Q & A
Physical Characteristics
Pando is the world's largest tree, but how big is it?
Pando spans 106 acres. Today, around 103 acres is visible to naked eye.
What species of tree is Pando?
Populus tremuloides Michx. Sometimes this species is called Trembling Aspen because of how the tree’s leaves tremble in the wind. Others call aspen like Pando, Quaking Aspen, because of how their trunks shake, shudder and groan in heavy winds. Locals call aspen “quakies“.
Is Pando all one tree trunk?
No. Pando features over 40,000 ramets (aka trunks, branches—see below) which looks like individual tree trunks, but are in fact, parts of a single tree interconnected by a massive root system.
Has the shape of Pando remained the same all its life?
No. Pando is constantly changing its shape and form and moves in any direction water, sun and soil conditions create an advantage. Any place a new trunk comes up, is a place where a new hub of roots can send the tree in a new direction. If you visit the tree and see new stems (trunks, ramets), you are witnessing the tree moving or “spreading” out in that direction. Friends of Pando estimates that during peak growing season (May to September), the Pando Tree can move about 0.41 inches a day in any direction.
The confusing language of Pando: Rhizome, Trunk, Stem, Ramets, Suckers and Branches
Pando defies both scientific and common sense descriptions people use when they talk about trees. A quick review of some key terms about Pando working from the ground up.
- Rhizome: The root system of the tree. Pando’s rhizome came from a single seed that started spreading out some 9,000 years ago.
- Genet: The term for a genetic clone. Pando is a single genet.
- Sucker: Term for fresh growth triggered by a hormone fluctuation in the tree. The hormone cycle that sends regeneration continues today, which is why we say Pando is not dying
- Ramet: An individual part of a genet. These look like tree trunks to us, but are part of the larger tree. Each ramet helps balance energy production, defense and regeneration for the whole. Today Pando has an estimated 47,000 ramets.
- With so many ways to describe the Pando, and most of them quite technical, for simplicity’s sake, we choose to use two terms. One term for what is above ground, “Branches”, as they are part of a larger tree and behave like branches on a more typical trees working to gather energy. Then, we use one word, “Root“, for what is below ground.
You can learn more about the larger body of language and concepts that describe the Pando Tree via the Science and Data Store.
Root and Branches: A less confusing way to understand Pando
For general education purposes, we use the term “root” to describe the part of the Pando tree that is below ground and primarily involved in distributing energy and regeneration. We use the term “branch” or “trunk” to describe any part of the tree that is visible and involved in gathering energy above ground.
How many Branches make up Pando?
Pando has an estimated 47,000 branches.
Is every branch connected to every other branch?
Generally speaking, yes. Each of Pando’s branches is connected to the others through a shared root system.
Can one part of the tree get disconnected from the larger tree?
Yes. Pando’s roots build up and fan out. Sometimes, one outlying part of the tree can get isolated from the rest. Despite this, that part of Pando will behave like the larger mass does in terms of yearly changes. Incredibly, if all other parts of the tree were lost but, the hypothetically isolated part, it would become the “new” Pando Tree.
How big is Pando's root system?
Today, we know little about the underground workings of the Pando Tree, but our field crews and independent scientists estimate the root system spans across at least 106 acres (42.89 hectares, 0.17 square miles) while observations indicate the root could reach as deep as 30 feet.
How long is Pando's root system?
Pando’s root system is a multi-layered hub of roots built up over thousands of years. A rapid field estimate by Aspen Ecologist Paul Rogers suggests that Pando’s roots could span 12,000 miles if laid end to end. That would be nearly half-way around the world!
I am having a hard time visualizing the roots. Help me out...
Gather a ball of yarn or string and unravel a about 10 feet and cut it.
Now, take the piece you cut, and hold it in your hand and let it fall on a table or the floor while you move your hand back and forth. across the surface .
Once you are done, push the edges of the pile inward until you can just barely see through the gaps between the yarn.
1. The layers of the string represent the root system built up over time.
2. The random paths going back and forth across the floor, are how the root system might look if we could see through the whole.
What does a typical branch of Pando look like?
It varies.
- New Growth: A small stem about as big around as a drinking straw with a few small leaves and a primary apical bud at the top. New growth lacks the white bark, but is highly flexible, which provides defense against trampling and wind.
- An Unsustainable “Bushy” Stem: This is new growth that has had it apical bud broken off by trampling, animals or falling tree debris. Once the apical bud is broken, the growth will “bush” out rather than grow tall, and in time will die as it cannot reach sunlight. Where found, these “bushes”, tend to be less than 3 feet tall, spread around about 2-3 feet and feature small leaves. In work to care for the tree, these are removed as they will not become productive member of the tree community, in fact will waste energy.
