Types of aspen trees

How Aspens Grow

Quaking Aspen (Populus tremuloides)

Young aspen grove. Photo by Linnea Hanson.

Aspen are medium-sized deciduous trees, commonly 20 to 80 feet in height, and 3 to 18 inches diameter. Trees more than 80 feet tall and larger than 24 inches diameter are occasionally found. Their bark is smooth, greenish-white, yellowish-white, yellowish-gray, or gray to almost white in color. The green color is from chlorophyll in the bark. Their bark may become rough and fissured with age.

Aspen leaves are are thin, firm, and nearly round, 1 1/2 to 3 inches diameter. They are pointed at the apex and rounded at the base, with many small rounded to sharply pointed teeth along their margins. Aspen leaves are smooth, bright green to yellowish-green, dull underneath, until they turn brilliant yellow, gold, orange, or slightly red in the fall. The leave’s small stem (petiole) is flattened along its entire length, perpendicular to the leaf blade. The flattened stem allow the leaves to quake or tremble in the slightest breeze; hence, their name. The leaves of young sucker aspens may be much larger, sometimes 7 to 8 inches long.

Aspen trees usually do not live more than 150 years, though they may persist more than 200 years. It grows on many soil types, especially sandy and gravelly slopes, and is quick to pioneer disturbed sites where there is bare soil. It grows best where soils are moist and sunshine is plentiful. Aspen is intolerant of shade, and does not compete well with more shade-tolerant conifer species.

Quaking aspen is an aggressive pioneer species. It readily colonizes burned areas and can persist even when subjected to frequent fires. In the Central Rocky Mountains, the extensive stands of aspen are usually attributed to repeated wildfires. It may dominate a site until replaced by less fire-enduring but more shade-tolerant conifers.

The southern-most aspen are found in central Mexico. Photo by J. Higginson.

Quaking aspen is the most widely distributed native North American tree species, growing in greatly diverse regions, environments, and communities. It occurs across Canada, through the United States, to Mexico, in a variety of habitats. In the western United States, aspen is generally found at 5,000 to 12,000 feet elevation. Aspen occurs in extensive pure stands in some areas, while in others, it is a minor component of the forest landscape. Most of the aspen forest in the United States is found in Utah and Colorado, though it is also scattered throughout all of the western states.

Aspen provide habitat for a wide variety of wildlife, including hare, moose, black bear, elk, deer, ruffed grouse, migratory birds, and a variety of smaller animals. Aspen stands produce livestock forage, biomass, and are a source for a variety of wood products. Aspens are visually appealing, as they provide contrast to the dark conifers during all seasons; and in the autumn, tourists come to the West to see the brilliant fall colors of the aspen groves.

Aspen Facts

Populus tremuloides, quaking aspen North American distribution map. From Digital Representations of Tree Species Range Maps from “Atlas of United States Trees” by Elbert L. Little, Jr., U.S. Geological Survey.

USDA NRCS PLANTS Database: Populus tremuloides Michx., quaking aspen.

Reproduction

Quaking aspen female catkins. Photo by B. Campbell.

Aspen reproduces both by seeds and by root sprouts, though sprouting is the most common and successful form of reproduction. Aspen produces small flowers, on catkins that are 1-2 inches long. These flowers are produced in the early spring before the leaves grow on the trees. Aspen is dioecious, with male and female flowers normally borne on separate trees. The catkins produce small fruit that split to release lots of tiny, cottony seeds that are dispersed by the wind. Germination occurs within a couple days of dispersal provided the seeds reaches a suitable moist seedbed. Few aspen seedlings survive in nature due to the short time a seed is viable, lack of moisture during seed dispersal, fungi, adverse day/night temperature changes, and unfavorable soil conditions.

Aspen suckers developing from an aspen root. Photo by B. Campbell.

Some of the clones in this picture are dying out in southern Utah. Photo by Linnea Hanson.

Aspen clones in an aspen grove in southern Utah, Fishlake National Forest. Photo by B. Campbell.

Aspen is noted for its ability to regenerate vegetatively by shoots and suckers arising along its long lateral roots. Root sprouting results in many genetically identical trees, in aggregate called a “clone”. All the trees in a clone have identical characteristics and share a root structure. The members of a clone can be distinguished from those of a neighboring clone often by a variety of traits such as leaf shape and size, bark character, branching habit, resistance to disease and air pollution, sex, time of flushing, and autumn leaf color. A clone may turn color earlier or later in the fall or exhibit a different fall color variation than its neighboring aspen clones, thus providing a means to tell them apart. Aspen clones can be less than an acre and up to 100 acres in size. There can be one clone in an aspen grove or there can be many.

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Watch how aspens grow and reproduce by sprouting. Courtesy of D. Bartos.

As aspen stands mature, they may begin to deteriorate as openings in the forest canopy are left by dying trees. Often, in the West, aspen is replaced by conifers in the absence of disturbance. On dryer sites, aspen may revert to rangeland dominated by shrubs, forbs, and grasses. However, root suckering will generally occur in the aspen stands as they deteriorate or as they are disturbed by fire or other events. When an aspen tree dies or as light becomes available from openings, chemical signals from the tree to the roots stimulate new sprouts to start growing. Through this regrowth, an aspen clone usually lives much longer than its individual trees. Even though individual aspen trees are not very old, aspen clones can be hundreds of years old.

The Pando Clone

The Pando Clone, Fishlake National Forest, Utah. Photo by B. Campbell.

Within the Pando Clone, Fishlake National Forest, Utah. Photo by B. Campbell.

Aspens are the largest plant and have a stamp to prove it!

The largest and oldest known aspen clone is the “Pando” clone on the Fishlake National Forest in southern Utah. Also known as the “Trembling Giant”, it is a clonal colony of an individual male quaking aspen determined to be a single living organism by identical genetic markers and believed to have one massive underground root system. It is over 100 acres in size and weighs more than 14 million pounds. That is more than 40 times the weight of the largest animal, a blue whale. It has been aged at 80,000 years, although 5-10,000 year-old clones are more common.

