Plant Profile: Common Elderberry

 Sambucus canadensis or Sambucus nigra subsp. canadensis

Common elderberry growing on the edge of a cattail marsh. The largest inflorescence (center left) is at least 10 inches wide.

Late June into July is prime time to spot common elderberry, also called black elderberry and American elderberry. These large, multi-stemmed shrubs produce small, white flowers in flat clusters that reach 10 inches wide -- the size of dinner plates. They're hard to miss.

Most likely, you'll find the shrubs along the edges of woodlands, wetlands, ponds, ditches and other moist to wet, open habitats. They grow to about 12 feet tall with slightly arching stems that are greenish when young and gray-brown when older. The bark of older stems is rough or warty from the presence of large, raised lenticels, areas of porous bark that allow the exchange of oxygen and carbon dioxide with the environment.

Older stems of common elderberry have prominent lenticels. Leaf scars are
left when last year's leaves fall of the stem.

Starting in late June, the shrubs produce flat or slightly domed inflorescences (clusters) of white florets at the ends of their stems. The florets are tiny -- no more than a quarter of an inch (about 5 mm) wide with five white petals, five stamens and a stubby, central pistil. The flowers are said to be fragrant, with a sweet, lemony, slightly musky odor. Some describe it as pleasant, others not so much. 

Common elderberry begins flowering in early summer. producing flat or slightly domed inflorescences of tiny florets. Each floret has five white petals, five radiating stamens and a short pistil.

The flowers attract a variety of pollinators. According to the Minnesota Pollination Guide, common elderberry is visited mostly by generalists, insects that seek pollen or nectar from many species of flowering plants. Illinois Wildflowers lists honeybees, carpenter bees, bee flies and scarab beetles among the plant's many pollinators.

The MN Pollination Guide also lists two moths as specialist pollinators: the elderberry shoot borer moth, Achatodes zeae, and the rusty tussock moth, Orygia antiqua. According to other sources, though, neither of them pollinates this plant. In fact, both are considered pests. Elderberry shoot moth larvae, also called spindle worms, bore into and feed inside elderberry stems, causing them to wilt (1). The larvae of rusty tussock moths feed on the leaves of many kinds of plants, evidently including elderberry (2). Many other insects also feed on various parts of the plant (3). 

Once pollinated, the flowers develop into small, deep purple fruits called drupes. Many birds eat the fruits, including robins, cardinals, blue jays, catbirds, song sparrows and wild turkeys (3). People, too, have long harvested the ripe fruits to make wine, pies, jelly and syrup. This takes some care, though, because elderberry stems, leaves, bark and unripe fruits contain potentially harmful levels of cyanogenic glycosides, which can release cyanide. Best advice is to avoid eating stems, leaves and unripe fruits and to cook ripe fruits before eating or baking with them (4, 5). 

Left: Common elderberry fruits turn from green to dark purple when they're ripe. Right: This single leaf is divided into seven leaflets. The lowermost leaflets are deeply lobed. They're almost divided into extra leaflets.

When it's not flowering or fruiting, common elderberry is identified by its opposite, pinnately divided leaves and its arching, warty stems. This is a pioneer species -- one that is among the first to inhabit an open or disturbed site  -- so it thrives in full sun. It spreads not only by seeds but also by rhizomes to form patches or thickets. This habit makes the shrub valuable for stablizing streambanks, wetland edges and other sites being reclaimed or restored (4, 6, 7). 

Common elderberry is similar to red elderberry (Sambucus racemosa), another native shrub, but the two are easily told apart by their flowering season, the shapes of their flower clusters, the color of their fruit and their habitats. Red elderberry blooms in early spring with pyramidal clusters of flowers that produce red fruits. In contrast, common elderberry blooms in early summer with more or less flat flower clusters that produce dark purple fruits. 

Red elderberry fruits, like the flowers, are in a pyramidal cluster.

Their habitats also differ. Red elderberry, the more shade-tolerant of the two, often grows in woodland understories. In contrast, common elderberry typically grows in open sites with more sun, although it's often spotted along woodland edges. 

In winter, elderberries can be identified by their clumps of arching stems, large lenticels, large opposite buds, and broadly triangular, V-shaped or U-shaped leaf scars. Common and red elderberry can be told apart by the color of the pith, the soft tissue in the center of the stem. Common elderberry has a white pith, whereas red elderberry has a yellow-brown pith.

