Oldest living individual tree

The oldest trees in the world are the bristlecone pines (Pinus longaeva) of California's White Mountains, USA. The oldest named individual tree, christened "Methuselah", was found by Dr Edmund Schulman (USA) and dated in 1957 from core samples as being more than 4,800 years old (4,852 years as of 2020); this age was later crossdated and confirmed by dendrochronologist Tom Harlan (d. 2013) at the Laboratory of Tree-Ring Research at the University of Arizona. An even older specimen of bristlecone sampled by Schulman in the White Mountains before he died was also crossdated by Tom Harlan, but not until 2009. This sample was also from a living tree, so the tree is aged 5,070 years as of 2020; this unnamed tree is currently the oldest verified living tree in the world. The precise locations of these trees are kept secret to protect them from vandalism/damage from over-trampling. The annual growth rings of old trees provide a valuable insight into our changing climate: the bristlecone climate record from dead wood extends back more than 9,000 years. The Ancient Bristlecone Pine Forest is located at around 3,050 metres (10,000 feet) above sea level in the White Mountains, east of the Sierra Nevada. Over time, the wind and rain has moulded the trees into strange shapes and forms made even more unusual by the sunshine, altitude and crisp air. Dr Schulman was a scientist from the University of Arizona when he came across Methuselah and an area in the forest is named the Schulman Grove in his honour.

Methuselah is classed as “individual" as it is not a clone. It is rare for any individual tree to exceed 3,000–4,000 years old.

Other long-lived individual tree species include: giant sequoia (Sequoiadendron giganteum, western juniper (Juniperus occidentalis and Patagonian cypress (Fitzroya cupressoides), all of which have had specimens aged to between 3,000–4,000 years and over.

There are older examples of clonal plants. For example, a creosote bush (Larrea tridentata) found in 1980 in the desert near Palm Springs, California, USA – aged at 11,700 years old – is a clone, as individual specimens of this species rarely exceed 200 years. Some scientists have suggested that the clonal forest of quaking aspen (Populus tremuloides), known as Pando, in the Wasatch Mountains of Utah, USA (the world's most massive single plant and heaviest organism) could date back as far as 14,000 years, which would also make it the world's oldest living organism, but this is widely debated and unconfirmed at this point.

Similarly, dead wood retrieved from the base of a Norway spruce (Picea abies), dubbed “Old Tjikko”, in Dalarna Province, Sweden, has been radiocarbon-dated to as old as 9,550 years. However, this too would be an example of vegetative cloning rather than an individual tree of this age, as spruce trees are thought to only live for, at most, a few centuries. Further, serious doubts have been cast that the dead wood is genetically associated with the current living specimen (Mackenthun, 2016; Farjon, Oct 2015), so it may be from a different spruce that formerly existed on the same site.