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.  

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.

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

Plant Profile: Wild Carrot

 Daucus carota L./Carrot family, Apiaceae

Wild carrot, Daucus carota, growing along a roadside near Maple Plain, MN, on August 10, 2024.

Wild carrot, also called Queen Anne’s lace, is a Eurasian biennial introduced to North America by colonists for food or medicinal use. It produces basal rosettes of carrot-like leaves the first year and leafy stems topped with umbels (umbrella-shaped clusters) of small, white flowers the second year. It blooms in mid- to late summer, typically in the dry soils and full sun of disturbed sites, such as abandoned lots, old fields, rail corridors, and roadsides. It spreads by seeds, and they are abundant. Because a single plant blooms continuously in its second year, that plant can produce thousands of seeds before it dies.

As the name “wild carrot” suggests, this is the ancestor of cultivated carrots. Wild carrot’s taproots are carrot-like in shape and smell, although they’re narrower than cultivated carrots and become bitter and woody with age, especially in the plant’s second year of growth.

Although some sources caution against eating wild carrot, it’s generally considered non-toxic and edible. Large quantities can raise blood pressure or make it difficult to regulate (1). In some people, sap from the plant can irritate the skin when it’s exposed to sunlight, a condition called phytophotodermatitis, literally “plant-light-skin inflammation” (2, 3, 4). In addition, carrot greens, presumably from cultivated carrots, are listed as mildly toxic on the list of poisonous plants from the MN Poison Control System, now the Minnesota Regional Poison Center. Wild carrot greens may have the same effect.

Deadly Look-Alikes

The much greater danger in foraging wild carrot is mistaking deadly look-alikes for this plant. Water hemlock (Cicuta maculata) and poison hemlock (Conium maculatum), also in the carrot family, resemble wild carrot and have accidentally been added to salads or sampled in the field or garden. The result can be severe illness and even death caused by the plants’ alkaloids, compounds many plants produce to deter herbivores. All parts of these plants are toxic.

Three look-alikes. From left: Wild carrot, water hemlock, poison hemlock. Water hemlock photo by Rob Routledge, Sault College, Bugwood.org. Poison hemlock photo by Eric Coombs, Oregon Department of Agriculture, Bugwood.org.

Accurate Identification is Crucial

Several resources help identify wild carrot and its look-alikes. A plant identification sheet from the University of Minnesota Extension Service contrasts poison hemlock with ten other plants, including water hemlock and wild carrot. An article by the Clearwater Conservancy in Pennsylvania includes a table contrasting the characteristics of seven members of the carrot family, including those featured here. The Minnesota Department of Transportation also has a guide to identifying poison hemlock and its look-alikes..

Here are some additional tips.

Tip 1: Wild carrot umbels sometimes have a dark red or purple flower in the center. Beneath the umbels are long, branched bracts. After flowering, the umbels curl up and in to form a bowl or nest. That’s why wild carrot is sometimes called bird’s nest. Neither water hemlock nor poison hemlock have these characteristics.

 

Left: After flowering, wild carrot umbels turn up and in to form a small nest. Notice the long, branched bracts below the umbel. Right: A purple flower in the center of a wild carrot umbel (arrow). Not all umbels have them.

Tip 2: The plants are hardest to distinguish in their first year of growth, when they produce only basal leaves. All three have pinnately divided leaves, but wild carrot leaves are narrower in outline and more finely divided into narrower leaflets. The leaves of both water hemlock and poison hemlock are broader, triangular in outline, and have wider leaflets. Poison hemlock leaves are often described as fern-like.

 

From left: Leaves of wild carrot, water hemlock, and poison hemlock. Not to scale. Water hemlock photo by Steve Dewey, Utah State University, Bugwood.org. Poison hemlock photo by John Cardina, The Ohio State University, Bugwood.org

Tip 3: Habitat and flowering phenology differ somewhat among these plants, but because they overlap, they are less reliable characteristics. In general, wild carrot thrives in sunny, well-drained, disturbed places such as pastures, old fields, roadsides, and railway corridors. In Minnesota it flowers as early as May and as late as October, but more typically from July to September.