Update (Wikipedia): Pando is currently thought to be dying. Though the exact reasons are not known, it is thought to be a combination of factors including drought, grazing, and fire suppression. The Western Aspen Alliance, a research group at Utah State University’s “S.J. & Jessie E. Quinney College of Natural Resources”, has been studying the tree in an effort to save it. The Forest Service is currently experimenting with several 5-acre sections of it in an effort to find a means to save it.

A study published in October 2018 concludes that Pando has not been growing for the past 30 to 40 years. Human interference was named as the primary cause, with the study specifically citing people allowing cattle and deer populations to thrive, their grazing resulting in fewer saplings and dying trees.

Old aspen trees get sick, weak, and die, or a fire or other disturbance might kill them. Even after they die, they provide homes and food for many small animals. The nutrients from decomposing wood and leaves return to the soil where they are used by the new generation of flowering plants and trees.

Aspens that Quake

Aspen leaves rustle in the wind. Photo by R. Lilly.

Aspen leaves are round with a flat stem. Photo by T. Rickman.

Take some time this year, during the spring, summer, or fall, and visit an aspen stand on one of our western national forests. Find a sunny spot, lay or sit down on the ground and listen to the trees whisper to one another as they make their quaking sound. The soft whispering rustle of a quaking aspen is unlike the sound of any other tree in the forest.

Quaking aspen is America’s liveliest tree. With just the slightest breeze, its round leaves tremble almost incessantly, like thousands of fluttering butterfly wings.

Watch the twinkling of just one leaf. The stem, from one and one-half to three inches long, is flat and turned at right angles with the blade of the leaf. This unique leaf stem allows the leaves of the aspen to quake.

Quaking aspen

(Image credit: Linda & Dr. Dick Buscher)

Quaking aspen (Populus tremuloides) is the most widely dispersed tree in North America. It is found growing across the northern regions of the United States and Canada from the Atlantic to the Pacific Oceans. Groves of quaking aspen trees are also found growing in the high mountains of central Mexico, as well as in mountainous regions as far north as the Arctic Circle.

Shorter days

(Image credit: Linda & Dr. Dick Buscher)

Each autumn, the shortening of the hours of daylight and the return of near freezing weather triggers the breakdown of chlorophyll, the chemical that gives plants their green color. As the green fades, the quaking aspen forests decorate their mountainous landscapes with spectacular displays of shades of yellow with occasional splashes of orange and red.

Standing tall

(Image credit: Linda & Dr. Dick Buscher)

Quaking aspens, with their tall, straight trunks, stand alongside the endless miles of meandering forest roads like sentinels guarding the entrance into a high-mountain magical kingdom.

Golden portrait

(Image credit: Linda & Dr. Dick Buscher)

And when discovered on a prairie at the base of an ancient volcano, a grove of quaking aspen becomes a palette of golden colors upon one of ol’ Jack Frost’s magnificent natural autumn portraits.

Fluttering leaves

(Image credit: Linda & Dr. Dick Buscher)

The name “quaking” comes from the fluttering action of the trees’ heart-shaped leaves when blown by the wind. This fluttering action is caused by the flattened petioles of the leaves. (Petioles are the stalks that attach the leaf blade to the stem.) The yellow-green color of the 1.5- to 3-inch (4- to 7.6-centimeter) leaf surface has an underside color of contrasting silver. The edge of each leaf is finely serrated.

Living high

(Image credit: Linda & Dr. Dick Buscher)

Quaking aspen are members of the willow family, Salicaceae. In the western mountains of the United States quaking aspen grow best at the 5,000- to 12,000-foot (1,500- to 3,700-meter) elevation range. Quaking aspen seldom grow below an elevation of 1,500 feet (460 m) due to the mildness of the winter found at this level. They are a short-lived species, having an average lifespan of 75 to 100 years.

Best of both worlds

(Image credit: Linda & Dr. Dick Buscher)

Quaking aspen trees generally grow to a height of about 50 feet (15 m) with a spreading crown of 25 feet (7.6 m). Larger species known as “old growth aspen” that measure some 100 feet (30.5 m) tall and 3 feet (1 m) in diameter have been found in the Rocky Mountains of Colorado and New Mexico. They are a fast-growing tree that prefers a moist, slightly acidic soil. Quaking aspen grow best when the summers are relatively dry with abundant sunshine and when winters see heavy snowfall that reinvigorate the forest soil, resulting in rapid spring and summer growth.

Smooth operator

(Image credit: Linda & Dr. Dick Buscher)

The bark of the quaking aspen is unique in its smooth texture and light gray or off-white color. Some refer to the color as greenish-white. Shallow furrows that look like horizontal lines often appear. Old aspen often have bark that has split, leaving furrows that are dark gray. Since quaking aspens self-prune their lower branches, eye-shaped black scars are common on the lower trunk.

Unique character

(Image credit: Linda & Dr. Dick Buscher)

There are both male and female aspen trees. During the time that both male and female trees flower, the male anthers and the female stigmas are both reddish in color adding to the unique character of the quaking aspen tree. Seeds are dispersed by the wind and only remain viable for two or three weeks. They require a moist environment and full sunlight to sprout.

Cloning network

(Image credit: Linda & Dr. Dick Buscher)

But most quaking aspen trees reproduce asexually by producing clones of the original tree from an ever-spreading root network. Groves of quaking aspen are really the stems of one of the Earth’s largest living organisms. Thousands of quaking aspen trees that are genetically identical to each other can be joined underground by a single root network that can continue to reproduce and live for hundreds if not thousands of years.

Returning home

(Image credit: Linda & Dr. Dick Buscher)

Because of this root suckering method of reproducing, quaking aspens are often the first to re-establish a forest environment after a forest fire or a man-made forest clearing. As the forest of aspens continues to grow, they begin to provide shade for the forest floor which is necessary for new conifers to sprout. Over time a new conifer forest will grow often replacing the aspen stand.

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It’s hard to decide what is most memorable about aspen: the vibrant yellow in the fall, the tall, tube-like clusters of white stands or the sound of the “quaking” leaves. Regardless of what comes to mind when you think of aspens, they hold the title of the most widespread tree in North America. From the Midwest, across Canada, north into Alaska and across the West through to Arizona and New Mexico, quaking aspens dot the edge of conifer forests in clusters or “clones.”

