The Quaking Aspen is a delight of color, movement and sound. It is a fast growing tree with striking, iconic white bark. In Autumn, its stunning yellow foliage brightens the landscape and has found its way onto many a calendar page and magazine cover. The slightest breeze will cause the leaves of this tree to tremble or “quake”, thus the name.
- ABOUT THE AUTHOR
- Quaking aspen
- How to Prune Quaking Aspen
- Forests on the Fringe
- Case Study: The Glorious, Golden, and Gigantic Quaking Aspen
- Quaking Aspen
The leaves are eaten by snowshoe hare, deer, and elk. It’s also is an important food supply and building material for beaver and grouse depend on the buds for winter food. It’s also a host to a wide range of birds and butterflies.
Among the trees, the Quaking Aspen has several amazing claims to fame! First, it has the widest natural range of any tree in North America, spanning 47 degrees of latitude (equal to half the distance from the equator to the North Pole), 110 degrees of longitude (nine time zones) and elevations from sea level to timberline. It also holds the amazing title of being the largest living organism! The reason is that aspens grow in stands (called clones) and reproduce primarily by sending up sprouts from their roots. This means that virtually all the trees in a clone are connected. One clone in Utah was observed to have 47,000 stems. It’s estimated that this interlinked organism weighs 6,000 tons. While individual aspen trees live a vigorous 100-150 years, a clone in Minnesota has been estimated to be 8,000 years old, making it one of the oldest living things on earth!
ABOUT THE AUTHOR
FEATURE — The Utah state tree since 2014 is the quaking aspen, one of North America’s most beautiful trees with its white peeling trunks, smooth spade-shaped leaves that tremble in the wind and turn brilliant yellow in the fall. This popular poplar stands no chance of extinction for its fierce self-propagation, a quality that makes the aspen resilient but difficult to manage in a controlled landscape – difficult but not impossible.
A Utah State University Extension horticulturist outlined tips in an article released this week that can help homeowners and landscapers incorporate aspens into non-native environments and even keep them healthy and happy with care.
This photo shows part of the Pando clone of aspen all sourcing from one root system. When scientists discovered it they named it Pando for the Latin word meaning “I spread.” An aspen clone starts with a single seed and spreads by sending up new shoots, or suckers, as the root system continues to expand. These shoots become trees that are genetically identical.
Pando is located in Fishlake National Forest and is believed to be the largest organism ever found weighing nearly 13 million pounds, according to the Forest Service, and spreading over 106 acres with more than 40,000 individual trees. Fishlake National Forest, Utah, date not specified | Photo by J Zapell courtesy of the U.S. Forest Service; St. George News
Naturally, aspens grow on moist uplands, dry mountainsides, high plateaus, mesas, avalanche chutes, talus, parklands, gentle slopes near valley bottoms, alluvial terraces and along watercourses, according to Utah State University Extension’s webpage on the quaking aspen. It is most common at elevations between 6,000 and 10,000 feet.
Aspens grow in clones from a single root system, a quality that inspired a group of fourth grade students at Monroe Elementary in Sevier County to suggest the Legislature substitute the aspen as its official state tree. The students said the aspen “reminds them of Utah where we all work together to reach new heights,” according to Utah Online Library.
That strong root system also appealed to Sen. Ralph Okerlund, the Library states, because of Utah’s emphasis on family history and genealogy.
Okerlund took the idea to the state Capitol and by May 2014, the quaking aspen had been named the new official tree of Utah with Gov. Gary Herbert signing the legislation before Monroe Elementary students that March. According to the Online Library, the governor used a chair, desk and 13 pens all made of quaking aspen during the signing ceremony.
The oldest known clone of aspens is known as Trembling Giant or Pando, which is Latin for “I spread.” It is located 1 mile southwest of Fish Lake on state Highway 25 in Fishlake National Forest north of Bryce Canyon National Park in central Utah. The National Park Service and others say the Pando clone is 80,000 years old.
When planted outside its native habitat, however, the aspen often struggles and has a much shorter life span – anywhere from five to 15 years – according to the article by horticulturist Taun Beddes released by USU Extension. The shortened life span of aspens in non-native growing environments is often because of insect and disease problems, he said, and nutrient deficiencies from stress.
Nonetheless, Beddes suggests it is possible to plant and enjoy aspens in home landscapes even if only to be enjoyed for the trees’ shorter lifetime.
Following are tips the USU Extension horticulturist offers for keeping aspens healthy and happy at home:
Surface roots and suckers
Aspens form surface roots and primarily propagate by sending out root suckers that form new trees connected to the mother plant (these create the clones in native habitats). This quality can make mowing around them difficult so planning your planting of aspens ought take this propensity for suckers into consideration.
To contain roots, one possible solution Beddes offers is to surround the rootball of newly planted trees with a cement or rust-proof metal ring 3 to 4 feet beyond the root system and about 2 feet deep.
Another possible solution to the root and sucker problem is the use of products such as Sucker Stopper. Spray the product on newly cut suckers to slow or prevent sucker formation from the spot where it is sprayed. This control method is not perfect, however, Beddes said, and is only good for one season. The spray can cost $20 to $60 per bottle, depending on the concentration.
Aspens do not usually grow large enough to damage foundations or cement due to their short lifespan outside their native habitat.
Landscaping with aspens
Even with their limitations, aspen can still be used in moderation in controlled landscapes if managed properly.
It is important to plant trees in a location where suckering will not be a problem such as landscape beds that are well away from turf areas.
Aspens can be enjoyed as long as they are healthy, Beddes said, and then cut down when they begin to decline.
Younger trees, formed by root suckers, will quickly mature and sustain the stand. If wanted, the young trees should be watered to a depth of 2 feet every two to four weeks.
Beddes does not recommend overly treating the trees with chemicals when problems occur regularly. Homeowners can easily spend more money on pesticides, she said, than the purchase price of a replacement tree.
Columnar Swedish aspen
Columnar Swedish aspen is similar to America’s native species but taller and narrower when mature. It is relatively new to the landscape, Beddes said in his article, and seems to send fewer root suckers. However, it is still susceptible to pests and diseases like the native aspen and can decline rather quickly.
Alternatives to aspens
Trees Beddes suggests as replacements for aspen include chanticleer/Cleveland pear, Queen Elizabeth maple, Tatarian maple, black alder, various crabapples and Sargent cherry.
The alternatives don’t look exactly like aspens, he said, but have their own ornamental qualities and are usually much less susceptible to pests and diseases. And, they live much longer.
