Everything You Wanted to Know about the Aspen Tree

By Kim Cassels   •   September 18, 2023

Everything You Wanted to Know about the Aspen Tree

Fall Aspen Leaves Outside Durango - San Juan Skyway - Mild to Wild

So, you’re looking for some cold hard facts about the aspen tree. Well, you’ve come to the right shady corner of the internet friend. That’s a pun on trees, in case you’ve got the wrong idea about that quality double entendre. 

Aspens, the quaking aspens of this particular discussion (genus matters when we’re talking flora people!), are splattered across the American West. When autumn hits the alpine each year, they have a tendency to steal the show on account of their obnoxiously glimmering shades of sunshine. 

So to the eager leafers out there who may have stumbled upon this tribute, and anyone else in their right mind who’s curious about this fascinating tree— Read on to learn about where aspens come from, how they’re doing lately, and why they’re always staring. Along with plenty of other info you’re definitely going to want (need) on Tree Trivia Night. 

trail through a dense aspen stand - Mild to Wild

The Aspen’s Contribution to Ancient Cultures 

Headache? BO? VD? Aspen’s got you covered. 

Indigenous peoples of North America had a number of uses for the handy aspen, many of them being medicinal and still in practice today. The Blackfeet Tribe would brew fresh aspen buds into a sweet smelling tea, which can then be used as droplets for the eyes when they’re inflamed, or for long term use to ward off blindness, per Galileo. It can also be used as perfume!

Utes used aspens to retell significant events by carving scenes into the bark. As for their medicinal uses of the bark itself, it can act similarly to aspirin due to its related compounds to treat pain and inflammation, per Colorado Encyclopedia.

The aspen also helped the Nuche and other original peoples with a swath of health conditions ranging from heart complications, venereal diseases, to common colds and tummy aches. 

Across the pond, Gaelic and Celts had a number of jobs for the aspen, including shields, oars and paddles, splints for busted bones, and flame retardant below the floorboards of homes, per Trees for Life

Hand showing the white chalky residue on aspen bark - Mild to Wild

Uses of the Aspen 

Beyond an enjoyable, elongated, leaf peeping stare.

Other than making alpine landscapes as splendid as tree huggingly possible, you can use aspen for a number of purposes beyond its commercialized products like toothpicks, matches, chopsticks and saunas, per Colorado Encyclopedia


Aspens are covered in a powdery film that forms from the bark shedding old cells, per University of Colorado Boulder. It’s safe to use on skin as sun protection if you’re in a pinch.  

Fire Starter

Aspen wood tends to burn way too quickly to keep a fire going. But because its fibers aren’t as dense, the bark is porous, and the internal tissue is gaseous, they burn quickly and easily. 


The chalky residue on aspen bark is chock full of yeast, enough to actually make bread with! Per Survival University

A nutritious snack

The internal layer of aspens is where the tree contains its own food source, aka cambium. You can peel off the outer bark and eat the stored sugars inside, which are green and stringy like spaghetti. While bitter, it’s sweet enough to stomach as Indigenous tribes would use it in cakes and syrups, per Colorado Encyclopedia

A burned trunk in a green aspen meadow - Mild to Wild

How to Grow a Quaking Aspen

Just add water! And fire! And avalanches! And… 

Like the grand redwoods of California, quaking aspens can only thrive when fire gussies up the soil with sweet, sweet ash. Ironically, they’re also very easily killed by fires, per Colorado State. Rest assured the relationship between aspens and wildfire is quite healthy, as an entire stand can reestablish itself within 20 years. 

Aspens like disturbed areas in general. They often go for openings created by avalanches, mudslides, and other situations that stuff nutrients right back into the dirt, per Nature. So essentially, if you knock an aspen down, it will get back up again, ain’t nothing—not even a natural disaster— gonna keep it down. Once established, aspens often live up to 150 years old, per Colorado State

Unlike the redwoods, aspens need between 6,500 and 11,500 feet of elevation to sprout. Every once in a while the tree can grow up to a whopping 80 feet high, but typically maxes out around 35 to 50 feet. Aspens are also quite thirsty and needy for sunshine, making it pretty competitive with its neighbors. At least the next door conifers are typically sturdy and stubborn. 

Although aspens have quite the checklist for where they choose to settle down, you’ll find them surprisingly all the way down to Mexico and over in China, but only at high altitudes. These factors have made it the only native, widespread tree in Colorado, per Colorado State Forest Service

medium shot of cabin centered in the woods with green foliage surrounding it

How old is the Aspen Tree? 

Old enough to tell you what to do. 

It is difficult to know how old the aspen exactly is. A study published in Frontiers states that members of the Salicaceae family may have started budding somewhere around present day Norway after a mass extinction 66 million years ago. 

You know, the one that annihilated the dinosaurs and 75% of Earth’s other species. The aspens said bring it on, asteroid! Or some form of them, and in the proverbial sense.  

In fact, the article proposes that climate change around 27 million years ago may have helped plants in general diversify into the beauties we know them as today. So in short, we don’t really know how old the aspen is, but probably a few million years. Give or take.  

Aspen Stands are Clones

And they’re coming for your meadows. 

It all starts with one aspen, man. Which occurs when aspens find an ideal spot to survive, nixing the need to do all the laborious work of reproduction. As roots begin to spread from one mighty seedling, new sprouts will germinate along them about two feet below the soil’s surface. This period of asexuality begins around two years old for an aspen. 