One aspen tree is actually only a small part of a larger organism. A stand or group of aspen trees is considered a singular organism with the main life force underground in the extensive root system. Before a single aspen trunk appears above the surface, the root system may lie dormant for many years until the conditions are just right, including sufficient sunlight. In a single stand, each tree is a genetic replicate of the other, hence the name a “clone” of aspens used to describe a stand.

Older than the massive Sequoias or the biblical Bristlecone Pines, the oldest known aspen clone has lived more than 80,000 years on Utah’s Fishlake National Forest. Not only is the clone the oldest living organism, weighing in at an estimated 6,600 tons, it is also the heaviest. Even if the trees of a stand are wiped out, it is very difficult to permanently extinguish an aspen’s root system due to the rapid rate in which it reproduces.

Among swaths of dark green conifers, the deciduous aspen stands thrive in a variety of environments. Aspens quickly colonize recently burned or bare areas to establish a stand of young trees given the proper conditions. They prefer moist soil but can survive near springs in desert conditions. Of the many variables for a healthy clone of aspens, the one that cannot waver is the need for abundant sunshine.

Aspens grow all the time—even in winter. Beneath the thin, white outer bark layer is a thin green photosynthetic layer that allows the tree to create sugars and grow when other deciduous trees would otherwise be dormant. During hard winters, the green, sugary layer provides necessary nutrients for deer and elk. Throughout the year, young aspens provide food or a variety of animals including moose, black bear, beaver, porcupine, ruffed grouse and rodents .

Although a soft wood, aspen is relatively strong and has been used in unique ways.

  • Matches – aspen wood is not as flammable as other species
  • Saunas – aspen wood does not splinter easily
  • Chopsticks – aspen is flexible and strong for your next tasty eggroll.
  • Ailments – historically used because aspen contains salicylates, chemicals similar to aspirin

Today, many places in the West have seen diebacks of aspen. In areas where grass is limited, deer and other ungulates are heavily feeding on young aspens, preventing the trees and clone from reaching maturity.

With support from Salt River Project, the National Forest Foundation helped provide fencing around 12 acres of key aspen stands on Arizona’s Kaibab National Forest to prevent elk from eating the trees. In Utah, the NFF brought together various stakeholders to form the Utah Forest Restoration Working Group. The collaborative created the “Guidelines for Aspen Restoration on the National Forests in Utah,” now used to standardize and implement restoration strategies for aspen across the state.

To support healthy trees and healthy forests, donate to the National Forest Foundation today.

Quaking Aspen

Plant Lore:
Aspen are remarkable and unique trees. In fact they are so different that it may be better not to think of aspens as trees. First of all, a stand of aspen is really only one huge organism where the main life force is underground. Think of aspens as large 1-20 acre systems of roots that remain hidden underground until there’s enough sunlight. Then the roots sprout up white things called trunks that then leaf off green things called leaves. This is called “vegetative” or asexual reproduction. Only after severe fire and under ideal climatic conditions, will aspen reproduce sexually as a flowering plant.
With careful inspection, clones can be mapped, as all the trees that sprout from a single clone will have the same branching structure because they are genetically identical to one another. Even easier and more obvious is to watch as aspen forests change color in the fall. Members of different clones will all have the same shade of color transitioning from green to yellow at the same time. By examining this different color patchwork along a mountainside you can distinguish individual clones from each other.
Asexual or vegetative reproduction from root systems offers many benefits including phenomenal longevity. Aspen “clones,” as the individual root systems are called, can live to be thousands of years old. The oldest known clone in existence is called “Pando” and is located in the Fishlake National Forest north of Bryce Canyon National Park in central Utah. It has been aged at 80,000 years! Although 5-10,000 year-old clones are much more common, even these youngsters are much older than Sequoias and even Bristlecone Pines. Current research on fungal mats in Oregon and Creosote Bushes in the Desert Southwest may rival aspen for the title of “Oldest-known Living Thing.”
The other aspect of their lifestyle that makes them unique is that beneath the thin white outer bark is a thin photosynthetic green layer that allows the plant to synthesize sugars and keep growing even during the winter when all other deciduous trees go into dormancy. This green layer of the bark makes it survival food for deer and elk during hard winters.

Of all the native trees in North America, quaking aspen (Populus tremuloides) has the greatest distribution. In grows from northern Alaska to Labrador and south into Mexico. It thrives on a wide variety of sites, from shallow rocky or clay soils to rich, sandy soils. The best growth occurs on soils which are rich and porous, often where lime or limestone is present. In Iowa, quaking aspen is very common in eastern Iowa and found locally in southern and western Iowa along the major river valleys. Because of intensive competition from other species in Iowa, it is most common on dry, upland soils.

Habitat: Grows in open woods and moist prairies or woodland edges. Most often found in the northern half of the state.

Hardiness: Zones 1 through 6


Quaking Aspen Leaves – Photo by Paul Wray, Iowa State University

Growth Rate: Fast

Mature Shape: Narrow to rounded

Height: Mature size varies with species, ranging from 50 feet to 100 feet.

Width: Varies with species.

Site Requirements: Native to North America, aspen trees grow naturally in moist sites and full sun.

Leaves: Alternate, simple, single toothed, and triangle shaped

Flowering Dates: March – May

Seed Dispersal Dates: May – June

Seed Bearing Age: 10- 20 years

Seed Bearing Frequency: Every 4 to 5 years

Seed Stratification: No stratification period is needed.

Quaking Aspen Twig – Photo by Paul Wray, Iowa State University

Aspen leaves are simple, alternate, nearly round in outline, 2 to 3 inches in diameter with a flattened petiole 2 to 3 inches long. The leaf is broadest near the base, has a short pointed tip and is finely toothed along the margin. Winter buds are 1/4 to 1/2 inch long, closely appressed to the twig, each with its lowest bud scale directly lined up with the leaf scar. The bud is shiny dark brown in color and slightly sticky. The bark on young trees is thin, pale-green to creamy white; on older trees it becomes thick, roughened by warty bands, divided into flattened ridges and almost black in color. Twigs are slender, orange to dark brown, with half-round leaf scars with three bundle scars.

