The oak is considered the king of the forest, and an apt choice for the first tree I will discuss.
It is the tree of Zeus, Jupiter, Hercules and The Dagda, leaders of men and Gods. Sacred fires across Europe were kindled only with oak wood.
In Celtic culture, 'derw' or 'duir' was the word for oak, and from this derives 'Druid.' The oak groves of Druidic tradition were integral to their religion.
And that king of the birds, the wren, who gained his title by cunning, as I've mentioned in an earlier post, has a similar derivation: the 'derw-ren' or oak-bird. The wren was also important in Celtic culture; its song was said to be prophetic, and it is said that a prospective Druid had to hear and understand the song of the wren before he was accepted as such.
The reason may be related to a second meaning of the word 'oak.' The word 'duir' is linked to 'door,' and the oak offers a doorway into other realms, both physically and spiritually. Oracular oak cults existed in Ammon in Libya and Dodona in the Mediterranean, and the wren may also have had a foot in this spiritual door.
It is not surprising, therefore that the oak is one of our most loved trees