According to Dr Stephen Harris of Oxford University’s Department of Plant Sciences:
The received wisdom regarding the black pine is that it was planted in 1799 from seed that was collected by the Third Sherardian Professor of Botany, John Sibthorp, in Austria. We know that Sibthorp sent considerable amounts of plant material to Oxford from the eastern Mediterranean in 1786/87 and that he was in Austria in 1785. He was also in regions of Black Pine growth in 1795 but he died in 1796.
If the story of the Black Pine is true then it should be at least 215 years old.
 See also
- Tolkien's black pine: Why do we love old trees? at independent.co.uk