The Burning Bush Story

Winged burning bush in a wooded understory. Its bright red fall color makes it easy to identify. 

Winged burning bush, Euonymus alatus, is beautiful in fall. Its vibrant orange to red-purple leaves are striking, and it has been widely planted for its burst of late-season color.

In Minnesota, however, the species and its cultivars are no longer available. Many homeowners and landscapers have been disappointed that the shrub is now considered invasive and is legally prohibited from sale. Some question this decision, saying that burning bush doesn’t spread to natural areas – not in great numbers, anyway.

What’s the story of burning bush? What evidence supports the claim that it invades natural areas? And if it does, what harm does it cause?

 

First Arrival

Winged burning bush is originally from northeast Asia, where it grows in forests, woodlands and shrub-dominated scrublands. Someone – it’s unknown who – introduced it into North America in the mid-1800s as an ornamental shrub prized for its winged stems, bright fall color and abundant red fruits (1).

Left: Burning bush in its blazing fall color. Center: Stems and older branches have corky wings. Leaves are opposite. Right: Reddish capsules open in fall to release seeds enclosed in bright red arils, or fleshy seed coverings.

By the early 1900s, burning bush had entered the nursery trade, and by the mid-1900s the shrub and its cultivars were well known. Plant catalogs from that time promote the plant’s fall color and attractive fruits. In 1934, Breck’s catalog included burning bush among several desirable shrubs, writing, “Those who enjoy having birds around their home will find no better way of attracting them” than to plant them (2).

In 1949, Adams Nursery wrote in its catalog, “No doubt one of the most conspicuous varieties in the autumn, with its brilliant scarlet foliage and fruits,” adding that one of the shrub’s cultivars is “[i]ndifferent to soil, shade, and city conditions.” In other words, it will grow just about anywhere it’s planted (3).

Other advertisements were similarly positive. Burning bush, they all said, is an ideal plant for a shrub border, foundation planting, specimen planting or other uses. At the time, there was no mention of it naturalizing.

Early Concerns

As burning bush became widely planted, observations of its unintentional spread started to accumulate. In 1973, botanists John Ebinger and Loy Phillippe published what may be the first documented observation of burning bush spreading beyond intentional plantings (4). During field work in Illinois, they found a sizeable, self-sustaining population of Euonymus alatus on a wooded hillside and valley. They wrote:

“The population studied dominates the understory in the more shaded parts of a north facing hillside and valley floor, being particularly abundant in small ravines. The entire population extends over an area of about 4 acres …. Numerous smaller plants and seedlings are also common.”

For the next 10 years, John Ebinger studied that site and documented what he found. In a 1983 report (5), he wrote that the burning bush population had expanded to 3 hectares (about 7.4 acres), with some plants more than 30 years old. Small plants and seedlings were still common. On the north-facing hillside, the seedling density was an average 138,500 per hectare (2.471 acres) and the density of saplings was an average 1,100 per hectare. On the ravine floor, the seedling density was an average 150,000 per hectare, and the density of saplings was an average 1,700 per hectare. He also noted that the population had almost doubled in number, and plants had spread to the forest edge and a nearby field.

About the plant’s invasive ability, he wrote, “Although not a major problem in natural areas, winged wahoo [another common name for Euonymus alatus] does have the potential to spread into good quality forests since it can grow and reproduce in dense shade. Most of the reproduction observed is from seeds falling from established plants. However, birds do regurgitate the seeds soon after ingesting them, and some seeds have been found to be viable after passing through the digestive tract.”

Later Decades

From the 1990s to the present, reports of naturalized burning bush have increased across North America. The greatest number are from the northeast US, but the plant is also spreading in the Midwest, including Minnesota. The map below is from EDDMapS, a reporting system for introduced plants that have become naturalized (6). Record density by county (or the equivalent in Canada) is indicated by color; the darker the shade, the greater the density.

 

Some of these reports are in or near natural areas, such as parks, forests, refuges and shorelands. For example, locations selected from the map above include Bedell Bridge State Park in New Hampshire, Griffy Lake Nature Preserve in Indiana, and Elroy-Sparta State Trail in Wisconsin. In Minnesota, burning bush has been reported in the Richard J. Dorer Memorial Hardwood State Forest, Great River Bluffs State Park, the Minnesota Valley National Wildlife Refuge and the Lower St. Croix National Scenic Riverway, among other places.