Quaking or trembling aspen is a short lived (50 years), fast growing, medium sized tree. It seldom exceeds 60 feet in height and 20 inches in diameter. It is considered a pioneer species; it is often a primary invader of sites which have been cleared or burned. Like most aspens, it reproduces rapidly from root suckers, forming dense stands when cut or harvested.

It has some good ornamental characteristics including trembling leaves, light-colored bark and its adaptation to a wide variety of sites, but its root sprouting habit discourages widespread use for shade or ornamental planting. Quaking aspen does play a very significant role in the lives of many other organisms. Throughout its range, more than 500 species of animals and plants utilize the aspen. Aspens are important browse for many game animals and the seed, buds and catkins are utilized by may birds including quail and grouse.

The wood of quaking aspen is light, soft, weak, light in color and probably of little economic importance in Iowa. In areas where aspen is more abundant, it is used extensively for particleboard, pulp and paper, boxes, crates pallets, and many other products.

Diseases that Can Affect Quaking Aspen

  • Leaf and Shoot Blight

Insects that Can Affect Quaking Aspen

  • Oystershell Scale

Quaking Aspen Flowers – Photos by Paul Wray, Iowa State University

Quaking Aspen Bark – Photos by Paul Wray, Iowa State University

Birch or Aspen trees? Photo via Flickr.

A Birch tree and an Aspen tree look similar, especially during the winter without leaves. Can you tell them apart?

Whenever I go hiking with my family I like to bring along Jake’s Nature Guide: Rocky Mountains to help me identify the common trees. One of the trees that is common and I am familiar with are Aspen trees. However, during the winter when we go hiking it is hard to identify it because the bark of an Aspen tree and a birch tree are similar. Here are some hints to help you tell them apart.

This is a grove of Aspen trees. Note there are no horizontal lines all over the bark, but there are old scars and knots. Photo via Flickr.

Bark of Aspen and Birch Tree

Aspen – the bark is greenish white and smooth. It stays the same white color its entire life.

Birch – the bark of young trees is a chalky white, but as it ages it becomes furrowed and brown.

Peel the bark – The bark of birch trees can easily peel back and off the tree like paper. The bark of Aspen trees does not peel off.

Look at the small horizontal markings all over the trunk of these Birch trees. Photo via Flickr.

Look at the markings on the trunk – Both trees have marks on their trunks, but they differ. Aspens tend to have scars or knots (which look like eyes) on the bark. Birch have more horizontal markings all over the trunk that are not associated with any previous branches or scarring.

Leaves of Aspen and Birch Tree

Aspen – the leaves are heart shaped to rounded and are about 2 to 2 1/2 inches long. They look broader or fatter than Birch leaves. The edges are finely serrated or toothed.

A birch leaf is longer than an Aspen leaf. The edges are more roughly serrated or toothed. Photo via Flickr.

Birch – the leaves are roughly serrated or toothed on the edges and are about 3 inches long in a long pointed shape.

This is an Aspen leaf. Look how broad it is and edges are finely serrated, not like the Birch leaves, which have bigger teeth on the edges of the leaf. Photo via Flickr.

Look at the shape of the leaves – Aspen leaves are shorter and rounder with smooth edges. On the other hand Birch leaves are a bit longer with rough or serrated edges.

Where Do They Grow

Aspen – these are among the most widespread trees, especially in the Rocky Mountains. They grow from low to high elevation and can often be found growing thick in areas after a burn, avalanche, or other disturbance.

Birch – they grow in moist lowland forests and in floodplains. They are generally in northern Idaho and north-eastern Montana.

Where are you – there are no birch trees growing naturally in the lower Rocky Mountains. If you are high up in elevation then it is an Aspen. If you are low down in a floodplain or shady area in the northern Rocky Mountains, then it could be a Birch.

It can be difficult to initially tell apart an Aspen and Birch. But, by following these few pointers I hope that you will be able to figure it out, even during the winter. You can always bring along the great book, Jake’s Nature Guide: Rocky Mountains, on your outings to help you identify the common species of the Rockies.

ANSWER – By the way, the photo of the trees at the top of the page are Birch trees. If you look closely you can see the many, small horizontal lines on the trunks of the trees.

Buy me a cup of coffee?

Aspen trees are a sight to behold with their autumn-turned yellow leaves so let’s take a closer look at the different types of Aspen trees that make a beautiful natural setting.

Aspen trees are a well-known tree type in certain regions of Canada and North America, particularly popular for elevating the appearance of the already naturally beautiful landscapes of these areas. These trees can be identified by their beautiful white bark and autumn-turned yellow colored leaves.

Scientifically speaking, Aspens trees belong to the genus populous, which is the same genus that is shared by tree types such as poplars and cottonwoods. Trees of this particular genus are easily identifiable because of their triangular, toothed leaves.

Furthermore, these trees are known to grow rather quickly, but do not live very long. Once dead, the roots of these dead-looking aspen trees keep on growing out new plants by means of root suckering. Botanists have recently discovered aspen groves sprouting from a basal rootstock dating over 10,000 years old.

Most Aspen trees don’t live longer than 5-15 years after which their roots start developing new aspen sprouts. These new suckers often grow into large trees with defined trunks, as long as they can get the required space and sunlight for growth.

Aspen trees are of numerous different types. Some of the most common ones are as follows:

  • Quaking Aspen (Populus tremuloides)
  • Korean Aspen (Populus davidiana)
  • Common/European Aspen (Populus tremula)
  • Japanese Aspen (Populus sieboldii)
  • Chinese Aspen (Populus adenopoda)
  • Bigtooth Aspen (Populus grandidentata)

Source: Gardening Knowhow

Related: All types of trees

Types

Quaking or Trembling Aspen (Populus tremuloides)

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Quaking, also known as trembling aspen trees, are the most popular among their kind. These aspens are scientifically referred to as Populus tremuloides and have earned this particular name because of how they appear to flutter or tremble on windy days, even in the lightest of breezes.