- Utah State University Extension Horticulturist Taun Beddes: Email [email protected] | telephone 801-851-8465
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Twitter: @JoyceKuzmanic @STGnews
Copyright St. George News, SaintGeorgeUtah.com LLC, 2016, all rights reserved.
Joyce Kuzmanic has been editor in chief of St. George News since 2012, having contributed as a reporter and assistant editor since the publication’s inception in 2010. Before St. George News, Joyce has been a private business owner and enjoyed a long career as a paralegal in real estate, business and tax law transactions. She enjoys hospitality, thinking, reading and adventuring in the great outdoors. Joyce currently resides in St. George with her husband and her dog, Scratch.
Tree & Plant Care
Best planted in moist soils in full sun. Intolerant of shade conditions.
Roots tend to sucker freely.
Does not tolerate summer heat or pollution.
Disease, pests, and problems
Numerous disease and pest problems if not sited correctly, Tree prefers cool summer climates.
Native geographic location and habitat
Native to northern portion of North America
Bark color and texture
Young trees have a grayish-white, smooth bark.
Stems are a slender, reddish brown.
On older trees bark is grayish white, furrowed, with darker areas.
Leaf or needle arrangement, size, shape, and texture
Alternate leaf arrangement, simple, 1 to 3 inches wide, oval to nearly round, with finely serrated margins.
Light green, smooth leaf turns a bright yellow in the fall.
Flattened leaf petioles allow the leaves to tremble in the wind creating a rustling sound.
Flower arrangement, shape, and size
Dioecious. Male and female trees separate. Flowers are dangling catkins that appear before the leaves.
Not ornamentally important.
Fruit, cone, nut, and seed descriptions
Fruit is a drooping cluster of capsules containing many seeds.
Cultivars and their differences
Prairie Gold® Quaking Aspen (Populus tremuloides ‘NE Arb’): This cultivar is more tolerant of the heat, drought and humidity found in the Midwest; golden yellow fall color.
How to Prune Quaking Aspen
Quaking aspen is known for smooth white bark that scars black, and heart shaped leaves with fine, saw-toothed markings. These leaves are attached to the tree with a long, flat stem. Because of this, the slightest breeze will cause the leaves to flutter, making the whole tree seem to shiver. It’s this distinctive characteristic that gives a quaking aspen it’s name. Quaking aspens grow in large colonies with a single root system, and can tolerate any soil. Pruning should only be undertaken to maintain the aspen’s shape and health or to remove branches for safety.
Wait until winter to prune your aspen tree. Trees that are pruned in the summer months are more prone to diseases. In winter months, the pruning wound will “scab over” and heal, without leaving the tree open to pests and disease.
Pinch young aspen shoots to shape them early in the growing process. Shaping aspens when they are young may prevent the need for serious pruning later on. Never pinch the topmost branches of an aspen. Topping, tipping or shearing an aspen tree creates an unnatural shape and may cause diseases later in the aspen’s life.
Sterilize your pruning saw with methanol to prune an established aspen tree. The recommended method for pruning an aspen is to thin it by cutting branches back to the trunk of a tree. Thinning the tree will help it to maintain shape and improve air circulation through the branches to prevent fungus from growing.
Decide which branches that you will remove with respect to the scarring pattern that you will leave behind, since each branch that is removed from an aspen will leave a black scar on the trunk.
Cut your branches with angular cuts that begin just outside of the bark ridge and angle down and away from the stem of the tree. Avoid injuring the bark ridge or branch collar. Always cut branches cleanly, without tearing.
Remove any diseased branches. Re-sterilize your saw with methanol after cutting each branch to prevent spreading infection.
Fall in Colorado ushers in a show that locals await breathlessly, when quaking aspens spangle our dark, conifer- cloaked mountainsides with gold.
This slender member of the poplar family, a North American jewel and icon of the Rocky Mountains, teases the eye with pockets of brilliant color tucked here and there before bursting across the mountains in a last hurrah to summer sun. But if you’ve re-created a slice of the Rockies by planting aspen in your own yard, though, be prepared to give them some tender loving care.
Aspen thrive in higher elevations. Plunked into our harsh lowland landscapes, heat and compacted soils can take their toll, setting up aspen for a host of troubles. For this tree, keeping its conditions ideal is your goal.Aspen do best in slightly moist soils with reduced soil compaction —away from the traffic of feet, paws, or tires. Berms that raise the tree provide deep soil for its roots (and make less desirable footpaths for wayward humans and pets).
If your aspen is in a lawn, keep it safe from the dreaded mower and its kin, the weed whacker. Damage to aspen trunks from clumsy lawn care is a common entryway for disease.
Tuck your tree in with a ring of mulch that extends from a few inches away from the trunk to several feet out.
Water aspen weekly in summer with irrigation that’s slow enough to sink deep into the soil. In dry winters, water once per month on days when temperatures are warmer than 45 degrees and there’s no snow on the ground.
Aspen benefit from spring fertilization, but newly planted aspen have sensitive roots, so wait until the tree establishes itself before fertilizing (remember this rule of thumb: each inch of trunk circumference equals a year that it will take roots to establish).
The thing to remember about aspen is this: They want to be a grove.
They can’t help themselves. They’ll send tiny sprouts from their roots springing up through the lawn. Mow these shoots regularly to keep your turf from becoming a forest. Because these sprouts arise from the roots, avoid chemical weed killers.
Online: Where to go leaf-peeping this fall denverpost.com/travel
Aspen’s least-wanted list
Here’s how to watch your aspen for the tree’s five most common disorders — and how to fight them if they show up.
• Iron chlorosis.This disorder occurs when aspen trees can’t take up iron from the soil to make chlorophyll. It appears as yellowing leaves with green veins. Drought, root stress and compacted soils aggravate this disorder, which can become severe enough to kill the tree. Applications of chelated iron into the soil, trunk injections, or foliar sprays of iron may help, along with reducing traffic under the tree and making sure it has proper irrigation.
• Cytospora. Stressed aspen often fall prey to cytospora, a canker-causing fungus that attacks trunks or branches. Entering the tree through wounds, cytospora creates long, oozing, orange cankers that stain the white bark. Stress reduction is key: The trees can live with cytospora if they’re watered properly and the infested branches are pruned off.
• Marssonina leaf blight. In spring, the fungal spores of this disorder spread from the leaf debris of the previous year. When temperatures warm, the fungus shows up on leaves as yellow-ringed dark spots that gradually enlarge and merge together. Infested leaves are shed, and though the tree can take some defoliation like this, extreme cases can make it susceptible to other problems. So clean up leaves in the fall to remove the problem, use drip irrigation, and keep trees spaced well apart for good air circulation.