Some of these reports are of single plants or a few scattered individuals. Others document higher density populations or even monocultures. The photographs below are from a wood line between a private residence and the Richard J. Dorer Memorial Hardwood State Forest, where photographer Peter M. Dzuik noted full canopy closure by mature shrubs and nearly full cover of the ground layer by seedlings (EDDMapS report 5235347.)

 

Impacts and Intervention

Clearly, burning bush can be invasive. With enough time and in favorable circumstances, a few naturalized shrubs can turn into many, including in natural areas. Looking back, it’s not surprising that burning bush can spread. Some of the qualities that made it popular, namely its wide tolerance of growing conditions, its abundant fruit production and its ability to attract birds, are traits common to many invasive plants (7).

Those traits helped burning bush spread to many habitats, and where its cover is extensive and dense, its effects are significant. In its 2019 assessment of burning bush (8), the Minnesota Department of Agriculture’s Noxious Weed Advisory Committee (NWAC) concluded in part that burning bush and its cultivars can “aggressively displace native species through competition” and have “the potential to change native ecosystems” by forming dense thickets and ground layers. The NWAC also noted that burning bush invades not only forest understories but also prairies, pastures and coastal shrublands. (See question 8 in the Assessment Worksheet; it includes several references.)

As a result, the committee recommended adding burning bush to Minnesota’s Noxious Weed List in 2020, initially designating the species and its cultivars as Specially Regulated (9). After a three-year phase-out period, the plant was moved to the Restricted list, meaning it can’t be “imported, sold, or transported in the state” without a permit. It also means that burning bush has become so widespread in Minnesota that eradicating it or preventing it from reproducing isn’t realistic.

How To Identify Burning Bush

It’s easy to identify burning bush in fall, when its bright red-orange color and red fruits make it obvious. At other times of the year, its winged stems and opposite leaves (or buds) are helpful characteristics. A native burning bush (Euonymus atropurpureus), also called eastern wahoo or spindle tree, is found in southern Minnesota, usually in lowlands but sometimes in uplands (10). Its stems are squarish in cross section, with shallow ridges or faint lines along the angles. Unlike the stems of Euonymus alatus, they lack well-defined wings.

 

In late fall and winter, burning bush can be identified by its winged stems and red fruits.

For more information about either species, see these Minnesota Wildflowers pages: Euonymus alatus, Euonymus atropurpureus.  

References

1. Winged Euonymus (Euonymus alatus). iNaturalist. Website accessed November 15, 2025.

2. Joseph Breck & Sons., et al. 1934, Everything for Farm, Garden & Lawn. Joseph Breck & Sons, 1934, https://www.biodiversitylibrary.org/item/269483.

3. Adams Nursery. & Henry G. Gilbert Nursery and Seed Trade Catalog Collection. (1949). 100th anniversary, 1849, 1949. Adams Nursery, Incorporated. https://www.biodiversitylibrary.org/item/304370

4. New Plant Records for Illinois. John E. Ebinger and Loy R. Phillippe. Transactions of the Illinois State Academy of Science Vol. 66. No. 3 & 4, page 115.

5. Exotic Shrubs: A Potential Problem in Natural Area Management in Illinois. John E. Ebinger. Natural Areas Journal Vol. 3, No. 1. pages 3-6. 1983.

6. EDDMapS. 2025. Early Detection & Distribution Mapping System. The University of Georgia - Center for Invasive Species and Ecosystem Health. Available online at http://www.eddmaps.org/; last accessed November 23, 2025.

7. Exotic, Invasive Plants 101: Characteristics and Identification. Belinda Eshan. Natural Resources Conservation Service (NRCS) and Tennessee Exotic Pest Plant Council (TNEPPC). 2012.

8. Assessment Worksheet for Winged Burning Bush. Noxious Weed Advisory Committee, Minnesota Department of Agriculture. 2019.

9. Minnesota Noxious Weed List. Minnesota Department of Agriculture. Website accessed Nov. 11, 2025.

10. Trees and Shrubs of Minnesota. Welby R. Smith, Minnesota Department of Natural Resources. University of Minnesota Press, 2008. 

Yes, These Are Flowers

The whitish, stalked, bud-like structures at the base of this common blue violet (Viola sororia) are flowers, and at about half an inch long, this is as big and showy as they get.

