Pinus longaeva, the Great Basin Bristlecone Pine, is a long-living species of tree found in the higher mountains of the southwest United States. The species is one of three closely related trees known as bristlecone pines and is sometimes known as the Intermountain or Western bristlecone pine. It is a medium-size tree, reaching 5 to 15 meter (16 to 49 feet) tall and with a trunk diameter of up to 2.5 to 3.6 meter (8 feet 2 inches to 11 feet 10 inches) in diameter. The bark is bright orange-yellow, thin and scaly at the base of the trunk. The leaves ('needles') are in fascicles of five, stout, 2.5 to 4 centimeter (0.98 to 1.6 inches) long, deep green to blue-green on the outer face, with stomata confined to a bright white band on the inner surfaces. The leaves show the longest persistence of any plant, with some remaining green for 45 years (Ewers & Schmid 1981).