Sessile oak

Appearance

The sessile oak is a large deciduous tree up to 20–40 m (66–130 ft) tall, in the white oak section of the genus 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 broad, evenly lobed with five to six lobes on each side, and a 1 cm petiole. The flowers are catkins, produced in the spring. The fruit is an acorn 2–3 cm long and 1–2 cm broad, which matures in about six months.

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". 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.

Naming

syn. Quercus sessiliflora

Uses

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

Cultural

What was considered to be the oldest 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 42 feet 5 inches (12.9 m). It was lost in April 2013 when it blew down in high winds.