Unlike the blue-purple flowers that bloom in spring, these flowers start to appear in summer and last into fall. They have little or no pigment, reduced or no petals, and no nectar. They don't need these things because they don't need to lure insect pollinators. They never open, so they pollinate themselves.  

In botanical terms, these closed flowers are cleistogamous (kly-STOG-amus), meaning "closed marriage." In contrast, the showier flowers of spring are chasmogamous (kaz-MOG-amus), meaning "open marriage."

Each type of flower can benefit the plant. The chasmogamous ones are cross-pollinated by insects, potentially mixing genes from different parents as pollen is carried from plant to plant. The resulting seeds grow into offspring that have gene combinations different from their parents and from each other, potentially giving them new traits that improve their survival and reproduction. 

That's an advantage if their environment changes over space or time. In a population, more genetic variation among individuals increases the odds that at least a few of them will have the traits needed to grow in uneven or changing conditions. 

The downside is that chasmogamous flowers are expensive. The plants spend much of their stored energy making pigments for petals, sugars for nectar, and longer stalks to lift the flowers to leaf height or above, where they will attract pollinators. If something happens to the flowers -- if they're eaten by an herbivore or if pollinators don't visit, for example -- that energy is wasted. That also puts the next generation at risk. If there are no seeds, there are no offspring.

The chasmogamous (open) flowers of common blue violet attract insect pollinators. The blue-purple pigments, darker nectar guides on the lower petal, and hairs on the lateral petals take much of the plant's stored energy to produce. 

Cleistogamous flowers provide a back-up, among other benefits. In terms of energy, they're much less expensive to make, and they don't rely on pollinators to make seeds. That's an advantage if the chasmogamous flowers are missing or aren't pollinated, because the plants have another way to produce seeds. It's a second chance.

Because they're self-pollinated, cleistogamous flowers produce seeds and offspring that are genetically identical to the parent and to each other. That's beneficial if environmental conditions are favorable and stable. If the parent is genetically well-adapted to the conditions, then the offspring will be, too, because those genes are preserved by self-pollination.

Self-pollination can also help get rid of versions of genes, called alleles (ah-LEELS), that reduce fitness, i.e., successful growth and reproduction. Cross-pollination can mask these harmful alleles by contributing healthier ones from other plants, thereby blunting any deleterious effects. Self-pollination, though, increases the odds that the effects of the alleles, now not partnered with more favorable ones, will show up in a plant's anatomy or physiology. That's bad for individuals that die or are unable to reproduce as a result, but the loss of those individuals can eliminate the responsible alleles from a population.  

Genetic uniformity can be a disadvantage, too, especially if conditions vary across a habitat or if they change over time.. A new environment may require adaptations the population doesn't have, because the plants are genetically identical. For example, if conditions are warmer and drier but the offspring come from a parent adapted to cooler, wetter conditions, they may not reproduce or even survive. 

Another potential disadvantage of cleistogamy is inbreeding depression, the loss of fitness that can result from maladaptive alleles that aren't "weeded out" by self-pollination, as described above. Also, although cleistogamous flowers usually produce more seeds than chasmogamous ones, the seeds tend to be dispersed closer to the parent plant, which can increase competition among siblings (1). 

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If you find cleistogamous flowers in violets or other plants, you'll be looking at something really old. Cleistogamy developed about 100 million years ago in some of the first flowering plants and has developed in many species since then. According to one estimate, worldwide there are at least 693 species of cleistogamous plants in 50 families (1). That was in 2007; more cleistogamous plants might have been discovered or confirmed since then. 

Although cleistogamy is present in a minority of plants, its long persistence among many species suggests that it has improved plant reproduction and survival. In at least 50 families, these plants converged independently on the same solution to the challenges of floral reproduction. That's profound, even amazing -- in a colorless, nectarless, inconspicuous kind of way.

Cited Reference

1) Theresa M. Culley and Matthew R. Klooster. The Cleistogamous BreedingSystem: A Review of its Frequency, Evolution and Ecology in Angiosperms. The Botanical Review 73 (1): 1-30. 2007. 

Additional References

Anne L. Sternberger and others. Environmental impact on the temporal production of chasmogamous and cleistogamous flowers in the mixed breeding system of Viola pubescens. PLoS One 15 (3). 2020. 

M.W. Austin, P.O. Cole, K.M. Olsen, and A.B. Smith. Climate change is associated with increased allocation to potential outcrossing in a common mixed mating species. Am J Bot.109(7): pp.1085-1096. 2022. 

