From PRI:
The largest organism on Earth probably isn't a whale or a giant octopus or anything else you might naturally think of first. It's a tree — or a group of genetically identical trees that stretches across more than 100 acres of Utah's Fishlake National Forest.
Called "Pando," which is Latin for “I spread," the group of quaking aspens is considered one of the largest — by area — and most massive living organisms on earth. The quaking aspen, found from coast to coast across North America, grows in groups called stands. Within these stands, a single tree will spread by sprouting new stems from its roots, often several feet from the original trunk.
“Those trees remain connected for a good long while,” explains Jennifer DeWoody, a geneticist with the US Forest Service. “This long process is over many years — suckers [or stems] coming up over a larger and larger area.” Their stems can share the products of photosynthesis, food, and possibly disease as well.
Because individual aspen stems generally live about 100-150 years, DeWoody says the origin mother stem is likely dead: “The only way the whole clone survives is to send up new suckers,” she says. While other trees can also clone in this way, “[aspens] do it the most broadly across so many different environments.”
Pando is unique because its stand is so massive compared to most others. University of Colorado scientists estimated in 1976 that it contained around 47,000 stems. Those scientists were also the first to describe Pando as a clone, based off of morphologic and aerial photographic analysis. But it wasn’t until 2008 that DeWoody and researchers from Utah State University confirming that Pando indeed was a single genetic individual, by collecting leaf and bark samples from the trees and analyzing their DNA.
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