Common Name:

General Information

Quercus arizonica is an evergreen or semievergreen tree with an irregular crown of stout, spreading branches; it usually grows 5 - 10 metres tall but occasionally reaches up to 18 metres. The bole of larger specimens can be up to 100cm in diameter[, , ].
The tree is harvested from the wild for local use, probably as a source of food and medicines, but mainly for its wood.
This species is widespread and occurs regularly throughout the northern part of its range. Subpopulations are scattered in southern and eastern parts of its range, making the species of concern in Mexico. Potential future threats do exist in light of scattered subpopulations, however, on a global scale these are not considered significant threats at present. Additionally, no pests and/or diseases threaten the survival of this species significantly. 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

Range

Southwestern N. America - Arizona, New Mexico, Texas, central and northern Mexico

Habitat

Arroyos, canyons, foothills, bajadas, rocky slopes, ridges, or steep sideslopes with westerly to northerly exposures[]. Oak and pinyon woodlands, margins of chaparral, arroyos; at elevations from 1,300 - 2,500 metres, occasionally 3,000) metres[].

Properties

Conservation Status	Least Concern
Edibility Rating
Medicinal Rating
Other Uses Rating
Habit	Semi-deciduous Tree
Height	8.00 m
Pollinators	Wind
Cultivation Status	Wild

Cultivation Details

Quercus arizonica is a moderately cold-hardy tree, tolerating temperatures down to around -15°c when dormant. It occurs in semiarid to arid climates with a bimodal precipitation regime, mild winters, and hot summers. In areas with cooler summers, such as the maritime regions of the temperate zone, it often grows poorly, failing to properly ripen its wood and suffering frost damage over the winter[].
Requires a sunny position, though seedlings are tolerant of considerable side shade[]. It is found in the wild on shallow to deep soils of moderate to very fine texture, consisting of old alluvium from mixed sedimentary, igneous, or granitic rocks. Rock cover may be more than 15%. Soils also may be cobbly loams that are deep and well-drained with low water-holding capacity[].
Quercus arizonica is a slow growing, large tree that reaches a maximum height at 18 metres tall[].
Seed production is highly variable. Large crops, with up to 32,600 acorns per tree, alternate with several years of low
acorn production[]. The seed ripens towards the end of its first growing season[].
Plants will resprout from the base if cut down or top-killed by fire[].
This species hybridizes with Quercus grisea where their ranges overlap[].

Edible Uses

The light brown, ovoid or oblong seed is 8 - 12mm long[]. This species belongs to the white oak subgenus, where the seeds are generally low in tannins and are often eaten[].
Although we have no specific information for this species, the seeds of all the species of oak are edible - indeed, several species have been used as staple foods, whilst most if not all have been used for food in times of shortage, when better foods were not available[].
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 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 close grained, heavy, hard, and strong. When it is of sufficient size, it is sometimes used to make furniture, but is seldom straight enough or large enough to be of commercial value[].
The wood burns well, 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.