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 bristlecone pines are the oldest single living organisms known (though some plants form clonal colonies which may be many times older). 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.