29 Interesting Secrets & Facts About Oak Trees

Secrets of the Wise Old Oaks

Oak trees are a familiar part of the landscape for generations as they dominate the skyline with their distinctive tree of life shape and have the presence of a kindly grandfather in parks and historic gardens. But what do you really know about them? Here we go with 29 interesting facts about oak trees.

Oak trees are present throughout history and arrived millions of years before humans. The first recognizable oak tree appeared 65 million years ago.  Today there are still 600 varieties of oaks throughout the world–China has over 100 different species.

Oak Trees in the UK

The United Kingdom is home to five species of oak–two are native (12,000 years since the last ice age), and three travelled here with human help.

English Oak Tree (Quercus Robur)

English Oak (Quercus Robur)

The English Oak built the navy and is celebrated by the Royal Navy in the marching song–‘Hearts of Oak.’ HMS victory consumed 6,000 oak trees in constructing her hull, masts, and other parts. This oak tree is the most common throughout England and is a native tree growing to 40m (131 feet) in height.

Sessile Oak (Quercus Petraea)

The sessile oak grows in hilly areas throughout Europe and is Ireland and Wales traditional oak tree. It is a native tree, and like the English oak grows to around 40m (131 feet) in height.

Holm Oak (Quercus ilex)

The holm oak arrived from the Mediterranean in the 1500s and is unique among the oaks because it is evergreen. The young leaves have spines and resemble holly leaves. Unless you are familiar with the holm oak, you wouldn’t recognize it as an oak tree until the appearance of the familiar acorns.

The Romans used it for wheels–carts and chariots. It doesn’t grow as tall as the native species–half the height at 20m (65 ft).

Red Oak (Quercus Rubra)

The date this American import arrived in the UK is unknown, perhaps it came with the grey squirrel into the parklands and gardens of the wealthy. The leaves turn vibrant red in autumn. The oak leaf is pointy, unlike the rounded shape of the English Oak.  It grows to 20m (65 ft) and is slower than the native oaks in producing acorns. The English and Sessile oaks start producing acorns at 20 years, but the red oak waits until it is 40.

Turkey Oak (Quercus cerris)

This deciduous tree arrived for ornamental plantings in the 18th Century from South-Eastern Europe and Asia Minor. This oak tree is sacred to Zeus (Jupiter) and Dagda. The leaves are the familiar rounded shape, but the acorn cups are slightly hairy compared to other oaks. It is host to the gall wasp, which is a pest that preys on native oak trees.  The maximum height is 30m (98 foot) midway between the native and the other imported oak species.

Interesting Oak Tree Wood

Oak in Symbols, Myth, and Lore

Oak trees and wood appear in many ways throughout history and in the present day as a representation of the qualities of strength, wisdom, and royalty.

National Trees

Along with flags and heraldic devices, almost every country has a national tree, the tree that has the qualities that reflect how the nation sees itself. Both England and Wales take the Oak as their national tree.

Plenty of other countries also claim the oak as a symbol of their national pride, but not the same species:

Pedunculate or English Oak (Quercus robur): Croatia, Denmark, England, Estonia, Germany, Latvia, Lithuania, Moldova, Poland, Romania, Serbia, United Kingdom, United States

Golden Oak (Quercus alnifolia): Cyprus

Sessile Oak (Quercus Petraea): Ireland, Wales

Cork Oak (Quercus Suber): Portugal.

Lunar Oak Month: 10 June to 7 July

As well as a zodiac sign from the solar calendar, you have a tree sign from the lunar calendar.  A child born in the oak month receives the blessings of generosity, nobility, honesty, and courage–along with the strength of the mighty oak.

Coins featuring Oaks

The oak features on old UK coinage–the sixpence, a coin referred to in many rhymes, and more recently as the ‘O’ in the alphabet series of 10p coins (issued in 2018) and pound coins.  Many other countries have put oak trees on their coins–America and Germany.

The slang name for the sixpence is ‘the tanner,’ a reference to the oak as a tanning agent in the leather industry.

New for 2020 is the gold and silver €20 gold and silver coin featuring oak leaves as the French symbol for happiness and liberty.

In the British Museum, you can see a gold coin featuring Emperor Augustus wearing an oak wreath- showing how long the oak has played a symbolic role in human lives.  If a roman soldier saved the life of a civilian in battle, he received a crown of oak–the civic oak in recognition of his actions.

