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. One member of this species, at 5062 years (as of 2012), is the oldest known living non-clonal organism on Earth.
Trees can be identified by examination of several characteristics.
The following guide applies to the trees which are indigenous to the region extending from the Atlantic Ocean to the Rocky Mountains and from Canada to the northern boundaries of the southern states, together with a few well-known and naturalized foreign trees.
The typical leaves of a species are to be found upon mature trees, not upon young ones. The leaflets of a compound leaf can be distinguished from simple leaves by the absence of leaf buds from the base of their stems.
To identify a tree check a characteristic and if it is present then examine the characteristics at the next level of indentation. For example, if the tree has simple leaves then see whether the leaves alternate along stem or leaves are opposite along stem.
This guide does not include the Conifers, which are cone-bearing seed plants with vascular tissue.