The current record for the world's oldest known tree is held by the Rocky Mountains bristlecone pine, which is found in California's White Mountains. More than 4000 years must pass before many of the trees begin to show signs of dying from old age, with the current record holder still alive after 47000 years. Bristlecone pines are very robust, needing little in the way of moisture and nutrients. Inconspicuous and unremarkable, they don't grow much above 12 m in height, which is probably why scientists didn't realize until the 1950's that they lived for such a very long time. Before their great age was established, everyone agreed that the huge sequoias-some of which were between 3000 and 3600 years old-were the oldest trees on our planet.