TreesWild and cultivated

Quercus petraea

Sessile Oak

An important oak of Irish upland woods. Compared with pedunculate oak, the most useful differences lie in leaf and acorn stalks.

See all four seasons Explore fruits, seeds & edibility ↓ Where to look & how to find it ↓

Some plants are poisonous. Do not identify by a photograph alone, and never taste them.

FIELDCRAFT · FIND WITH CARE

Finding guide

Habitat first

Choose the season, find the habitat, then watch patiently. Search guidance is not a measure of rarity or conservation status.

When to go: New leaves in spring, acorns and leaf fall in autumn, exposed branching in winter.
Where to start: Oakwoods around Killarney, Wicklow and elsewhere in Ireland. Cross-check several leaf and fruit characters.
What to do when you arrive: Choose mature oak woodland, checking longer leaf stalks in summer and short-stalked or almost stalkless acorns in autumn. Compare several features with Pedunculate Oak and hybrids without collecting branches or fruit.

Habitat and behaviour reference: Tree Council of Ireland ↗ · The practical steps are editorial advice based on the references, not live sightings.

What does the map mark?

Markers show approximate public destinations or visitor bases, not individuals, nests, rare plants or exact entrances. Follow the operator’s routes and signs for access.

Base map: Natural Earth · Public domain
Destination positions: © OpenStreetMap contributors · ODbL

Tomies Wood · established woodland paths

Operator or specialist guide

NPWS lists Tomies among native oak woods and describes a largely Sessile Oak canopy. The marker represents the woodland area, not an exact tree, entrance or parking position.

Before you goUse the official access road and car park rather than old approaches across private land. Check current entrance, gate and route notices. View leaves and acorns from paths without climbing or collecting.

Official routes & visiting information ↗ Find the destination on OpenStreetMap ↗
Destination evidence & review date

Sources reviewed: 2026-10-20 · A review date is not a sighting date; recheck access before travelling.

ONE PLANT · FOUR SEASONS

One plant. Four seasons.

Look beyond the flowers: fresh leaves, fruits, bare stems and dormancy.

Meteorological seasons: spring March–May, summer June–August, autumn September–November and winter December–February. Irish weather, cultivar, pruning and plant age affect timing and appearance.

Photos illustrate the relevant feature, not the same plant photographed through a year in Ireland. Features shared across seasons, such as evergreen leaves, may use the same reference. Missing reliable photos are marked; dormancy is not death.

Spring

Mar–May

Shoots and buds

Rounded-lobed leaves unfold on noticeable stalks, with small flower structures.

Summer

Jun–Aug

Foliage and growth

A green crown shelters young acorns with little or no stalk.

Autumn

Sep–Nov

Fruits

Acorns ripen and foliage turns yellow-brown; compare pedunculate oak and hybrids.

Winter

Dec–Feb

Bare branches or dry stems

Major branches are exposed; young trees may retain some dead leaves and clustered buds.

Seasonal references: Tree Council of Ireland ↗ · Photo resized, converted to JPEG and stripped of metadata.

FRUIT · SEED · FOOD SAFETY

Fruits, seeds & edibility

Know the structure, then the part. Recognising a plant does not make it food.

Fruit

Sessile Oak · Nearly stalkless acorns with foliage. — Nearly stalkless acorns with foliage.
MPF at en.wikipedia · CC BY-SA 3.0 ↗ License terms

Acorns are true nuts with cupules and very short or inconspicuous stalks.

Food use of this part: Food use only after appropriate processing; not for raw eating

Seeds & dispersal units

Verified close-up not yet available

Refer to the description below until a suitable photo is verified; flowers or other species are not substituted.

The seed and its kernel lie inside the hard fruit wall; the cupule is not part of the seed.

Food use of this part: Food use only after appropriate processing; not for raw eating

Some seed references show intact one-seeded fruits or dispersal units, as identified in their captions. A whole-fruit photo is not a close-up of the enclosed seed. Cones and arils are not true fruits of flowering plants.

Sources & limitations

Tree Council of Ireland ↗ · Botanical description, not proof of food safety
NC State Extension · Plant Toolbox ↗

No field detoxification methods or safe doses are provided. Never taste a plant to identify it or eat treated or contaminated specimens. Seek professional help after suspected accidental ingestion. National Poisons Information Centre, Ireland ↗

Photo resized, converted to JPEG and stripped of metadata.

BOTANICAL NOTESPlant notes

How to identify it

Acorns nearly stalkless, leaf stalks conspicuous and leaf bases usually lacking pronounced ear-like lobes. The two oaks can hybridise.

Where it grows

Poorer, acidic upland woodland, also planted settings.

Growth and ecology

A long-lived deciduous tree supporting diverse woodland life. Acorn crops vary greatly between years.

Flowering and seasons

New leaves in spring, acorns and leaf fall in autumn, exposed branching in winter.

Where to look

Oakwoods around Killarney, Wicklow and elsewhere in Ireland. Cross-check several leaf and fruit characters.

Seasons vary with weather and location. Suggested habitats are places to look, not guaranteed sightings. Photos show only some features; check leaves, flowers, fruits and specialist references together.

Further reading:Tree Council of Ireland ↗

Photo license: Willow · CC BY 2.5 ↗ · License terms ↗
Photo resized, converted to JPEG and stripped of metadata.

← Back to the plant guide Meet the island's birds →