- A Typical Branch: Long and straight, about 5-8 inches in diameter, and at least 8-12 foot tall with a crown that reaches around 6 feet in diameter. At this stage, the characteristic white bark is thin and remains quite pliable. The bark also features small black “eyes”, which are in fact, scars left where smaller less productive branches have fallen off the body.
- A Mature Branch: Between 18-36 inches in diameter and able to reach heights of up to 80 feet with a crown that spans outward up to 30 feet. The bark is thicker, features large branch scars (aka “eyes”). The base of the oldest branches often features “elephant toes” at the base; long gray furrows in the bark where the skin has stretched out as the tree increased in diameter over time.
Longevity
Is Pando 80,000 years old?
No. At most, Pando is between 9,000 and 14,000 years old because the land it calls home was dominated by glacier’s which influenced weather patterns making the Pando Tree’s homeland too cold for germination or for growth to survive the harsh environment.
Most Aspen tend to die out after a while, how does Pando keep going?
Scientists call an aspen clone like the Pando Tree, a “stable” clone because as these trees grow in size, they starts to dominate the water and nutrient supply.
If I visit Pando, would I be able to see the part that is 9,000 years old?
No. Each branch of Pando only lives between 110-150 years. The root itself is constantly spreading and building up, extending the system, and spreading out again. This means it is unlikely any part of the “original” root system remains for testing we can do today.
It may be helpful to think about in this way; every part of Pando, is genetically identical to the Pando seed, which set down thousands of years ago.
I read pando is "breaking-aprt", is this true?
No.Think of Pando as an amoeba, is it changing shape and form all the time. Some areas may flourish while others may shrink. You can learn more about such claims in our Science Communication Center.
Health
What kind of soil does Pando like?
Pando, like most aspen, enjoys moist, well-drained soils. As aspen are one of the most widely distributed species in North America, they can be found in acidic, loamy, sandy or clay soils. In addition, a study in 1987 suggests that an aspen clone can produce 900-2,000 pounds of biomass per acre via leaf droppings and dropping dead trunks or branches. In this way, while initial soil conditions may not be ideal, aspen clones can create soil conditions that favor their development over time.
How much sunlight does Pando need?
Pando’s is light hungry and very competitive reaching upwards of 80 feet into the sky to maximize light gathering. An estimate by scientists who research solar radiation suggests Pando’s land mass receives enough sunlight to power 210 homes a day.
If I had to water Pando, how much water would I need?
Quick estimate: 8.46 Million Gallons every three weeks
The Math
As a gardener’s rule of thumb, you should give a mature tree about 10 gallons of water for each inch of diameter of the trunk. Since Pando has around 47,000 branches (trunks, see above), each of which can reach up to 36 inches in diameter, we are talking about a lot of water.
47,000 Branches x 18 inches (conservative diameter of a mature tree) X 10 gallons
=8,460,000 gallons of water every three weeks.
Fun Fact
Pando is so large that a single inch of rain falling on its landmass equals 2 million gallons of water!
If Pando needs that much water, where is it getting it from?
Natural Springs, snow melt and summer rain. Pando lives along the lower edges of the Fish Lake Basin, a steep, high-mountain watershed that feeds Fish Lake. Fish Lake spans nearly 6 miles and reaches depths of 120 feet. We know 70% of Fish Lake is fed by springs. While we still have much to learn about hydrology in Pando, it is arguable, Pando is getting most of its water from below ground, as all the water that collects in the basin soaks into the ground and moves downward toward Fish Lake.
What kinds of diseases would I have to treat if I had to take care of Pando?
Pando like all aspen trees, is prone to bacterial, fungal and insect-borne diseases. We still have a lot to learn about diseases in Pando and the role they play in its health.
How drought tolerant is Pando?
Aspen are drought tolerant. We know from historical records that Pando has survived droughts that have spanned decades or centuries at a time. What’s more, Pando’s homeland along the lower edge of a large watershed probably gives Pando an advantage during dry spells.
Reproduction
How does Pando reproduce?
Pando self-propagates from suckering, a hormonal process.
How Suckering Works: When the growth hormone cytokinins build up along the edge of a root, they spur the creation of a ramet. If conditions are right, the ramet will send up a new stem called a “sucker”. Given time to grow, that sucker will mature and the roots of that branch will also spread outward so that the process can begin again.
