Paleo Slide Set: Tree Rings: Ancient Chronicles of Environmental Change
Bristlecone pine (Pinus longaeva), White Mountains, California.

Since one of the goals of dendroclimatology is to reconstruct climate 
for as long of a period as possible, the oldest trees that can be found 
are sampled. Old trees are not always the biggest trees, but are commonly 
characterized by heavy, gnarled limbs, spiked tops, and in the case of 
ancient bristlecone pine, "strip bark" stems with only a narrow ribbon 
of living bark (cambium). Bristlecone pine of the Great Basin region of 
western North America are the oldest known living trees, up to 5,000 years old.

Photo Credits:
Jonathan Pilcher
Palaeoecology Centre, Queen's University, Belfast