When you think of an aspen tree, you are most likely thinking of a tall, white-barked, slender tree that has golden-yellow leaves in the fall. This is a Quaking Aspen. But did you know there is another, less-well-known aspen tree growing in North America?
The quaking aspen and bigtooth aspen are the two types of aspen trees found in North America. There are a few ways to tell these trees apart, including the shape of their leaves, the bark color and texture, the height of the trees, and where they are found in North America.
Aspen trees are beautiful to see and are quite unique because they can clone themselves. Read on to discover the 9 differences between bigtooth aspens and quaking aspens.
Are Aspens And Quaking Aspens The Same?
There are six species of aspen trees, but only two are found in North America. The quaking aspen and the bigtooth aspen. These trees are very closely related to poplar trees, both of which are part of the genus Populus.
Aspen trees are only differentiated from poplar trees by their scientific classification. Even then, the lines become a little blurred. Although grey poplar and white poplar are different species, they are still part of the Populus genus and are even classified in the same section as aspen trees.
So, are aspens and quaking aspens the same thing? Yes! It is similar to asking if a grey wolf is a wolf… yes, of course! But a grey wolf is a species of wolf, just like quaking aspen is a species of aspen.
Zooming out further, aspen trees are part of the willow tree family. These include willows, poplars, aspens, and cottonwoods.
Aspens are deciduous trees, meaning they lose their leaves in the fall. According to Bryce Canyon National Park Service, the aspen flowering season is in May and June, but aspen tree seeds rarely successfully establish themselves. Instead, they reproduce by cloning themselves.
Wait, what? Don’t worry, more on that later…
First, let’s check out the major differences between bigtooth aspens and quaking aspens. We’ll also go over how these trees are similar.
9 Differences Between Aspen And Quaking Aspen
The differences between trees may not be as obvious as the differences in animals. But if you look closely, you can see subtle differences that will clue you into what type of aspen tree you are looking at!
Along with the descriptions below, you can use something like Mark Mikolas’s Beginner’s Guide to Recognizing Trees of the Northeast. This can further aid you in your quest to differentiate one aspen from another.
With location maps for each species and over 400 pictures, you are sure to recognize more of the trees around you!
|Heart-shaped with small, jagged teeth on the outer rim
|Heart-shaped with large jagged teeth on the outer rim. Larger leaves than quaking aspen
|White to yellowish/grey-white
|Olive green to brownish green
|3-18 inches in diameter
|8-10 inches in diameter
|All across Canada & Alaska, Northeast & Northcentral U.S. with some patches in the west
|Southeast Canada & Northeast/Northcentral U.S.
|Mountainous regions up to 11,500’ elevation
|Gently sloping terrain, sandy loam, up to 3,000’ elevation
|Catkins; dispersal is approximately May-June. Usually before bigtooth aspens
|Catkins; dispersal is approximately May-June. Typically 1-3 weeks after quaking aspen dispersal
|50 years for individuals
|60-70 years for individuals
|Quaking - named for the way the leaves appear to quake/tremble in the slightest breeze
|Bigtooth - named for the tooth-like serrations on the leaves
Aspen & Quaking Aspen Leaf Difference
The first difference we’ll look at is the leaves of the tree. You’ll have to look close in the spring, summer, and early fall to use this to differentiate. Both quaking and bigtooth aspen are deciduous trees, so they will not have leaves in the winter.
According to NCR Forest Management, both trembling aspen and bigtooth aspen have heart-shaped leaves that are green in the spring and yellow, golden, or (more rarely) red, in the fall.
The biggest difference will be in the outer edges of the leaves. Quaking aspens will appear smooth but have small jagged edges. Bigtooth aspen will have much more pronounced edges, hence the name ‘bigtooth’ aspen.
Another difference in the leaves is the size. Bigtooth aspen leaves are bigger than quaking aspens, reaching up to five inches in diameter while quaking aspens are only two to three.
Aspen & Quaking Aspen Bark Difference
Using bark to tell the difference between trees is a great tool to have in the winter when it’s impossible to see the leaves because, well, they’re all on the ground!
The bark of quaking aspen is typically white with black scars running along the width of it. These scars are where lower branches were naturally self-pruned while growing.