• Oystershell scale. This sap-sucking insect (Lepidosaphes ulmi)
moves about as a crawler on trunks or branches, then settles, dropping its legs in exchange for a hard, protective shell. It kills the area on which it feeds. Control it with crawler sprays, insecticidal soap, or oils in late May. Or you can lightly scrape them off with a plastic dish pad in April. If you’re scraping, go gently, you’d don’t want to flay the bark from the tree.
• Poplar Twiggal Fly. If your aspen has lumpy twigs, it’s being visited by the Poplar Twiggall Fly (Hexomyza schineri). These small, dark flies insert eggs in spring into soft new twigs. There, its larvae grow, protected from harm by the woody gall formed around them. The little maggots don’t harm the tree, though many homeowners find the swollen galls unattractive. Learn to live with them: Insecticides aren’t very effective, and pruning the affected twigs out won’t control the bug. Just let the flies’ natural enemies (mainly birds and parasitic wasps) do the trick. — Carol O’Meara
Click on image to enlarge
black cottonwood (Populus trichocarpa)
(click on each photo to enlarge image)
Size: Grows to 200′ tall and 6′ in diameter.
Leaves: Simple, alternate, deciduous. Triangular; 3″-6″ long (but sometimes much larger); green above and white below, often with rusty markings. Margins are smooth or with rounded teeth.
Fruit: Round capsules on a string; contain numerous tiny cottony seeds.
Twigs: Stout. Terminal buds are cigar-shaped, sticky, and smelly.
Bark: Smooth and gray on young trees. Furrowed and ridged on mature trees.
Distribution: Black cottonwoods are found from southeast Alaska into Baja California and from the Pacific to the Dakotas. But for much of its range, it only grows along rivers and streams, avoiding the hot, dry territory they travel through.
quaking aspen (Populus tremuloides)
(click on each photo to enlarge image)
Size: Small tree growing to 80′ tall and 2′ in diameter. Short lived.
Leaves: Simple, alternate, deciduous. Ovate to round; 2″-3″ in diameter; green above and paler below; edges smooth or with rounded teeth. Petioles long and flat.
Fruit: Cone-shaped capsule with cottony seeds.
Bark: Greenish-white when young. May turn dark and furrowed with age.
Distribution: quaking aspen grows in more states than any other tree. However it is only found in scattered areas of Oregon. It occurs in our upper Cascades and eastward.
For more information about these species see “Trees to Know in Oregon”.
Forests on the Fringe
Throughout its history, Missouri has been known as a border state. It is a place where north meets south, and east meets west. It is also where the forests of each of these regions come together.
Missouri lies at the western fringe of the central hardwoods, a transition zone between forest and tallgrass prairie. This makes for a diverse and complex landscape. Trees typical of Ozark and Appalachian forests grow in north Missouri woodlots, while islands of tallgrass prairie are found deep in the Ozark hills.
Stretching from the Appalachian Mountains to the Great Plains, the central hardwood forest blankets the nation’s mid-section. It is one of the largest forested areas in the country, and it contains a great diversity of plants and animals. This diversity includes more than 70 hardwood trees, several conifers and many shrubs and plants. The great richness of plants and animals is the result of the wide diversity of soils, geology, geography and climate in the region.
Other boundaries also put Missouri’s forests on the fringe. Glaciers advanced about as far south as the Missouri River during the last ice age. They scoured north Missouri flat and left behind a thick layer of glacial till. Plants retreated ahead of the glacier to sanctuaries in the Ozarks, where some remain even today. In the southeast corner of the state, the Ozarks drop abruptly into the Bootheel and the lush, alluvial land of the Mississippi River. With different geographic and climatic regions pushing against it, Missouri serves as a haven for a variety of plants and animals from all sides.
If you were to drive from the northwest corner to the southeast corner of the state, you would get a sense of the richness of our forests and the variety of life they support.
Geologically speaking, North Missouri was covered by glaciers in recent times. About 500,000 years ago, the Kansan glaciers retreated, leaving a layer of soil and rock several hundred feet deep. In presettlement times, we think the region’s vegetation consisted of upland and bottomland prairies with relatively large tracts of forest in the river bottoms and steep side slopes. This vegetative pattern still holds true today, except much of the prairie and bottomland forest is now agricultural land.
Bur oak is more prevalent in northwest Missouri than white oak, but white oak is more common over the rest of the state. Bur oak’s thicker bark makes it more resistant to the prairie fires that helped shape this region’s landscape. Although eastern redcedar is found here, it is not as invasive in old fields and abused woodlots as honey locust, elm and Osage-orange.
Those who look for the blooming of flowering dogwood as the harbinger of spring will be disappointed. It doesn’t grow in northwest Missouri. Neither does sassafras. Taking their place in the forest understory are pawpaw and eastern hophornbeam, also called ironwood. In some places they can grow so thick they shade out oak and hickory seedlings.
A few tree species are unique to north Missouri. Quaking aspen, northern pin oak, rock elm and bigtooth aspen can all be found here, but are more common in forests farther to the north. Perhaps after the glaciers retreated, these species found some Missouri sites to their liking, or they may be slowly migrating back north.
Heading southeast from the glaciated plains, the next natural feature a traveler would encounter is what is commonly called the river hills. The River Hills are the bluffs and steep hills along the Missouri and Mississippi rivers. An unusual characteristic of the River Hills is the loess soils. These windblown soils formed after the last ice age and have the remarkable ability to erode into nearly vertical slopes. Loess hills are best developed along the Missouri River from the Iowa line to Kansas City, but loess soils are found along most of the length of the Missouri and Mississippi.
These soils are rich, but because they’re too steep to be farmed, they grow a wide variety of trees. Many species of oaks and hickories are found here, as well as ash, sugar maple, walnut, cherry and elm. This variety of trees, along with the beauty of the river bluffs, makes the river hills a favorite place to view fall color.
After crossing the Missouri River, you are in the Ozarks. This region makes up about half the state and is roughly bounded by a line from St. Louis to Boonville to Springfield and Joplin. It is the most complex region of the state, geologically, topographically and botanically. Ancient volcanoes, caves, springs, sinkholes, steep hills and swift rivers all contribute to this complexity.
Oaks and hickories are abundant here. Missouri is home to 21 different species of oak and eight species of hickory, nearly all of which are native to the Ozarks. White, black and northern red oak, as well as shagbark and mockernut hickory, are common on better soils. Post and blackjack oak, and black and pignut hickory, are found on dry sites. Several southern oaks are at the northern extent of their range in the Ozarks. Southern red oak, swamp chestnut oak, water oak, Nuttall oak and willow oak are more common in the forests of the southern United States.