Somewhere around 80,000 years ago (a very approximate guess, per Nature) in a big beautiful field where we now call Utah’s Fishlake National Forest, one aspen found THE spot of spots to propagate an army of one.  

Millennium after millennium, this swath of clones arose so victorious, they collectively weigh 13 millions pounds today. Or about 32 blue whales if that’s easier to visualize. The organism, known as Pando the Giant (meaning “I spread”), is the largest and oldest on the planet. Pando covers 106 acres with around 40,000 trees in its fleet, per the US Forest Service

Fall La Plata Jeep Tour - Durango Jeep Tour - Mild to Wild

It’s a Willow Tree

Totally serious. Kind of.  

As many of us tend to exclaim into a gorgeous mountain meadow on occasion; “Who are you and where did you come from, aspen?!” The answer is quite surprising. So hold onto your hats folks because… The aspen is in the Salicaceae family, aka the Willow Family! 

We know, we know, all this time you thought the aspen was really just a birch tree with a bougie name. But they aren’t even in the same family. Aspen bark doesn’t peel like birch, their leaves are different, and each tree only produces one sex while birches can produce both, per Black Hills Badlands

But how can this be possible when they don’t even weep, they quake? You ask with righteous indignation. Well, the qualifications to be included as a Salicaceae member are pretty widespread, considering they cover a solid swath of the Northern Hemisphere. But in short, what makes a tree willow-related is usually its simplistic leaf patterns and clusters of single sex, petal-less flowers, per Britannica

A Legend of Why the Aspen Quakes  

One that would leave you quaking too. 

If you’ve ever strolled through an aspen grove, it’s pretty obvious where the quake in their name comes from. The music of these fluttering leaves has long been a source of enchantment and story of ancient peoples. 

The Blackfeet Tribe, who thrived among the central plains of North America before moving into today’s Montana and western Rockies, hold an intriguing legend for why these trees shiver even at the slightest breeze.  

It starts with the demigod, Napi, aka the “Old Man” who created the land on Earth along with the plants, animals and people in it, per First People. Out of respect for the Creator, the forests would bow to Napi on his walks each day. 

The aspens decided they were tired of this tradition, and collectively agreed to stand tall the next time he came through the forest. So when Napi came along on his usual stroll and noticed the aspens’ bad behavior, he summoned a fury of lightning bolts striking straight for the grove. The aspens understandably trembled in fear, and to this day can’t help but shiver when they hear someone coming down the trail, per Galileo

Green forest floor of an aspen grove - Mild to Wild

Their Essential Role in Biodiversity 

Cue the birdsong! 

This goes for aspens all over the Northern Hemisphere. These trees provide a number of opportunities for other species to thrive that many others can’t. Like the optimal conditions for various grasses, fungi, and mosses to grow. This in turn attracts a number of salad and bug-loving animals in and around the stands, per the National Wildlife Federation

A wide variety of bird species love aspens for nesting and pecking, including woodpeckers, bluebirds, ruffed grouse, sapsuckers and more, per Pacific Forest Trust. On the mammal side, elk, deer and porcupines tend to find the trees themselves just as delectable, which is a bit of a conundrum when it comes to the health and longevity of these forests. Beavers also like to capitalize the groves, and other than Douglas-fir bark beetles, tend to be the only threat to downing fully mature aspens. Other than humans, cough cough.

Aspens trees surrounding Lake Eileen near Vallecito, Colorado - Mild to Wild

The Aspen Tree may be Dying Breed

Thanks, climate change.

The Significant Aspen Decline, aka SAD (astutely named because it very much is), began occurring across the central West in 2004. Two years before, Colorado experienced its most extreme “global-change-type drought” on record. The rapid death of aspens that followed has a strong association to event, particularly across the Western Slope, per USDA Forest Service

It also doesn’t help that young aspen sprouts are a staple in grazing animal diets. AND that they’re super susceptible to damage and disease from aphids and tree beetles. Even Pando the Giant is experiencing the affects of the decline.

The study predicts that with the ongoing trend of less rain and snowfall combined with hotter temperatures, Colorado and the surrounding states won’t be hospitable for aspens by 2060, Colorado State Forest Service

In the meantime, researchers are monitoring the continued decline of aspen stands across the region. They may plan to intervene by providing more resources for the trees to thrive, like water and controlled fires. 

close up of aspen trunks showing the eye design in their white bark - Mild to Wild

Why do Aspens Have Eyes?

And they’re all on you. 

If you’ve ever met an aspen, chances are you’ve made eye contact with at least a few of its pupils. The reason why aspens have this unique and uncanny pattern is from a process of self-pruning, per Northern Woodlands. Because aspens are always competing for sunlight, the bottom branches often get left behind in the shade. 

Once the leaves can’t thoroughly photosynthesize, the tree will stop sending its delicious and nutritious sap to those branches. The branches then die and fall off, leaving behind the perfect peeper shape behind.  

View of Engineer Mountain from Old Lime Creek Road - Mild to Wild

Wondering where to enjoy aspen trees in all their quaking glory? For some of the most spectacular fall colors, head to alpine areas between 8,000 – 11,000 feet between late September and mid-October. Many folks are partial to Colorado for good reason, on account of the spectacular routes between fourteen-thousand-foot peaks, like the Million Dollar Highway between Durango and Silverton.

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