The Birnam Oak, a sessile oak, so called because its acorns are not on stalks (the Latin word sessilis means stalkless), is believed to be a remnant from the great forest celebrated in Shakespeare’s Macbeth. However, it probably isn’t old enough to have itself been the source of greenery to camouflage Malcolm’s army in 1057 but it is one of the oldest trees in the area. It's possible Shakespeare may have visited the area in 1599 with a troupe of touring players sent by Elizabeth I after a request from King James IV.
The massive sycamore close to the Birnam Oak is thought to be about 300 years old. Its gnarled shape may be a result of pollarding, where the upper branches are cut regularly leaving a tall stump to sprout back. This was common practice in the past to increase the supply of young, straight stems.