Pinus longaeva

Pinus longaeva, known as the Great Basin bristlecone pine, intermountain bristlecone pine, or western bristlecone pine, is a long-lived tree that grows in the high mountains of California, Nevada, and Utah. In 1987, it became one of Nevada’s state trees. The oldest known non-clonal living organism on Earth is a specimen called Methuselah, which is 4,858 years old.

This medium-size tree typically reaches 5 to 15 meters tall, with a trunk diameter of 2.5 to 3.6 meters. Its bark is bright orange-yellow, thin, and scaly near the base. The needles grow in bundles of five, are stout and 2.5 to 4 centimeters long, deep green to blue-green on the outer side, with a bright white band of stomata on the inner surface. Some needles remain green for up to 45 years, among the longest persistence of any plant.

The cones are ovoid-cylindrical, 5 to 10 centimeters long and 3 to 4 centimeters wide when closed. They start green or purple and turn orange-buff after 16 months. Each cone has many thin, fragile scales, each tipped with a bristle-like spine 2 to 5 millimeters long. When mature, the cones open to 4 to 6 centimeters wide, releasing seeds immediately. The seeds are 5 millimeters long with a wing of 12 to 22 millimeters, mostly dispersed by wind, though Clark’s nutcrackers also help.

Old trees have a gnarled, stunted look, especially at high altitudes, with reddish-brown bark and deep fissures. As they age, much of the vascular cambium may die, leaving only a narrow strip of living tissue connecting roots to a few live branches.

The Great Basin bristlecone pine differs from the Rocky Mountain bristlecone pine because its needles always have two uninterrupted resin canals and lack small white resin flecks. It differs from the foxtail pine because its cone bristles are over 2 millimeters long and the cone base is rounded, not conic. The green needles give twisted branches a bottle-brush appearance. The name “bristlecone pine” comes from the dark purple female cones, which have incurved prickles.

The species is found in Utah, Nevada, and eastern California. In California, it grows in the White Mountains, Inyo Mountains, and Panamint Range in Mono and Inyo counties. In Nevada, it occurs in most high ranges of the Basin and Range, from the Spring Mountains near Las Vegas north to the Ruby Mountains. In Utah, it extends northeast to South Tent in the Wasatch Range. Because many sites are hard to reach, information on location and abundance is incomplete, so environmental niche modeling using GIS data has helped map its distribution.

Pinus longaeva grows in large open stands, unlike the related foxtail pine, which can form dense forests. It generally does not create closed canopies, covering only 15 to 50 percent of the ground. It shares habitats with ponderosa pine, white fir, and limber pine. It is a vigorous primary succession species, growing quickly on open ground, but is a poor competitor in good soils, thriving best in harsh terrain. It often dominates high-elevation dolomite soils where few other plants survive.

Bristlecone pines are protected in federal areas like the Ancient Bristlecone Pine Forest in California and Great Basin National Park in Nevada, where cutting or gathering wood is banned. Clark’s nutcrackers may help disperse seeds, though direct observations of them eating these seeds are unreported. The birds store conifer seeds in the ground, and unused seeds can sprout, sometimes producing multi-trunk trees. The prevalence of such multi-trunk individuals where nutcrackers live supports this idea.

An introduced fungal disease, white pine blister rust (Cronartium ribicola), is believed to affect some trees. In 1998, the species was listed as Vulnerable on the IUCN Red List. However, a 2011 population survey found the population stable, with no known subpopulations shrinking. Blister rust had a negligible effect, so the species was moved to Least Concern.

The tree is extremely fire-susceptible; even low-intensity burns damage it. Its resinous bark ignites quickly, and a crown fire almost always kills it. Yet populations are very resilient, and as a primary succession species, it would likely reestablish quickly after a fire. Large-scale fires are very rare where it grows and are not a major threat. Historically, stands experienced low to high severity fires, with fuel structures changing over time.