bristlecone pine

from The American Heritage® Dictionary of the English Language, 5th Edition.

• noun Either of two small slow-growing pines (Pinus aristata or P. longaeva) found at higher elevations of the western United States, having needles in fascicles of five. Specimens of P. longaeva in east-central California are among the oldest known living trees, achieving ages well over 4,000 years.

from Wiktionary, Creative Commons Attribution/Share-Alike License.

• noun Any of a small number of different small, slow-growing pine trees found in the western United States, some of which are over 4,000 years old.

from WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.

• noun small slow-growing upland pine of western United States (Rocky Mountains) having dense branches with fissured rust-brown bark and short needles in bunches of 5 and thorn-tipped cone scales; among the oldest living things some over 4500 years old