Why Leave the Leaves?  Ask a Red-banded Hairstreak!

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Thinking about doing a fall clean-up in your garden?  Maybe you are planning to remove the layer of naturally fallen leaves that are beginning to blanket your planting beds?

I hope my encounter with a Red-banded Hairstreak will prompt you to change your plans.

On a recent walk on a woodland trail near my home in central New Jersey, I had just turned around to head back to my car when I noticed a flutter of brownish wings at ground level at the edge of the trail. My first thought was that it was probably a moth, but when I saw the insect in profile, I could tell it was a butterfly. As I looked more closely, I saw the tell-tale markings of a Red-banded Hairstreak.  I decided to watch for a while.

A Red-banded Hairstreak walking on the forest floor
A Red-banded Hairstreak walking on the forest floor

She stayed on the ground, walking over obstacles that seemed like they would be a challenge for someone her size, especially when she could choose to fly. While I observed her, she climbed over leaves, rocks, leaf stems and small branches, never once taking to the air.  Several times she paused in place for a few seconds.  Was she just resting, or maybe getting her bearings? No! She had a purpose in mind.

The Red-banded Hairstreak pauses.  Wait! Is she laying an egg?
The Red-banded Hairstreak pauses. Wait! Is she laying an egg?
No question this time! This Red-banded Hairstreak is laying an egg. Her curved abdomen is the tell-tale sign.
No question this time! This Red-banded Hairstreak is ovipositing (laying an egg). Her curved abdomen is the tell-tale sign.

Red-banded Hairstreak caterpillars eat fallen leaves and other decaying plant matter.  This little female was laying eggs on or near the kinds of material that her caterpillars would need to eat when they hatched. She alternated walking for a bit with brief pauses to lay an egg.

She walks on, over leaves and twigs.
She continues walking, over leaves and twigs.
Our Red-banded Hairstreak pauses at another promising spot to lay an egg.
Our Red-banded Hairstreak pauses at another promising spot to lay an egg.
She walks on over rocks . . .
She walks on over rocks . . .
She walks over twigs until she pauses one more time to lay an egg on detritus
She walks over twigs until she pauses one more time to lay an egg on detritus

After nearly five minutes, she flew off, presumably scouting for another promising location to lay more eggs.

The caterpillars that hatched from her eggs will spend the winter snug in the fallen leaves, waiting for warm spring days to arrive before completing their metamorphosis to become the next generation of Red-banded Hairstreaks.

Since my encounter with the Red-banded Hairstreak in the woods, I’ve seen other individuals in my own shade garden several times.  Fortunately for them and for me, I leave the fallen leaves undisturbed in the garden. I recommend you do the same!

Red-banded Hairstreak on White Wood Aster (Eurybia divaricata) in our shade garden
Red-banded Hairstreak on White Wood Aster (Eurybia divaricata) in our shade garden

Enchanter’s Nightshade

Enchanter’s Nightshade (Circaea canadensis), also called Broadleaf Enchanter’s Nightshade, is a small but eye-catching perennial that blooms in early to mid-summer along forest trails. Where I live and play in central New Jersey and Pennsylvania, that means late June through mid-July.

Enchanter’s Nightshade (Circaea canadensis)

This diminutive resident of the forest floor has several pairs of leaves opposite each other along the stem, with a cluster of tiny flowers rising above them. It often grows to about a foot (.4 m), but can reach as much as two feet (.7 m) in height, including the flower cluster (infloresence). The tiny white flowers are only about an eighth of an inch (4 mm) in diameter, and yet in the dim light of summer in the woods they are attention-grabbing, for both humans and pollinators.

Enchanter’s Nightshade (Circaea canadensis)

Each flower has two deeply lobed white petals that look a little like mouse ears, backed by two green, wing-shaped sepals that protected the flower before it opened. Two stamens, the male reproductive parts, reach out like arms from each side at the center of the flower, the anthers at their tips resembling mittened hands. The long narrow structure projecting from the very center of the flower is the pistil, the female reproductive part.  The circular washer-shaped tissue at the base of the pistil is the source of the flower’s nectar, which is offered to entice pollinators to visit.

