# Quercus petraea

Quercus petraea, commonly known as the sessile oak, Welsh oak, Cornish oak, Irish oak or durmast oak, is a species of oak tree native to most of Europe and into Anatolia and Iran. The sessile oak is the national tree of Ireland, and an unofficial emblem in Wales and Cornwall.

## Description

The sessile oak is a large deciduous tree up to 40 metres (130 feet) 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 centimetres (2+3⁄4–5+1⁄2 inches) long and 4–8 cm (1+1⁄2–3 in) broad, evenly lobed with five to six lobes on each side and a 1 cm-long (1⁄2 in) petiole. The male flowers are grouped into catkins, produced in the spring. The fruit is an acorn 2–3 cm (3⁄4–1+1⁄4 in) long and 1–2 cm (1⁄2–3⁄4 in) broad, which matures in about six months.
* Old sacred oak (zapis) in Divljana, Serbia
* Shoot with leaves and acorn
* An inosculated tree

### Comparison with pedunculate oak

Significant botanical differences from pedunculate oak (Q. robur) include the stalked leaves, and the stalkless (sessile) acorns from which one of its common names is derived. (With the pedunculate oak, it is the acorns which are pedunculate, i.e. on stalks, while the leaves are not.) It occurs in upland areas of altitudes over 300 m (984 ft) with higher rainfall and shallow, acidic, sandy soils. Its specific epithet petraea means "of rocky places". Q. 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.
Charles Darwin, in Chapter II of On the Origin of Species, noted that the sessile and pedunculate oaks had been described as both distinct species and mere varieties depending on the authority consulted.

## Taxonomy

Quercus petraea was first described by Heinrich Gottfried von Mattuschka in 1777 as a variety of Quercus robur, Quercus robur var. petraea. It was raised to a full species by Franz Kaspar Lieblein in 1784.

### Subspecies

As of March 2023, Plants of the World Online accepted five subspecies:
* Quercus petraea subsp. austrotyrrhenica Brullo, Guarino & Siracusa
* Quercus petraea subsp. huguetiana Franco & G.López
* Quercus petraea subsp. petraea
* Quercus petraea subsp. pinnatiloba (K.Koch) Menitsky
* Quercus petraea subsp. polycarpa (Schur) Soó

## Diseases and pests

* Acute oak decline
* Sudden oak death
* The Welsh oak longhorn beetle (Pyrrhidium sanguineum) is named after its host tree; the larvae feed at the bark interface of dead wood.

## Uses

Sessile oak is one of the most important species in Europe both economically and ecologically. Oak timber is traditionally used for building, ships and furniture. Today the best woods are used for quality cabinetmaking, veneers and barrel staves. Rougher material is used for fence construction, roof beams and specialist building work. The wood also has antimicrobial properties. It is also a good fuel wood. During autumns with good acorn crops (the mast years), animals are traditionally grazed under the trees to fatten them.

## Pontfadog Oak

Known as "Wales's national tree", the Pontfadog Oak was a sessile oak considered to be the oldest oak tree in the UK. Located near Chirk in North Wales, its girth was measured as over 16 metres (53 ft) in 1881 and 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 m (42 ft 5 in).
The tree was lost in April 2013 when it blew down in high winds. However, the Crown Estate propagated a sapling from the original tree and planted it in Windsor Great Park. A further five saplings have been cloned from the Pontfadog Oak, three of which will be planted at the National Botanic Garden of Wales, with the other two going to sites near Pontfadog; one at Chirk Castle and the other at Erddig, as part of a woodland memorial to those who died during the COVID-19 pandemic.