Shortleaf pine, Missouri’s only native pine, grows in the Ozarks. It once dominated much more of the Ozark landscape than it does today. The appeal of quick profits from milling the big pines attracted eastern lumbermen to the Ozarks in the late 19th century. The pine was cut for building material and the oak for railroad ties. By the 1920s, most of the Ozarks had been cut over. Past land practices of livestock grazing and wildfires prevented shortleaf pine from regenerating, and oak took its place. Today we know that certain sites where oak is found today should be returned to pine to improve the health of the forest.
Missouri probably has more glades than any other state, and most of these glades are found in the Ozarks. Glade comes from the Old English “glad,” meaning a shining place, which a glade may seem to someone after a long hike in the woods. Glades are areas of thin soil and exposed bedrock. They are usually found on steep south- and west-facing slopes. The plants growing on glades must endure environmental extremes, from heat and frost heaving to drought and soil saturation.
The plant community found on glades is similar to that of prairies. Stunted trees of winged elm, redcedar, post oak, blackjack oak and sumac may be found on the edges of glades. Glade openings grow or shrink depending on precipitation cycles. During a wet cycle, openings shrink as trees invade. During droughts, glades get larger as trees unable to survive on the drier soil die.
The Ozarks are home to dogwood, blackgum, serviceberry, walnut, white ash, sassafras, scarlet oak, mulberry and sugar and red maple-just to name a few. These are familiar trees, but the Ozarks also contain some unusual trees that are more common in other states.
In southwest Missouri, several tree species reach into the state from Texas and Oklahoma. Smoketree, Ashe juniper, fringe tree and yellowwood are found only in the White River drainage. Western soapberry and Ozark chinkapin are native only to the southwest corner of the state. Osage-orange, now found in nearly every part of the state, is thought to be originally from Texas and Oklahoma. It was brought to Missouri by American Indians for use in bow making. In southeast Missouri, Ozark witchhazel is known only from the St. Francois Mountain region.
Not long after dropping off the Ozark Plateau in southeast Missouri, you will cross a low ridge. After driving through the steep hills of the Ozarks, it is hardly cause to slow down. However, Crowley’s Ridge is a unique land feature in the Bootheel, a remnant from the time when the Mississippi River followed a different channel. Evidence indicates that the Mississippi River flowed on the west side of Crowley’s Ridge until recently in geologic terms, when the channel of the river changed to its present course on the east side of the ridge.
The vegetation supports this theory. Some of the species found on Crowley’s Ridge and the rim of the Ozark Plateau are at the western limit of their range. Trees that seem more at home in the southern Appalachians are found here, including tulip-poplar, sweetgum, American holly, American beech and cucumbertree.
East of Crowley’s Ridge are Missouri’s southeast lowlands and the head of the Mississippi Embayment. This is the warmest and wettest part of the state. The flat, alluvial plain was formed by the river. Most of the region was originally forested with a dense growth of deciduous trees, many of which are typical of the Gulf Coastal Plain. The trees were cleared and the swamps drained to make the Bootheel one of the state’s richest agricultural areas. A glimpse of the original Bootheel landscape can still be seen at Allred Lake Natural Area, Mingo National Wildlife Refuge, Big Oak Tree State Park and Donaldson Point Conservation Area.
Many of the trees that grow here, such as cottonwood, sycamore, willow, green ash, silver maple, hackberry, box-elder and elm, are the same species found in bottomland forests throughout the state. However, some trees found in the Bootheel are found nowhere else in Missouri.
Small differences in elevation determine which trees grow where. Completely different species will grow on “ridges” that are only one or two feet higher than the surrounding land. In the permanently wet swamps, the dominant trees and shrubs are baldcypress, water tupelo, water locust, swamp cottonwood, buttonbush and corkwood. The low flats next to backwater sloughs support water hickory, pumpkin ash, Nuttall oak and overcup oak. On higher ground where soil drainage is better, sweetgum, swamp chestnut oak, willow oak and cherrybark oak are found. Swamps are complex places with a great variety of plants, each finding its own niche in the ecosystem.
Across Missouri, you’ll find many interesting niches harboring a diversity of tree and plant life. Missouri allows you to enjoy forests from other parts of the country without leaving the borders of the state.
The rain fell harder against the window as that girl returned to her older self, almost thirty years later, crying because it couldn’t be real, crying because she knew it was, crying because more would come, so many memories tucked away into the sinews of her body. So many dark rooms tucked away within her life.
I jogged the last quarter mile to the car, tried not to look at the drawn curtains of the camper, backed up a little too fast in the gravel lot, and returned to town.
• • •
For the first fifteen years of my life I didn’t know my mother had been sexually abused by her father. To me, her habits were like the stars in the sky, their patterns self-evident: she often read during the two hours before dawn, often slept on the couch, often gasped when woken, often flinched if you came up behind her. I didn’t know why. I never imagined that “why” was a question to be asked. Instead, I learned to balance risk and reward when I flailed up from my own nightmares, learned to weigh seriously each decision to pad down the hall to the other bedroom, where my father slept too heavy to be stirred and my mother too lightly to be comfortable. “Mom,” I would whisper at the side of the bed. “Mom. Mom,” as I reached hesitant fingers to her wrist, barely brushing skin before the hand shot up to shield the face suddenly alert and contorted, a soundless scream.
Without realizing what I was doing, I arranged the oddities around me into normalcy, my brain automatically correcting a world that would have otherwise appeared upside down. I learned to navigate by an incomplete set of stars, assumed my mother had nightmares the way I had nightmares, the same way we both had light brown hair and big, angular ears. I used her bad nights to explain my own, found comfort in the explanation, believed I was following her down life’s trail.
And then one afternoon in late summer, she asked my sister and me to take a seat on the living room couch, with a stiff formality neither of us were used to. As we perched on the cushions, she sat across from us in her great-grandmother’s rocking chair. I watched the water build in her eyes. I do not remember what sentence she used, “My father used to sexually assault me”; “My father was sexually abusive”; “My father raped me.” I knew the words but couldn’t understand them. I cried only because she did. Beside me on the couch, Sara did, too. “This has already happened,” Mom told us. “It’s just that now you know. Now you know why I don’t sleep. Now you know what my nightmares are. Now you know who your grandfather was.” A world upended. Nothing changed but everything different.