Theresa M. Culley. Reproductive Biology and Delayed Selfing in Viola pubescens (Violaceae), an understory herb with chasmogamous and cleistogamous flowers.International Journal of Plant Sciences 163 (1): pp. 113-122. 2002. [Available to view with a free JSTOR account.]

Plant Profile: Ragweeds

 Common ragweed, Ambrosia artemisiifolia, and great ragweed, A. trifida.

Common ragweed, Ambrosia artemisiifolia, flowering in late August. 

For people with seasonal allergies, ragweeds are beasts.

Pollen from these plants, also called hay fever weeds, cause much of the sneezing, watering eyes, coughing, wheezing and other symptoms that torment allergy and asthma sufferers in late summer and early fall.

Both great ragweed and common ragweed, the two species frequently found here, are native annuals. They’re often found along roadsides, in abandoned lots, along field edges and in other disturbed places. Most seeds germinate in early spring, but some may germinate as late as July. Flowering peaks in August and September and lasts until the first frost.

Common ragweed plants are 1-3 feet tall at maturity. Leaves are opposite below and alternate above, divided and deeply lobed, to 6 inches long and 4 inches wide at the base.

Great ragweed is 3-12 feet tall at maturity. Leaves are opposite, the lower ones three-lobed and the upper ones simple and ellpitical. Largest leaves grow up to 12 inches long and 8 inches wide.

Ragweeds produce separate staminate (male, or pollen-producing) and pistillate (female, or seed-producing) flower heads on spike-like racemes. Both kinds of flowers are found on the same plant; in other words, the plants are monoecious (mo-NEE-shus). Staminate flowers are grouped into stalked, downward-facing heads on the upper part of each raceme. Pistillate flowers are clustered below, often nestled in leaf axils.

After pollination, pistillate flowers develop small diamond- or top-shaped fruits with a central “beak” surrounded by ridges, each ridge ending in a short spine. The fruits look like miniature crowns, so ragweeds are also called crown weeds. Each fruit contains a single seed, and an individual plant of either species can produce thousands of seeds each season. Common ragweed seeds are viable in soil for two to three years and up to 40 years (3). Giant ragweed seeds are less durable; most lose viability after one year (4).

 

Left: Great ragweed racemes are 3-8 inches long. Right: Closer view of ragweed flower heads. Staminate heads are stalked and face downward. Pistillate heads contain only one flower. The one at the arrow has been pollinated and a young, green fruit is developing. Common ragweed racemes are shorter but otherwise similar.

Both types of flowers are small and simple; they have no large, colorful petals. That’s because the plants are primarily wind-pollinated and therefore don’t invest in structures needed to attract insects. Typical of wind-pollinated plants, the staminate flowers produce tremendous amounts of pollen. Many sources state that a single plant can release up to 10 million pollen grains a day and up to 1 billion grains a year.

It’s unclear where those numbers come from, but recent studies confirm similarly large amounts. In France, where ragweed is introduced and invasive, researchers found that a single common ragweed (A. artemisiifolia) produces from 100 million to 3 billion pollen grains per season (1). A study of intact vs. mowed common ragweed in Quebec found that an intact plant produces more than 100 million pollen grains per season (2).

These great ragweed leaves are dusted with yellow pollen.

Those millions of grains, multiplied by the number of plants that can densely fill an optimal habitat, present a serious health threat to people with ragweed allergies. The plants do have some ecological benefits, however. As colonizers of disturbed places, they can hold soils in place as other plants succeed them. In addition, their protein- and oil-rich seeds are eaten by migrating and winter-resident song birds and game birds, as well as by chipmunks, voles, and other rodents.

Beastly or beneficial, ragweeds are an enduring part of our landscape. Maybe that’s why Linnaeus put them in the genus Ambrosia, Greek for “immortal,” “divine,” or “food of the gods.” Given the seeminly unending symptoms ragweed pollen can cause, the first meaning, immortal, seems to fit. The last two, though, are hard to fathom. Ragweeds are indeed persistent. But for allergy sufferers, they are anything but divine.

References 

1. Boris Fumanal, Bruno Chauvel, François Bretagnolle. 2007. Estimation of the pollen and seed production of common ragweed in Europe. Annals of Agricultural and Environmental Medicine (AAEM) 14 (2), pp. 233-236.