Enchanter’s Nightshade (Circaea canadensis) flower, with 2 deeply-lobed white petals, 2 stamens reaching out like arms, and one pistil in the center with a circular nectary at its base.

In profile it’s easy to see the veining on the flower’s petals. They are nectar guides, directing pollinators to a potential reward inside.  The stigma reaches out beyond the petals, ready to accept incoming pollen on the stigma at its tip, positioned to be the first thing a pollinator encounters when visiting. The flower’s ovary, covered in hooked hairs, is visible behind the sepals. If pollination is successful, this will ripen to become a small burr-like fruit.

Enchanter’s Nightshade (Circaea canadensis) flower. Notice the veins that act as nectar guides on the petals, the pistil extending beyond the petals, and the hairy ovary behind the green sepals.

The stems of the entire inflorescence are covered with glandular hairs. Hairs on plant tissue usually serve to discourage herbivores from eating the plant, and glandular hairs often have the added benefit of emitting a chemical offense to enhance the deterrent effect.    

Enchanter’s Nightshade (Circaea canadensis) inflorescence. Note that in addition to the flower ovaries, the main stem and flower pedicels (stems) are all covered with glandular hairs, a deterrent to herbivores.

Even such tiny flowers have pollinators who are perfectly matched for them, primarily sweat bees (Halictidae) in the genus Lasioglossum and tiny flower flies, most commonly of the species Toxomerous geminatus. The group of bees called sweat bees get this common name from their habit of obtaining nutrients by licking up human sweat.

Enchanter’s Nightshade (Circaea canadensis) inflorescence, with a sweat bee visiting a flower near the top, and a flower fly perched at the tip of the branch in the lower right.

The bees visit the flowers for both nectar and pollen.  The little sweat bee in the photo below is feeding herself, but also gathering pollen, visible on her hind legs, to bring back to her nest for her larvae. 

Sweat bee, Lasioglossum species, visiting Enchanter’s Nightshade (Circaea canadensis) flower for nectar and pollen. Notice the pollen on her hind legs, which she will bring back to her nest to feed her larvae.
Sweat bee, Lasioglossum species, harvesting pollen from the anther at the tip of the stamen of an Enchanter’s Nightshade (Circaea canadensis) flower

On several occasions, I have watched small swarms of tiny flower flies hovering around Enchanter’s Nightshade flowers.  ‘Hover fly’ is another common name for this group of insects, because of their ability to perform this maneuver. Any individual I was able to see well enough to identify was a Toxomerous geminatus

A flower fly, Toxomerus geminatus, hovering near an Enchanter’s Nightshade (Circaea canadensis) inflorescence

Like the bees, the flies visit the flowers for both nectar and pollen, both of which are important food sources for them.

A flower fly, Toxomerus geminatus, harvesting pollen from an Enchanter’s Nightshade (Circaea canadensis) flower. As it first approached the flower, it came in contact with the stigma at the tip of the pistil, the female reproductive part, before moving on to harvest pollen.
Toxomerus geminatus at rest on a nearby leaf.

After pollination, the flower’s petals, sepals, stamens and pistils wither and fall away, leaving the ovary to ripen to a fruit.

The ovary of an Enchanter’s Nightshade (Circaea canadensis) flower, after its petals, sepals, stamens and pistils have withered and fallen off

As the ovary matures to a fruit, the hooked hairs covering the fruit stiffen, becoming an effective mechanism to grab on to the fur or pants of a passing animal who then unknowingly helps to disperse the seeds. 

Enchanter’s Nightshade (Circaea canadensis) inflorescence with many mature fruits positioned to hitch a ride on the fur or pants of a passing animal.

Enchanter’s Nightshade also has the ability to reproduce through its underground parts, sending up additional shoots to form colonies. 