In contrast, water hemlock is an obligate wetland plant. It needs the moist soils of wet prairies, wet meadows, marshes, and streambanks. It flowers from June to September. Poison hemlock also prefers wet or moist soils, but it will tolerate drier conditions. Its habitats include streambanks, ditches, roadsides, and pastures. It flowers in June and July.

If You Find Poison Hemlock

Because poison hemlock, an introduced plant, is so hazardous and because it’s not yet so widespread in Minnesota that it can’t be controlled, its locations should be reported to Report A Pest or EDDMapS. Do not remove it without taking serious precautions. Better yet, hire a professional (5).

Cited References

1)     Wild Carrot. Missouri Poison Center. Accessed August 11, 2024.

2)     Wild Carrot. Minnesota Department of Agriculture. Accessed August 11, 2024.

3)     Phytophotodermatitis Clinical Presentation. William P. Baugh, MD. Editor William D. James, MD. Medscape. Updated November 4, 2021.

4)     Queen Anne’s lace (Daucus carota). Minnesota Department of Natural Resources. Accessed August 12, 2024.

5)     Poison hemlock. A. Gupta, A. Rager, and M. M. Weber. University of Minnesota Extension Service. Reviewed in 2020. Accessed August 12, 2024.

Additional References

Daucus carota (Queen Anne’s Lace). Minnesota Wildflowers. Accessed August 12, 2024.

Water Hemlock. G.D. Bebeau, The Friends of the Wildflower Garden, Inc. Accessed August 12, 2024.

Cicuta maculata (Water Hemlock). Minnesota Wildflowers. Accessed August 12, 2024.

Poison hemlock (Conium maculatum). Minnesota Department of Natural Resources. Accessed August 12, 2024.

Poison Hemlock. Minnesota Department of Agriculture. Accessed August 12, 2024.

Poison hemlock (Conium maculatum). Minnesota Department of Natural Resources. Accessed August 12, 2024.

Minnesota Noxious Weed List. Minnesota Department of Agriculture. Accessed August 12, 2024.

Chadde, S.W. 2012. Wetland Plants of Minnesota. 2^nd ed. A Bogman Guide.

Plant Profile: Wild Ginger

A single flower emerges between a pair of leaves of wild ginger, Asarum canadense.

In spring, wild ginger is one of the first plants to emerge on the deciduous forest floor. Softly hairy leaves grow in pairs from shallow rhizomes, eventually expanding into heart- or kidney-shaped blades 3-5 inches wide. Mature petioles, or leaf stalks, are several inches long, and like the leaves, they are finely white-hairy. To an imaginative observer, they resemble pipe cleaners.

A single, reddish-brown, tubular flower develops in the axil of each pair of leaves. The flower is close to the ground on a slightly bent peduncle, or flower stalk. The flower has no petals, but its three, long-pointed sepal resemble petals and curve back over an open floral cup.

Inside the cup, the stigmas – the parts that receive pollen – mature first. They’re in the center of the flower, supported by their styles and surrounded by 12 stamens. Initially the stamens bend down and away from the stigmas, their pollen-bearing anthers lying parallel with the bottom of the cup. Over several days, the stamens straighten.

This dissected flower shows a central column of several upright stamens (solid arrow) surrounding stigmas and styles, which are hidden. The whitish dust around the top of the column is pollen. Several anthers still rest on the bottom of the cup (dashed arrow). 

Left: A flower with most stamens upright and a few still lying on the bottom of the floral cup.
Right: An older flower with all stamens upright.

A Pollination Puzzle

Pollination is a bit of a mystery. Many general references say the flowers are pollinated by flies and ground beetles attracted to the flowers’ fleshy color and supposed rotting-meat odor. As it turns out, that’s an assumption passed from one reference to the next, but it’s easy to see why it persisted.

Wild ginger doesn’t look like something pollinated by bees or butterflies. Although the flowers are beautiful in their details, they’re generally drab and mostly hidden under the leaves. They don’t look anything like the brightly colored, conspicuous flowers typically pollinated by bees or butterflies. Instead, their maroon to brown color matches that of animal flesh, like the flowers of some other plants pollinated by flies.

The bright yellow flowers of marsh marigold (Caltha palustris), left, are typical those pollinated by bees and other insects. The flower structure of skunk cabbage, center, looks and smells like decaying animal flesh and is pollinated by flies. Wild ginger, right, more closely resembles a fly-pollinated flower, at least in color. Photos not to scale. Skunk cabbage photo © 2009 Katy Chayka at Minnesota Wildflowers, used with permission granted on the website. 

