The term bristlecone pine covers three species of pine tree (family Pinaceae, genus Pinus, subsection Balfourianae). All three species are long-lived and highly resilient to harsh weather and bad soils. One of the three species, Pinus longaeva, is among the longest-lived life forms on Earth. The oldest of this species is more than 4,800 years old, making it the oldest known individual of any species.

Despite their potential age and low reproductive rate, bristlecone pines, particularly Pinus longaeva, are usually a first-succession species, tending to occupy new open ground. They generally compete poorly in less-than-harsh environments, making them hard to cultivate. In gardens, they succumb quickly to root rot. They do very well, however, where most other plants cannot even grow, such as in rocky dolomitic soils in areas with virtually no rainfall.

Bristlecone pines grow in scattered subalpine groves at high altitude in arid regions of the Western United States. Bristlecones, along with all related species in class Pinopsida, are cone-bearing seed plants commonly known as conifers; the name comes from the prickles on the female cones.