• • •
The second morning of my search, I drove to the eastern trailhead before the sun had cleared the ridge, frost casting the ground in metal tones. As I hiked down among the fescue fields, grasshoppers leapt from my boot steps as if I were splashing through a pool of bright green bodies. The ice on bluestem glistened.
Looking across the meadow, I noticed a row of pale, straight trunks to my right, their leaves already brown but almost the same shape as the one in my photo. I scrabbled down into an empty streambed, grabbed hold of a vine, and earned eight parallel scratches from wrist to thumb, the red looking bright among all the grays. I made it to the trees, but the curled leaves I found beneath were too triangular, the teeth lining their edges too small. I returned to the field to chase down a bunch of sycamores, then an unfamiliar type of birch, then some cottonwood. On and on, zigzagging through the woods.
As the shadows disappeared under the high sun, I hiked along a creek in the deep valley of the preserve, my boots sinking far into the silt, a crow startling each time I rounded a bend, leaping up with its harsh cry to fly farther downstream, ever ahead of me. From the east ridge I’d seen a group of light-gray branches reaching up above the dark mess of forest. Gray was not yellow, but the little hope I had left needed direction to keep burning. I crossed a fork in the stream and found the trees clustered around a giant oak that had fallen across the water. Perching on its moss-covered bench, I ate an apple, and I tried to ignore the fact that their bark was the wrong color, the leaves shaped more like spades than teardrops. I tried to tell myself these were the aspen, that somehow the photographs were wrong, or that I’d misunderstood the online descriptions. My feet ached. The crow cawed somewhere out of sight.
Before the flashbacks began, Mom always believed her love of the trees was intrinsic to her, as close as her green eyes and blond hair, just like I have always known the pleasure I take in rolling their names through my mouth—sycamore—the upward pressure in my chest at the stained-glass light of summer woods, comes from her. Of course, we have always known that our love stems in part from the forester, from the man smoking Winstons in the cab of his truck, but, in the same way that our parents’ noses simply become our noses, we never questioned the origin of our tree love. We never hesitated at this guidepost of who we are. The revelation of the abuse also revealed that this simple love is more complicated than we’d imagined. To the girl my mother once was—wandering the boulder-strewn hills, sitting on the trunk of the bent oak—the shade of the forest felt better than that of the farmhouse. It felt safer, even if she didn’t recognize the feeling at the time.
“I left her out here,” Mom says to me sometimes, meaning the part of herself she forgot for thirty years, that overtakes her in the darkness of her bedroom, the girl with tears beading on her cheeks who never makes a sound. I know a little bit what she means. There is a split between two halves of our lives. Between our lives before we knew, and after, but also, for her, the between the self she carried with her from year to year, and the self her mind buried in its bid to survive, the self she forgot until after her father’s death. So much lost then regained, so much held but already slipping through our fingers.
I finished my apple and looked around. These were not the aspens, not the place my mother had cradled in her mind from her early twenties to now. I tossed the core away, jumped down from the fallen trunk, and walked back upstream the way I had come.
• • •
When Mom told my sister and me, “This has already happened; it’s just that now you know,” she’d meant it as a comfort, a sign that things were not so different. She was trying to imply that we were already living this truth. But of course we weren’t, not really. A few days after Mom told us what her father had done, what he had been, I stood next to her in church and watched her shake, her head whipping back and forth, her arms locked at her sides, as if she was trying to break out of someone’s grip. I had never noticed until that Sunday, even though she told me later it happened almost every week. How many Sundays of my life was that? How many times that I’d sat next to her without noticing?
Across the aisle the family that always sat new from there went on singing, either not noticing or carefully not looking. Beside me, Dad was staring down at his hymnal, mouthing along in his usual pitch-free mumble. Only Sara—standing on Mom’s other side—was also staring, her mouth slightly open, her dark eyes full of all the deep water I was trying to wade out of. She noticed me looking at her, and, for a moment, we stared into each other’s faces, not so much seeing the other person as searching them, fighting for purchase on ground turned to marsh. The hymn carried on without us. Her black eyes looked bottomless. Where were we standing? What was this place? Who were these people? Where was the door, the sun, the way out of this air we were suddenly breathing?
The hymn ended. Mom stilled. Dad reached behind me to rub her shoulder. She patted his hand twice before joining the prayers with the rest of the crowd. Sara and I watched, still silent, still stunned.
When something terrible happens in the present tense—car crash, injury, violence, assault—the main arena of change is the future. Plans interrupted. Relationships altered. A river flowing forward suddenly dammed and forced to change course. As Sara and I stood staring at each other, our gazes empty, our mother reliving her childhood in the space between us, I realized: when the past changes, it takes everything with it.
• • •
As I hiked back to the car—down the riverbed and up the ridge, through the fescue fields—I no longer had an eye for trees. I didn’t want to acknowledge the possibility that I’d missed something on the walk down, and I was too tired to let my return trip take the same meandering path the outbound one had. Batting away the brambles that left my sweater peppered with Velcro seeds, I told myself that I would drive to the last trailhead on the map, hike it, return to my hotel, watch crappy TV, and head home in the morning. Wave the white flag and sound the retreat.
I got back in the car around two-o-clock. Sitting in the driver’s seat, I glowered at the highly minimalist map on the Big Grove brochure, comparing it to the highly uncertain GPS on my phone. I wasn’t at all sure I’d covered even a fraction of the preserve. Throwing the car in reverse, I glanced out the windshield and noticed a slight opening in the trees fifteen feet beyond my right headlight, an opening marked nowhere on my paper and digital guides. I hesitated, wanting nothing more than to drive to the country deli and get a bad sandwich, to hike the northern trail and declare my mission impossible, the trees disappeared or lost, the mirage vanished into fantasy. I wavered. Then sighed. Standing from the car, my map still lying in the passenger’s seat, I let out a long breath and walked past the bright orange blaze into the woods.
• • •
I’ve often asked Mom why she told the story of the aspens so frequently. “I don’t know,” she’d say and shrug. “It just seemed interesting.” That response doesn’t square with the tone of her voice when she tells it, doesn’t square with the decades that she carried that one scrap of lecture with her.
I sometimes wonder if her thirty-year-old self—caught among flashbacks and an unraveling sense of her own past—began telling the story to her children as an act of salvage, the dream of a grove whose comfort was not undergirded by fear. The aspens were trees she could pass on to us without complication, a place where the forester had never ever set foot. “Call me Nancy,” she said in a letter to him a few years after his death, denying him the pet name, “Toots,” he’d called her for her entire life.
