(species Pinus longaeva and P. aristata), small pine tree ranging from about 5 to 16 metres (15 to 50 feet) in height and belonging to the family Pinaceae. The species are native to the Rocky Mountains and other ranges of the southwestern United States, occurring usually at elevations above 1,700 metres (5,500 feet). P. longaeva has the longest life-span of any conifer known. A stand of western bristlecone pine on Wheeler Peak in eastern Nevada is known to contain several trees over 3,000 years old, and one of them is thought to be about 5,000 years old.