construction, fellies of wheels etcl[, , , , ]. It is a good source of pulp and can be harvested for this purpose when quite young[].
The wood is used for fuel and to make 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.