Quercus robur (English Oak)

Michael's Opinion

This slow growing tree can survive for centuries. The largest English Oaks have decayed centers but are estimated at 1000 to 2000 years old.

Botanical Information

FamilyFagaceae
GenusQuercus
Speciesrobur
CategoryWoody
TypeTree (deciduous)
OriginEurope, Northern Africa and Western Asia.
Pronunciation

Details

USDA Hardiness Zone5 - 8
USDA Hardiness Ref.
Canadian Hardiness Zone4a - 8a
Canada Hardiness Ref.
RHS Hardiness ZoneH7 - H4
RHS Hardiness Ref.
Temperature (°C)(-26) - (-7)
Temperature (°F)(-15) - 20
Height12-23 m
Spread12-23 m
GrowthSlow
Flowering PeriodApril

Description and Growing Information

General DescriptionLarge heavy branches, with a majestically domed crown and foliage set in bunches. This species has been placed on the IUCN Red List as least concern.
ID CharacteristicDistinctly large reddish acorns, and extremely short petioles. Undulate or wavy leaf edges.
ShapeBroadly rounded crown.
LandscapeIn parts of Europe, it is planted along the axis and borders of public plazas, to provide shade and cool the air. However it is quite suited to North American landscapes as a ‘center piece’ or focal point within a landscape venue especially when the tree has grown significantly enough to make an impact.
PropagationCommonly through seed, although the seed is reclacitrant (will not store).
CultivationQuercus robur is tolerant to a variety of soils, even heavy wet clays. However it prefers to grow out in the open or in a hedgerow. It responds well to bur lapping and containers in production, however one must note that it has deep tap roots.
PestsErysiphe alphitoides (Powdery mildew). Although powdery mildew is unattractive, it is rarely fatal to the oak, however it does put stress on the tree, and can interfere with photosynthesis and transpiration.
Notable SpecimensUniversity of Western Ontario, Sherwood Fox Arboretum, London, Ontario, Canada. Westonbirt, The National Arboretum, Tetbury, Gloucestershire, England. Lanhydrock Gardens, England, Cornwall. One of the oldest trees in Europe is the Allerton Oak at Calderstones Park in Liverpool, England. It was mentioned in the Doomsday Book and is estimated to be over 1000 years old.
HabitatClimax forests in England and Europe.
Bark/Stem DescriptionAsh-coloured, coarsely textured with black fissures and vertical ridges.
Flower/Leaf Bud DescriptionThe terminal buds are rather large, measuring 1 cm in length, being a reddish brown colour. The bud scales themselves are somewhat fringed with hairs, when mature, they develop shallow grooves.
Leaf DescriptionSmall undulate leaves, measuring 8-13 cm in length, with 5 to 7 pairs of subtly rounded lobes, as well as small earlike lobes at the base of the leaf.
Flower DescriptionSmall, delicate, white and inflorescent in nature. They are arranged on the sides of thin dangling stems 4 cm long. The female flowers are solitary.
Fruit DescriptionThe acorns of Quercus robur are approximately 2.5 cm in length, and are a third covered by a cap. They are suspended by a long (10 cm) peduncle and can be found in clusters of three to five.
Colour DescriptionJade green on the upper surface with subtle hues of pastel green underneath. In the autumn the leaves turn a rich tan colour.
Texture DescriptionRelatively thin as far as leaves are concerned. The upper-epidermis feels like soft leather, the lower surface has a ‘cotton paper’ like feel.

Photographs