Tree 19: English Oak
English Oak is one of our commonest native trees, easily confused with Sessile Oak with which it freely hybridizes. These two native oaks are the most northern representatives of the huge genus Quercus., all of which bear fruits known as acorns, The English Oak can be distinguished from the Sessile Oak by the long stalks (peduncles) of its acorn cups and short leaf stalks. A long-lived oak is a massive tree, reaching up to 30m tall and 50m broad with its lowest branches at right angles to the ground. A rule of thumb for ancient oaks is that they grow for 300 years, mature for another 300 years and then “veteranise”, or decay, for a final 300 years. Our English Oak in the Park is in its growing phase. There are over 700 named veteran oaks in Britain.
The English Oak is perhaps the most loved and feted tree in Europe, widely claimed as a national or regional emblem and as a symbol of countless businesses, charities, community groups and institutions. Historically, open oak woodlands in Britain were deer parks, sporting grounds for the rich and places to fatten up pigs for the less wealthy. The scientific name robur references the strength of its timber which was peerless for building Elizabethan farmhouses, cathedral roofs, panelled rooms in stately homes and coaching inns. Oak timbers built ships for the navy and came to symbolize national liberty as immortalized in poems and songs.
The English Oak is a “keystone plant” supporting more species than any other native tree, Up to 400 species of insects have been recorded on a single specimen and 100 different moth caterpillars are associated with it, Green woodpeckers, pigeons and carrion crows nest in it and squirrels build their dreys in it. Its open canopy allows light to penetrate through to the woodland floor, where primroses and bluebells flower. In autumn many acorns do not germinate, being a rich food source for mice, voles, deer, rooks, jays and wood pigeons.
A mature, veteran oak will live with mosses, lichens, algae and ferns growing from it but eventually it will be invaded by one of many fungi that will cause the decay of its heartwood and its inevitable downfall.
