Most oak trees lose all of their leaves in autumn . Some kinds of oak tree , the `` live oak '' , that grows in the American South or the Holm oak that grows in Europe keep their leaves through winter It is called the `` live oak '' in the United States of America because it keeps many of its leaves during winter . Several individual oak trees , such as the Royal Oak in Britain and the Charter Oak in the United States , are of great historical or cultural importance ; for a list of important oaks , see Individual oak trees .