Acorn (Oak)

Acorns foraged from oak tree (Quercus sp)
The majestic Oak tree is the most common in Britain and holds the status of national emblem. The acorn that produces the tree have been a source of food and medicine for many cultures around the world since ancient times.

Table of Contents

Oak: Plant profile

Common names

Oak Tree, English Oak, European Oak, Pedunculated Oak, Sessile Oak, Dair Ghallda

Botanical name

Quercus robur, Quercus petraea & other Quercus spp.

Plant family

Fagaceae (Beech)

Distribution

Oak is native to Europe, north Africa and western Asia, though planted worldwide. Very common in the UK and Ireland.

Where to find Acorns

Acorns come from Oak trees growing in hedgerow, woodland and in parks.

When to find Acorns

Acorns are ripe in early autumn, when they start to fall down.

How to identify Oak

Oak is a large, deciduous tree growing up to 40m tall. It has wide-spreading, branches on a short, robust trunk with greyish-brown bark. Most oak trees have simple, lobed leaves,which are dark green on top and pale green beneath.Male flowers are on catkins and hang down, while female flowers are small and red and are located on short stalks called peduncles. The encased brown fruit is the acorn and resemble a nut.

Oak lookalikes

There are hundreds of different species of Oak tree and Quercus robur and Quercus petraea are the most common in the British Isles. All of them are edible, but acorns from certain species may be extremely bitter.

Oaks hanging on the tree (Quercus sp)

All about Acorns

Oak is the most common woodland tree in the UK and Ireland; so much that it has been a national symbol of strength and longevity for English culture, heavily featured on folklore, literature and local history. The saying goes “Mighty oaks from tiny acorns grow” meaning that something great may come from a modest beginning.

Acorn is the nut of the Oak Tree (Quercus sp). There are two native species in Britain: the English Oak (Quercus robur) and Sessile Oak (Quercus petraea).  Both of them have slight differences and often hybridise in the wild (Quercus x rosacea).

Medicinal properties of Acorns

The oak tree has a long history of medicinal use and it has been valued for its astringent properties. All parts of the oak, including wood, bark, leaves, acorns and galls, have been used for medicinal purposes.

Acorns are nutrient-rich and contain starch, oil, protein and minerals.

Culinary use and recipes with Acorns

The trees are all around us and are quite prolific; yet rare are the people who bother with acorns. The issue with the nuts is not their flavour but the effort involved in getting them processed, because they are naturally inedible to us humans. Acorns are packed in tannins; which is a compound that makes them astringent, therefore they must be processed or “leached” to make them palatable.

The nuts are very nutritious and provide a complete vegetable protein, the starch, which is the toughest thing to forage for. Nutty and sweet, they provide an alternative gluten-free version for regular grain flours that contains large amounts of protein, carbohydrates and fats.

Acorn flour can be used to make bread, pancakes and burger patties. Koreans eat dotorimuk, which is a jelly made of acorn.

Oaks hanging on the tree (Quercus sp)

Safe foraging of Acorns

The high tannin content in oak may irritate the digestive system. Leaching is necessary before consumption.

Ecological importance of Oak

Oak trees support more life than any other native tree species in the British Isles and Acorns are a significant food source for a number of small mammals such as mice and squirrel, and some birds, such as jays . A lot of insect species depend on Oaks too.

Easy foraging - Free Ebook

Want to improve your foraging skills?

Join my newsletter to get a FREE ebook and receive plant profiles, seasonal reminders and foraging tips.

You agree to our Terms & Conditions and Privacy Policy 

Alvaro Docio

Alvaro Docio

I am the person behind British Local Food. As a forager and wild food educator, my aim is to inspire you to go outdoors, familiarise with your local plants and make the best of their culinary and medicinal properties, in the hope you'd pass on any knowledge gained down to the next generation.

Liked it? Share with friends!

Share on facebook
Share on twitter
Share on pinterest
Share on whatsapp
Share on email
Share on print

22 thoughts on “Acorn (Oak)”

    • Hi Nigel,
      1. How long can you store acorns? Due to their high oil content, acorns can go rancid over time, so don’t let them for long. Maybe up to four months.
      2. How best to store acorns? Discard any damaged nuts, lay them flat in single layer sheets and dry in a dehydrator or radiator (They’ll dry faster out of their husk).
      Afterwards, store the dried acorns in canvas bags or baskets in a cool, dark place.
      Alternatively, you can brine or freeze them after hot leached. Store the acorn flour in a cool place.
      3. Can acorns be picked green? I always pick them brown because they are already ripe and the flavour is developed, but I hear some people pick them green.

      Reply
  1. Hi, thanks for a great article. I collected a few acorns to try and have put them in water. I did a combination of cold soaking and hot soaking (just when I remembered to change the hot water), not boiled at all though. After a day or so they turned brown. Is this normal? When shelling them, one was already dark inside the shell, and I decided to discard it – sort of mottled – but that’s the colour these have gone now anyway.

    Reply
    • Hi John,
      I cannot say without seeing them.
      Overly hot water could caramelise the nut and turn it brown. After shelling them, the exposed nut could oxidise and turn mottled if scrapped off.
      Next time, I’d recommend you shell them before cold leaching, as it will take less time anyway.
      Just try a few nuts at a time with different batches, different trees… until you get to know the process.
      Hope it helps.

      Reply
      • Thanks Alvaro, I’ll keep experimenting. I forgot to say I scraped the inner membrane off the nuts, following something I’d seen a guy do on youtube to make flour. He seemed to think it was part of the leeching process or had a lot of tannins in it or something, but I guess this isn’t necessary (and it would be prohibitively time consuming for a larger number of acorns).

        Reply
    • Hi Mandy,
      Any nuts can be used to substitute pine nuts in a pesto recipe (including acorns), each of them providing a slightly different flavour profile to the authentic recipe.
      Never tried acorns on pesto myself, but I am sure it’s good. There is only one way to find out… trying!

      Reply
  2. Alvaro, great post as always. As a keen forager I’m always reading, always learning and find your posts to be so very informative and your site a great resource. My thanks

    Reply
  3. As a child we were told the acorn can be processed but the process can be ineffective enough to cause painful sickness if such occurs. Adding , eat them if you want to but don’t say you weren’t warned. How long does leaching tannin take to be completed in your understanding ?

    Reply
  4. Cam you please tell me when they stop falling from the tree? They hit the roof right next to my head every couple of minutes and I can’t sleep!!!!

    Reply
  5. Hello,

    Thank you for this post! It’s amazing that all this food is around us and many, including myself, have no idea it’s edible. That’s why posts like this are very important!

    I was wondering, once leaching the tannins out by soaking, would you say acorns are safe to eat raw? (without the shells).

    Many thanks,

    James

    Reply
  6. Hi there

    Do you have a recipe for the acorn sauce for game? I’d love to try it out, but can’t find a recipe on the Internet.

    Many thanks,

    Susan

    Reply

Leave a comment