2. Simard M.J., and Benoit, D.L. 2011. Effect of repetitive mowing on common ragweed (Ambrosia 
artemisiifolia L.) pollen and seed production. Annals of Agricultural and Environmental Medicine (AAEM)18 (1), pp. 55–62.

3. Cornell College of Agriculture and Life Sciences. Common ragweed. Website accessed 9/5/25.

4. The Ohio State University. College of Food, Agricultural, and Environmental Sciences. Giant ragweed: A weed of extremes. 9/27/16.

Plant Profile: Virginia Waterleaf

Hydrophyllum virginianum

Virginia waterleaf flowers in May and early June with purple to almost white flowers. Early in the season, the leaves bear whitish marks that resemble water stains.

Virginia waterleaf, a native perennial also called eastern waterleaf, is one of the first plants to emerge in spring in moist forest understories. Initially its deeply lobed and toothed leaves have white patches that resemble water stains. The patches tend to fade as the leaves age, so by summer they are a uniform green.

From May into June, waterleaf produces clusters of nodding, bell-shaped flowers with five purple to white petals and five hairy, green sepals. Each flower has five stamens with hairy filaments and yellow anthers that later turn brown. A single pistil with a divided stigma emerges from the center of each flower. Both the stamens and pistil are exserted, meaning they extend beyond the petals. This gives the flowers a spiky or fringed appearance.

In waterleaf and many other flowering plants, the pistils mature later than the stamens. Typically, the stigma of a pistil isn’t ready to accept pollen until the anthers in the same flower have matured and released their pollen. This difference in timing, called dichogamy (dy-KOG-ah-mee), favors cross-pollination and the potential adaptive benefit of mixing genes from different plants.

Left: Flowers of Virginia waterleaf have distinctive hairy filaments. Both the stamens and the pistils extend beyond the petals. Right: A flower closeup showing four of five stamens, a pistil with a divided stigma (top arrow) and a nectary (bottom arrow). 

The flowers are pollinated by a variety of insects seeking pollen and nectar. Bumble bees are common visitors; they reach deep into the flower for nectar and are dusted with pollen in the process. Sweat bees, mason bees and mining bees also visit the flowers for pollen or nectar, or both. The waterleaf mining bee, Andrena geranii, is a specialist on this plant, collecting both pollen and nectar (1).

Another significant pollinator is the federally endangered rusty-patched bumble bee, Bombus affinis, Minnesota’s state bee. Early in the season, this bee relies on spring-flowering plants such as waterleaf for nourishment. This led a group of researchers to include Hydrophyllum, Dicentra (Dutchman’s breeches, e.g.) and other spring bloomers in a full-season menu of plants to support these bees (2).

After flowering and pollination, waterleaf develops spherical capsules containing 2-4 wrinkled, brown seeds that mature in late June or early July. Most references state that the seeds germinate after experiencing winter conditions outdoors or winter-like conditions (in a refrigerator) indoors. 

Maturing capsules are about 1/4 inch (~5 mm) across.

A related species, appendaged waterleaf (H. appendiculatum) breaks seed dormancy in two stages. After a period of warmth, the root breaks dormancy first and emerges from the seed in the cooler temperatures of fall. Then, after winter, the shoot breaks dormancy (3). It’s unclear if the same is true of Virginia waterleaf, but because the seeds are released in June, with at least a couple of months of warmth before cooler temperatures arrive, it’s possible that its seeds also have two stages of dormancy.

Waterleaf also reproduces vegetatively, spreading quickly by rhizomes to form dense patches. This is a faster way for the plant to produce mature individuals, but this kind of reproduction sacrifices genetic diversity. All plants grown from a common rhizome are clones – they are genetically identical. In a stable, suitable environment, this is successful, but in a changing environment, vegetative reproduction can leave the plants without the potential adaptations that gene exchange can bring.

Virginia waterleaf reproduces not just by seed but also by rhizome. Left: A rhizome bears a single leaf and several roots.
Right: Rhizomes help waterleaf grow into dense patches. 

