Creosote bushes (Larrea tridentata) grow in concentric rings by a process in which the main stem of a bush splits apart and new shoots grow from the outer edge of each section of stem, forming new bushes. The successive generations are genetically identical, so many consider the ring to be the same plant as that first sprouted from a seed (at the center). The oldest known ring is over 11,500 years old and some 50 feet in diameter, located in the Mojave Desert of Southern California. The age was determined by carbon dating, and makes it the oldest living thing known to man.