The largest and densest organism in the world is thought to be Pando (aka the Trembling Giant). Pando appears to visitors to be just another patch of aspen forest but is actually a clonal colony of an individual male quaking aspen - a single living organism. It is assumed to have one massive underground root system and to be among the oldest organisms in the world.

Its root system is also believed to be thousands of years old - which would also make it one of the oldest living organisms on the planet. The tallest trees in the world are in California, and everyone should see these impressive sequoias before they disappear to forest fires. The oldest (nonclonal) trees in the world are thought to be the groves of ancient bristlecone pines in the Great Basin National Park.


The Size Of Pando

Pando is Latin for "I spread" and is also known as "the trembling giant". It takes up an area of 108 acres (or 43.6 hectares) and is thought to weigh around 6,000 tons in total (making it the heaviest known organism in the world).

It is thought to be the largest organism by mass but not distance. Oregon's "humongous fungus" spans an even greater distance. It is made of over 40,000 individual trees.

All of its 40,000 trees (47,000 by some estimates) are genetically identical quaking aspen trees, and all stem from a single root system.

  • Individual Trees: Has Over 40,000 Individual Trees
  • Location: Fishlake National Forest in South Central Utah
  • Size: 108 Acres or 43.6 Hectares

Related: How You Can Visit The Giant Sequoias Of Yosemite National Park

The Age of Pando

Pando originated from a single seed thousands of years ago and spread by sending out new shoots from its expanding root system. According to the U.S. Forest Service:

"The exact age of the clone and its root system is difficult to calculate, but it is estimated to have started at the end of the last ice age. Some of the trees are over 130 years old. It was first recognized by researchers in the 1970s and more recently proven by geneticists."

According to the National Park Service, it may be as much as 80,000 years old. Through cloning themselves, aspens can live for a very long time - although it is much more common for them to be "only" 5,000 to 10,000 years old (which is still enough to make them older than the Sequoias and even Bristlecone Pines.

  • Age: From The End of The Last Ice Age Or Up To 80 Years Old
  • Oldest Living Thing: May Be The Fungal Mats In Oregan And Creosote Bushes in The Desert Southwest

Determining the age is difficult and current research on fungal mats in Oregon and Creosote Bushes in the Desert Southwest may rival aspen for the title of "Oldest-known Living Thing."

Related: Where To Visit California's Stunning Coastal Redwoods, And What To Expect There

Threats And Current Decline

Worryingly, Pando is showing signs of decline and specialists have become concerned about the wellbeing of the organism. The driving factors are thought to be a lack of regeneration as well as insects and disease.

The lack of regeneration is thought to be due to overgrazing by deer. While the insects like bark beetles and diseases like root rot and cankers have been taking a toll on the overstory trees, weakening and killing them.


  • Lack of Regeneration: Driven By Overgrazings
  • Insects and Diseases: Weakening and Killing The Overstory Trees

Troublingly there are no young or middle-aged trees at all, instead, Pando is now made up almost entirely of elderly trees.

There is a risk that Pando could become a smaller clone or even die off altogether. To see more about the restoration efforts and more information about Pando, watch the Forest Service's dedicated video.

One of the problems is that there are no long apex predators in the area due to overhunting by people. Today there are few or no wolves, mountain lions, and grizzly bears in the area that would otherwise have kept the mule deer in check. In an effort to protect Pando. Much of the area is now fenced but it seems the deer can just jump it.

Still there remains hope that Pando can be saved and many efforts and studies are being undertaken to preserve it.

Visiting Pando

Pando must be one of the few organisms in the world to have a full road running through it. One can visit it (and drive through it) on State Highway 25.

  • Highway: State Highway 25
  • When: The Most Popular Time Is In Fall For The Fall Colors

Since being discovered in the 1970s, Pando has rocked to world fame and many visitors flock to see Pando. The most popular season is during the fall when the leaves turn yellow and orange.

Next time traveling in Utah, consider a side trip to see the largest organism in the United States!

Next: 20 Reasons To Explore Europe’s Only Remaining Ancient Forest