Is there a limit to how long Pando can re-produce by suckering?
None that we know of today. Each new stem that becomes a branch or trunk of the Pando Tree can send out roots that will repeat the process indefinitely as long as the tree remains healthy.
Does Pando makes seeds?
Pando is male, and so, only produces pollen. It can (and likely has) mated with female aspen in its homeland, meaning Pando could have sons and daughters in the Fish Lake Basin.
Environment
Is Pando's land mass all just the Pando tree?
Generally speaking, yes. Other trees can take up inside Pando, including Spruce, Juniper Bushes, and other non-Pando Aspen Trees. Generally, other trees don’t tend to do well within Pando’s landmass because Pando dominates gathering of available water, nutrients and sunshine.
Can Pando survive a wildfire?
Aspen, including Pando, are tolerant of low-to-medium intensity ground fires as their branches hold enormous amounts of water while the crowns reach high into the sky. In some cases, fire is used to help stimulate regeneration.
If a fire was hot enough to burn Pando down, would that be the end of Pando?
No. The growth hormones that spurs regeneration is concentrated in the root of the Pando Tree and distributed across the uncountable nodes of the root network. If a branch (trunk) is burned, cut or knocked over, the hormone balance in the roots shifts–starting the process of regeneration all over again. You may be surprised to learn that fire has been used to purposefully shift the hormone balance to spur regeneration.
Animal Interaction
I've heard that deer are a problem in Pando, help me understand...?
The problem with deer and elk is their preference for eating the stems of new growth and sometimes nibbling on old growth. When animals eat new growth, it hinders Pando’s ability to keep energy production and regeneration in balance. When deer or elk eat at the bark of mature trees, it can create pathways for diseases and other animals to destroy healthy branches (trunks).
How do we keep Deer out of Pando?
Wildlife Control and a lot of it. Today, the Forest Service uses about 16,000 feet of 8-foot tall fencing to keep deer and elk from destroying Pando. Today, that wildlife control encloses some 80 acres of the tree and is regularly monitored and maintained by Friends of Pando, Fishlake National Forestry and the Utah Division of Wildlife Resources.
Friends of Pando also gathers wildlfie data and uses that control populations and shape their behavior moving them around Pando. Since 2023, Friends of Pando and our partners at Utah Division of Wildlife Resources and Fishlake National Forest—have worked to move animals around, and reshape their habitual use of Pando’s landmass.
Are all Deer and Elk bad?
No. Deer and Elk play a role in the nutrient cycle and have been part of Pando’s ecology since its birth. Pando’s homeland is an high desert oasis which attracts animals from all around—as it is the largest freshwater source in the region. Our role is to shape their relationship to the tree, and limit the damage they can do as we estimate a Mule deer can eat 262 baby stems if that is all it eats in order to meet it nutritional needs.
What about Cattle Grazing?
Cattle Grazing and has never been allowed inside fenced in areas of Pando dating back to the 2010’s. Cattle Grazing of all kinds, ended in Pando’s landmass in 2024. Friends of Pando and local grazer groups collaborate on work to care for the tree, and worked together to secure support for the Pando Protection plan built in 2025 which brought 80% of the tree into protective care.
Would introducing Wolves help manage Deer and Elk Populations?
In short, no. While wolves have been successfully introduced in wilderness areas to help keep Deer and Elk populations in check in places such as Yellowstone, Pando’s homeland is an oasis that has been used by humans and animals for some 10,000 years. In short, there is no way to bring wolves and make them stay. What’s more, both humans and animals both rely on the waters of Fish Lake to sustain themselves.
Could Hunting of Deer and Elk help Pando?
Possibly. Pando’s homeland is a high desert oasis which features ample water, forage and cover for thosuands of animals. While hunting would not control the large numbers of Deer and Elk that come through, it could help deter them by making Pando’s landmass uncomfortable. The challenges with hunting today, are three fold.
- First, Pando’s homeland is and oasis—animals come year-round while hunting is only allowed a few weeks a year. So, we likely wouldn’t be able to hunt enough animals to have an impact.
- Second, Pando’s homeland was set aside for recreation in 1976, meaning it contains and is close to facilities where we have lots of human activity, making hunting unsafe and potentially cruel for hunters, humans and animals alike.
- Third, some argue, Deer, Elk and other wildlife are part of what makes Pando’s homeland beautiful, many would rather see animals than not.
Friends of Pando and our partners continue to work on methods and models that make the Pando Tree uncomfortable for animals and explore practical models to re-introduce hunting, but this work is expected to take years or even decades.
