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Quick facts

Common names: English oak, pedunculate oak

Scientific name: Quercus robur

Family: Fagaceae

Origin: native

A large, deciduous tree growing up to 20–40m tall. As common oaks mature they form a broad and spreading crown with sturdy branches beneath. Oaks even shorten with age in order to extend their lifespan.

Look out for: its distinctive round-lobed leaves with short leaf stalks (petioles).

Identified in winter by: rounded buds in clusters. Each bud has more than three scales.

What does English oak look like?

English oak single leaf close-up

Credit: Laurie Campbell / WTML

Leaves

Around 10cm long with 4–5 deep lobes with smooth edges. Leaf-burst occurs mid-May and the leaves have almost no stem and grow in bunches.

English oak male flowers

Credit: Geogphotos / Alamy Stock Photo

Flowers

Long, yellow hanging catkins which distribute pollen into the air.

English oak acorns

Credit: Colin Varndell / WTML

Fruits

Acorns are 2–2.5cm long, on long stalks and in cupules (the cup-shaped base of the acorn). As it ripens, the green acorn turns brown, loosens from the cupule and falls to the canopy below, sprouting the following spring.

Watch oak leaf budburst

Not to be confused with:

Sessile oak (Quercus petraea). Its leaves have stalks and its acorns don’t have stalks (whereas it’s the opposite in English oak which has tiny or no leaf stalks and acorns with long stalks).

Child and parent looking at autumn leaves with magnifying glass

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Where to find English oak

English oak is the second most common tree species in the UK, after birch. It’s especially common in deciduous woods in southern and central Britain. In fact, it’s so frequent that it has assumed the status of a national emblem.

Did you know?

The large round growths found on the trunks of oak trees, caused by a species of gall wasp, were used to make ink for over a thousand years, right through to the 20th century.

Value to wildlife

Oak forests support more life forms than any other native forest. They are host to hundreds of insect species, supplying many birds with an important food source. In autumn, mammals such as squirrels, badgers and deer feed on acorns.

Flower and leaf buds of English oak are the food plants of the caterpillars of purple hairstreak butterflies.

The soft leaves of English oaks break down with ease in autumn and form a rich leaf mould beneath the tree, supporting invertebrates such as the stag beetle, and fungi, like the oakbug milkcap. Holes and crevices in the tree bark are perfect nesting spots for the pied flycatcher or marsh tit.

Bats also roost in old woodpecker holes or under loose bark, as well as feeding on the rich supply of insects in the tree canopy.

Mythology and symbolism

The oak was sacred to many gods, including Zeus, Jupiter and the Celtic Dagda. Each of these gods ruled over thunder and lightning, and oak trees are often hit by lightning as they are the tallest living feature in the landscape.

Druids practised rituals in oak groves and cherished the mistletoe that grows in oak-tree branches. It’s also linked with royalty: ancient kings and Roman Emperors wore crowns of oak leaves.

In England, the oak is a national symbol of strength. Couples were wed under ancient oaks in Oliver Cromwell’s time. Oak is the emblem of many environmental groups, including the Woodland Trust.

Uses of English oak

Oaks produce one of the hardest and most durable timbers on the planet. 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 and is still used for flooring, wine barrels and firewood.

Other uses of oak:

  • Leaves, bark and acorns were believed to heal many medical ailments, including diarrhoea, inflammation and kidney stones.
  • Acorns have also been used to make flour for bread making.
  • Tannin found in the bark has been used to tan leather since at least Roman times.
Did you know?

Most acorns will never get the chance to germinate as they are a rich food source, eaten by many wild creatures, including jays, mice and squirrels.

Threats and conservation

Acute oak decline and chronic oak decline are serious conditions affecting Britain’s oaks, with several contributing factors linked to the diseases. Decline of mature oaks first aroused concern in the 1920s and today most cases are in central, southern and eastern England.

The oak processionary moth is a non-native pest that has been found in London, Surrey 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 respiratory problems.