This forest of 47,000 aspen trees is actually one single organism.
On a Utah hillside, some 47,000 quaking aspen trunks spread across 43 hectares. Genetically they are all one male individual, joined by a shared root system. Named Pando, Latin for 'I spread', it weighs an estimated 6,000 tonnes and is generally considered the heaviest organism on Earth.
Quaking aspens often reproduce by 'suckering': a tree sends out roots that push up new stems, which look like separate trees but are genetically identical parts of the same individual. Over time a whole grove can grow from a single seedling. Burton Barnes and Jerry Kemperman identified Pando in 1976 using aerial photographs and features such as leaf shape. In 1992 Michael Grant, Jeffrey Mitton and Yan Linhart confirmed it was a single male clone, and Grant gave it its name. Genetic sampling published in 2008 backed them up.
Its trunks rarely live beyond about 100 to 130 years, but the roots persist, sending up replacements as old stems die. That makes Pando's true age hard to pin down, since tree rings cannot reveal it. Many news stories say 80,000 years, but that figure traces back to a National Park Service web page that removed the claim in 2023. Glaciers capped the nearby mountains during the last ice age, and climate modelling suggests it would then have been too cold for aspen to take hold. Charcoal studies put the lower bound at about 9,000 years, a recent estimate suggests 16,000, and claims of greater ages have not yet passed peer review.
The bigger worry is the future. Pando has survived droughts and fires, regrowing from its roots after burns; aspens hold so much water that fire scientists call them 'asbestos forests'. But mule deer and elk eat young shoots before they can replace dying trunks, and researchers say reducing that browsing is critical. Since the 1990s, fences have kept animals out of much of the grove, with promising regrowth inside. Cattle grazing ended in 2024, and new fencing finished in 2025 brought around 80 per cent of the tree into protection.
Whether Pando is the 'largest' living thing depends on the measure. The General Sherman giant sequoia holds the record for the greatest volume in a single trunk, and other trees, such as redwoods, can clone themselves too. But by weight, Pando is generally held to be the largest organism in the world: one living individual that looks exactly like a forest.
Source: Wikipedia — Pando (tree) · Text summarised from Wikipedia (CC BY-SA 4.0)
