In Botany, the oak is a tree. Among the Greeks, and the Germans, the Oak was the life-giver and the life-sustainer. The Oak is
one of the 7 Sacred Trees of Druids: Brehon Law Ireland;
one of the 7 Chieftan Trees;
one of the 8 Noble Treas;
one of the 12 Sacred Trees and
one of the 12 Trees of the Celtic Calendar.
The oak represents the 6 months from the winter solstice to the summer solstice when the light is waxing. Male Wood The Oak is a male wood which is ideal for the construction of any tool that needs the male influence such as Athames, certain wands and staffs. The midsummer fire is always Oak and the need fire is always kindled in an Oak log. http://druidsutterance.net/20060522166/Magickal_Properties_of_Wood
In Russia, oak (дуб) is linked with the God Perun.