Why the name Enchanter’s Nightshade?  The Greek goddess and accomplished enchantress Circe reportedly often used potions and herbs to achieve her ends, sometimes turning enemies into other animal species. Plants in this genus, Circaea, were thought to be among the ingredients she used, so were named for her. So far, unfortunately, I haven’t found any of her recipes.   

Enchanter’s Nightshade can be found along forest trails in the United States from Maine west to North Dakota, south as far as Oklahoma, Louisiana, and Georgia, and in Canada from Quebec and Nova Scotia west to Manitoba.  

Take a cooling summer walk in the woods to look for Enchanter’s Nightshade and its pollinators.

Small Enchanter’s Nightshade (Circaea canadensis) colony

Note:  Some sources refer to this species as Circaea lutetiana, Circaea lutetiana L. ssp. canadensis, or Circaea  quadrisulcata.

Resources

Boufford, David E. “The Systematics and Evolution of Circaea (Onagraceae).” Annals of the Missouri Botanical Garden, vol. 69, no. 4, 1982, pp. 804–994. JSTOR,

Global Biodiversity Information Facility (GBIF)

Illinois Wildflowers

Minnesota Seasons.com

Minnesota Wildflowers, copy and paste: https://www.minnesotawildflowers.info/flower/enchanters-nightshade

Niering, William A. The Audubon Field Guide to North American Wildflowers, Eastern Region. 1979.

USDA NRCS Plants Database

Wikipedia

Zakaria Hazzoumi, Youssef Moustakime and Khalid Amrani Joutei (June 24th 2019). Essential Oil and Glandular Hairs: Diversity and Roles, Essential Oils – Oils of Nature, Hany A. El-Shemy, IntechOpen, DOI: 10.5772/intechopen.86571.

Pink Lady’s Slipper – So lovely, so deceptive!

Pink Lady’s Slipper (Cypripedium acaule) emerging from its winter blanket of leaves
Pink Lady’s Slipper (Cypripedium acaule) emerging from its winter blanket of leaves

On a recent trip to Vermont, Pink Lady’s Slipper orchids (Cypripedium acaule), also called Moccasin Flower, were just emerging from their winter blanket of leaves, shyly raising their showy pink blossoms, some still partially obscured by the protective sepal and bract draped over the flowers from above.

Pink Lady’s Slipper orchids (Cypripedium acaule)
Pink Lady’s Slipper orchids (Cypripedium acaule)

Each of these lovely orchid plants has two deeply-veined leaves at its base, from which a single flower stem emerges, topped by a spectacular pink slipper (or moccasin) shaped flower.

Pink Lady’s Slipper orchids (Cypripedium acaule)
Pink Lady’s Slipper orchids (Cypripedium acaule)

Lady’s Slipper orchids have three petals, one that forms the ‘slipper’, while the other two are shaped like slightly curly ribbons or ties, positioned just above the slipper in the perfect location to secure it around a slender ankle. One sepal projects directly above the slipper, adding to the floral display, while two more sepals are fused and extend down the back of the flower. The sepals acted as bud scales protecting the flower before it opened.

Pink Lady’s Slipper orchid (Cypripedium acaule)
Pink Lady’s Slipper orchid (Cypripedium acaule)

Pink Lady’s Slippers invest a lot of energy to produce these lovely flowers to entice pollinators to assist with the cross pollination that the plants are unable to achieve on their own. In addition to their alluring appearance, the flowers produce a mild scent to add to the attraction for insect pollinators. Insects are not altruistic, however. They expect a reward in return for their efforts, in the form of nectar and pollen.

Veining on the flower adds to the attraction, and helps steer potential pollinators to the flower’s entrance at its front. The entrance is also typically highlighted with striping that acts as a directional signal (or nectar guide) for floral visitors.

Pink Lady’s Slipper orchid (Cypripedium acaule). The striped veins direct pollinators to the the flower's entrance at its front.
Pink Lady’s Slipper orchid (Cypripedium acaule). The striped veins direct pollinators to the the flower’s entrance at its front.