As I hiked the unmapped trail into Big Grove, wandering the narrow dirt track deeper into the trees, I knew that for me the aspens had slowly come to symbolize a bit of the past I wasn’t ready to let go, the past before I knew how much we’d already lost. Hickory, walnut, redbud, willow—my mantra steadies me less with rough hands all mixed up in it. The tree names of Missouri, even of the Ohio woods where I grew up, come from the forester. Our very words, our very landscape begins to bend.
“I was having a memory,” Mom will say, part of our code, our way of shielding ourselves from the air we walk through. Memory means flashback. Tired is when the memories loom up, threatening to grab her. Shaky is the final precursor. Laying down means jumping into the jaws of the past, letting it have her.
“I’ve already lived through this,” she tells herself on the bad days, the days she spends in bed while everyone else tiptoes on the floor above. When Dad moves around the basement, getting ready for work in the early morning, he taps the walls as he walks, making himself a constant presence on her radar, because if someone walks up behind her that she doesn’t know is there, the surprise can make her collapse to the floor, where she lies fully conscious but unable to command her own muscles. “He scared me,” she says. When that happens, laughter is the most reliable cure. Some of the family’s favorite jokes are the punch lines that woke her from paralysis. We repeat them at the dinner table. They pepper our long-distance phone conversations. This is our way of treading lightly, of acknowledging the uncertain ground we walk on while carrying on our way.
• • •
The trail wound down through stands of oak and pine along a west-facing slope before curving across the stream to climb toward the preserve’s farthest edge. What would Mom’s younger self have thought if she’d come here, I wondered, walking through the trees in search of the grove thought lost. I used to think that longing for the time before I knew—before Mom asked Sara and me to take a seat on the couch, before tree names came with bruises—was a sign of weakness, a nostalgia for a past that never actually existed, the childish part of me wanting to hide from ugly truths that had always been there. But to deny that longing—to deny the past I lived, Mom lived, Sara lived—is to reduce everything we are to the ashes of a fire set by Ambrose’s hands. “We are not that,” I grunted as I walked higher and higher up the ridge, the trail turning from gravel to sand beneath my boots. I know it is important not to let ourselves die beneath the weight of what we learned. The father, childhood, life, and self that Mom knew before the flashbacks was not false, simply partial.
A bright, yellow leaf lay between my boot tips. I started, pulled the folded photograph out of my pocket and laid it on the dirt. The two glowed beside each other, the charm and its fulfillment. I bent and picked up one in each hand, holding them up to the trees around me. The leaf was a smooth, unbruised yellow, without the black spots of decay or pinpricks of insect bites. It hadn’t been lying on the path very long, had probably fallen earlier that day. Which way was the wind blowing? I stared around, searching, walking. I came to the top of the ridge, and there they were, a cluster of pale yellow trunks standing crisp against the autumn sky. I left the trail, wading through wintercreeper and multiflora rose until I could put both hands against their bark, could string my body between two trees and breathe the space between them.
The grove in Mom’s story is more than a grove: beneath the ground the trees have woven a connected floor of roots, the same organism, the same DNA, sharing water and food amongst its many selves. Aspens are particular in how they grow. They can reproduce from seeds like other trees, but a single tree can also send its roots far around itself, growing clones in the sunshine it finds nearby, saplings to replace the older trees that died and fell, blackened at their broken tips. The trees of my mother’s story are not separate any more than the five fingers of my hand, and to sit among them is to sit within a single, living organism, a room growing within the forest, a womb.
I set my pack down and lay with my back against it, watching the tips of the trees shuddering against the bright atmosphere, imagining their roots coiling beneath me. The rangers say it’s possible that these trees never belonged here, that my mother’s story—a past in which aspens grew more commonly in Missouri, but slowly died back, leaving this southern island—is only one theory among several. In other forests they have found similar, isolated groves: a stand of persimmons not native to the area, a pair of magnolias on the bank of a lake, a sudden field of Calgary pear. Near some of those trees they found broken rectangles of stacked stone, iron nails, bits of rust, evidence of a homesteader who came to this territory centuries ago, built a house, planted trees to shade her door and block the wind, to keep a little scrap of whatever home she’d come from, to hold on. No one has found such clues near my mother’s aspens, but that gives little proof in either direction. It’s possible there was once a home here, its histories forgotten or only imagined, possible that four walls and a roof have been replaced by a loose arrangement of trunks waving pale fingers in the blue sky.
Case Study: The Glorious, Golden, and Gigantic Quaking Aspen
Populus tremuloides, the quaking aspen of the North American continent, stands as one of the most easily recognized, most beautiful and most admired of all tree species. In order to help appreciate this magnificent species, we here highlight some of its key biological attributes.
Perhaps most impressively, along with its very similar sister species of European and Asian distribution — the Eurasian aspen (Populus tremula) — these two species occupy the broadest range of any tree species in the world. Why is that so?
Quaking aspen can be found from Alaska to Mexico and from Vancouver to Maine (Jones et al. 1985; Mitton & Grant 1996). In the north-central part of the continent, quaking aspen occurs at almost any elevation, while in the southern part of the US and in Mexico, it tends to be found only at higher elevations. A similar distribution pattern exists for Populus tremula in Europe and Asia. Admirers frequently note the striking white bark of quaking aspen. This bark lives and carries out photosynthesis, attributes that make it unique among North American trees and likely contribute to its impressive geographic range (Figure 1).
Figure 1: Living bark The white bark is living tissue, unique among North American trees.
Aspen drops its leaves in winter but, of course, remains alive and thus requires metabolic energy. The soft tan to greenish hues often visible in aspen bark mark an important photosynthetic capability provided by the differing levels of chloroplasts. Stem photosynthesis contributes significantly to aspen’s over-wintering survival capabilities (Bervieller et al. 2007; Foote et al. 1978; Knowlton et al. 1976). The disadvantages of this type of bark include low fire resistance, ease with which people carve their initials in it and attractiveness as a food source for elk, numerous insects and fungi.
Aspen form individual patches comprised of numerous stems, termed ramets, each with its own trunk, branches, leaves and a shared root system (Figure 2). All of these structures arose from a single aspen seed, often in the very distant past; while these patches remain connected via root systems, they comprise a single clone. If the root system between patches is severed, the patches form physiologically separate entitites but are generally still considered part of the same clone given that they are composed of genetically identical patches and parts, having been produced vegetatively. The boundaries of different clones stand out most clearly in the early spring when flowering and leafing-out occur (in that order). Aspen occur as males and females separately (dioecious), unlike the majority of tree species, which support both male and female reproductive parts on each individual (monoecious or hermaphroditic).
