The Birnam Oak is an example of Sessile oak (Quercus petraea) at Birnam, Perth and Kinross, Scotland (grid reference NO032421). 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 5.5 metres 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 tree is listed as one of the Forestry Commission's Heritage Trees.[3]