These aspens, unlike most of their fellow genus species, have round edged leaves instead of the usual pointed ones with the characteristic single teeth pointing outwards. The trembling aspens are regarded as tall and quick growing trees. With a total length of around 65–80 feet when fully grown, the trunk alone can reach 8 inches to 2 feet 7 inches in diameter. The tallest quaking recorded was about 119 feet 9 inches in length and 4 feet 6 inches in diameter.

These aspens’ barks are fairly smooth and greenish-white to gray in color with wide, black horizontal markings and dense black knots across them.

The Populus tremuloides trees are indigenous to both of the two American coasts, and because of their habitat, these trees can withstand severe cold weathers, so much so that they can even grow in the harsh climate of northern Canada.

The leaves change color with the change in seasons, turning from a rich summer green to yellow in the fall. Although these trees are strikingly beautiful, they do pose a serious threat to footpaths, drainage pipes, and sewers because of their extensive root network and recurrent root suckering.

Source: Hunker

Korean Aspen (Populus davidiana)

The Korean aspen trees are scientifically known as Populus davidiana. They stand at a height of 25 m with a trunk of a diameter of 60 cm. These trees have greenish gray to white barks that are smooth for the most part of the trunk with just the basal part being rough. While their barks have a light color usually, their branches are of much darker hues, like red or brown. Korean aspens have the traditional triangular, sharp edged, toothed leaves that make them easily identifiable.

Eurasian aspen (Populus tremula)

Populus tremula, or better known as the European aspen, is one of the most spotted species of this genus. These trees cover a wide global area in terms of distribution, stretching from the Arctic region to northern Africa and ranging from Western Europe to Japan. Similar to the trembling aspen trees, the European aspen too have rounded, fluttering leaves with curvy margins. Their foliage appears to have copperish brown hues in the spring and turns to green or at times yellow in the autumn.

These aspen trees exercise quick root suckering, with new shoots and groves sprouting out of the roots of old and dead trees frequently. They also act as fodder for wild animals such as elk, deer, moose, bears, and beavers and as shelters for birds like the woodpecker.

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Source: Hunker

Japanese Aspen (Populus sieboldii)

Populus siebodlii, or more commonly known as Japanese Aspen, are deciduos trees that grow at a fairly fast rate. These trees are commonly found growing on mountains all over Japan. Japanese Aspen trees grow to height of about 20m and are grown easily in a soil that is heavy and damp. These trees prefer growing in a soil that is well-drained. Japanese Aspen does not perform very well in exposed upland regions.

Japanese Aspen trees have numerous uses. The extract from the shoots is used as a rooting hormone for cuttings of all types. The wood of Japanese Aspen is soft and woolly in texture, and tasteless and odourless, having low-flammability. The wood is resistant to abrasion.

Chinese Aspen (Populus adenopoda)

The Chinese aspen, or Populus adenopoda, is a species from the genus populous. These aspen trees predominantly originate from China, and this is where they are found in most abundance, hence the name Chinese Aspen. The Populus adenopoda aspen trees are noted for being able to reach total heights of almost 30 meters, despite their growing locations, which are mostly mountainous slopes that are elevated at 300–2500 meters.

Chinese aspens offer numerous uses, with the most prominent ones being supplying wood for construction and furniture making. The timber from these trees also helps in the manufacturing of farm tools, carts, and wood pulp.

Bigtooth aspen (Populus grandidentata)

The bigtooth aspen, or Populus grandidentata, are deciduous trees with limited growth and distribution region compared to the other aspen species. These trees are chiefly found in parts of northeastern and north-central America, as well as in southeastern Canada. Populus grandidentata also goes by other names such as the large-tooth aspen, American aspen or white poplar.

This species gets its name “bigtooth” from its relatively larger teeth on the leaves as compared to the teeth on the leaves of other aspen species’ trees. The name Populus in the species’ genus is in Latin and means poplar in English, while grandidentata refers to the uneven and rough teeth on the leaves, where grandis means “large “and dentata means “toothed.” The barks of these trees are thin, olive-green colored, and smooth when they are young. On fully developing, after 30–40 years, the barks turn gray, thick and rough with knots and grooves.

The wood from these trees is light-shaded, fine-grained, straight-textured, and soft. It is mostly used for wood pulp, but is also seldom used for making particle boards and structural panels. Other, less common uses include pallets, log homes, boxes, chopsticks, match splints, hockey sticks, cricket bats and ladders. The bark is also often pelletized for fuel and additional cattle supply.

Habitat-wise, these trees prefer to grow in sandy soils and flooded plains. It is in such circumstances that this species grows to its full potential height and width. Bigtooth aspen trees grow predominantly in areas where they can find other species of aspens and poplars. Their foliage, as well as twigs and shrubs, feed the local wildlife. If the trees are removed from their favored habitat or location in a forest, they are quick to re-colonize the area.

Source: Hunker

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Most of these aspen species’ trees are accustomed to cold climates and regions where even the summers are relatively cooler than in other parts of the world. They are chiefly found in the north of the Northern Hemisphere, stretching to the south in high-altitude areas such as mountains or high floodplains. These deciduous trees are mostly medium-sized aspens growing to heights of 49 to 98 ft. Some of these aspen types are identified by their unique characteristics, like the fluttering and trembling of the leaves of the Populus tremuloides trees in soft breezes. This happens because of the flattened petioles of the leaves that consequently minimize the aerodynamic drag on the trunk and branches, thus making the leaflets flutter frequently.

Poplars normally cultivate in areas that are typically dominated by species of coniferous trees, where large deciduous tree species are absent or insufficient. These aspen trees are able to thrive in such conditions because of the evolutionary adaptations that help them in surviving in such settings. One such adaptation is the flattened leaf petioles; these petioles decrease the overall aerodynamic drag on the trunks of these trees during strong winds and reduce the chances of branch or trunk breaking. Another example of their evolutionary adaptations is how these trees drop their leaves in the winters, thus helping to prevent any damages to the trees or the leaves by the heavy snowfall. Moreover, the barks of aspens are photosynthetic, which means that the trees can still grow and develop even if the leaves have been damaged or shed. Additionally, the barks also feature small pores called lenticels, like the stomata on leaves that serve as apertures for gaseous exchanges.