Left: The white pith of common elderberry. Right: The yellow-brown pith of red elderberry. 

Several dogwood (Cornus) and Viburnum shrubs also resemble common elderberry in having flat inflorescences of small, white florets. Even their widest inflorescences are not as wide as those of common elderberry, however, and their leaves are smaller and simple, not divided. They bloom in spring instead of early summer. 

Highbush cranberry, Viburnum opulus var. americanum, has flat clusters of white
florets, but the outer florets are much larger than the inner florets. As seen in the
 upper right, the leaves are three-lobed but not divided.

Nannyberry, Viburnum lentago, has simple leaves. Typically the inflorescence
is 2-3 inches wide. Photo (c) 2005 Peter M. Dziuk, Minnesota Wildflowers. 

The inflorescences of pagoda dogwood, Cornus alternifolia, are 1-3 inches wide.
Florets have four petals, not five.  Leaves are simple with arcing veins.
Photo (c) 2014 Peter M. Dziuk, Minnesota Wildflowers.

Cited references

1. Integrated Pest Management, University of Missouri: Spindleworms in Elderberry Shoots

2. iNaturalist: Rusty tussock moth.

3. Illinois Wildflowers: Common Elderberry (Sambucus nigra canadensis)

4. Three Rivers Park District: Species Spotlight - Elderberries. 

5. Michael K Appenteng, Ritter Krueger, Mitch C Johnson and others. Cyanogenic Glycoside Analysis in American Elderberry. Molecules, Vol. 4, No. 5. March 4, 2021.

6. Rose C. Wetlzel, Adrienne R. Hobbins, and Matthew J. Wilson. Survival and Growth of Wetland Species as Live Stakes with Lessons for Effective Management Practices. Natural Areas Journal, Vol. 43, No. 4. 2023. Note: Abstract only.

7. Hannah E. Ormshaw and Toim P. Duval. Response of thicket swamp species to soil moisture levels: Implications for restoration. Ecological Engineering, Vol. 153. 2020. Note: Abstract and Introduction only.

Additional references

Minnesota Wildflowers

Three Rivers Park District

BWSR Featured Plant

Minnesota DNR - Minnesota Pollination Guide

Integrated Pest Management, University of Missouri: Spindleworms in Elderberry Shoots

Plant Profile: Illinois Carrion Flower

This plant of semi shade smells like its name.

Illinois carrion flower in bloom in late May.

The flowers smell, faintly, of rotting meat. 

It's not overwhelming, but if you stick your nose close to the flowers and take a whiff, you'll pick it up: Definitely carcass-like. 

The odor may make you recoil, but to insects it's alluring. Many kinds of flies are attracted not only by the smell but also by the pollen and nectar the flowers offer. They and an assortment of beetles and bees are the plant's primary pollinators (1, 2). 

Pollination happens in spring, when nearly spherical flower clusters, called umbels, grow from the lower nodes. Each flower is light green and just a quarter of an inch (about 5 mm) across, with six tepals -- three sepals and three petals that look so much alike that they are indistinguishable. 

Male (staminate) and female (pistillate) flowers are on separate plants, which means this species is dioecious (dy-EE-shus, literally meaning "two houses."). Male flowers have only stamens, six on each flower. They radiate outward like spokes on a bicycle wheel. Anthers, the pollen-producing organs on the tips of the stamens, are white to yellow. 

Left: An umbel of male flowers, each with six stamens tipped with white anthers. Right: An umbel of female flowers with bulbous ovaries, short styles, and three lighter green, thread-like stigmas. This photo is (c) 2018 by Katy Chayka of Minnesota Wildflowers.

Female flowers contains pistils, organs made of a somewhat bulbous ovary at the base, a neck called a style, and, at the tip, thread-like, pollen-collecting stigmas. Sterile stamens, called staminodes, may surround the pistil. They don't produce viable pollen, but they may serve some other function.

The smooth, round stems of carrion flower are more or less upright, unbranched and 2 to 3 feet long. Bract-like leaves grow at the base of the stem and broad, elliptical to egg-shaped leaves grow farther up. All leaves are alternate -- in other words, they are attached singly at the nodes, not in pairs or whorls. 