The bark of bigtooth aspen is more of a greenish color, according to the Maine Forest Service, but smooth in appearance except in older trees. Older trees may have furrows in the bark, especially at the base of the tree.
The bark of both the bigtooth and the quaking aspen has a remarkable property – they can photosynthesize in the winter! While most other trees are being lazy and dormant during the winter, aspen trees are still hard at work, growing and producing sugars and carbohydrates!
This is possible because the bark is so thin on aspen trees. Beneath this thin layer is a green layer that is filled with chloroplasts needed for photosynthesis.
Aspen & Quaking Aspen Height Difference
Aspens are medium-sized trees. They’re certainly not grouped with giant sequoias, but neither are they secluded to small, shrub-sized trees.
That being said, quaking and bigtooth aspens differ in the final height they will reach at maturity. In general, both trees are considered fast growers, especially because of their ability to continue growing in winter.
Quaking aspens can reach a height of up to 80 feet but typically range somewhere between 20 and 80 feet. Bigtooth aspens also max out around 80 feet, but they are often taller, averaging around 60 to 80 feet.
Aspen & Quaking Aspen Width Difference
As with height, the diameter of quaking and bigtooth aspens differ slightly, giving you a good indication if you are unable to identify the leaves.
Quaking aspens are usually 3-18 inches in diameter according to the U.S. Forest Service. Bigtooth aspens average 8-10 inches.
So, while bigtooth aspens are generally taller than quaking aspens, they are usually thinner around the middle.
Aspen & Quaking Aspen Common Range
Quaking aspens are widely distributed in the United States. In fact, they are the most predominant deciduous tree in North America!
In terms of range, quaking aspens are found throughout Canada and into Alaska. They can be found as far south as Mexico, but the largest continuous stands are found in the northeast and the north-central regions of the U.S.
Patchy areas in the west can be found, especially in Utah and Colorado.
The bigtooth aspen is less widely distributed than the quaking aspen. They are found primarily in the northeast and north-central United States. You can find them in southeast Canada as well.
In areas where quaking aspen and bigtooth aspen coexist, they often grow near each other or in the same stand.
Aspen & Quaking Aspen Preferred Environmental Conditions
Some things that affect a tree’s ability to grow include PH, precipitation, and soil type. For aspens, they’re like coyotes and will thrive almost anywhere!
Bigtooth aspens prefer gently rolling hills, floodplains, sandy areas, and the bottom of upland slopes. But really, they’ve been found in almost every soil type and condition. They have a soil PH limit of 4.0, which is pretty acidic!
These aspens are found at lower elevations than quaking aspens, typically thriving at elevations lower than 3,000 feet, according to the USDA Fire Effects Information System.
Quaking aspens are more at home in the mountains. They prefer mountainsides, mesas, plateaus, and can be found at the bottom of valleys and canyons. You might spot one up to 11,500 feet, which is why a lot of leaf peepers love to go to the Colorado mountains to see the aspens change!
In terms of soil, quaking aspens also like sandy conditions, but will thrive in shallow and rocky terrain as well.
Both quaking and bigtooth aspens need moist, well-drained soil to thrive and expand their root systems. Both trees are shade-intolerant, although bigtooth aspens can tolerate shade better than quaking aspens.
Aspen & Quaking Aspen Seed Dispersal
Both quaking and bigtooth aspens are dioecious. Soooo what does that mean? All dioecious means is that there are distinct male and female trees, similar to how boxelder trees are.
Flowering for quaking and bigtooth aspens begins around March-April. The bigtooth aspen has a shorter duration of active flowering than the quaking aspen, and seed dispersal happens up to 3 weeks after the quaking aspen disperses its seeds.
The fruits of both trees are called catkins. These catkins contain pear-shaped seeds with white tufts. Each tree can produce up to 1.5 million seeds per season!
Believe it or not, almost none of these seeds will turn into full-grown aspens. Conditions have to be perfect for an aspen seedling to grow, and these conditions are rarely met. This is mainly because of the tree’s extreme intolerance to shade. It often gets overshadowed by larger trees or saplings.
Aspen & Quaking Aspen Average Longevity
Aspens are not long-lived trees. Unlike the mighty oak, which some species can live for centuries, aspens rarely live beyond 100 years.