Division of patches is also a faster way to multiply the plant for restorations or gardens. Iowa State University rates waterleaf's woodland restoration potential as high by transplant, meaning it can “establish and reproduce quickly.” (4)

Waterleaf can also help capture nutrients that would otherwise flow from agricultural land to adjacent water bodies, especially in spring. In one study, researchers found that Virginia waterleaf and other selected plants excelled at accumulating biomass and capturing nitrogen, a significant water pollutant (5). The study supports the idea that intentional transplant of waterleaf and other high-biomass, spring-emergent plants into disturbed or restored floodplain forest can be as effective at capturing nutrients as a buffer of undisturbed native forest understory.

Cited References

1) Pollinators of Native Plants. Heather Holm. Pollination Press LLC, Minnetonka, MN. 2014.

2) Floral resources used by ­the endangered rusty patched bumble bee (Bombus affinis) in the Midwestern United States. Amy T. Wolf and others. Natural Areas Journal vol. 42, no. 4, pages 301-312. 2022.

3) Germination Ecophysiology of Hydrophyllum appendiculatum, a Mesic Forest Biennial. Jerry M. Baskin and Carol C. Baskin. American Journal of Botany vol. 72, no. 2, pages 185-190. 1985. Available to read with a free account at JSTOR.

4) Native Iowa Woodland Understory Restoration: A Guide to Species Reintroduction. Iowa State University. Website accessed June 29, 2025.

5) Restoring Nutrient Capture in Forest Herbaceous Layers of the Midwest (Iowa). Michaeleen Gerken Golay and others. Ecological Restoration vol. 28, no. 1, pages 14-17. 2010. Accessed through Iowa State University Digital Repository.

Additional References

Virginia Waterleaf (Hydrophyllum virginianum). Minnesota Wildflowers. Website accessed 6/26/25.

Virginia Waterleaf (Eastern Waterleaf). The Friends of the Wildflower Garden, Inc. Website accessed 6/26/25.

Virginia Waterleaf (Hydrophyllum virginianum). University of Wisconsin – Madison. Website accessed 6/26/25.  

Where to Find Remnant and Restored Prairies in Minnesota

A restored prairie at Elm Creek Park Reserve, Maple Grove, MN.

On a windy summer day, a Minnesota prairie looks like an ocean. The tallest grasses move like waves, their stems bending, rebounding and bending again, an imaginary sea of grass. 

For prairie plants, bending without breaking isn’t just a metaphor for survival; it is survival, one of many adaptations for life in a dry, often windy, fire-prone upland. These forces have literally shaped the grasses that dominate the landscape. Their narrow leaves minimize water loss, their low growing points help them recover after fire or grazing, and their deep roots serve to both anchor and absorb. (See this illustration of prairie plant root systems.)

Among the grasses are a variety of forbs, non-woody plants other than grasses. Depending on the site, there may be pasque flowers (Anemone patens), lupine (Lupinus perennis), butterfly milkweed (Asclepias tuberosa), prairie clovers (Dalea species), boneset (Eupatorium perfoliatum), gentians (Gentiana species), sunflowers (Helianthus speces) and many others, each flowering in its own season.

From left: Prairie larkspur (Delphinium carolinianum), butterfly milkweed, and bottle gentian (Gentiana andrewsii).

 
They're all part of Minnesota's northern tallgrass prairie, part of a larger grassland biome in the central United States and south­ central Canada. Northern tallgrass once covered roughly 18 million acres in the southern and western parts of the state. About 235,000 acres remain, less than two percent of the original area.

 

The Minnesota DNR's map of original prairie (yellow) and remaining prairie (red).The original, readable map is here.  

That's not much, but there are still places to find remnants and restorations of this now-limited ecosystem. Here are some resources to help find them.

The Minnesota DNR's Prairie Finder maps public lands you can visit to explore prairies. These are state parks, historic sites, national wildlife refuges and other places where prairie is protected or restored for education, research, and enjoyment. One such place is the Northern Tallgrass Prairie National Wildlife Refuge in western Minnesota. 

The U of M's Minnesota Natural Resource Atlas is an interactive map that allows you to search for native prairies and other natural resources in the state. At the website, select the Interactive Map and choose Add Layers. In the pull-down menu, check the box for Native Prairie in the Biota category and wait for the map to load. Keep in mind that some of the prairies are on private land.

In the Twin Cities area, Three Rivers Park District has restored about 1,600 acres of prairie. Crow-Hassan Park Reserve in Hanover, Murphy-Hanrehan Park Reserve in Savage and Carver Park Reserve in Victoria have the largest holdings. Entry to the parks is free. Public seed collections in late summer and fall help support additional restoration.

