English Oak – Quercus robur

For many, the very mention of tree climbing conjures up nostalgic memories of youth and this month’s tree species is the perfect apparatus for this favoured past time! The English oak is a tree of extremes, not only is it the largest and most common of our native, broad-leaves (along with sessile oak), it is also one of the most long-lived. In fact, their longevity means that the trees you played upon were probably equally cherished by previous generations and will continue to be enjoyed by many to come. For us long-life may be crowned with the arrival of great-grand children or reaching our 100th birthday. Comparatively, a newly emerged oak sapling standing a mere 20cm from the ground today has the capacity to live over 1000 years, produce over 25 million acorns and may well welcome in the next millennia as one of our gentle giants – a humbling thought indeed. 

Image: Hannah Cole

(a) Bark rubbing of mature English oak tree and (b) leaf rubbing of leaves, highlighting their rounded lobes and well-defined veins

Description:

Typically measuring around 10cm in length, the oak’s 4-5 deeply lobed leaves (1) with smooth edges is one of its most distinguishable features. Leaf-burst occurs mid-May and, unlike it’s close relative the sessile oak, Quercus petraea, the leaves have almost no stem (2) and grow in bunches. Its fruit, commonly known as the acorn, are 2 – 2.5cm long, borne on lengthy stalks and held tightly by cupules (the cup-shaped base of the acorn). As it ripens, the initially green acorn takes on a more autumnal, browner colouration, loosens from the cupule and falls to the canopy below. At the same time these deciduous trees begin to litter the ground with their leaves.  Most acorns will never get the chance to germinate, they are a starch-rich food source, utilised by many wild creatures including jays, mice and squirrels. Acorns need to germinate and root quickly to prevent drying out or becoming victims of the harvest. Following successful germination, a new sapling will appear the following spring.

Interesting Fact: Acorns are not produced until the tree is at least 40 years old. Peak acorn fecundity usually occurs around 80 – 120 years.

As English oaks mature they have a tendency to form a broad and spreading crown with sturdy, inviting branches beneath. Like the Ash, their open canopy enables light to penetrate through to the woodland floor, allowing magnificent floral displays of bluebells and primroses below.  Their smooth and silvery brown bark transforms with age and becomes rugged and deeply fissured. Oak tree growth is particularly rapid in youth but gradually slows around 120 years. Oaks even shorten with age, retrenching their energy heavy canopy in order to extend their lifespan.

Image: Hannah Cole

Light and airy oak tree canopy

Woodland Ecology:

Oak forests provide a habitat rich in biodiversity; they support a larger number of different life forms than any other native trees. They play host to over 280 species of insect and over 300 species/sub-species of lichens can be found on any one tree.

The diverse array of insects form part of a fascinating food chain and supply many British birds with a crucial food source. In autumn mammals such as badgers, boars and deer take advantage of the falling acorns. Historically humans also collected acorns and processed them into flour for bread making. These culinary techniques have mostly died out following the domestication of wheat production 10,000 years ago, leaving the harvest for wild birds and mammals.

The soft leaves of English oaks breakdown with ease in autumn and form a rich leaf mould beneath the tree.  Search carefully among the decaying leaves and you may find invertebrates, such as the stag beetle, and numerous fungi, like the oakbug milkcap.

Take a few moments to identify any holes or crevices in the tree bark, these could belong to a nesting pied flycatcher or marsh tit.  Several British bat species may also roost in old woodpecker holes or under loose bark, as well as feeding on the rich supply of insects in the tree canopy.

Image: Hannah Cole

Loose bark creates crevices for bats to roost under and rest during foraging activity

Mythology/ Symbolism:

The oak is held in high esteem across most major cultures in Europe. The oak was sacred to many gods including Zeus (Greek), Jupiter (Roman) and Dagda (Celtic). Each of these gods ruled over thunder and lightening, and oak trees are prone to lightening strikes as they are often the tallest living feature in the landscape. Druids frequently practised and worshipped their rituals in oak groves and cherished the mistletoe that frequents oak tree branches. Royalty has had a long association with oak trees too; ancient kings adorned themselves with crowns of oak leaves, King Charles II hid from his pursuers in an oak tree at Boscobel House and Roman Emperors were presented with crowns of oak leaves during victory parades.