Skunk cabbage (Symplocarpus foetidus), another Minnesota native, is a good example. It emerges in late winter or very early spring, even while snow covers the ground. Its flowering structure is a reddish-brown, leaf-like spathe enclosing a club of flowers called a spadix. As the plant’s name suggests, the structure has a fetid, dead-skunk smell. The small flowers on the spadix are pollinated by flies and beetles drawn to the plant’s carrion-like color and odor.

Other Evidence

Wild ginger doesn’t smell that bad. A sniff test finds that, at worst, the flowers can have a slightly unpleasant odor, but they don’t smell so strongly of rotting carcass that you would recoil. “Earthy” might be the best word to describe it. Some even say the flowers have a sweet smell. In any case, they aren’t obvious fly bait.

Early studies of wild ginger find other contradictions with the fly-pollination hypothesis. In the late 1940s, Harvey E. Wildman of the University of West Virginia experimented with wild ginger flowers to answer the question of how they’re pollinated (1). He removed the stamens from one group of flowers and left another group intact. In each group, he covered some of the flowers in wax paper bags (after ensuring no insects were inside the flowers) and left others uncovered. After several weeks, he checked the flowers for seed development.

None of the flowers with stamens removed, even those that were uncovered, developed seeds. In fact, all such flowers he checked had either fallen off or withered. In contrast, most of the flowers left intact developed “sound seeds.” That includes the ones that were covered. Wildman also reported that few insects were found inside any of the flowers.

If the flowers were strictly cross-pollinated by flies or other insects, at least some of the uncovered ones without stamens would have developed seeds, because something would have brought pollen to their stigmas. At the same time, the intact, covered flowers would not have developed seeds, because insects did not have access. Wildman concluded that wild ginger is primarily self-pollinated, not cross-pollinated.

Timed for Cross-Pollination?

Although Wildman’s experiment is illuminating, pollination is still a head-scratcher. One way plants foster cross-pollination is by staggering the development of stigmas and anthers inside a single flower, and wild ginger does exactly that. As mentioned above, the stigmas mature first, Eventually the filaments and anthers straighten and approach the stigmas, but not before the flowers have had a chance to receive pollen from another plant. This suggests that self-pollination is a back-up rather than a primary means of fertilization. Are we missing a pollinator? 

Whether self-pollinated or somehow cross-pollinated, fertilized flowers later develop seeds within capsules. When the capsules open in mid-summer, they expose small seeds with tiny fat bodies attached. The bodies, called elaiosomes (e-LY-oh-somes or e-LAY-oh-somes) attract ants, which carry the seeds back to a nest, eat the elaiosomes or feed them to their young, and leave the seeds to germinate, safely out of reach of seed predators. Seeds can also fall next to the parent plant and germinate there.

Left: The swollen ovary at the base of the flower indicates that this flower has been fertilized. Center: The same flower viewed from above. Each of the twelve dots around the center is what remains of a stamen. Right: Seeds are released in mid-summer. Each is just a few millimeters wide and long, with a golden-brown elaiosome attached. 

Rhizomes for Spread, Not for Spice

A rhizome of wild ginger (arrow).

If its seeds don’t succeed in helping wild ginger reproduce, its rhizomes can. (See the previous post for more about rhizomes.) The plant is almost aggressive in its vegetative spread, quickly filling suitable habitat, especially where it has limited competition.

Many say the rhizomes are aromatic and ginger-y in smell and taste. Although they have a long history of use as medicine and flavoring, ingesting them in any form is discouraged now. Wild ginger rhizomes and other parts have been found to contain variable amounts of aristolochic acid, a compound known to damage kidneys and perhaps cause cancer (2, 3). Handling the plants can also cause dermatitis.

This isn’t true of ginger roots (rhizomes) or ginger spice found in grocery stores. Culinary ginger is “true” ginger, Zingiber officinale, a tropical plant. It is not related to Asarum canadense.

Where to Find Wild Ginger

Wild ginger is native to deciduous and mixed deciduous-coniferous forests. It prefers full to part shade and moist, humus-rich soils. It wilts in prolonged drought. 

