The bristlecone pines are a small group of pine trees (Family Pinaceae, genus Pinus, subsection Balfourianae) that are thought to reach an age far greater than that of any other single living organism known, up to nearly 5,000 years.
There are three closely related species of bristlecone pine:
Rocky Mountains 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
Bristlecone pines grow in isolated groves at and just below the tree line. Because of cold temperatures, dry soils, 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, and other potential pests. As the tree ages, much of its vascular cambium layer may die. In very old specimens, often only a narrow strip of living tissue connects the roots to a handful of live branches.
Oldest living organisms
The oldest single living organisms known are bristlecone pines, though some plants such as creosote bush or aspen form clonal colonies that may be many times older. Recently, Swedish researchers discovered a self-cloning spruce in Dalarna that has been dated to just under 10,000 years old. The existing growth in clonal colonies sprang as shoots from older growth so there is an unbroken chain of life that sometimes dates back several tens of thousands of years. However, the original ancient growth in these colonies is long dead. The oldest bristlecone pines are single plants that have been alive for a little less than 5,000 years. These very old trees are of great importance in dendrochronology or tree-ring dating.
The oldest (acknowledged) living organism known is a bristlecone pine tree nicknamed "Methuselah" (after Methuselah, the longest-lived person in the Bible). Methuselah is located in the Ancient Bristlecone Pine Forest in the White Mountains of eastern California, however its precise location is undisclosed by the U.S. Forest Service to protect the tree from vandalism. The age of Methuselah was measured by core samples in 1957 to be 4,789 years old.
In the Snake Range of eastern Nevada Donald R. Currey, a student of the University of North Carolina, was taking core samples of bristlecones in 1964. He discovered that "Prometheus" in a cirque below Wheeler Peak was over 4,000 years old. His coring tool broke, so the U.S. Forest service granted permission to cut down "Prometheus". 4,844 rings were counted on a cross-section of the tree, making "Prometheus" at least 4,844 years old, the oldest non-clonal living thing known to man.
The other two species, Pinus balfouriana and Pinus aristata 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. It is rumored that a specimen older than "Methuselah" has been discovered, but this has not been widely publicized.