Image: WTPL


Emblems of the Woodland Trust, National Trust and Nature Conservancy all feature the oak leaf and/or acorn.

In England the oak has for centuries been a national symbol of strength and survival. It has played an important part in our culture – couples were wed under ancient oaks in Oliver Cromwell’s time, the festive Yule Log was traditionally cut from oak, it features on the 1987 pound coin and is the inspiration for the emblem of many environmentally focused organisations, including the Woodland Trust.

Popular Uses:

Oaks produce one of the hardest and most durable timbers on the planet, even its Latin name, Quercus robur, means strength. However, it takes up to 150 years before an oak is ready to use in construction. It has been a prized hardwood timber for thousands of years, was the primary ship building material until the mid 19th century and remains a popular wood for architectural beams. Traditionally the leaves, bark and acorns were believed to heal many medical ailments including diarrhoea, inflammation and kidney stones. Tannin, found in the bark has been used as a leather tanner since Roman times. Nowadays Britain’s only remaining oak-bark tannery is based in Colyton, Devon. Modern uses of English oak include flooring, wine barrels and firewood.

Threats:

Despite their high numbers in Britain and protection from over-harvest, our oak trees are threatened by a number of pests and pathogens. The oak processionary moth is a non-native pest that has been found in London and Berkshire. Not only does it damage the foliage of the trees and increase the oak’s susceptibility to other diseases, it is actually a risk to human health. The moth’s hairs are toxic and can lead to itching and/or respiratory problems if breathed in.

Acute Oak Decline (AOD) and chronic oak decline (COD) are serious conditions affecting Britain’s oaks, several contributing factors are linked to the diseases. Decline of mature oaks first aroused concern in the 1920s, today most cases are in central, southern and eastern England. Key symptoms include canopy thinning, branch dieback and black weeping patches on stems and lesions underlying the bleed spots.

Read more about oak processionary moth, AOD and COD in our tree pests and diseases issue of Wood Wise

Quick oak facts…

Click here to see other blogs in this series on tree species.

Hannah Cole, Conservation Communications Intern

About Kay Haw

Assistant Conservation Adviser, Woodland Trust. Nature is my passion, especially woods and trees which are just amazing elements of life. One day (soon) I hope we humans learn to work in harmony with Mother Earth.
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14 Responses to English Oak – Quercus robur

  1. Pingback: Silver birch – Betula pendula | Woodland Matters

  2. Ash says:

    Thank you Kay for an good read. Unfortunately I have a very small garden but I just adore the large oak in next doors. I love to watch it change through the seasons, at this very moment, a pair of collared doves are sitting enjoying the evening sun.

  3. Valerie Smith says:

    We have an oak tree at the bottom of our garden, in Aldwick, West Sussex, PO21 3RD. We have noticed in recent years that the acorns of the tree are not forming to their normal size and are dropping off the tree in large amounts. Can you tell me why this is please.

    Valerie Smith

  4. In autumn 2012, Zac Goldsmith MP and something called the Countryside Restoration Trust published a study called “The Threat to Engand’s Trees”. It identified six major NEW invasive threats in the form of pests and diseases.

    I have not read it yet, but it appears to take a holistic view which includes more general threats to the powerful immune system of trees from pollution, climate change, soil poverty, mild drought, etc.

