Practical
Plants

Quercus oblongifolia

Mexican Blue Oak

a perennial woody evergreen member of the Quercus genus in the family Fagaceae.

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Taxonomy and growth

Family
Fagaceae
Genus
Quercus
Life cycle
perennial
Foliage
evergreen
Woodiness
woody
Height
8 m
Fertility
Wind
Flower type
monoecious
Pollinators
Wind

Uses

Edible uses

This section contains historical Plants For A Future notes marked noncommercial.

Seed - raw or cooked[3][5]. A staple food for some native North American Indian tribes[9]. Very sweet[4][7], it is up to 2cm long and 8mm wide[11][7]. The seed can be dried, ground into a powder and used as a thickening in stews etc or mixed with cereals for making bread. If any seed contains bitter tannins, these can be leached out by thoroughly washing the seed in running water though many minerals will also be lost. Either the whole seed can be used or the seed can be dried and ground it into a powder. It can take several days or even weeks to properly leach whole seeds, one method was to wrap them in a cloth bag and place them in a stream. Leaching the powder is quicker. A simple taste test can tell when the tannin has been leached. The traditional method of preparing the seed was to bury it in boggy ground overwinter. The germinating seed was dug up in the spring when it would have lost most of its astringency. The roasted seed is a coffee substitute.

Product or use
Coffee
Plant part
Seed

Medicinal uses

Historical medicinal uses. These records describe reported uses. They do not establish safety or effectiveness. Ask a qualified health professional before using any plant medicinally.

This section contains historical Plants For A Future notes marked noncommercial.

Any galls produced on the tree are strongly astringent and can be used in the treatment of haemorrhages, chronic diarrhoea, dysentery etc[10].

Product or use
Astringent

Material uses

This section contains historical Plants For A Future notes marked noncommercial.

A mulch of the leaves repels slugs, grubs etc, though fresh leaves should not be used as these can inhibit plant growth[6]. 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[10]. Wood - very heavy, hard, strong, brittle[11]. It is sometimes used as a fuel[11].

Product or use
Repellent
Product or use
Tannin
Product or use
Wood

Ecology and functions

Ecosystem niche
Secondary canopy

Environment

Range
South-western N. America - Texas, New Mexico, Arizona, Mexico.
Habitat
A common tree of open oak woodlands in foothills, mountain slopes and in canyons, 1500 - 2000 metres[8].
Light
full sun
Shade tolerance
light shade
Water
moderate
Hardiness
Zone 7+
Soil textures
loamy, clay
Soil pH
acid, neutral, alkaline
Tolerances
high wind
Wind
Yes
Tolerates Nutritionally Poor Soil
No
Drought
intolerant

Propagation

This section contains historical Plants For A Future notes marked noncommercial.

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[2]. Trees should not be left in a nursery bed for more than 2 growing seasons without being moved or they will transplant very badly.

Cultivation

This section contains historical Plants For A Future notes marked noncommercial.

Prefers a good deep fertile loam which can be on the stiff side[1][2]. Young plants tolerate reasonable levels of side shade[7]. Tolerates moderate exposure, surviving well but being somewhat stunted[7]. 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[7]. The tree flowers on new growth produced in spring, the seed ripening in its first year[7][8]. Intolerant of root disturbance, trees should be planted in their permanent positions whilst young[2]. Hybridizes freely with other members of the genus[7]. Plants in this genus are notably resistant to honey fungus[7].

References

  1. F. Chittendon. RHS Dictionary of Plants plus Supplement. 1956 Oxford University Press 1951-00-00

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  2. Bean. W. Trees and Shrubs Hardy in Great Britain. Vol 1 - 4 and Supplement. Murray 1981-00-00

    ↩1↩2↩3

  3. Yanovsky. E. Food Plants of the N. American Indians. Publication no. 237. U.S. Depf of Agriculture.

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  4. Kunkel. G. Plants for Human Consumption. Koeltz Scientific Books 1984-00-00 ISBN 3874292169

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  5. Pesman. M. W. Meet Flora Mexicana. Dale S. King. Arizona. 1962-00-00

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  6. Riotte. L. Companion Planting for Successful Gardening. Garden Way, Vermont, USA. 1978-00-00 ISBN 0-88266-064-0

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  7. Huxley. A. The New RHS Dictionary of Gardening. 1992. MacMillan Press 1992-00-00 ISBN 0-333-47494-5

    ↩1↩2↩3↩4↩5↩6↩7↩8

  8. Elias. T. The Complete Trees of N. America. Field Guide and Natural History. Van Nostrand Reinhold Co. 1980-00-00 ISBN 0442238622

    ↩1↩2

  9. Moerman. D. Native American Ethnobotany Timber Press. Oregon. 1998-00-00 ISBN 0-88192-453-9

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  10. Grieve. A Modern Herbal. Penguin 1984-00-00 ISBN 0-14-046-440-9

    ↩1↩2

  11. Sargent. C. S. Manual of the Trees of N. America. Dover Publications Inc. New York. 1965-00-00 ISBN 0-486-20278-X

    ↩1↩2↩3

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