Aspen trees boast another unique feature – their root systems possess a rhizomatic behavior. Most of the aspen species tend to grow in large colonies of cloned and identical trees, all originating from one single seedling, spread by the root suckering technique. New stems and groves in these colonies can grow at distances as far as 98 to 131 ft from the original tree. Each of these individual trees can thrive for as long as 40 to 140 years above the surface. However, the extensive root network lives for an even longer time.

An important fact about these trees is that they cannot survive in the shade both as seedlings as well as root sprouting. Seedlings find it difficult to grow in the absence of sufficient sunlight. Another important key fact is that aspen trees can indirectly benefit from forest fires because these enable the fresh saplings to grow well in the open sunlight of the cleared landscape due to the burnt trees.

Aspens have made a name for themselves because of their immensely fast growth rate and sprout regeneration ability. This aspect of the aspen trees reduces the plantation and cultivation costs of these trees, thus making them the ideal species for reforestation since little to no planting or sowing is required for these trees.

Aspen trees and barks are considered base-rich plants because of how they are hosting grounds for bryophytes. This allows them to act as feeding grounds for larvae such as the butterfly larvae.

Uses

Aspen trees’ wood appears to be light colored in most instances, usually being white or gray and very soft but incredibly strong. This wood boasts low flammability and because of this, proves to be a very useful kind of wood. Among its many uses, matches and paper production continue to be the most dominant ones where its low combustibility makes this wood a safer option to use when compared to the other wood types.

Similarly, shredded aspen wood pieces also referred to as excelsior (wood wool), serve packing and stuffing purposes. These trees also produce flakes called the aspen flakes, which are the most widely used wood species used for making strand and structured boards as well as animal bedding. Dried out aspen woods sheets are a popular construction alternate in rural areas for rural building, particularly famous for roof thatching.

These are all the common types of aspen trees that are found around the globe. After reading this article, we are sure you will be able to identify your aspen trees easily. Happy planting!

Home Stratosphere is an award-winning home and garden online publication that’s a result of our talented researchers and writers who work directly with hundreds of professional interior designers, furniture designers, landscape designers and architects from around the world to create helpful, informative, entertaining and inspiring articles and design galleries.

Tags: Trees Categories: Gardens and Landscaping
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Aspen Tree Names, Pictures and Types of Aspen Species

Aspen Tree Colony; (Aspen Grove, Aspen Stand, Aspen Group)

Picture of a Quaking Aspen Colony in the Autumn. (Populus tremuloides)

All species known as Aspen, typically grow in colonies (a group of similar trees) . These colonies are made up of (of what appear to be individual) stems trunks or trees (see Aspen picture on right), however they are all clones of the original seedling connected together by one root system. An Aspen clone colony may appear to be made up of many individual trees, however these are developed suckers that have sprouted from the root system of the original tree. Aspens do spread by means of root sprouts known as “Suckers”, new stems in the colony may appear at up to 30 ↔ 40m (98 ↔ 130ft) from the closest tree trunk. Due to the Aspens ability to spread using root systems and Suckers, (commonly known as “Suckering”), the Aspen colonies can become very large over the years, spreading about 1m (3ft) per year, eventually covering many acres.

Aspen Colony Longevity, Age;

Each tree trunk may live for 40 ↔ 150 years above ground, but the root system of the colony is even older. In some cases, thousands of years old, sending up new trunks as the older trunks die off above ground. One such colony in Utah, given the nickname of “Pando”, is estimated to be 80,000 years old, making it possibly the oldest living colony of trees in the world. One of the many reasons why Aspen colony trees can live for so long is because they are able to survive forest fires.

Aspen Regeneration and Growth;

Picture showing the leaves on the left are from a branch on a mature tree, the leaf on the right is from a root sprout or “Sucker” from the same tree.
European Aspen (Populus tremula)

The Aspen colony can survive forest fires because the colony roots are in the soil, below the heat of the fire. After the fire is burnt out, the Aspen colony root system is free to start growing new sprouts (known as “Suckers”), which eventually form the tree trunks.

Aspen sprouts or Suckers grow differently from that of a seedling, specifically the growth rate is increased exponentially as the small sucker has a enormous root system to feed it. Suckers have been documented to grow very fast, over 1m (4ft) in height from the ground up in one season. Another Sucker phenomenon is that the leaves are much larger than those on a mature branch, even the shape and colour is different (see Aspen leaves picture on right). All these differences occur to aid the large root system below which needs energy from photosynthesis quickly. These growth habits can be observed if you cut off an established Aspen tree near the base of the trunk, and watch the Suckers grow from the stump over the next few months.

Aspens like more direct sunlight than shade, and it is difficult for seedlings to grow in an already mature Aspen colony, subsequently most seedlings succeed away from the colony, hopefully in a open area where conditions are right for another colony to develop. Forest fires can indirectly benefit Aspen trees, as the fire can open up an area allowing the seedlings and or suckers to grow in open sunlight.

Aspen use in Forestry;

Aspen species have increased in popularity in the forestry industry, mostly because of their fast growth rate and ability to regenerate from their roots, and using sprouts, making reforestation after clear cutting (harvesting) much quicker and cheaper, since no planting or seeding is needed. Additionally there is in some Forests an added benefit that there is less ground erosion after clear cutting because of the Aspens large connected and interwoven root system.

If you’re searching for a native, medium-sized tree that grows fast and brings fall color to your landscape, aspen might be the tree for you. Typically found in mountainous forests, they are a suitable choice to naturalize your landscape.

Basic Characteristics and Common Types

Quacking aspen (Populus tremuloides) and bigtooth aspen (Populus grandidentata), both common names, are the most likely types of the trees you will find in the wild and planted in home landscapes. Both are very similar in looks and preferences for growth. They are hardy, growing throughout USDA zones 1 through 6, withstanding the coldest temperatures winter throws at them.