Leaf blades are dark to medium green on the upper surface and lighter below from fine, white hairs . To use the botanical term, the lower surface is pubescent. Several prominent, parallel veins run the length of the blades. Petioles (leaf stalks) of the largest leaves are at least as long as the leaf blades (1), but this characteristic is variable. The base of the blade is truncate (straight across) or rounded. 

Leaf blade upper surface (left) and lower surface (right). The lower surface appears lighter green from the presence of short, fine, white hairs. 

Ends of stems bear tendrils.

Short tendrils grow at the ends of the stems. Unlike the tendrils of many vines, these usually don't grasp anything, so the plants don't use them to hold themselves upright. The upper stem tends to lean over, however, and if the tendrils contact something -- the stem of a nearby plant, for example -- they'll grasp it.

After the pistillate flowers are pollinated, the ovaries grow into purple-black berries that are eaten by a variety of mammals and birds, such as raccoons, squirrels, cedar waxwings and cardinals. White-tailed deer will eat the young leaves (1). 

According to MNTaxa, Illinois carrion flower is one of five Smilax species in Minnesota. All five are listed below, with synonyms in parentheses.  

• S. ecirrhata, erect carrion flower
• S. herbacea, smooth carrion flower (S. herbacea var. herbacea)
• S. illinoensis, Illinois carrion flower 
• S. lasioneura, common carrion flower (S. herbacea var. lasioneura)
• S. tamnoides, bristly greenbrier (S. hispida)

In contrast to MNTaxa, Minnesota Wildflowers reports only four species; noting that Smilax herbacea is not found in the state. All four species grow in the shade to part shade of deciduous woods, thickets, and similar habitats. The Upper Midwest range map for Illinois carrion flower is below, from the USDA Plants Database.

Several species look alike and can be hard to tell apart. The Minnesota Wildflowers website describes the characteristics that identify them, and this key from Michigan Flora also may be helpful. It includes S. hispida, a synonym for S. tamnoides, as well as S. rotundifolia, which has not been reported in Minnesota.

The Flora of North America also has a key to Smilax. It includes 20 species, including those found in Minnesota.

Cited References

1. Illinois Wildflowers

2. Minnesota Pollination Guide

Additional References

Minnesota Wildflowers

Michigan Flora (key to Smilax species)

MNTaxa: The State of Minnesota Vascular Plant Checklist

Flora of North America

Natural Resources Conservation Service. PLANTS Database. United States Department of Agriculture. Accessed May 30, 2026, from https://plants.usda.gov.

What Are Spring Ephemerals?

In early spring, the understory of this deciduous woodland is bright with the flowers of false rue anemone (Enemion biternatum) and other spring ephemerals.

Spring ephemerals are herbaceous (non-woody) plants that emerge, flower, set seed and die back in spring. Many are woodland plants that take advantage of the brighter sunlight and more abundant moisture early in the season, before trees are fully leafed out.

These plants are an important source of nectar and pollen for insects that also emerge in early spring. The insects, in turn, are important pollinators for these plants. Ephemerals depend on them to fertilize their flowers so they can develop seeds. 

Because spring can be fickle, though, some ephemerals can also self-pollinate. If it's too cold for insects to fly, for example, several species can fertilize themselves. The resulting seeds carry the same genes as their parent, so the plants that grow from them are clones of that parent.

Vegetative reproduction also helps the plants spread. The false rue anemone pictured above, for example, produces not only seeds but also tuberous roots that can grow new plants. The large colony in the photograph is largely created in this way.

Most if not all spring ephemerals are perennials. After the plants flower and release seeds, the leaves of true ephemerals die back to bulbs, rhizomes, or other underground parts that store energy for next spring's growth. Some early-flowering plants keep their leaves for much of the growing season. Although these plants aren't true ephemerals, they are often included in that group.

Two Common Ephemerals

Dutchman's Breeches (Dicentra cucullaria)

Dutchman's breeches flower in April or May in the understory of deciduous forests. True to its name, its flowers resemble breeches (or britches) hanging upside down on a clothesline. 

Left to right: Dutchman's breeches flowering in early April; seed capsules ripening in mid-May; leaves gone by late May, leaving only light red tuber-like structures that store energy for next season's growth. 