Wild ginger range in the upper Midwest and North America. Maps from USDA NRCS Plants Database (4).

Cited References

1)      Wildman, Harvey E. 1950. Pollination of Asarum Canadense L. Science 111 (2890): 551. http://www.jstor.org/stable/1676584.

2)      McMillin, D.L., Nelson, C.D., Richards, D.G., and Mein, E.A. 2003. Research Report: Determination of Aristolochic Acid in Asarum canadense (Wild Ginger). Meridian Institute.

3)      Qingqing Zhou, et al. 2023. Overview of aristolochic acid nephropathy: an update. Kidney Res Clin Pract 42 (5): 579-590.

4)      USDA, NRCS. 2024. The PLANTS Database (http://plants.usda.gov, 05/01/2024). National Plant Data Team, Greensboro, NC USA.

Other References and More Information

Anderson, M.K. Ed. 2000, 2003 and 2006. Plant Guide: Canadian Wildginger. USDA NRCS National Plant Data Center, Davis, California.

Baskin, J. M., & Baskin, C. C. 1986. Seed Germination Ecophysiology of the Woodland Herb Asarum canadense. The American Midland Naturalist, 116 (1), 132–139. https://doi.org/10.2307/2425945

Dunphy, S.A. Meadley, K. M. Prior, and M.E. Frederickson. 2016. An invasive slug exploits an ant-seed dispersal mutualism. Oecologia 181: 149-159. DOI 10.1007/s00442-015-3530-0 .

Hayden, W. John. 2010. Don't Judge a Book by its Cover: The Curious Case of Wild Ginger Pollination. Bulletin of the Virginia Native Plant Society 29 (1): 1, 6.

Schultz, K. 2014. Using shade to propagate Canadian wild ginger (Asarum canadense L.) and other woodland forbs. Native Plants Journal 15 (3): 231-235. DOI: https://doi.org/10.3368/npj.15.3.231.

Stritch, L. No date. Plant of the Week: Wild Ginger (Asarum canadense L.). USDA, US Forest Service.

 

Plant profile: Jumpseed

Persicaria virginiana, formerly Polygonum virginianum, Antenoron virginianum, Tovara virginiana

 

Jumpseed, also called Virginia knotweed or woodland knotweed, is a perennial herbaceous plant native to the eastern U.S., including southeast and east central Minnesota. It thrives in the damp soils and part shade of deciduous woods and edges, often where there has been some disturbance. These plants were growing along a trail through a woodland.

From July into September, the plants produce long, slender racemes bearing tiny, whitish flowers, each just a few millimeters across when fully open. After pollination by honeybees, bumble bees, leaf-cutting bees, and other bees and wasps, the flowers form small fruits that are deflexed – they angle downward on their short pedicels (flower stalks), a tensioned position that needs only a slight touch to be released. When it is, the fruits “jump” off the plant. Their hooked ends, formed by remnants of their styles, can latch on to fur or clothing and help the seeds travel farther from their parents.

Jumpseed flowers in mid to late summer, producing slender racemes up to 16 inches (40 cm) long. The small flowers
have four sepals, but no petals. Fruits have hooked tips that can latch on to passing animals, including humans. 

Jumpseed also spreads by rhizomes, underground stems that form patches of plants. Where the plants aren’t desired, this can be a problem, because they tend to persist even after pulling. The same is true for eastern jumpseed, an introduced plant. Once considered a variety P. virginiana called filiformis but now recognized as a separate species, Persicaria filiformis, it is beginning to develop a reputation as invasive because of its rhizomatous habit. It differs from P. virginiana in having pink to red flowers and often variegated leaves, characteristics that make it popular in the horticultural trade. Several cultivars of eastern jumpseed, such as ‘Painter’s Palette,’ ‘Lance Corporal,' and ‘Batwings,’ are offered for sale from some nurseries.

The last two cultivar names come from colorations on jumpseed’s leaves. In spring, the leaves are marked with maroon or dark green chevrons, upside down V’s that resemble military insignia or wings. The chevrons on Virginia jumpseed disappear by the time the plants flower, but those on eastern jumpseed leaves may persist.

Jumpseed has alternate leaves and hairy ocreas.
Notice the swollen nodes. 

