Back in 1954 my parents bought the World Book Encyclopedia. I began reading it like many people might read magazines or novels. We never got National Geographic, but often enough I was somewhere that had either current or old issues around. It was in one or the other that I read about the bristlecone pine, then thought to be the oldest living tree in the world. I would've thought the oldest living tree would be a giant sequoia, but the gnarled pine growing in the White Mountains of California southeast of Yosemite National Park on the Nevada border was older.
Earlier today I encountered the website of photographer Rachel Sussman. She has a portfolio of photographs of the world's oldest living things. It appears the bristlecone pine has a lot of competition. There's links to a location map which shows that the largest single living organism on the planet is in Oregon and a blog she adds to occasionally.