The flowers are pollinated primarily by bumblebees and honey bees (1), but they can self-pollinate if the bees are absent. Seeds produced by self-fertilization may not be viable, however, and some consider the plants to be obligate out-crossers, meaning they form viable seeds only by out-crossing (2). After flowering, the plants develop elongated capsules containing dark, roundish seeds that are dropped from the capsules and distributed by ants (3). (See also Antsy Plants, a post about seed dispersal by ants.)

After flowering and seed formation, the leaves of Dutchman's breeches quickly decline. By late spring  only small, reddish bulbs or tubers remain. These storage organs are dormant until fall, when they develop leaf primordia (embryonic leaves) and flower buds. The primordia and buds then are dormant until spring, when they give rise to leaves and flowers (4). 

Bloodroot (Sanguinaria canadensis)

Another early spring bloomer, bloodroot is named for the red sap that fills its roots, flower stalks and leaf stalks. It emerges a little earlier than Dutchman's breeches, but the two overlap in their flowering time. Bloodroot is pollinated primarily by mining bees, but also by cuckoo bees, bee flies and sweat bees (5). 

Left to right: Bloodroot flowering in mid-April; elongated capsules maturing in mid-May; brown seeds with white elaiosomes in early June. 

Initially, bloodroot leaves are wrapped around flower stalks like cloaks, but eventually they unfurl, flatten and expand. Unlike Dutchman's breeches, bloodroot leaves persist until late summer before they die back..

In early to mid summer, bloodroot flowers are replaced by elongated capsules full of ant-dispersed seeds. Like Dutchman's breeches, bloodroot seeds have attached elaiosomes (eh-LAY-oh-sohms, literally "fat bodies"), They look like tiny worms, but these plant tissues are full of protein and fat that entice ants to carry the seeds to their nest, detach the elaiosomes to feed to their larvae and leave the seeds to germinate in a presumably safer place. 

Where to Find Spring Ephemerals

Wherever there are native deciduous forests, there should be spring ephemerals. Visit Scientific and Natural Areas and state and regional parks, such as Nerstrand Big Woods State Park in southeast Minnesota, Elm Creek Park Reserve in Maple Grove, or Mille Lacs Kathio State Park near Onamia. 

White trout lily (Erythronium albidum) flowering near Mille Lacs Kathio State Park in late April.

There are many more places to enjoy spring ephemerals. To find them, visit iNaturalist and look up the species described above (or others), or use the Minnesota Natural Resource Atlas. To use the atlas, open the Mapping Tool, choose Add Layers from the Options menu box, and in the Biota category choose Native Plant Communities -- Parks & Trails. Zoom in and look for areas of Mesic Hardwood Forest System.

Wisconsin and Iowa are also good places to look for spring ephemerals. A quick search finds that, in Wisconsin, the Northwoods Wildlife Center near Minocqua and Rib Mountain State Park near Rib Mountain are full of spring ephemerals. The Iowa DNR has a webpage dedicated to Woodland Wildflowers & Reports. The listed sites are from 2025, but the same should be true for 2026. 

References

1. The pollination ecology of Dicentra cucullaria. Lazarus Walter Macior, American Journal of Botany, Vol. 57, No. 1. 1970. 

2. Flowering ecology of some spring woodland herbs. Douglas W. Schemske and others. Ecology, Vol. 59, No. 2. 1978.

3. Myrmecochory: How Ants Shape Plant Communities. Julie Michaelson, Xerces Society. 2024. 

4. Dicentra cucullaria. Flora of North America, Vol. 3. Website accessed 2-17-26.

5. Pollinators of Native Plants: Attract, Observe and Identify Pollinators and Beneficial Insects with Native Plants. Heather Holm. Pollination Press, LLC. 2014. Available here and at some libraries.

Native Plant Seed Germination: Some Resources

There's something deeply satisfying about growing plants from seeds. More than cuttings or divisions, seeds hold the promise, or at least the potential, for new life. 

Most seeds packaged for sale in retail stores are easy to germinate. They might take a week or more to emerge, but they don't require special treatment other than adequate warmth, moisture, oxygen and sometimes light.

Seeds purchased from native plant nurseries or collected from wild native plants often need more attention. Many of these seeds are dormant, meaning they won't germinate even in favorable conditions. It's an adaptation that prevents the seeds from germinating when the seedlings are unlikely to survive, such as in late fall heading into winter.

