How to identify Pedunculate Oak
Quercus robur
Oak can live for over 500 years. Coppiced specimens may reach 1000 years.
Many old oak woodlands in Northern Ireland are under protection to ensure that this very important natural habitat remains for the future.
Upland oakwoods are subject to a habitat action plan as part of the UK Biodiversity Action Plan (UKBAP), recognising this type of habitat as one in need of immediate attention.
One of the main threats to our ancient oakwoods is their isolation.
Pedunculate or English oak is tolerant of extremes of climate. It grows on soil which is rich in nutrients and not too acidic. It is a thirsty tree and needs plenty of water. It grows in valleys, near to rivers, and on damp, moist land.
The sessile or Irish oak is a more modest tree. It grows up in more acid and poor soils. In contrast with the pedunculate oak, the sessile oak is not tolerant of flooding.
Oaks is a tree that can form an important component of a wood. Oakwoods are bright, letting sunlight through, providing good conditions for other plants like grasses, herbs and shrubs.
Key facts about Pedunculate Oak
Common name(s)
Pedunculate Oak
Scientific name
Quercus robur
Common family name
Beech
Scientific family name
Fagaceae
- How to grow Pedunculate Oak
Where does grow?
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- W2 Alder woodland with common reed
- W6 Alder woodland with stinging nettle
- W7 Alder-ash woodland with yellow pimpernel
- W8 Lowland mixed broadleaved woodland with dog’s mercury
- W9 Upland mixed broadleaved woodland with dog’s mercury
- W10 Lowland mixed broadleaved woodland with bluebell
- W11 Upland oak-birch woodland with bluebell
- W12 Beech-ash woodland with dog’s mercury
- W14 Beech-oak woodland with bramble
- W15 Beech-oak woodland with wavy hair-grass
- W16 Lowland oak-birch woodland with bilberry
- W17 Upland oak-birch woodland with bilberry
- High forest tree
Characteristics of Pedunculate Oak
The following characteristics give us all the clues we need to identify a Pedunculate Oak.
Leaves
The leaves are dark green above and lighter below.
Leaves of pedunculate oak (Quercus robur) appear about a fortnight earlier than those of sessile oak (Q. petraea).
There are physical differences in the shape of the leaves too. Pedunculate oak has a short leaf stem and 2 ‘earlobes’ at the base of the leaf. Sessile oak has a long stem and is missing the ‘earlobes’.
Flowers
Male flowers (catkins) appear together with the leaves in late April and early May. They are yellow-green in colour.
After this, the new shoots appear carrying the female flowers, which are very small and inconspicuous. The flowers are wind-pollinated.
Fruit
The fruits (acorns) ripen during late October.
The acorns are mostly in pairs, each in a ‘cup’ and are borne on a stalk. On pedunculate oak this stalk is long (maybe 10cm). On sessile oak the stalk is only 1-2cm long.
The two kinds of oak native to Northern Ireland are easiest to distinguish when the acorns are present.
Bark
Young plants have a smooth, shiny bark, which varies from brown to grey in colour. It turns much darker with age.
The creases in the bark provide shelter and home for insects. The trunk can grow to be 3m or more in circumference.
Each year as an oak grows, it makes two growth rings. One is the spring wood which is lighter. The summer wood is darker. The rings show the age of a tree and help us to understand the climate conditions at the time it was growing.
