The tree species that includes the oldest known non-clonal tree is Pinus longaeva, the Great Basin bristlecone pine.
This species grows in the high mountains of California, Nevada, and Utah, where cold, dry conditions and poor soils slow its growth. The famous Methuselah tree, whose exact location is kept secret, is a Pinus longaeva specimen in California’s White Mountains and has been dated to roughly 4,850 years old by counting annual rings.
Bristlecone pines survive extreme age through a strategy called strip growth. Much of an old tree may die, while narrow sections of living cambium continue connecting the roots to a few branches. Their dense, resinous wood also resists decay, so dead trunks and branches can remain preserved for thousands of years.
A historical complication is the tree called Prometheus, another Pinus longaeva that was cut down in Nevada in 1964. It was later estimated to have been at least about 4,800 years old. Some estimates for other ancient trees are disputed, but Pinus longaeva remains the canonical species associated with the oldest confirmed non-clonal tree.