The Ash of Yggdrasil : It is the Best of Trees

An Ash I know standing    It is called Yggdrasil

A high tree sprinkled    with shining drops

From there come the dews     which in the dales fall

It stands ever green     above the Well of Urd (or "Above the Well of Weird")

images: Wikimedia Commons (top image, bottom image).

Is Yggdrasil an Ash, or a Yew?

The debate continues to this day, but I am quite sure that the mighty World Tree is found in the Invisible Realm and is seen in the celestial realm, rather than the terrestrial.

Above are two descriptions of Yggdrasil from the Poetic Edda, one from the Voluspa and one from the Grimnismal.