Bristlecone pines are a small group of pine trees (Family Pinaceae, genus Pinus, subsection Balfourianae) that can reach an age far greater than that of any other living thing known - up to nearly 5,000 years. There are three closely related species:

Rocky Mountain bristlecone pine Pinus aristata in Colorado, New Mexico and Arizona
Great Basin bristlecone pine Pinus longaeva in Utah, Nevada and eastern California
Foxtail pine Pinus balfouriana in California

Currently, the oldest living specimen known is an individual of Pinus longaeva nick-named "Methuselah", located in the White Mountains of eastern California, measured by sample cores to be about 4,700 years old. There could possibly be older specimens surviving elsewhere in the White Mountains and/or in remote parts of Nevada, but none have yet been located. The recordholder, however, was one named "Prometheus", which was cut down in 1964 by a geography graduate student performing research in an area now protected by Great Basin National Park in Nevada. Its rings were counted (not easy because the trunks are very twisted and distorted), and its age determined to be about 4,900 years old. "Prometheus" did not die just to have its rings counted. The carbon content of the wood from its various rings was analyzed, providing an important calibration for radiocarbon dating. The other two species are also long-lived, though not to the extreme extent of P. longaeva; specimens of both have been measured or estimated to be up to 3,000 years old.

Bristlecone pines grow in isolated groves just below tree-line. Between cold temperatures, high winds, and short growing seasons, the trees grow very slowly. The wood is very dense and resinous, and thus resistant to invasion by insects, fungi, at other potential pests. As the tree ages, much of its bark may die; in very old specimens often leaving only a narrow strip of living tissue to connect the roots to the handful of live branches.

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