Quercus petraea

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Quercus petraea
Quercus petraea 06.jpg
Sessile oak
Scientific classification
Kingdom: Plantae
(unranked): Angiosperms
(unranked): Eudicots
(unranked): Rosids
Order: Fagales
Family: Fagaceae
Genus: Quercus
Section: Quercus
Species: Q. petraea
Binomial name
Quercus petraea
(Mattuschka) Liebl. 1784
Shoot with leaves and acorn
An inosculated tree

Quercus petraea (syn. Quercus sessiliflora),[2] the sessile oak, also known as the Irish oak. It is sometimes also called the Welsh oak, Cornish oak or Durmast oak, is a species of oak tree native to most of Europe, into Anatolia and Iran.

The sessile oak is the official national tree of Ireland, (where it is known as the Irish oak or Dair ghaelach).[3] Similarly, it is an unofficial emblem in Wales (where it is called Welsh oak)[4] and Cornwall (where it is referred to as the Cornish oak).[5][6]


The sessile oak is a large deciduous tree up to 20–40 m (66–131 ft) tall, in the white oak section of the genus (Quercus sect. Quercus) and similar to the pedunculate oak, Q. robur, with which it overlaps extensively in range. The leaves are 7–14 cm (2.8–5.5 in) long and 4–8 cm (1.6–3.1 in) broad, evenly lobed with five to six lobes on each side, and a 1-centimetre-long (0.39 in) petiole. The flowers are catkins, produced in the spring. The fruit is an acorn 2–3 cm (0.79–1.18 in) long and 1–2 cm (0.39–0.79 in) broad, which matures in about six months.

Comparison with pedunculate oak[edit]

Significant botanical differences from pedunculate oak (Quercus robur) include the stalked leaves, and the stalkless (sessile) acorns from which one of its common names is derived. It occurs in upland areas over 300 m (984 ft) with higher rainfall and shallow, acidic, sandy soils. Its specific epithet petraea means "of rocky places".[7] Quercus robur, on the other hand, prefers deeper, richer soils at lower altitude. Fertile hybrids with Quercus robur named Quercus × rosacea are found wherever the two parent species occur and share or are intermediate in characters between the parents.


In cultivation, this tree has gained the Royal Horticultural Society's Award of Garden Merit.[8] The wood is important, used for construction purposes (particularly timber framing), shipbuilding, and oak barrels for wine.

Pontfadog Oak[edit]

What was considered to be the oldest oak tree in the UK was a sessile oak, the Pontfadog Oak. This grew near Chirk in North Wales. It was understood to be over 1,200 years old, an age that was due to regular pollarding for much of its life. The hollow trunk had a girth of 12.9 metres (42 ft 5 in). It was lost in April 2013 when it blew down in high winds.[9]

Diseases and pests[edit]


  1. ^ The Plant List, Quercus petraea (Matt.) Liebl.
  2. ^ "Quercus sessiliflora Salisb.". USDA GRIN Taxonomy for Plants. 
  3. ^ Our Trees (2000) Tree Council of Ireland
  4. ^ "Tree trail with worldwide flavour", BBC News, 23 July 2004
  5. ^ James Minahan, The complete guide to national symbols and emblems , Volume 1, 2009
  6. ^ West Briton, September 01, 2011, Will native trees thrive in the future?
  7. ^ Harrison, Lorraine (2012). RHS Latin for gardeners. United Kingdom: Mitchell Beazley. p. 224. ISBN 9781845337315. 
  8. ^ Royal Horticultural Society
  9. ^ "Pontfadog Oak: 1,200-year-old tree toppled by winds". BBC News Online. 18 April 2013. 
  10. ^ Bullock, J.A. 1992. Host Plants of British Beetles: A List of Recorded Associations - Amateur Entomologists' Society (AES) publication volume 11a: A supplement to A Coleopterist's Handbook.

See also[edit]