Quercus emoryi

Quercus emoryi, the Emory oak, is a species of oak common in Arizona (including inside Saguaro National Park), New Mexico and western Texas (including inside Big Bend National Park), United States, and northern Mexico (Sonora, Chihuahua, Coahuila (including Parque Nacional Maderas del Carmen), Durango, Nuevo León, and San Luis Potosí). It typically grows in dry hills at moderate altitudes.

Description

Evergreen tree reaching 12m tall at slow growth rate. Hardy to UK zone 7. Maintains foliage year-round, flowers in May with seeds ripening in September. Monoecious, wind-pollinated. Grows in medium loamy and heavy clay soils with mildly acid to basic pH. Tolerates semi-shade or full sun, prefers moist soil, and withstands strong winds but not coastal exposure.

Edible Uses

The acorn can be eaten raw or cooked and has a sweet flavour. It is an important food source for Indigenous peoples in southern Arizona and northern Mexico, where it is also sold in local markets. The seed is up to 2cm long and 1cm thick. It can be dried and ground into flour for thickening stews or combining with cereals for bread. Where bitter tannins are present, they can be leached out by washing thoroughly in running water, though minerals are lost in the process. Whole seeds may take several days or weeks to leach; placing them wrapped in a cloth bag in a running stream is one method. Ground meal leaches faster. A simple taste test confirms when the tannin is sufficiently removed. Traditionally, seeds were buried in boggy ground over winter and dug up in spring once most astringency had gone. The roasted seed makes a coffee substitute.

Traditional Uses

The acorns are eaten whole and raw. They are also ground or boiled. They are used as thickening for stew. The acorns are stored for later use.

This uses section is brief — help expand it

Medicinal Uses

Any galls that form on the tree are strongly astringent and have been used in the treatment of haemorrhages, chronic diarrhoea, and dysentery.

Distribution

It is a temperate plant. In Melbourne Botanical Gardens.

Where It Grows

Australia, Central America, Mexico, North America, USA,

Cultivation

Prefers a good deep fertile loam which can be on the stiff side. Young plants tolerate reasonable levels of side shade. Tolerates moderate exposure, surviving well but being somewhat stunted. Prefers warmer summers than are usually experienced in Britain, trees often grow poorly in this country and fail to properly ripen their wood resulting in frost damage overwinter. A slow-growing tree in its native range. Seed production is cyclical, with a year of high production followed by a few years of low production. The tree flowers on new growth produced in spring, the seed ripening in its first year. Intolerant of root disturbance, trees should be planted in their permanent positions whilst young. Hybridizes freely with other members of the genus. Plants in this genus are notably resistant to honey fungus.

Propagation

Acorns lose viability quickly if allowed to dry out. They can be stored moist and cool over winter, but are best sown as soon as ripe in an outdoor seed bed with protection from mice and squirrels. Small quantities can be sown in deep pots in a cold frame. Because plants develop a deep taproot early, they should be moved to permanent positions as soon as possible — seed sown in situ produces the best trees. Do not leave trees in a nursery bed for more than 2 growing seasons, as they transplant very poorly after that point.

Other Uses

A mulch of the leaves repels slugs and grubs, though fresh leaves should not be used as they can inhibit plant growth. Oak galls, produced by the larvae of various insects, can be harvested after the insect pupates and leaves — they yield a rich source of tannin that also functions as a dyestuff. The wood is heavy, hard, strong, brittle, and close-grained. It has little commercial value but is an important fuel within its native range.

Other Information

The nuts are sold in local markets.

Notes

There are about 600 Quercus species.

Synonyms

Also Known As

Blackjack oak, Bellota, Encino

References (14)

• Beckstrom-Sternberg, Stephen M., and James A. Duke. "The Foodplant Database." http://probe.nalusda.gov:8300/cgi-bin/browse/foodplantdb.(ACEDB version 4.0 - data version July 1994)
• Desert Survivors Online Plant Database
• W. H. Emory, Not. mil. reconn. 151, t. 9. 1848
• Estrada-Castillon, E., et al, 2014, Ethnobotany in Rayones, Nuevo Leon, Mexico. Journal of Ethnobiology and Ethnomedicine, 10:62
• Felger, R.S., Ancient Crops for the Twenty first century, in Rickie, G.A., (ed), 1979, New Agricultural Crops, AAAS Selected Symposium 38. Westview Press, Colarado. p 10

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