Size, Shape, and Longevity

Both types reach a mature height of approximately 50 to 60 feet, though they can grow as tall as 100 feet, and 30 feet wide, with an open canopy. On average, each tree has a lifespan of 50 years due to pests and disease problems.

Bark and Foliage

The light-colored, whitish bark looks similar to that of a birch, making it an eye-catching landscape addition. Trees have one main, straight trunk. As the tree matures, the bark develops warty ridges. Its wood is weak, due to the fast growth, so it’s best planted in a site where potential fallen branches don’t damage structures or power lines.

When temperatures are warm and the trees are actively growing, the foliage is green and changes to a yellowish color in autumn before it drops for winter. The 3-inch foliage is oval-shaped with pointy tips and toothed edges. It is easy to identify the two trees by inspecting their foliage. The bigtooth has heavier toothed leaves than that of the quaking. Other than the differences in the foliage, the two trees look alike.

Aspen bark Aspen leaves

Flowers, Seeds and Reproduction

The trees are dioecious, meaning that separate trees produce male and female flowers or catkins. The 2-inch long, yellowish catkins bloom before the foliage sprouts in early springtime. Over several months, the catkins ripen producing cottony seeds, with female trees producing more of a cottony mass than male trees. Seeds do not require stratification to germinate and are ready for planting as soon as the catkin splits showing the ripe seed. The tree reaches a seed-bearing age when it reaches around 10-years-old.

All reproduce through seeds and root sprouts, with root sprouts the most common way of reproduction. Gardeners will notice an aspen in their landscape sending up multiple sprouts around the tree.

Purchase Considerations and Sellers

You can probably locate specimens for sale in local nurseries or native plant sellers throughout the tree’s growing range. If purchasing a tree, make sure its foliage is healthy and free of spots or other signs of diseases or pests.

Inspect the tree’s container, making sure the tree hasn’t outgrown it with roots growing out the drain holes. Living too long in containers that are too small can permanently affect the tree’s growth stunting the tree.

If you cannot locate one in your local area, a variety of online plant nurseries sell them. Trees are usually around one year old or younger and shipped in their deciduous stage before they leaf-out in springtime. Online nurseries include Cold Stream Farm and the Arbor Day Foundation.

Uses in the Landscape and Considerations

Aspens make handsome trees utilized in the proper area of the landscape where its aggressive root system does not create problems. Do not plant the tree close to house foundations, sidewalks or driveways, as the roots will lift the structures. Since the tree’s roots seek out moisture, you do not want to plant the tree close to septic systems, sewers or drains, as the root system will do damage.

The trees make terrific additions to native and wildlife gardens. Many types of birds utilize the seeds as a food source and woodpeckers use the tree as a nesting site. They also offer filtered shade and their medium size won’t overpower smaller yards.

Preferred Conditions for Growth

For aspens to grow properly, it’s necessary to plant and grow the tree in its preferred conditions.

Preferences for Light

For the best growth, plant in a location that receives full sun throughout the day.

Preferences for Soil

In the wild, the trees grow in moist locations. When selecting a site to plant the tree, make sure to choose a location that is rich in organic materials, drains well but is moist. The tree does not perform well in alkaline soils that have a tendency to be dry and will decrease its lifespan.

Water Requirements

They require regular applications of water to grow properly. Water the tree deeply weekly, especially when conditions are dry and throughout the spring into early fall. During the dormant season through winter, the tree only requires a monthly application. Water the tree right after planting and continue applying water several times weekly for several months while the root system establishes itself into the landscape.

Planting Tips

After selecting the appropriate location in the landscape to plant your aspen, it’s time to prepare the area for introducing the tree. Clear all weeds and grasses growing in a planting site that is at least 3 feet in diameter. The unwanted growth robs the tree of moisture and nutrients and harbors pests and diseases. Keeping the area under the tree clean makes it less likely lawn equipment will bump into the trunk damaging it, which leads to diseases.

Digging the Hole

Loosen the soil in the planting site to make it easier for the tree’s root system to spread by digging a hole that is twice as deep and wide as the root ball. Backfill enough soil into the hole so the tree is sitting as deep as it was growing in its container. You don’t want to put undue stress upon the tree by planting it too deep.

Plant Roots

Gently tease the roots apart and place the root ball into the hole, backfilling halfway with soil. Firm the area around the roots and saturate with water to release any pockets of air and settle the soil. Fill the remainder of the hole with soil and saturate the area again with water.

Mulch

To help reduce weeds and grasses, apply a 3- to 4-inch layer of organic mulch over the planting site. Pull back any mulch that is butting against the trunk and keep it several inches away.

Continued Care

Annual applications of fertilizer and trimming keep the tree healthy.

Applying Fertilizer

Fertilize in springtime with an all-purpose blend specifically formulated for trees, such as a 19-8-10. Use approximately 1/2 pound of fertilizer for each 1-inch diameter of the trunk. Spread the fertilizer evenly under the tree’s canopy and water in well.

When to Prune

The trees have a tendency to bleed whenever they are pruned, but the bleeding is normal and doesn’t harm the tree. However, it’s best to do any heavy pruning in winter. Trim off any crossing, broken, damaged or diseased branches back to a main branch. It is fine to prune off damaged or diseased branches anytime throughout the year.

Aspens are notorious for sending up root suckers that grow a good distance from the tree and pop up in the lawn. Cut these off at ground level by using a lawn mower or string trimmer. If left uncut, the suckers eventually grow into clones of the mother tree.

Since they are susceptible to a host of diseases, use sterilized pruning tools when pruning. Sterilizing your tool’s blades is as easy as wiping them off with a damp cloth saturated in alcohol.

Common Aspen Diseases and Pests

Aspens are a bit needy when it comes to pests and diseases as the tree is susceptible to a variety of problems. As with any tree, providing it with the proper growing conditions and cleaning up fallen debris under the tree goes a long way in helping the tree remain healthy.

Problematic Pests

Depending on the culprit, some pests only create cosmetic damage and treatment isn’t necessary. However, other more damaging pests may warrant a treatment of insecticides to control the problem.