According to the National Wildlife Federation, quaking aspens typically live for about 50 years. Bigtooth aspens average 60-70 years before they begin deteriorating.
Most tree deterioration is caused by fungus rot or pests such as gypsy moths. Quaking aspens are more susceptible to disease and pests than bigtooth aspens.
Aspen & Quaking Aspen Name Differences
This difference is a bit of a cheap shot, but names are important!
Populus tremuloides, the quaking aspen, is so named because of the way its leaves flutter with the slightest breeze.
This is because the leaves are attached to branches by a thing called a petiole that is long and flat. This petiole allows the leaves to swivel even with the lightest touch of wind. Hence the name quaking or trembling aspen.
The bigtooth aspen is named after the large tooth-like serrations that are found on the leaves. The bigtooth aspen also has petioles that allow the leaves to swivel in the wind, but it’s not as impressive as on the quaking aspen.
What’s So Special About Quaking Aspens?
Everyone seems to make a fuss over these trees. Is it their leaves? Their stark white bark? What’s so special about quaking aspens?
Probably the most unique feature of quaking aspens is Pando. Pando means “I spread” in Latin and refers to the largest organism on earth – a stand of quaking aspen trees!
I’m sure you have a lot of questions bursting at this point: how can an aspen tree be bigger than a whale, for starters.
A single aspen tree is not bigger than a whale, but aspen trees have a unique way of reproducing called suckering. When a stump or root system dies, new stems can grow from them through a unique process done only by aspen and some poplar trees.
The most interesting part? These new stems that eventually grow into new trees are a clone of the original tree. This means these clones are identical to the parent trees in terms of genetic makeup.
Meaning…it’s all one organism! Pando is still being argued over in the scientific community, as a few people aren’t willing to call the cloned trees part of the same organism, but still. It’s pretty amazing, right?
Pando weighs in at about 13 million pounds and covers 106 acres. It came from a single male aspen tree, but now contains over 40,000 individual trees! Pando is located in Fishlake National Forest in central Utah.
Because of this amazing ability to clone itself, quaking aspens are often the first trees to reestablish after disasters like flooding and forest fires. Once the fires or floods have raged through, fresh shoots will develop quickly from the dead stumps or dying root systems.
This is true for areas that have been affected by mining as well. As long as the parent tree is still present, aspens will flourish in the area! Although, after 30-40 years, they will begin being out-competed by taller trees that cast shade on the aspens, killing them off.
Wrapping Things Up!
That’s all we have for now on aspen trees! To recap, there are two types of aspen trees in North America: Quaking aspens and bigtooth aspens.
Quaking aspens are the most widespread and well-known aspens, distinguished by their white bark and small, heart-shaped leaves. Bigtooth aspens have greenish bark with bigger, jagged-edged leaves.
Both trees can clone themselves through suckering, but if not, they can produce millions of seeds each year to establish new trees.
All in all, aspens are pretty unique and are beautiful to see in the fall when their leaves turn golden yellow. They are a keystone species, and many plants and animals would be out of home and shelter if not for the mighty aspen stands!
Campbell, R. B., & Bartos, D. L. (2001). Aspen Ecosystems: Objectives for Sustaining Biodiversity [USDA Forest Service Proceedings] [P299-305]. https://www.fs.fed.us/rm/pubs/rmrs_p018/rmrs_p018_299_310.pdf
Davis, D. D., & Frontz, T. M. (2003). Growth and mortality of bigtooth aspen trees stressed by defoliation [General Technical Report]. North Central Research Station. https://www.fs.usda.gov/treesearch/pubs/15850
Painter, L. E., Beschta, R. L., Larsen, E. J., & Ripple, W. J. (2015, January 01). Recovering aspen follow changing elk dynamics in Yellowstone: evidence of a trophic cascade? Ecology, 96(1), 252-263.
Shepperd, Wayne D.; Binkley, Dan; Bartos, Dale L.; Stohlgren, Thomas J.; and Eskew, Lane G., compilers. 2001. Sustaining Aspen in Western Landscapes: Symposium Proceedings; 13–15 June 2000; Grand Junction, CO. Proceedings RMRS-P-18. Fort Collins, CO: U.S. Department of Agriculture, Forest Service, Rocky Mountain Research Station. 460 p
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