Bristlecone pine

Bristlecone pine — The 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 single living organism known, up to nearly 5,000 years.

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.

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. 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.