Oaks on Postage Stamps

In, 1973 the Royal mail issued a 9p stamp featuring an oak tree as part of the British trees collection. Other countries using the oak on postage include America–the white oak, the Soviet Union, Cyprus, Spain, and Canada (red oak).

Oak tree of life

The Tree of Life

The tree of life has its roots in many cultures, and a biblical reference.  They often use an oak tree as a tree of life symbol in jewelry and paintings because the spreading canopy with its mirroring root system gives a sense of the majesty of life represented by an immense tree.

An oak tree is an excellent choice for the tree of life because it supports so many other living creatures:

  • Birds and animals eat the acorns: jays, pigeons, ducks, boars, pigs, deer, bears, rats, squirrels, and mice.
  • 30 Species of birds use oak trees for foraging and nesting.
  • 45 species of bugs and insects make oak trees their home and food.
  • 200 different moths associate with oak trees.

Facts about Oak leaves and acorns

As well as the birds and animals that use the oak tree, there are the associated benefits from providing leaves for the forest floor, shade, and shelter. Other animals eat the insects and bugs that inhabit the oak.

The oldest oak tree in the world is the Pechanga Great oak tree in the United States that is over 2,000 years old. In England, there are around 3,400 oaks that class as ancient (over 400 years) with 117 aged over 800 years.  The oldest oaks in the UK are in Cheshire, Shropshire, and Lincolnshire. Oak trees live centuries.

Oak Trees in the Bible

The bible mentions oak trees 28 times. Examples include the ‘oaks of righteousness’ and the Oaks of Bashan and Mamre. The Bashan oaks provided wood for oars. The Mamre oaks are the site of Abram’s altar to the Lord.

Oak Trees in Plays and Stories

Oak trees make guest appearances in many books, plays, and stories, sometimes as scenery and sometimes as symbols of human strengths and weaknesses.

William Shakespeare refers to the felling of a mighty oak in Henry VI (Part Iii):

“Many strokes, though with a little axe,

Hew down and fell the hardest-timber’d oak.”

Aesop’s fables compare the strength of the oak to the weakness of the reed (or willow in later versions) as a moral lesson that sometimes you need to bend to survive.

Harper Lee’s book (To Kill a Mockingbird), features an oak tree as a character symbolizing the opposite traits of kindness and then intolerance.

Virginia Woolf (Orlando) uses a poem about an oak tree as a central focus for her long-lived poet.

In AA Milne’s stories about Winnie the Pooh, the loveable bear finds bees (and honey) at the top of a large oak tree.

Finally, where would Robin Hood be without the oaks of Sherwood Forest?

Military and Heraldic

In heraldic terms, the oak leaf shows faith and endurance and on a coat of arms’ strength and great age. The Mansfield coat of arms granted to the city on 10 June 1987 includes an oak tree as a reference to Sherwood Forest. The city motto is “Industry flourishes as the oak.”

The US uses gold and silver oak leaves to show rank, and oak clusters appear on many medals.

Green man oak facts

Green Man

The green man or foliate heads appears among the stone and wood carvings in many old churches and cathedrals. Look closely, and you see that the forest spirit includes oak leaves and acorns in most cases.

Oak and Its Many Uses

Before the industrial revolution, the forest was an essential resource, and oak continues to supply material for many applications today.


Herbal medicine accesses the medically useful components of plants. Modern medicine uses purer forms of these active ingredients.  Before, the rise of the pharmaceutical industry trial and error identified valuable drugs from the forest.

Bruised oak leaves applied to wounds was a remedy utilised by Galen of Pergamon, a doctor in the Roman Empire.

Oak bark substitutes for quinine, and in herbal medicine, it has the properties of a tonic, astringent and antiseptic. Water or alcohol extracts useful chemical compounds. The uses relate to dysentery and bleeding.

Acorns and oak bark steeped in milk provide an antidote to ingesting poisonous herbs and medicines.


The high level of tannic acid means large quantities of acorns are toxic to dogs, horses, cows, goats, and sheep. But the acorns are an excellent food for pigs and were harvested for that purpose for many years. Free-range boars and pigs rooting about in the forest fatten on fallen acorns.

Acorns provide protein, carbohydrate, and healthy unsaturated fats. They are also rich in potassium, manganese, calcium, phosphorus, and niacin. They contain plenty of useful nutrients but seldom appear on the human menu because there is no profit in selling acorns, and the taste is bitter. Bitter foods are better for health, but most people avoid bitter tastes in favour of sweet.

