Alder Tree and Celtic folklore

The alder tree is important to Celtic folklore as a place of hiding and secrecy. In the story of Deirdre of the Sorrows, Deirdre elopes with Naoise, son of Usna, and they hide together from King Conchobar mac Nessa, Deirdre's betrothed, in the alder woods of Glen Etibhe. They eventually leave the forest, and are then discovered by one of King Conchobar's spies. Naoise throws a golden chess piece at the spy and puts out one of his eyes, but he is still able to report to the king where the lovers are. (As in all good tragedies, both lovers die and everyone else lives.) This story relates to Kinbote's own escape and hiding, except Kinbote is the king that is hiding from Gradus, the person of lower status, rather than the lower Naoise hiding from King Conchobar.

The alder tree is considered a place of hiding in Celtic folklore primarily because it is believed that the trunk of the alder tree conceals doorways into the fairy realm. Alice goes through the looking glass, the crazy Kinbote immerses himself in Shade's poem while in Utana, and the father and his child ride "through the night, dark and drear." It is in the alderwood that the child is transported from life into the dark oblivion afterward, and it is the Alder King who transports the boy to his fairy kingdom with his fairy wife and fairy daughters.