The most likely pollinators for Pink Lady’s Slipper are queen Bumble Bees of several species. These bees have the strength required to muscle their way through the narrow slit that offers access to what they anticipate will be a floral reward.

Once inside, however, bees may begin to have second thoughts about the enterprise. The entrance to the flower is one way.  They can’t exit the same way they entered, because the edges of the entryway are curved inward, making an exit impossible. They are trapped inside until they find a different way out, one engineered by the plant to require traversal of a snug passage past the flower’s reproductive parts. The flower’s pistil (female reproductive part) and two fertile stamens (male reproductive parts) are tucked behind the shield-shaped flower part pointing downward at the back of the slipper. This flower part is a modified stamen, called a staminode.

Pink Lady’s Slipper orchid (Cypripedium acaule). Queen Bumble Bees enter the flower through the slit bordered by striped veins in the center of the slipper.
Pink Lady’s Slipper orchid (Cypripedium acaule). Queen Bumble Bees enter the flower through the slit bordered by striped veins in the center of the slipper.

Hairs inside the slipper direct the hapless bee toward the back of the slipper, its reproductive parts, and finally the flower’s exits. There are two possible exits, one on each side of the staminode, and each partially obstructed by an anther from which pollen is dispensed. To get to an exit, the bee first has to brush against the flower’s stigma at the tip of the pistil. This is the spot where pollen must be placed in order for pollination to occur.  If the bee is bringing in pollen, it will be deposited on the stigma as the bee squeezes past it. The exits are within sight now, but before reaching one, the bee will brush against an anther, from which a pollinium (a package with thousands of tiny grains of pollen) will be attached to its back. Then, freedom!

One of two exits available for a bee to escape from a Pink Lady’s Slipper (Cypripedium acaule). The round, cream-colored, seed-like object obstructing the exit is the anther that deposits the pollinia on the bee as it escapes the flower.
One of two exits available for a bee to escape from a Pink Lady’s Slipper (Cypripedium acaule). The round, cream-colored, seed-like object obstructing the exit is the anther that deposits the pollinia on the bee as it escapes the flower.

Throughout this adventure, no nectar was provided to the flower’s visitor. Pollen is an important food for bees, but when it is packaged in pollinia as it is in the Lady’s Slippers, it isn’t accessible for bees to eat. The bees visiting these flowers are seduced by false advertising into assisting the Pink Lady’s Slipper with cross-pollination, but they receive no reward for their efforts. Hopefully, they’ll attempt the quest for food again with another Pink Lady’s Slipper, but it may not take many visits before a bee gets wise to the deception, and stops visiting these flowers.

If Pink Lady’s Slipper’s duplicitous plot succeeds and pollination takes place, a fruit capsule will develop, like those in the photo below. Making the most of this success, each capsule contains thousands of dust-like seeds. In order to obtain the soil nutrients it needs to germinate and grow, each seed needs to find a fungus of the genus Rhizoctonia with which to partner in the location where it lands. Without this partnership, the seeds won’t be viable, and the plant won’t develop. The fungus must be present throughout the Pink Lady’s Slipper’s life to enable the plant’s survival. In return, when the plant is mature enough, it will provide payment to the fungus in the form of carbohydrates.

Pink Lady’s Slipper (Cypripedium acaule) in bloom. At left, mature fruit capsules from successful pollination of a flower from the previous season.
Pink Lady’s Slipper (Cypripedium acaule) in bloom. At left, mature fruit capsules from successful pollination of a flower from the previous season.

Pink Lady’s Slipper is also capable of sending up additional shoots from its rhizome (underground stem), so you may sometimes see it growing in large groups, or colonies.

Colony of Pink Lady’s Slippers
Colony of Pink Lady’s Slippers

The color of the slipper can vary from a deep to pale pink, sometimes even white.

Pink Lady’s Slipper's color can vary from deep to pale pink, sometimes even white.
Pink Lady’s Slipper’s color can vary from deep to pale pink, sometimes even white.

