Oak

Oak is arguably Britain’s most beloved tree and can live up to 800 years. The fruit it bears – the acorn – has been popular as a source of food and medicine since ancient times.

All parts of the oak were once considered edible making this tree quite the forager’s feast!

Scientific Name

Quercus robur

Family

Fagaceae.

Botanical Description

This majestic-looking tree has wide-spreading, branches on a short, stout trunk. The bark is brown-grey and the leaves are dark green on top and pale blue-green beneath. The tree bears male and female flowers – male flowers are slender catkins and female flowers are globe-shaped and pale brown. The easily recognisable fruit – acorns – resemble a small nut inside a stalked cup.

Status

Perennial. Native.

Habitat and Distribution

Deciduous woodland, hedgerows.

Parts Used for Food

Leaves, flowering buds, fruit (acorns).

Harvest Time

Spring for leaves. Autumn for acorns.

Food Uses of Oak

Humans have consumed acorns since ancient times.

Classical authors write of the early inhabitants of Greece and southern Europe being fat on the fruits of the oak. They were the Balanophagi, or ‘eaters of acorns’.

In pastimes, acorns were collected and ground to meal for flour. The ‘acorn milk’, a byproduct of this process, was also drunk.

Acorns were gathered for snacking, roasting, boiling or drying to add to meals.

However, it is worth noting that caution is now given before eating acorns that have not been properly treated – leached of their plant tannins – and that eating the nuts raw is not recommended (see the section on ‘Cautions’).

Oak leaves were once used to make wine and even the trunk of the tree has provided an edible source of gum.

Oak Recipes

• How to Process Acorns
• Spiced Pickled Acorns

Nutritional Profile of Oak

Acorns are nutrient-rich containing starches, oils, proteins, minerals (such as calcium, phosphorus and potassium) as well as several B vitamins (although these are water-soluble and often lost during the process of preparing the nut to eat), as well as plant sugars and tannins.

Herbal Medicine Uses of Oak

All parts of the oak – wood, bark, leaves, acorns and gallnuts – have traditionally been used in medicine since ancient times.

The tree was valued for its astringent properties most likely due to the high content of tannins.

It was used for wide-ranging ailments from mouth disease and skin complaints to rheumatism and digestive problems.

Surprisingly oak galls (a parasitic infection of the tree caused by a tiny wasp) had an even wider range of use from treating mouth diseases, infected eyes and ears, toothache, stomach disorders, dysentery, rashes, abscesses, skin ailments and burns, swollen spleens and regulating menses.

Other Uses of Oak

Oak is a well-known wood used for making furniture. However, some traditional uses of oak that we might find novel today have included making wooden bowls, milk pails, butter-firkins, baskets, fighting clubs, tool handles, coffins and even spinning wheels.

Safety Note

The plant tannins in oak may irritate the digestive lining if taken in excess.

Other sources suggest that oak is less edible than others, that the foliage can be poisonous and that the acorns should be properly treated (leached of the bitter tannins and then roasted) before consumption.

While there is little information on other side effects to the use of oak as a food or medicine, this is not absolute proof of its safety and bearing in mind these cautions, it may be best to avoid consuming or using oak as a food or medicine during pregnancy or when breastfeeding.

Consult a medical professional if taken for a specific condition.

References

Haines A. Ancestral Plants Volume 2: A Primitive Skills Guide to Important Edible, Medicinal, and Useful Plants of the Northwest. Vol 2. Anaskimin; 2015.

Warren P. British Native Trees: Their Past and Present Uses: Including a Guide to Burning Wood in the Home. Wildeye; 2006.

Cleene M de, Lejeune MC. Compendium of Symbolic and Ritual Plants in Europe. Man & Culture; 2002.

Watts D. Dictionary of Plant Lore. Elsevier; 2007.

Hatfield G. Hatfield’s Herbal: The Secret History of British Plants. Penguin; 2008.

Wyse Jackson P. Ireland’s Generous Nature: The Past and Present Uses of Wild Plants in Ireland. Missouri Botanical Garden Press; 2013.

Mac Coitir N, Langrishe G, Collins Press (Cork I. Ireland’s Trees: Myths, Legends and Folklore.; 2015.

Thayer S. Nature’s Garden: A Guide to Identifying, Harvesting, and Preparing Edible Wild Plants. Forager’s Harvest; 2010.

Folkard R. Plant Lore, Legends, and Lyrics. Sampson Low, Marston, Searle, and Rivington; 1884.

Kunkel G. Plants for Human Consumption: An Annotated Checklist of the Edible Phanerogams and Ferns. Koeltz Scientific Books; 1984.

Couplan F. The Encyclopedia of Edible Plants of North America. Keats Pub; 1998.

Karalliedde L, Shaw D, Gawarammana I. Traditional Herbal Medicines: A Guide to Their Safer Use. Hammersmith; 2008.

Kuhnlein HV, Turner NJ. Traditional Plant Foods of Canadian Indigenous Peoples: Nutrition, Botany and Use. Routledge; 1991.