You can grind acorns to flour or roast and grind as a coffee substitute.  The taste is bitter, but in hungry times the acorn provides nourishment if properly processed to leach out some tannic acid by soaking in water.

You can use acorn flour the same way as wheat flour, but not for bread making as it is gluten-free. Roasted acorns can add to stews, or you can eat as a nut snack.

The roots of oak trees have a symbiotic relationship with truffles–one of the most expensive food products. You can’t plant truffles–you need to plant oak trees and hope for the best.

Colours from the Oak

Various techniques extract dye from plant material. Different plants, leaves, fruits, and stems yield unique colours.

Oak leaves, acorns, and bark give a range of brown colours. The tannic acid means that oak dyes don’t need a mordant to fix the dye to the fibre.

Oak galls yield greys and blacks for dyed materials.

The Aleppo oak gall started the ink industry as it has a high concentration of the wasp larvae. The ground oak galls provide a deep black ink.

Leather Production

Oak bark is rich in tannin, and this property allows it to tan hides into leather. The process takes twelve months or more. Traditional oak tanning produces excellent high-quality leather and still used today for premium leather products.

Interesting Oak Corks

Bottle Stoppers

The national tree of Portugal is the cork oak, and Portugal is the source of 55% of natural cork.  The cork oak contributes massively to the economies of the seven countries in Europe involved with cork harvesting.


Oak Swill baskets are a traditional craft still practiced in the Lake District, England.  Coppiced oak and hazel combine to make a hard-wearing basket used in industry, agriculture, and domestic purposes. The oak trunks (4-6 inches) turn into thin pliable ribbons of oak that weave around flexible hazel sticks. The process involves cleaving and soaking.

Houses and Ships

Oak timber is famed for its capacity to construct buildings (Houses of Westminster, churches, cathedrals, and Tudor homes) and ships (Viking longboats and Tudor warships).  The high tannin content of oak timber provides resistance to insects and mold.

Oak is a hardwood and makes long-lived items of furniture that are beautiful and highly prized and although expensive are an investment because they resist damage. Today oak flooring is gorgeous, durable, and warm underfoot.

Interesting Oak Tree Treen

Oak Treen

Treen–of the tree, is an all-purpose term for any item made from wood that is not a ship, piece of furniture or a house. Treen covers knickknacks, jewelry, and other small useful or decorative items.

Oak wooden items can be created by carving and turning.  Oak has a reputation for being difficult to work due to the fibrous grain, but in the hands of a skilled craftsman, the bowls, pens, bottle openers, and carvings are exquisite and tactile objects.

Oak Whiskey Barrels

Oak Barrels

Oak is a useful and practical material for making barrels, but it adds a richness of flavour including smokey, vanilla, and oaky.

The three principle benefits of using oak barrels for wine are:

  1. Additional flavour notes.
  2. Slow addition of oxygen–decreases astringency and improves smoothness.
  3. Provides conditions for malolactic fermentation–a process that produces a creamy taste.

Oak barrels provide the following flavour compounds:

  • Syringaldehyde–like vanilla.
  • Oak lactone–herby flavours like dill, woody notes, and a hint of coconut.
  • Eugenol–think smokey spices and cloves.
  • Guaiacol–a hint of burnt toffee.
  • Furfural–burnt caramel, bitter almond and dried fruits.

Oak barrels not only improve whisky (whiskey, bourbon, brandy), but they are essential for imparting colour and the distinctive taste. Whisky is an alchemist’s brew of water, alcohol, and oak. For whisky barrels, oak is seasoned (dried), toasted and charred–the exact degree of each is part of the whisky makers art.

Whisky barrels may pass on to the wine industry or on for other uses. At this stage, the barrel may be 50-60 years old, but the wood is still useful for–barbecue smoking chips, barrel planters, and woodcrafts using the staves. The timber is still fit for purpose and can turn into practical oak gifts like bottle openers or pens.

Farewell to the Oak

The UK contains around 121 million oak trees, and these are both iconic and treasured because of the role they play in promoting biodiversity and their many uses, from producing leather and whisky to providing shade and clean air in the park.

An oak tree produces 2,000 to 9,000 acorns a year, but only one in 10,000 has the possibility of growing into a new oak tree. An oak tree takes decades if not hundreds of years to mature. When you plant an oak tree, you are planting for the next generation, not for yourself. If you have any wonderful facts about oak trees message me below.

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