Jumpseeds belong to the buckwheat or knotweed family, Polygonaceae (poly-gon-AY-see-ee). A typical trait of the family is a thin sheath called an ocrea (or ochrea) above each node. In formal terms, the sheath is described as scarious, meaning it is dry and membranous. The ocrea is formed from stipules that, sometime in the long history of knotweeds, fused to form a tube around the stem. 

Another trait that identifies this family is its knobby or swollen nodes. They resemble knees, if you use your imagination. Polygonaceae means “many knees.”

References

Minnesota Wildflowers

Illinois Wildflowers

Maryland Invasive Species Council (Persicaria filiformis)

John Philip Baumgardt. How to Identify Flowering Plant Families: A Practical Guide for Horticulturists and Plant Lovers. Timber Press, 1982. 

Plant Profile: Michigan Lily

 

Michigan lily flowering in mid-July in Hennepin County, Minnesota.

This lone Michigan lily (Lilium michiganense), barely out of reach of the ditch mower and surrounded by invasive reed canary grass (Phalaris arundinacea), grows at the edge of a wetland. That’s typical for this native perennial, which is also found along streambanks and shores and in wet meadows, prairies, bogs and woodland edges and openings.

Michigan lily looks much like Turk’s cap lily (Lilium superbum), another native that grows in the same habitats farther south. In fact, some references call Lilium michiganense Turk’s cap lily, a mix-up that shows why scientific names are helpful. They may be tongue-twisters, but unlike common names, scientific names are usually the same no matter where you are (or what you’re reading), so there’s less confusion.

According to most references, this one is almost certainly Michigan lily. It’s 3–4 feet tall, well within the 3– to 6–foot height typical of this species. Turk’s cap lily tends to grow taller, usually 5–7 feet.

Their flowers also differ, but the differences are subtle. Both species have umbels of nodding flowers with orange-red, dark-spotted tepals (similar petals and sepals) that are reflexed, bending back toward the base of the flower. Large stamens and a long pistil emerge from the center of the flowers and hang downward.

Umbels of Michigan lily flowers (left) and sets of whorled leaves on the stem (right).

In Michigan lilies the tips of the tepals are said to reach the base of the flower, but not much farther. In contrast, the tepals of Turk’s cap lily reach so far back they go beyond the base of the flower and may touch each other. In addition, their anthers, the pollen-bearing tips of the stamens, differ in length. According to several references, those of Michigan lily are never more than ½ inch long, whereas those of Turk’s cap lily are at least ½ inch long or longer.

If you don’t have a ruler handy, there are other differences to look for. If flower buds are present, look at their shapes. Michigan lily buds are more or less round in cross section, whereas Turk's cap lily buds are triangular. Open flowers also display differences. The pistil of Michigan lily is orange-red, whereas the pistil of Turk’s cap lily is greenish white to whitish orange. Looking deep into the flower, you’ll sometimes see a green, star-shaped center in Turk’s cap lily, but not in Michigan lily. 

Another look-alike is the introduced tiger lily, Lilium lancifolium, a garden favorite. It differs from both Michigan and Turk’s cap lilies in that it has alternate, not whorled, leaves, and small bulbs in the leaf axils.

Growing near this Michigan lily was yet another look-alike, Tawny day lily, Hemerocallis fulva. Also called ditch lily for its common habitat, it has orange-red flowers that open upward and have streaked but not spotted tepals. Day lilies have strap-shaped basal leaves but no leafy stems.

Tawny day lily flowers on leafless stems amid strap-shaped basal leaves. The flowers open upward, their red-orange tepals streaked but not spotted.

Michigan lily ranges throughout the upper Midwest and the Great Lakes region and less commonly farther east and south. In this region, it flowers in July. Pollinators are thought to be hummingbirds, butterflies and moths.

Michigan lily's range in North America (left) and the Upper Midwest (right). Maps from USDA Plants Database.

References

Minnesota Wildflowers - Michigan Lily

Friends of Eloise Butler Wildflower Garden - Turk's Cap Lily

Illinois Wildflowers - Michigan Lily

Illinois Wildflowers - Turk's Cap Lily

Flora of North America – Michigan Lily

Flora of North America – Turk’s Cap Lily

USDA, NRCS. 2023. The PLANTS Database (http://plants.usda.gov, 07/18/2023). National Plant Data Team, Greensboro, NC USA.