Figure 2: Aspen asexual and sexual reproduction
In early spring, an aspen clone will produce small, inconspicuous strings of reproductive parts called catkins, which are either male and produce pollen or female and produce eggs. Huge numbers of viable, tiny seeds mature and float off from the female on a tangle of cotton-like seed hairs that catch air currents, sometimes traveling great distances. Immediately after shedding their pollen and seeds, the clones then produce leaves that usually appear at the same time in all stems of a given clone. This time of the spring is when the boundaries of aspen clones stand out most visibly and reliably.
However, most aspen watchers tend to focus on the brilliant colors of aspen in the late fall prior to dropping their leaves (Figure 3). The dramatic visual show in the Rocky Mountains attracts many “leaf peepers” who find the brilliant gold, yellow, rose and even red leaf colors especially striking set against the dark green of their evergreen neighbors. But these color patches do not mark clonal boundaries as reliably as does leafing in the early spring because the chemical processes that produce the colors tend to be very sensitive to local micro-climate conditions such as aspect (whether north or south facing), soil moisture, etc. (personal observations). A single clone may exhibit multiple colors simultaneously. In aspen, all the pigments that give rise to these glorious colors can be found in the leaf from spring all the way through fall (see here). As summer begins to end and overnight temperatures drop, the aspen begin to first break down the green chlorophyll molecules that dominate the spring through summer color. The other pigment molecules — there all summer — then become more and more visible. This process reveals the golds, yellows and reds allowing aspen to really show their stuff until their leaves drop (Vogel 1993).
Figure 3: September colors Numerous aspen clones are embedded in a lodgepole pine forest in Colorado.
For many years, most western forest ecologists thought aspen reproduction from seeds was so rare as to warrant a publication of a single found seedling (Ellison 1943). However, it turns out that successful establishment of aspen via seeds occurs more frequently than previously thought (Mock et al. 2008). The ability of aspen to produce whole stands of “trees” vegetatively provides yet another key element in explaining the species’ ability to occupy huge geographic ranges.
There are several benefits of asexual expansion — spreading via roots which then send up shoots. As is true of other species of vegetatively-spreading plants (DeByle 1964; de Kroon & van Groenendael 1997; Jónsdóttir & Watson, 1997), one part of a clone might be near an important water source and thus “share” that water with parts of the clone (i.e., the other ramets in the clone) while those in a drier area may have greater access to a vital soil nutrient (e.g., phosphorous) that can also be distributed around the clone (Hansen & Dickson, 1979; Peltzer 2002; Pitelka & Ashmun 1985).
Quaking aspen also tends to be a disturbed habitat species, meaning it often lives where avalanches, mudslides and fires occur frequently. So both the regenerative capability and the clonal reproductive capability allow aspen to initially establish or to re-establish into an area after disturbances occur, especially spectacular ones like the 1988 fires in Yellowstone National Park (Romme et al. 1997). Careful observers of steep mountainous slopes along the Rocky Mountain Cordillera will regularly see avalanche and mudslide tracks populated by young, light-green aspen clones re-colonizing those spaces with shoot densities up to 30,000 per acre (Jones et al. 1985). Similar patterns often follow forest fires. Rarely will a fire burn hot enough to kill the entire root system from which these stems arise, so an individual clone may occupy a given space and be completely wiped out on the surface but re-grow from the root system many times.
Figure 4: Part of Pando There are approximately 47,000 of these ramets (i.e. “trees”) in this single clone. Indeed, one remarkable clone in the Fishlake National Forest named Pando (Latin for “I spread”; Grant 1993) represents the astonishing capabilities of an individual clone to spread itself over a huge area (Barnes 1966, 1975; Grant et al. 1992). Pando covers about 107 acres and contains about 47,000 individual ramets, each complete with stem, branches and leaves (Barnes 1975; Grant et al. 1992; DeWoody et al. 2008). To date, this clone remains the most massive living organism ever reported with an estimated weight of at least 6,600 tons, exceeding that of the famous giant sequoia, General Sherman (Figure 4).
Given its size, it may also be very old, perhaps 80,000 years, but good dating of the time the original, tiny seed germinated and established this clone lies beyond current scientific capabilities. Plausible estimates have been offered ranging from several thousands to a million years in age, although recent molecular work argues that these may be overestimates (Barnes 1975; Mock et al. 2008). Whatever its age, Pando certainly represents one of the most remarkable individuals among all living organisms.
In order to have this single genotype occupy this space for those huge spans of time, the external environment must have had just the right balance of disturbance and stability. If an aspen stand does not experience periodic disturbances such as fire or avalanche, more shade-tolerant conifers tend to establish and shade out the high-light-requiring aspen stems. If the disturbances are too frequent, then the clone could not establish and spread to this extent.
Clone structure varies with geography but also varies due to the strong influences of rainfall and relative humidity. The largest clones generally occur in semi-arid environments such as the mountains of the western and southwestern US. Clones tend to be smaller in areas where the climate supports seed germination and establishment somewhat more readily (e.g., the eastern parts of North America and the upper Midwest).
The last particular attribute of quaking aspen we here highlight as important in contributing to its ability to occupy huge ranges derives from the comparatively high level of genetic variability among clones (Cheliak & Dancik 1982; Kanaga et al. 2008; Madritch et al. 2009; Mock et al. 2008). These interclonal levels of variability provide the raw material for evolutionary change across generational times. The large number of seeds produced from genetically variable sources generates an enormous array of potentially successful genotypes for establishment in newly opened areas and probably takes place at higher rates than previously thought by forest ecologists. These insights derive from the application of modern molecular techniques to quaking aspen in the field.
With only a bit of whimsy, we have saved one of the most obvious attributes for last: Why do quaking aspen leaves quake and tremble? The leaves of this species quake, shake and tremble in the presence of even the slightest breeze due to the physical structure of the leaf stem (petiole) which traces a flat, oblong, elliptical pattern when viewed in cross section (i.e., perpendicular to the stem itself) so it has strength in one dimension (the long part of the ellipsis) and minimal strength in the second dimension (the narrow part of the ellipsis), so even a gentle wind causes shaking, quaking and trembling. We understand this phenomenon very well mechanically, yet a deeper question can be posed: Why does the petiole develop this way? Plant physiologists have pointed out several consequences of the trembling leaf behavior to include minimizing the risk of too much sunlight on the photosynthetic apparatus (photoinhibition), reducing the risk of overheating in intense, high elevation sunlight and improving photosynthetic rates by keeping a fresh supply of carbon dioxide near the leaf surface where the plant takes up that compound. Taking a different approach, one of our students did a small scale independent study several years ago where she identified matched pairs of aspen leaves and stabilized one with tubing to reduce its ability to tremble, then measured the amount of leaf damage due to insects near the end of the summer, comparing the leaves which could tremble with ones that could not. She found the insect damage to the ‘fixed’ leaves was, on average, about 27% higher in the stabilized members of the pairs.
