(
Pinus longaeva) is the longest living tree species on Earth. The
oldest trees are determined by
growth rings, which can be seen if the tree is cut down, or in cores taken from the bark to the center of the tree. Accurate determination is only possible for trees that produce growth rings, generally those in seasonal climates. Trees in uniform non-seasonal tropical climates grow continuously and do not have distinct growth rings. It is also only possible for trees that are solid to the center. Many very old trees become hollow as the dead
heartwood decays. For some of these species, age estimates have been made on the basis of extrapolating current growth rates, but the results are usually largely speculation. White (1998) proposes a method of estimating the age of large and veteran trees in the United Kingdom through the correlation of a tree's age with its diameter and growth character. The verified oldest measured ages are: Other species suspected of reaching exceptional age include
European Yew (
Taxus baccata) (probably over 5,000 years),
Sugi (
Cryptomeria japonica) (3,000 years or more), and
Western Redcedar (
Thuja plicata). The oldest known European Yew may be the
Llangernyw Yew in the Churchyard of
Llangernyw village in
North Wales, or the
Fortingall Yew in Perthshire, Scotland. The Llangernyw Yew has been estimated as between 4000 and 5000 years in age by David Bellamy, who also used radiocarbon dating to estimate an age of around 4000 years for the Tisbury Yew in Wiltshire, while the Fortingall Yew with its former 16 to 17-meter girth is estimated at 5,000 years of age. However, ageing yews is very difficult due to the loss of heartwood in very ancient trees, and one or two sources believe the trees to be far younger at around 1500–3000 years.
Lagarostrobos franklinii, known as Huon pine, is native to the wet southwestern corner of Tasmania, Australia. A stand of trees in excess of 10,500 years old was found in 1955 in western Tasmania on
Mount Read. Each of the trees in this stand is a genetically identical male that has
reproduced vegetatively. Although no single tree in this stand is of that age, the stand itself as a single organism has existed that long. Individual trees in the clonal patch have been listed as having ages of 2000 or even to 3000 years old. The
olive tree also can live for centuries. Previously the oldest age verified by carbon dating was 900 years for a tree in the
Gethsemane garden in Jerusalem. In 2024 research was published showing that one of the trees in the
Sisters Olive Trees of Noah to be years old, plus or minus 131 years, by carbon dating. Previously they had been reputed to be around 6,000 years old. ==Deepest and longest tree roots==