Oak
The oak is the most regal of trees (cf.). It is linked to sky and thunder gods, symbolizing strength (the Latin word robur means both oak and strength), power, longevity, spiritual elevation, and more; it often represents the world axis and the connection between heaven, earth, and possibly the underworld.
Like all remarkable trees in dreams, the oak can express the source and goal of the individuation process. Trees carry both masculine and feminine qualities, and the oak, specifically, was sacred to Jupiter but also dedicated to Juno, for instance.