Causes and Treatments

Seed dormancy has many causes, and different species have different causes. For example, the seeds of ironweed, Vernonia fasciculata, need cold, moist conditions for a month or two before they'll germinate. That's likely due to immature embryos that need time to develop and/or chemical inhbitors that must leach out or otherwise diminish in concentration before the embryos can grow (1). 

Ironweed flowers in late summer and early fall with brilliant purple heads of flowers. These plants were about 6 feet tall. Eventually the heads fill with bundles of seeds that are wind-dispersed.

Nature provides those conditions over winter, but the seeds can also be treated artificially. In a process called cold-moist stratification, the seeds are placed in a damp medium or on damp filter paper and refrigerated for some length of time. How long the seeds must be stratified depends on the species. For ironweed, it's one or two months.

Another example is smooth wild rose, Rosa blanda. The small, seed-like fruits, called achenes (ah-KEENs) of this native shrub are doubly dormant, meaning they have two types of dormancy that must be overcome before the seeds will germinate. In this case, the embryos are immature even when the hips are red and ripe, In addition, the seeds are surrounded by a hard pericarp, or fruit wall, that physically prevents germination (2).

Smooth rose blooms in late spring and early summer. Rose hips ripen in early fall, Each hip contains several small, seed-like fruits called achenes.Each achene has a hard fruit wall, or pericarp.

In nature, the double dormancy of the achenes is broken by up to two years of cold (winter) and warm (summer) conditions. The seeds then germinate the second spring after they are produced. 

Artificial treatment of the achenes begins with scarification, a wearing away of the pericarp by immersing the achenes in boilng water, rubbing them lightly with sandpaper, or using other methods.  Then the seeds are stratified in alternating temperatures, starting with cold-moist stratification, then warm-moist stratification (60-70 F), then another cold-moist stratification (3, 4). The Propagation Protocol Database (5) recommends one month of warm-moist stratification followed by four months of cold-moist stratification. 

Seed dormancy is a complex topic involving biochemistry, ecology and evolution. To learn more about it and to learn how to break the seed dormancy of particular species, see the reference sections after Cited References.

Cited References

1. Germination of Native Prairie Forb Seeds. J.T. Sorensen and D.J. Holden. Journal of Range Management Volume 27, No. 2. 1974.

2. Seed Germination within Genus Rosa: The Complexity of the Process and Influencing Factors. Roxana L. Stoian-Dod and others. Horticulturae Vol. 9, No. 8. 2023.

3. Smooth Rose (Early Wild Rose, Meadow Wild Rose, Labrador Rose). G.D. Bebeau. The Friends of the Wildflower Garden, Inc. Trees & Shrubs of the Eloise Butler Wildflower Garden. 2013. 

4. Rosa blanda, Early Wild Rose. Prairie Moon Nursery. Website accessed December 24, 2025. 

Seed Dormancy References

Understanding Seed Dormancy and Germination Requirements of Rare Plants. Dustin Wolkis, Center for Plant Conservation. 2022.

Seed Dormancy: What Is It? SeedImages.com, Colorado State University. Website accessed December 20, 2025. 

Seed Dormancy Mechanisms. SeedImages.com, Colorado State University. Website accessed December 20, 2025.

Seeds: Ecology, Biogeography, and Evolution of Dormancy and Germination. Carol C. Baskin and Jerry M. Baskin. 2nd edition. 2014. Academic Press, San Diego. (This is a textbook available through several booksellers.)

The evolution of seed dormancy: environmental cues, evolutionary hubs, and diversification of the seed plants. Charles G. Willis and others. New Phytologist Vol. 203, Issue 1. 2014. 

Species-Specific Methods to Break Dormancy

Propagation Protocol Database. Native Plant Network. Search for the plant of interest by entering its genus, then choose the species.

Prairie Moon Nursery. The website for this Minnesota-based native plant nursery includes germination information for many species. Search for and select the species of interest, then look for a table entry called Germination Code. See also their list of seeds that need no treatment.

Native Seed Propagation Methods. This guide from the Missouri Botanical Garden includes instructions for many methods of breaking seed dormancy, along with specific treatments for selected native plants. Some of the species listed may not be native to the Minnesota region.

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. 

Plant Profile: Zigzag Goldenrod

 Solidago flexicaulis | Family Asteraceae (Aster) 

Zigzag goldenrod along a woodland edge in August.