Pink Lady’s Slipper is found in acidic soil in various habitats including deciduous woods or mixed forests of hardwood and coniferous trees, often with pine or hemlock, and in bogs. It is native in Canada in the Northwest Territories and from Alberta to Newfoundland, in the United States from Minnesota to Maine, then south as far as Alabama and South Carolina.  

Pink Lady’s Slipper growing with ferns and Canada Mayflower (Maianthemum canadense)
Pink Lady’s Slipper growing with ferns and Canada Mayflower (Maianthemum canadense)

Look for it blooming near you!      

Pink Lady’s Slipper orchid (Cypripedium acaule) in bloom
Pink Lady’s Slipper orchid (Cypripedium acaule) in bloom

Related Posts

Yellow Lady’s Slipper – Like Winning the Lottery

Resources

USDA Forest Service – Plant of the Week

USDA NRCS Plant Database

North American Orchard Conservation Center

Orchids of the North: the life of the Pink Lady’s Slipper

Davis, Richard W. The Pollination Biology of Cypripedium Acaule (Orchidaceae)

Flora of Newfoundland and Labrador

Minnesota Seasons

Where do Winterberries Come From?

It’s difficult to walk past Winterberry Holly (Ilex verticillata) when it’s in fruit without noticing it.  The abundant, vividly red, globular, fleshy fruits of this aptly named shrub never fail to catch the eye.  

Winterberry Holly (Ilex verticillata) in fruit
Winterberry Holly (Ilex verticillata) in fruit

Where do all of those luscious-looking fruits come from?  

Have you ever noticed Winterberry Holly in bloom?

In late spring, Winterberry Holly is covered with an equally large number of somewhat inconspicuous greenish-white flowers. The flowers bloom gradually over a period of a few weeks. 

Like all hollies, Winterberry usually has male and female flowers on separate plants. Only female flowers can develop fruit. Although it isn’t typical, there may occasionally be a specimen with male and female flowers on the same plant, or some flowers that are perfect, that is, they have both male and female parts. Plants often have some variation, as they continue to evolve to try to find the most effective and efficient survival strategies.

Female flowers are usually in small clusters of up to three. The flowers have a single pistil (the female reproductive part) at their center. The green rounded base of the pistil is the ovary. If a flower is successfully pollinated, the ovary will mature, becoming the bright red fruit we see later in the season. The ovary is topped by a stigma, where pollen must be deposited in order for pollination to occur and fruit to develop.

Winterberry Holly (Ilex verticillata) female flowers in bloom.  The whitish specks on the branches are lenticels, through which the plant exchanges gases with the surrounding atmosphere. Lenticels are commonly seen on Winterberry holly branches.
Winterberry Holly (Ilex verticillata) female flowers in bloom. The whitish specks on the branches are lenticels, through which the plant exchanges gases with the surrounding atmosphere. Lenticels are characteristic of Winterberry holly branches.

The white arrow- or spade-shaped projections in between the petals of the female flowers are sterile stamens; they don’t produce pollen that can fertilize the flowers.  It’s likely that they help attract pollinators. As these sterile stamens age, they turn brown.

Winterberry Holly (Ilex verticillata) female flowers in bloom.  The female reproductive part, the pistil, is the green mound-shaped object in the center of the flower.  The ovary is at the base, and will develop into a fruit if pollination is successful and the ovules inside are fertilized. The flat-ish tissue at the top is the stigma, where pollen must be placed by an incoming bee or other pollinator.  The white arrow- or spade-shaped projections in between the petals are sterile stamens.
Winterberry Holly (Ilex verticillata) female flowers in bloom. The female reproductive part, the pistil, is the green volcano-shaped object in the center of the flower. The ovary is the base of the volcano, and will develop into a fruit if pollination is successful and the ovules inside are fertilized. The flat-ish tissue at the top is the stigma, where pollen must be placed by an incoming bee or other pollinator. The white arrow- or spade-shaped projections in between the petals are sterile stamens.

Male flowers often bloom in crowded clusters of up to 10 or more.  The male reproductive parts, called stamens, reach upward from the face of the flower, the anthers at their tips ready to deposit pollen on a flower visitor.   