This recently burned prairie at Crow Hassan Park Reserve is already growing back, and with vigor. This is lupine, Lupinus perennis.

 
The Prairie Wetlands Learning Center, part of the Fergus Falls Wetland Management District, showcases the eastern-most part of the prairie pothole region, a mix of shallow wetland depressions and upland prairie. Trails are open to the public any time. Call for Visitor Center hours. The Learning Center also offers programs for students and teachers.

If you can't visit a prairie but want to see one, you can go there virtually. Minnesota Scientific and Natural Areas Virtual Visits can take you to several, such as Bluestem Prairie near Glyndon and Lost Valley Prairie near Hastings. The websites for many state parks also offer virtual tours of their lands, such as Buffalo River State Park's panoramic views of Prairie View Trail and Big Sky Trail.

Another option is to view the PBS video Life of a Prairie, about a private, undisturbed prairie in western Minnesota. For a compilation of information about prairies, including some great photography, see the DNR's Prairie Stories. 

Spring ID of Bittersweet Vines

American bittersweet (Celastrus scandens) and invasive round leaf bittersweet (C. orbiculatus) are like identical twins: Only subtle differences tell them apart. 

This is especially true after their leaves have expanded and before they develop flowers. In this in-between time, the vines are practically impossible to distinguish. Both have twining stems with alternate, toothed leaves. Leaf shape is generally round, eliptical or egg-shaped with pointed tips, but their shapes are variable and overlapping. Even the name "round leaf" isn't much help to detect the invasive species, because its leaves aren't always round. 

In spring, though, two characteristics can help with ID: the way the leaves unfold or unfurl from the buds, called vernation, and how the flowers are positioned along the stem. 

Vernation

Inside the bud and as they begin to emerge, the edges of American bittersweet leaves are rolled inward, toward the upper side of the leaf. The botanical term for this is involute. In contrast, the leaves of round leaf bittersweet are folded vertically along the midvein, so the upper sides of the blade face each other. This is a conduplicate pattern. Depending on weather, vernation may happen quickly. Early observations are helpful. 

Left: American bittersweet leaves are involute -- they are rolled inwards in the bud and as they emerge. Middle and right: Round leaf bittersweet leaves are conduplicate -- intially, they are folded inward along the midvein. Photos by Lisa McIntire.

Flower Position

Bittersweet vines typically flower in May and June. The flowers of both vines are about 1/4 inch (5 mm) across and greenish white to greenish yellow with five petals. Male and female flowers are on separate vines.

The difference is the flowers' positions. American bittersweet flowers are clustered only at the ends of stems, whereas the flowers of round leaf bittersweet grow from leaf axils, the areas where leaves join stems.

American bittersweet flowers are clustered at the ends of stems and branches. No clusters grow from the axils. These are male (pollen-producing) flowers. Photo by Peter Dziuk, (c) 2011, from Minnesota Wildflowers. 

Unlike American bittersweet, clusters of round leaf bittersweet flowers grow from leaf axils. These are female (seed-producing) flowers. Photo by K. Chayka, (c) 2013, from Minnesota Wildflowers.

After flowering, male vines can't be identified to species using visible characteristics. Female vines, though, will develop fruits, and they are in the same positions as the flowers: American bittersweet at the ends of stems, round leaf bittersweet at the axils. 

The spherical capsules are initially green, but as the season progresses their walls ultimately turn either orange (American) or yellow (round leaf). In later summer and fall, the capsules split open to reveal red arils, fleshy berry-like structures that enclose the seeds. American bittersweet capsules contain only one seed; round leaf bittersweet capsules contain five. 

Left: Mature American bittersweet capsules are orange, later splitting to reveal red arils. Right: Mature round leaf bittersweet capsules are yellow. These have already opened. Both photos by Leslie J. Mehrhoff, University of Connecticut, Bugwood.org.

Why Early ID Is Important

Round leaf bittersweet is originally from Asia, introduced here for its colorful fruiting vines. It's more aggressive than native American bittersweet and will girdle and smother the trees it grows on. Its dense growth can shade out any plants below. The result is lower plant biodiversity, with consequent effects on insects, birds, and other animals. 

In Minnesota, round leaf bittersweet is listed as a noxious weed, and by law it must be prevented from spreading. Identifying the plant early, especially before it produces fruits, is important to contain its spread. More information is available from the Minnesota Department of Agriculture and the Minnesota Department of Natural Resources. 