Zigzag goldenrod, also called big leaf goldenrod, is a native perennial of forest edges and openings. It’s literally a late bloomer, flowering from August into October with narrow, upright clusters of yellow-gold flowers at the top of the plant and from the upper nodes.

Each “flower” is actually a group of small flowers in a head inflorescence, an arrangement typical of plants in the aster family. The central flowers, called disk flowers, have small, recurved, yellow petals that are easiest to see with a magnifying lens. Around them are several ray flowers, so called because each bears a single, petal-like ray. Zigzag goldenrod heads typically have 3-5 rays at their peak.

Left: A single head of small flowers. Two rays are visible. The "spears" emerging from the flowers are stamens and pistils, the reproductive parts of the flower. Right: A single head dissected to show disk and ray flowers. The white threads at the base of the flowers are a group of modified sepals called a pappus.

At the base of either kind of flower are white, thread-like, modified sepals, together called the pappus. Unlike the leafy or petal-like sepals many plants have, these tiny filaments persist after flowering. They are attached to the top of small, linear fruits called achenes (ah-KEENS). A single plant produces hundreds (thousands?) of them, each carried by wind with the help of its parachute-like pappus.

Left: The fruits on this zigzag goldenrod are ready to catch the wind.
Right: Individual achenes, each just a millimeter or two long and topped with a spreading pappus. 

Even before it flowers, zigzag goldenrod is easy to recognize. As its name suggests, the stems typically zig and zag from one node to the next. The pattern is subtle, but it’s still a good identifying characteristic.

The name “big leaf” refers to the lower leaves, which are egg-shaped and up to 4 inches wide and 6 inches long. Their margins (edges) are coarsely toothed and their petioles are winged, especially where they meet the leaf blades. Farther up the stem, the leaves are smaller and lance shaped.

Left: A stem with a typical zig zag pattern. Upper right: Lower and middle leaves are egg shaped and sharply toothed.
Lower right: Upper stem leaves are lance shaped, becoming smaller up the stem.

Zigzag goldenrod spreads not just with seeds but also with rhizomes to form colonies. It isn’t as aggressive as Canada goldenrod, but patches will expand noticeably in a few years. That’s helpful where cover is desired but not so helpful in formal gardens, where plants are often preferred to stay in place.

Zigzag goldenrod is pollinated by a variety of insects, including bees, flies, wasps and butterflies. Goldenrods in general, along with asters, are important sources of food for pollinators late in the season. Goldenrods also host insect larvae, such as the colorful caterpillar of the brown-headed owlet moth.

Left: A bumble bee pollinates zigzag goldenrod while gathering nectar and pollen.
Right: A caterpillar of the brown hooded owlet moth feeds on zigzag goldenrod.

It’s hard to fault zigzag goldenrod for anything, but goldenrods in general have a reputation for causing seasonal allergies. Their pollen, however, is relatively heavy and sticky, ideal for attaching to insect bodies but not for catching the wind. The pollen of common ragweed and giant ragweed, however, is light, dry and wind-borne, and it’s released from mid-summer to mid-fall, about the same time as goldenrods. Also, ragweed grows in the same dry, sunny habitats that favor some goldenrods, so the latter gets a bad rap.

It’s undeserved. No need for tissues to enjoy zigzag goldenrod. Just a semi-shady spot and an appreciation for this golden yellow pollinator magnet.

References

Minnesota Wildflowers

Board of Water and Soil Resources

Blue Thumb

Illinois Wildflowers

Plants for Bee Specialists

Jerusalem artichoke, Helianthus tuberosus, is one of several sunflower species favored by the sunflower mining bee, a specialist pollinator.

The sunflower mining bee, Andrena helianthi, has discriminating tastes.

This native bee is a specialist, gathering pollen primarily from plants in the aster family, Asteraceae (formerly Compositae, also called composites). To be more specific, it favors pollen from plants in the genus Helianthus, the sunflowers, to feed its larvae. (1).

In pollinator terminology, the sunflower mining bee is oligolectic, meaning “few chosen.” It’s far from alone in having narrow food preferences. According to the recent Minnesota Statewide Bee Survey (2), about 30% of the nearly 360 bee species confirmed in the survey are oligolectic.