Winterberry Holly (Ilex verticillata) male flowers, blooming in densely-packed clusters.
Winterberry Holly (Ilex verticillata) male flowers, blooming in densely-packed clusters.
Winterberry Holly (Ilex verticillata) male flowers in bloom. The male reproductive parts, called stamens, reach up from the face of the flowers.  Pollen is produced from the anthers at their tips.
Winterberry Holly (Ilex verticillata) male flowers in bloom. The male reproductive parts, called stamens, reach up from the face of the flowers. Pollen is produced from the tan anthers at their tips.

Winterberry Holly needs third party assistance to move pollen from a male flower on one plant to a female flower on another plant, in order to achieve pollination. It may be easy for people to walk past without noticing when these shrubs are in bloom, but fortunately the flowers are enticing beacons to potential pollinators of many different species, especially bees. A recent study showed Winterberry Holly to be among the most attractive to bees of the flowering shrubs.

In my own garden I spotted Bumble Bees, Mining Bees, Sweat Bees, Small Carpenter Bees and a wasp visiting the flowers for nectar rewards. Bees also eat pollen, and female bees may collect pollen to feed their larvae.

Confusing or Perplexing Bumble Bee (Bombus perplexus) visiting a Winterberry Holly (Ilex verticillata) female flower.
Confusing or Perplexing Bumble Bee (Bombus perplexus) visiting a Winterberry Holly (Ilex verticillata) female flower.
Mining Bee with a Winterberry Holly (Ilex verticillata) flower.
Mining Bee drinking nectar from a Winterberry Holly (Ilex verticillata) flower.
Sweat Bee with a Winterberry Holly (Ilex verticillata) female flower.
Sweat Bee visiting a Winterberry Holly (Ilex verticillata) female flower.
Small Carpenter Bee (Ceratina species) departing from a Winterberry Holly (Ilex verticillata) flower.
Small Carpenter Bee (Ceratina species) departing from a Winterberry Holly (Ilex verticillata) female flower.
Eastern yellow Jacket drinking from a Winterberry Holly (Ilex verticillata) female flower.
Eastern Yellow Jacket drinking from a Winterberry Holly (Ilex verticillata) female flower.

Without the assistance of these flower visitors, pollination would not take place, no fruit would develop, and Winterberry Holly would not be able to reproduce. If these pollinators do the job the plants have enticed them to do, fruit develops, ripening by fall.

Winterberry Holly (Ilex verticillata) in fruit.
Winterberry Holly (Ilex verticillata) in fruit.

Birds are the primary target audience for the colorful display of Winterberry Holly’s bright red fruit. Many different species of birds including Eastern Bluebirds,

Eastern Bluebirds enjoy Winterberry Holly (Ilex verticillata) fruit
Eastern Bluebirds enjoy Winterberry Holly (Ilex verticillata) fruit

White-throated Sparrows,

White-throated Sparrows are among the birds that eat Winterberry Holly (Ilex verticillata) fruit.
White-throated Sparrows are among the birds that eat Winterberry Holly (Ilex verticillata) fruit.

and Hermit Thrush

Hermit Thrush sitting in a Winterberry Holly (Ilex verticillata)
Hermit Thrush in a Winterberry Holly (Ilex verticillata)

eat the fleshy fruit and later become the unwitting dispersers of the seeds inside as they deposit them with natural fertilizer when defecating.

Small mammals like mice and squirrels may eat Winterberry fruit, too. People are just the accidental beneficiaries of the bright spectacle, but shouldn’t eat the fruit, which is toxic to humans.

Winterberry Holly fruits contain more carbohydrates than fats, making them less preferred by birds than some other fruit available in the fall. As a result, Winterberry fruit is frequently passed over until later in the season, often well into winter, although sometimes a flock of hungry American Robins or Cedar Waxwings will strip a Winterberry Holly of all its fruit in a matter of hours.

