Q. robur is a large deciduous tree 25–35 m tall (exceptionally to 50 m), with lobed and nearly sessile (very short-stalked) leaves 7–14 cm long. Flowering takes place in mid spring, and their fruit, called acorns, ripen by the following autumn. The acorns are 2–2.5 cm long, pedunculate (having a peduncle or acorn-stalk, 3–7 cm long) with one to four acorns on each peduncle.
It is a long-lived tree, with a large widespreading crown of rugged branches. While it may naturally live to an age of a few centuries, many of the oldest trees are pollarded or coppiced, both pruning techniques that extend the tree's potential lifespan, if not its health. A specimen of notable longevity is one in Stelmužė, Lithuania which is believed to be approximately 1,500 years old, possibly making it the oldest oak in Europe; another specimen, called the 'Kongeegen' ('Kings Oak'), estimated to be about 1,200 years old, grows in Jaegerspris, Denmark. Yet another can be found in Kvilleken, Sweden, .It is over 1,000 years old and 14 meters around.[1] Of maiden (not pollarded) specimens, one of the oldest is the great oak of Ivenack, Germany. Tree-ring research of this tree and other oaks nearby gives an estimated age of 700 to 800 years old. Also the Bowthorpe Oak in Lincolnshire, England is estimated to be 1,000 years old making it the oldest in the UK, although there is Knightwood Oak in the New Forest which is also said to be as old.