Benefits and Drawbacks of Oligolecty

Given that high number, there must be advantages to oligolecty. One possibility is that the bees co-evolved with a few host plants that offer more digestible pollen (3). Entomologists at the University of Wisconsin found that the larvae of the blueberry mason bee, Osmia ribifloris, thrived when fed preferred host pollen that also included the microbes naturally found in that pollen. In contrast, larvae fed microbe-free pollen from the preferred host plant were much less fit, and larvae fed pollen from non-host plants had intermediate fitness (4).

Plants benefit from the relationship, too. Species visited by oligolectic bees have dedicated pollinators that transfer pollen among only a few kinds of plants, which makes successful pollination more likely. The plant loses less pollen to insects that carry it to a wider variety of plants, most of which can’t use it.

The potential disadvantage for both oligolectic bees and their plant hosts is that if either one becomes rare, its partner could become rare, too. A spiraling decline of both bees and plants happens when, for example, a plant population is displaced by an invasive species or fails to thrive in a warmer or wetter environment. As the plant becomes less abundant, so does the oligolectic bee that depends on it. In turn, as the oligolectic bee becomes less abundant, so can the plant that depends on it for pollination. If fewer seeds are produced, the population may decline further, with consequent effects on the oligolectic bee, and so on. It’s a vicious circle that can be difficult to interrupt.

The Habitat Solution

Difficult but not impossible. The answer is to provide habitat, including preferred host plants, for the sunflower mining bee and other oligolectic species. Fortunately, there are several resources to learn which plants or groups of plants benefit which bee species.

Entomologist and ecologist Jarrod Fowler compiled a list of bee specialists documented in the Central U.S., a region that includes Minnesota, Iowa, Wisconsin, North Dakota, and South Dakota (3). He also tabulated their preferred plant(s) and found that species in the aster or sunflower family, Asteraceae, and the bean or pea family, Fabaceae, were visited most frequently by specialist bees in this region.

In addition, he noted the top 25 genera that support oligolectic bees. The genera found in this region include Helianthus (sunflowers), Heterotheca (false goldenasters), Solidago (goldenrods), and Symphyotrichum (asters).

Although Helianthus is a favorite of sunflower mining bee, the insect has also been collected from the flowers of (l to r) cup plant (Silphium perfoliatum), New England aster (Symphyotrichum novae-angliae) and goldenrod (Solidago) species, here showy goldenrod (S. speciosa).(1)

The Minnesota Department of Natural Resources’ Minnesota Bee Species List is another useful resource (5). The list of around 460 bees includes both those that collect pollen and those that are parasites on other bees’ nests. For those that collect pollen, the table provides the species’ lecty (range of pollen preference, either oligo- or poly-) and its nesting habitat, if either is known.

The species list in the Minnesota Statewide Bee Survey (2) includes not only the bees’ names and lecty, if the latter is known, but also the ecological province(s) where each species was found. The report includes distribution maps of the bee species as well as their conservation status, or S-rank, which can range from S1 (critically imperiled) to S5 (secure).

The 2024 Featured Plant series from the Board of Water and Soil Resources (6) highlights several plants that support specialist bees or other insects. A Featured Plant is posted online at the beginning of each month.

If you observe and photograph bees visiting plants, consider submitting your records to iNaturalist. Several bee-related projects are hosted on this online platform, including Minnesota Native Bees. To find other projects, go to the iNaturalist website, choose Projects from the Community drop-down menu, and type “bees” into the search box.

Who knows, maybe the sunflowers you watch this summer and fall will host sunflower mining bees. Although the bees were uncommon to rare in the state’s bee survey, you could be the lucky one who spots this specialist pollinator.

References

1)  Andrena helianthi, Robertson 1891. Discover Life. Website accessed July 3, 2024.

2)   Minnesota Statewide Bee Survey 2014-2023. Minnesota Department of Natural Resources.

3)   Pollen Specialist Bees of the Central United States. Jarrod Fowler, 2020.

4)   Dharampal, P.S., Hetherington, M.C., and Steffan, S.A. 2020. Microbes make the meal: oligolectic bees require microbes within their host pollen to thrive. Ecological Entomology 45: 1418-1427. DOI: 10.1111/een.12926. https://par.nsf.gov/servlets/purl/10253224

5)    Minnesota Bee Species List. Minnesota Department of Natural Resources, August 2023.

6)     Board of Water Resources Featured Plant series, 2024. (Red-berried elder is the July featured plant; plants featured in earlier months are in the Featured Plant archive.)