American Robin in Winterberry Holly (Ilex verticillata).  A flock of hungry Robins can strip a shrub of its fruit in a matter of hours.
American Robin in Winterberry Holly (Ilex verticillata). A flock of hungry Robins can strip a shrub of its fruit in a matter of hours.

Winterberry Holly is a deciduous shrub or understory tree that grows to a maximum height of about 15 – 20 feet (5 – 6 meters). It prefers moist soil, and is indigenous in bogs and wet woods in the eastern half of the United States and Canada. It makes a great addition to your own landscape for its benefit to pollinators, birds and other wildlife. It doesn’t hurt that Winterberry Holly adds some bright color to a winter landscape.

Winterberry Holly (Ilex verticillata) in fruit.
Winterberry Holly (Ilex verticillata) in fruit.

Resources

Eastman, John.  The Book of Swamp and Bog.  1995.

Eaton, Eric R.; Kauffman, Ken.  Kaufman Field Guide to Insects of North America.  2007.

Mach, Bernadette M.; Potter, Daniel A. Quantifying bee assemblages and attractiveness of flowering woody landscape plants for urban pollinator conservation. 2018.

Rhoads, Ann Fowler; Block, Timothy A.  The Plants of Pennsylvania.  2007

Williams, Paul; Thorp, Robin; Richardson, Leif; Colla, Sheila. Bumble Bees of North America. 2014.

Wilson, Joseph S.; Carril, Olivia Messinger.  The Bees in Your Backyard. 2016.

Illinois Wildflowers

Minnesota Wildflowers

Missouri Botanical Garden Plant Finder

USDA NRCS Plant Database

American Cranberrybush

American Cranberrybush  (Viburnum opulus var. americanum synonym V. trilobum), also called Highbush Cranberry, Cranberrybush Viburnum, and several other common names, is not the source of the cranberries often served for Thanksgiving dinner.  Those cranberries come from an unrelated species, Cranberry (Vaccinium macrocarpon), a member of the heath family, and a plant that is more closely related to blueberries than it is to American Cranberrybush.

American Cranberrybush (Viburnum opulus var. americanum) fruit

American Cranberrybush gets its common name from the color of its bright red fruit, which does resemble the cranberries so often used to make holiday side dishes or to garnish a salad.  The common name Highbush Cranberry refers to this shrub’s height, which can be in the range of 8 to 12 feet (2.5 – 3.6 meters), much taller than the species that yield fruit for those traditional dishes.

This lovely shrub blooms in spring, usually some time in May.  Its floral display consists of two types of flowers arranged in a large rounded cluster, creating a lace-cap effect.  Large white sterile flowers form the perimeter of the flower cluster, surrounding a dense group of much smaller fertile flowers that make up most of the inflorescence.  The job of the sterile flowers is to be showy enough to attract potential pollinators to the fertile flowers, where the work of reproduction is carried out.  This floral strategy is shared by Hobblebush Viburnum (Viburnum lantanoides, synonym V. alnifolia) and some of the hydrangeas.

The sterile perimeter flowers bloom first.

American Cranberrybush (Viburnum opulus var. americanum) flower cluster. The large sterile flowers around the perimeter are in bloom, while the fertile flowers are still in bud.

Then gradually, the fertile flowers open for business, enticing pollinators to visit, including many flies, bees and beetles, all important pollinators.

American Cranberrybush (Viburnum opulus var. americanum) flower clusters. Many of the small fertile flowers in the center of the inflorescences are in bloom, in addition to the sterile flowers around the perimeter. If you look closely at the top cluster, you can see a fly (a potential pollinator) foraging for nectar and pollen.
Foraging Mining Bee (Andrena sp.) on blooming American Cranberrybush (Viburnum opulus var. americanum) flowers.
Mining Bee (Andrena sp.) and another tiny pollinator a bit above and to her right, on blooming American Cranberrybush (Viburnum opulus var. americanum) flowers.

Spring Azure butterflies use the flowers and buds of this and other spring-blooming viburnums, and a few other woody species as food for their caterpillars. 

