The Birnam Oak is an example of Sessile oak (Quercus petraea) at Birnam, Perth and Kinross, Scotland . Sometimes known as Macbeth's oak, as it is a relic of Birnam Wood, mentioned in William Shakespeare's play, the tree is found in a strip of woodland on the south bank of the River Tay.[1] The trunk is wide and its large spreading branches have latterly been supported on a number of struts to prevent them from collapsing under their own weight.[2] The exact age is unknown, but the girth suggests an age of around 600 years old which would mean it was already a mature tree at the time of Shakespeare's presumed visit to Perthshire in 1589.[3] The tree is listed by Forestry and Land Scotland as one of Scotland's most famous oak trees.[4]