  • Aphids: Aphids are a common insect found on the tree. The small pear-shaped insects feed on the plant’s juices and cause distortion in the foliage, discoloration and their secretions cause the black fungus sooty mold to cover the leaves. Rarely are aphids life-threatening, but if outbreaks are severe, you can treat the tree with an insecticidal soap.
  • Oystershell scale: This is the most damaging sapsucker. The scale is dark gray to brown and attach along the tree’s branches sucking out the juices. When infestations are heavy, the scale can weaken or kill an otherwise healthy tree. If the problem is small, you can scrape the insects off the affected branch. In large infestations, spray the entire tree with horticultural oil in springtime just as the tree is beginning to leaf out.
  • Tent-making caterpillars: Tent caterpillars create a fine mass of white webbing generally in the crotches of trees making the pest easy to identify. The caterpillars feed on the foliage and if the outbreak is severe can defoliate the tree. If the problem is severe, the caterpillar weakens and kills trees. Pick small infestations off and drop into a bucket of soapy water, but if the outbreak is large, spray the tree with Bacillus thuringiensis or spinosad as soon as you notice the problem will help in controlling the caterpillar damage.
  • Bark borers: They are susceptible to several bark borers with the poplar borer being the most common pest affecting the tree. The beetle lays its egg on the tree’s bark, which then tunnels inside eating at the inside and weakening the tree and creating holes in the bark. Trees that are unhealthy and stressed are most susceptible to a borer attack. Insecticidal treatment is only successful when the pest is active and laying eggs on the outside of the bark, usually in late spring through summer. Saturating the bark and trunk with a product containing carbaryl should control the pest problem.

Fungi That Cause Cankers

Aspens are susceptible to several fungi causing deep cankers in the bark and trunk. The cankers are most damaging to younger trees, though some are lethal to older and established trees. Sooty bark canker can kill mature specimens and the fungus enters the tree through wounds and affects the heart of the tree. The canker creates a sunken area in the bark, which eventually strips off leaving a black ringlike appearance lining the trunk. There is no treatment for the problem and not wounding the bark is the only preventative measure.

Black canker is a slowly developing problem that usually isn’t life-threatening and causes trunk deformity. Large, black conks form around the affected area and cause sunken areas in the trunk. Affected areas eventually die and can become susceptible to borer problems. Prevent the problem by keeping the tree healthy and the bark free of wounds.

Foliage Diseases

Several foliage diseases affect aspen trees and are preventable by cleaning up fallen debris under the tree where the disease overwinters. Ink spot fungus is most prevalent when springtime weather is rainy. Dark brown spots appear on the foliage in summer and increase in size eventually forming shot holes. In severe outbreaks, the tree can suffer leaf drop, which can affect the health of the tree. Spraying the tree with a copper fungicide in winter before the foliage sprouts helps control the problem.

Marssonina leaf spot fungi overwinter in fallen debris under the tree. Outbreaks are most common when springtime weather is warm and rainy. The fungus creates small dark brown spots on the leaves with a yellow circle. When the problem is severe, foliage drops from the tree. The best prevention is keeping the area under the tree clean and in the event of a severe outbreak, spraying the tree with a copper fungicide helps control the problem.

A Tree Worth the Attention

Due to their tendency to be a high-maintenance tree, aspens might not be everyone’s cup of tea. However, when properly cared for, their tall and striking form makes them worth the extra care they require.

If you follow my blog you’ll know that many times I talk about looking to Nature for answers to life’s mysteries. For me, no matter the question, if I spend time in the woods I’ll find the answer.

Nature has a wisdom to it that can teach us so much- if we pay attention.

The aspen tree is the perfect example. The leaves of the quaking aspen have an unusual ability to twist and bend to protect the trees from severe winds. Their twisting motion helps the tree to dissipate the energy more uniformly throughout the canopy- to reduce the stress on the tree. Additionally, the quaking movement is thought to aid in the tree’s growth, because the constant movement increases the intake of air by the leaves. Lastly, moving the leaves increases the ability for sunlight to shine on the lower leaves, thereby improving the rate of photosynthesis for the trees.

Or perhaps I should say TREE (singular).

Aspens are unique in that a forest of trees can be actually one tree. Aspens grow in large colonies derived from a single seedling and spread the roots to create new trees. The new saplings may appear as far as 30-40 meters from the parent tree, yet they are a part of the same system. The individual trees may live 40-150 years above the ground but the roots can live for thousands of years. There is one colony in Utah that is believed to be over 80,000 years old! Aspen colonies can even survive forest fires because their roots are so well protected.

And because the colony is actually one system, they are quite generous to what could appear to be ” another tree”. If a tree on one side of the forest is thirsty, the trees will work in unison to pass water through the root system to the ailing tree from one that is in an area where water is more abundant. If another needs nutrients or minerals, again it will be passed through the root system from one tree to the one in need. How cool is that?

Imagine a world where we all acted like aspen trees….

– Recognize and appreciate that movement helps us grow.

– Move aside to help and encourage the sunlight to shine on those below us.

– Share energy and stress with one another as a unit- so that we can better handle the ups and downs of life.

– When someone is in need, share our abundance, knowing that as a part of the whole, we can never truly be in need.

– Know that we are all one, with no need for competition.

– Know that our roots are deep and can withstand even the worst of disasters.

Just like the aspen tree, we are all connected to one another at the source of our being. The basic premise of all religions is that we are one. We are all brothers and sisters, just like the aspen tree. We are all a part of something so much greater than our individual selves. We are connected by our roots.

For me, in this realization, there is beauty and there is peace. Peace in knowing that we are not alone. Peace in knowing that even when the winds of life are cold and blowing hard, all we need to do is turn our leaves and allow the colony- our community- to shoulder the burden with us, for we are all connected.

On those beautiful, easy days filled with the warm sunshine, remember to step aside and allow the sun to shine on those less fortunate.

Nature does have a lot to offer, if we pay attention. I’m going for a walk in the woods today to see what lessons Nature has in store for me. Please share your insights with our community- your fellow aspen trees. And just like that drink of water shared from one part of the colony to another, if one of us shares a nugget of wisdom and passes it through our roots to the other “trees”, we all benefit. I like being an aspen tree. 🙂

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