    On 1st Nov. 2012, Zac Goldsmith MP tabled an Early Day Motion, asking the government to fund urgent research into the 6 major threats. I don’t know what happened to this. No doubt ZG or his researcher will welcome queries for an update, even if you are not in his constituency. MPs have a general duty to the nation in national/international matters, as well as a duty to their constituents – and ZG is more conscious than most MPs of his national and international remit, simply because Environmentalism has to be both global and local.

    http://www.telegraph.co.uk/earth/earthnews/9650195/Oak-trees-also-threatened-by-diseases-report.html

    There may be no connection – but 2 days ago the Global Footprint Network said it was “Earth Overshoot Day” – the day in the year after which the whole of humanity moves into Ecological Debt for the rest of the year, having used up the Planet’s replenishable biosystems by that day. The day seems to come earlier every year. Some nations need 3 or 4 times their available resources every day, some are still in Credit – but those in Credit are edging towards Debt all the time and this makes the overall Ecological Debt worse all the time.

    http://www.dailymail.co.uk/sciencetech/article-2397292/Weve-used-resources-Earth-provide-year-overdraft-campaigners-warn.html

    I know it is not provable, but surely the general health of trees is affected by all this – after all pollution travels round the globe with the weather systems. We really have to move into De-Growth fast. The 4th international De-Growth Conference will be in Leipzig in 2014 – they are held every 2 years (since 2008). You might ask how attending a conference assist De-Growth – but it is a bit of a revolutionary notion so a bit of solidarity now and then is needed to get it up and running.

    http://www.degrowth.org/conferences

  5. Pingback: English Oak – Quercus robur | Woodland Ma...

  6. thehutts says:

    My love of oaks also started as a child as we had 2 old oaks in our garden which we loved to play in. You have prompted me to look for them and I can see from Google Earth they were still there in 2007. Sally

  7. Maureen Hart says:

    Hello,
    I fell in love with Oak trees when at age about 6 managed to climb 3 branches up the old Oak growing in our local park.

    Would have got higher but got caught by my Dad & made to climb back down. Kept creeping off
    to climb again every chance i got.

    Too old to climb trees now but still love all trees but Oaks remain my favourites.

    Thanks for article.

  8. Phil says:

    In January against my better judgement I was persuaded to remove our oldest oak. It was a quercus robur purchased as a half inch thick sapling about 15 years ago and had reached about four inches at the base where i cut it and ten feet in height. It had its first acorns at about five years that were followed in quick succession by both marble galls and oak apples. It was considered to be “in the way”.

    So far I haven’t been persuaded to remove the numerous three foot long coppice shoots that appeared in June.

    I have three of its children in a bucket.

    Phil

  9. Interesting article Kay. However, I do have a couple of comments. First, I share your passion for nature, and make it my life’s ambition to help humans live in harmony with nature.

    There is a tree species that is larger than both species of Oak and also native to Britain, and this is the Black Poplar (Populus nigra). Black Poplars are the only tree that could be planted in ancient woodland, because it has become so rare, however, it is a flood-plain tree, and is unlikely to survive in woodlands not in flood plains.

    One reason for older oaks aparently shrinking is because they are pruned by the strong winds that we have in the British Isles. The same species of oaks grow much taller on mainland Europe.

    The Jay (sometimes called Oak Jay Garrulus glandarius) is probably the main dispersal agent for oaks transporting massive quantities of acorns in the autumn and burying them in mainly open ground.

    Best wishes, Martyn.

  10. As a big fan of the oak and also an avid breadmaker, I’ve often wondered what bread made from acron flour tastes like. Has anybody tried it and is it possible to buy acorn flour (or will I have to grind my own)?

  11. Rwthless says:

    Very interesting post. I’m not sure that the Sessile Oak is inferior though. People hardly ever write about it. Grammar hiccup on abundance in statistics box. Either most common or just commonest. (Old pedant commenting for future professionalism)

    • Phil Yardley says:

      Rwthless; “On abundance” or should it be “In abundance” as it is written in a box within an article containing interesting statistics?

  12. lesley.crowcroft@gmail.com says:

    hello, Please can you change my email address to lesley.crowcroft@gmail.com I do not want to miss any of your excellent posts, Many thanks Lesley

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