This tree species seems to almost have it all: powerful, opportunistic, sexual reproduction, long-distance seed dispersal, effective vegetative spread, clonal reproduction, regeneration from roots, high levels of genetic variability, living bark and a potentially enormous life span.
We anticipate that this glorious, golden, and gigantic species will provide great pleasure for future admirers of its beauty as well as revealing a rich trove of scientific insights as we learn from its enormously successful colonization of a huge geographic range.
Populus tremuloides Michx.
Scientific Name Synonyms:
another synonym goes here additional information
Life Span: Perennial
Growth Characteristics: Aspen is an attractive deciduous tree, growing up to 40 feet tall. The trunk is generally long and slender, but can be up to nearly 3 feet in diameter. It flowers April to June, and fruits ripen May to July. The tree grows rapidly from basal sprouts and root sprouts. It seldom reproduces from seeds.
Flowers/Inflorescence: Inflorescence is a catkin.
Fruits/Seeds: Fruit is tufted capsules borne in catkins. Range in color from light green to brown. The seeds have very specific conditions needed to germinate, and therefore, under current climatic conditions, seldom produce aspen seedlings that survive.
Leaves: Aspen has alternate leaves, the blades being highly variable, from oval to broadly oval, the top of the leaf coming to a point or being rounded, and the base being round to square. The margins are serrated, with the teeth being mostly rounded. The upper surface of the leaf is dark green with a prominent white midvein. The underside of the leaf is pale green. The petiole is flattened and as long as the leaf. This petiole allows the leaves to “quake” in the wind, hence the name “quakie.” The leaves change from green to bright yellow or yellowish-orange in the fall.
Stems: Twigs are slender, reddish-brown to gray. The trunk bark is thin, smooth, and chalky white. The bark becomes darker and breaks into blocks or plates with age or damage (i.e. fire, carving).
Quaking aspen occurs on a wide variety of sites. It grows on moist uplands, dry mountainsides, high plateaus, mesas, avalanche chutes, talus, parklands, gentle slopes near valley bottoms, alluvial terraces, and along watercourses. It is most common at elevations between 6,000 and 10,000 feet. Most of the reproduction of Aspen is by root-sprouting, many trees in a grove being connected together by a common root system in what are referred to as “clones.” Because the trees are in clones, they are genetically identical. This species is not shade tolerant, and entire clones can be lost due to the encroachment of spruce and fir into this type of ecosystem. Aspen is dependant on fire, clear cutting, or other “clearing” disturbance to keep stands open, free of conifers, and reproducing from suckers.
Soils: Quaking aspen grows on soils ranging from shallow and rocky to deep loamy sands and heavy clays. Good quaking aspen sites are usually well-drained, loamy, and high in organic matter and nutrients.
Associated Species: Mountian brome, snowberry, blue wildrye, larkspur, waterleaf, Rocky Mountain maple, and chokecherry.
Uses and Management:
Aspen’s main uses in Utah have been for fence poles and buildings, and as firewood. Some trees have been sawed into lumber or pulp. Recently, it has been used for paneling.
Aspen is good to excellent forage for sheep, and fair for cattle. The twigs, bark, and buds are browsed by wildlife and birds eat the seeds. Grazing of aspen sprouts, especially by cattle and elk, is a growing concern in the maintenance of aspen stands.
Wild and domestic ungulates use quaking aspen for summer shade. Seral quaking aspen communities provide excellent hiding cover for moose, elk, and deer. Deer use quaking aspen stands for fawning grounds.
Well-stocked quaking aspen stands provide excellent watershed protection. The trees, the shrub and herbaceous understories, and the litter of quaking aspen stands provide nearly 100 percent soil cover. Soil cover and the intermixture of herbaceous and woody roots protect soil except during very intense rains. Quaking aspen intercepts less snow and transpires less water than conifers, so snowpack and runoff is greater under quaking aspen.
Quaking aspen is valued for its aesthetic qualities at all times of the year. The yellow, orange, and red foliage of autumn particularly enhances recreational value of quaking aspen sites.
The bark of quaking aspen was used by pioneers and American Indians as a fever remedy, as well as for scurvy. It contains salicin (similar to the active ingredient in aspirin). A substance similar to turpentine was extracted and used internally as an expectorant and externally as a counterirritant.
Male and female flowers are on separate trees (dioecious) in hanging clusters (catkins) from the leaf axils of 1 year old branches. Male catkins are 1¼ to 3¼ inches long with tiers of red stamens that mature from the bottom up and are mixed with long, silky hairs. Female catkins are 1¼ to 2¼ inches long with red stigmas that are also mixed in with long silky hairs..
Leaves and stems:
Leaves are alternate and simple with a flat leaf stalk that cause leaves to flutter in the slightest breeze. The blade is 1¼ to 3 inches long and similar in width, broadly oval to nearly round, abruptly tapered to a pointed tip, mostly rounded at the base, with very short, rounded teeth all around the edge. New leaves often have very fine, scattered silky hairs, especially along the edges but these are quickly lost. Both leaf surfaces of mature leaves are hairless, the upper surface waxy and dark green, the lower much paler.
New shoots are green and mostly smooth or briefly with very short, fine hairs. Twigs are reddish brown and shiny, the buds slender round and sharply pointed, the lateral buds often with a tip curled into the branch. Bark is thin and smooth, a creamy greenish white to nearly bright white on branches and trunk. Deeply furrowed dark gray bark forms at the base of the trunk on older trees. While Minnesota’s champion tree for this species is nearly 40 inches in diameter at breast height, 24 inches or less is more typical.
The fruits are green, round and conical capsules arranged on the long pendulous catkins. The capsules split into two halves when mature, releasing the cottony seed.
Quaking Aspen is the most abundant and widespread tree in Minnesota today and the most common Populus species in North America. The huge stands across northern Minnesota are the result of clear cutting our expansive pine forests a century ago. A pioneer species, it can spread aggressively via root suckers, eventually producing hundreds—if not thousands—of trees, covering acres, all from a single tree. Fire suppression has also allowed it to expand into historical prairie habitats were subsoil moisture is adequate to sustain it through dry periods. In the winter months its bark could be confused with other Populus species but its small, shiny and hairless buds that are not coated with resin distinguishes it from other similar species.