The common oak is a deciduous tree that can reach around 40 metres in height. It develops a broad, richly branched crown and is distinguished by its smooth bark when young, which becomes thick and deeply fissured with age. It is one of the most emblematic trees of Europe’s Atlantic forests.

A native species in Portugal, it is characteristic of regions under Atlantic influence, where it finds deep, fertile soils with a good supply of water. It prefers humid and temperate climates, forming forests rich in biodiversity or forming part of mixed oak forests alongside other tree species.

The flowers appear in spring and develop into acorns that ripen in autumn. These provide an important food source for numerous species of birds and mammals. Common oak woodlands are among the most biodiverse ecosystems in Portugal, providing shelter, food, and breeding sites for a wide variety of organisms.

The common oak’s wood, which is hard, durable, and of exceptional quality, has been widely used throughout history in construction, carpentry, and shipbuilding, and is still regarded as one of the most valuable woods in Europe today. The specific epithet robur is derived from the Latin word meaning “strength” or “robustness”, a clear reference to the solidity and durability that characterise this species.

A tree of remarkable longevity, the common oak can live for several centuries. Its acorns have been used as a food source by humans for generations. As with many other species of Quercus, galls may develop on its branches. These structures are formed by the tree in response to the egg-laying activity of certain insects. These formations, which are not fruits, provide a curious example of the interaction between oaks and the wildlife that depends upon them.