Quercus robur, commonly known European oak, is native to most of Europe west of the Caucasus • It is a long-lived tree, with a large wide spreading crown of rugged branches. It may naturally live to an age of a few centuries. The acorns form a valuable food resource for small mammals and some birds. Bird were the primary propagators of oaks before humans began planting them commercially (and remain the principal propagators for wild oaks), because of their habit of taking acorns from the umbra of its parent tree and burying them undamaged elsewhere. Mammals, notably squirrels who tend to hoard acorns and other nuts usually leave them too abused to grow in the action of moving or storing them. In Latvia, the oak tree is the national symbol.