Despite control efforts, round leaf bittersweet still finds its way into Minnesota. Seeds are dispersed by birds, and some online sellers will ship seeds or live plants into the state. Mistaken identity can be a problem, too. What's sold as American bittersweet is sometimes round leaf. Look at any photos on the seller's website and compare them to the pictures above. Better yet, if you want American bittersweet, buy it from a reputable, local native plant nursery.

If Round Leaf Bittersweet Is on Your Private Property

The Minnesota Department of Agriculture advises removing the vine but keeping it on your property to decay. Transporting it increases the possibility of fruits and seeds escaping.

If you have a wreath, spray or garland made from real fruiting vines, keep it indoors. Don't toss it outdoors, and don't throw it in the trash. Both will aid its spread. If you want to dispose of it and there is no other round leaf bittersweet on your property, take it to a composting site that accepts noxious weeds (call first) or enclose it in a clear plastic bag and put it in the sun for several weeks to months to kill any viable seeds. Crushing the seeds with a hammer may also be effective.

Plant Profile: Sharp-lobed Hepatica

Sharp-lobed hepatica (Anemone acutiloba) flowering in late April 2021 in southeast Minnesota.

 
Sharp-lobed hepatica, also called liverwort or liver leaf from the shape of its leaves, is a native woodland perennial that flowers before the canopy leafs out. As for other woodland wildflowers, this timing takes advantage of the brighter light and more abundant moisture on the forest floor in early spring.

Depending on the year, hepatica begins flowering in March or April and continues for about a month. Its leaves persist through winter and resume photosynthesis in spring. Around the time hepatica stops flowering, new leaves emerge and last year's leaves die. New leaves are covered with long hairs that help protect them from cold spells. The hairs are lost as the leaves age.

Left: Last year's leaves persist through winter, giving hepatica a head start on photosynthesis when spring arrives.

Right: New leaves emerge when hepatica nears the end of its flowering period. 

Hepatica is in the buttercup family, Ranunculaceae (ra-nun-cue-LAY-cee-ee). Typical of that family, the center of each flower is dome-shaped and bears many simple pistils and numerous stamens. Pistils are the seed-producing parts of a flower; simple pistils are composed of a single carpel, which evolved long ago from a seed-bearing leaf. Stamens are the pollen-producing parts of a flower.

Hepatica and several other members of the Ranunculaceae have no petals. Instead, their flowers have petal-like sepals above three green bracts. The flowers have pollen but no nectar and are an early-season source of food for several kinds of bees.

The color of sepals ranges from deep to light purple to white. Left: The profusion of white stamens and yellow pistils in the center of the flower is typical of plants in the buttercup family. Right: A mining bee (Andrena species) benefits from this early source of pollen.

Pollinated flowers eventually form achenes (ah-KEENs), small, dry, indehiscent (non-splitting) fruits that bear just one seed. (Like in-the-shell sunflower seeds.) Attached to the achenes are tiny bodies of fat called elaiosomes (eh-LY-oh-somes). These nutritious packets attract ants, which collect the achenes and bring them back to their nest. There, they eat the elaiosomes and leave the achenes in a presumably safe place for their seeds to germinate. (For more information about ant dispersal, see Antsy Plants.)

Hepatica also reproduces by rhizomes, underground stems that grow from a parent plant to produce genetically identical offspring – clones, in other words. As explained in an earlier post (What is a rhizome?), vegetative reproduction is faster and less expensive in terms of energy, but it sacrifices genetic variability among the offspring. That variability can be an asset to a population if it's faced with a changed environment, because more genetic variety offers greater potential adaptability. 

Range of sharp-lobed hepatica (left) and round-lobed hepatica (right) in the Minnesota region. Maps from USDA Plants Database (1).  

 A look-alike, round-lobed hepatica (Anemone americana), also grows in Minnesota. As its name suggests, its leaves have rounded instead of pointed lobes. Both species are found throughout the eastern half of the lower 48 states and adjacent provinces of Canada.

 

Cited References

1. Natural Resources Conservation Service. PLANTS Database. United States Department of Agriculture. Accessed April 14, 2025, from https://plants.usda.gov.

More Information

Minnesota Wildflowers

The Friends of the Wildflower Garden, Inc. Plants of the Eloise Butler Wildflower Garden.