Spring Azure butterfly

Hummingbird Clearwing and several other moth species also use this and other viburnums as food for their caterpillars.

Hummingbird Clearwing (Hemaris thysbe) moth

American Cranberrybush leaves have three lobes, resembling the leaves of Red Maple (Acer rubrum). To protect itself from hungry marauding caterpillars, American Cranberrybush has glands on its leaf stems just below where the stem meets the leaf blade. These glands are extra-floral nectaries, designed to lure insects that can be enticed by both a sweet nectar treat and the protein available from a caterpillar. Ants, wasps, even some flies are potential security guards that are paid for their presence with nectar from these glands, with the potential for a bonus: as many caterpillars as they can find.  Ants drink nectar and eat caterpillars and other insects. Wasps and flies drink nectar, and some also hunt caterpillars or other insects to feed their young.  The presence of these predatory insects helps protect American Cranberrybush from foraging caterpillars.

Note the bumps on the leaf stem, just below the 3-lobed leaf blade. They are the extra-floral nectaries.

American Cranberrybush is a variety of a look-alike shrub, European Cranberrybush (Viburnum opulus) which is of European origin and can become invasive in North America.  The two can interbreed, which has the undesirable potential to lead to the loss or alteration of the native variety. The best way to tell the two apart is by their extra-floral nectaries.  On American Cranberrybush, these nectaries are somewhat convex or slightly rounded at the top, while those on European Cranberrybush leaf petioles (stems) are concave.

By late June, developing fruit replaces successfully pollinated flowers, ripening as the summer goes on.  The fruit is a drupe, a fleshy fruit with a single seed encased in a stony pit. Peaches and cherries are examples of fruits that are drupes.

American Cranberrybush (Viburnum opulus var. americanum) developing fruit, late June in Pennsylvania.
American Cranberrybush (Viburnum opulus var. americanum) ripening fruit, mid-July in Pennsylvania.

American Cranberrybush fruit has a relatively low fat content, so it is less desirable for migrating birds than some other options like Spicebush (Lindera benzoin).  It often lasts well into the winter, but this year, where I live and play in central New Jersey and eastern Pennsylvania, the fruit was already gone by mid-November. Of course, we have already had a few hard freezes, followed by warm-ups.

American Cranberrybush (Viburnum opulus var. americanum) fruit, November, in Pennsylvania.

Robins, Bluebirds, Hermit Thrush, Cedar Waxwings, grouse and many more birds eat American Cranberrybush fruit. 

Cedar Waxing – they are among the birds who eat American Cranberrybush fruit.

All kinds of animals, from moose to fox to squirrels and mice also eat the fruit.

Gray squirrels and many other animals eat American Cranberrybush fruit.

What about humans?  If we get to it before our animal neighbors do, can we use this fruit as an actual cranberry substitute?  If it is cooked with sugar or other sweetener added, people find the fruit of American Cranberrybush edible, too. Some sources say that fruit from European Cranberrybush tends to be more bitter.

Look for American Cranberrybush in wet woods or along streams in its native range, from Nova Scotia to British Columbia in Canada, and in the United States from Maine to Washington state, south to New Jersey, West Virginia and Illinois, although it is more common in the eastern US. The USDA also shows it in one county in New Mexico.

Happy Thanksgiving!  Enjoy those cranberries!

American Cranberrybush (Viburnum opulus var. americanum) fruit

Related Posts

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Resources

Beadle, David; Leckie, Seabrooke. Peterson Field Guide to Moths of Northeastern North America. 2012.

Cech, Rick; Tudor, Guy.  Butterflies of the East Coast.  2005.

Eastman, John.  The Book of Forest and Thicket.  1992.

Levine, Carol. A Guide to Wildflowers in Winter. 1995.

Peterson, Lee Allen.  A Field Guide to Edible Wild Plants of Eastern and Central North America. 1977.

Illinois Wildflowers

USDA NRCS Plant Database

USDA NRCS Plant Guide

Missouri Botanical Garden Plant Finder