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

Time for Cranberries!

Praying for Spring? So is Hobblebush Viburnum

‘Will Work for Food’ – Extra-floral Nectaries

Partridge Pea Puzzles

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

A Dose of Spring

One thing we can still do while keeping a safe distance from other humans during the Covid-19 virus outbreak is to go outside for a walk.  It’s a great boost to your immune system, and contributes to an overall feeling of well-being.  If you go for a walk in a natural area, it’s especially beneficial.

Swan Creek, Rockhopper Trail, West Amwell Twp. NJ

Life goes on for the other species in the world while we humans are focused on the virus. Here are some animals and plants you might see if you go for a walk in my neighborhood in the mid-Atlantic United States.

Every morning now I hear Wrens, Cardinals, Titmice and other birds singing.  For several weeks Carolina Wren couples have been out shopping for real estate, looking for a good location to build a nest for the upcoming season.  These birds nest in cavities, usually from three to six feet off the ground.  A stump with a pre-made cavity like the one that the couple in the photos below is inspecting looks like very a very desirable property.

Carolina Wrens investigating a nesting site.

Carolina Wren investigating a fallen log with a natural cavity as a possible nesting site.

Carolina Wren standing watch at a possible nesting site.

While walking in the woods, you might hear a chorus of male wood frogs calling from a vernal pool, or see a mass of eggs that resulted from successful wood frog mating.

Male Wood Frogs

Wood Frog

Wood Frog egg mass

When temperatures are warm, bees and some butterflies may be active.  Even when spring temperatures are cooler, flies are active.

Greenbottle Fly (Lucilia sericata). This adult fly can be an effective pollinator, while its larvae are crime scene investigators’ friends, consuming dead rotting flesh or other decaying matter, a task that never goes out of season. The presence of these insects’ larvae can help determine time of death of a corpse.

Fly, unidentified.

Winter was unusually warm where I live in New Jersey.  As a result, the spring bloom season is about 3-4 weeks earlier than normal.  (This is a bit alarming, but since we have enough to worry about right now, I’m just going to focus on enjoying it.) With each passing day, more and more buds break and flowers bloom.

Leatherwood (Dirca palustris) is an early blooming shrub whose flower buds come with their own ‘fur’ coat, just in case the temperatures take a tumble. If the temperatures are warm, a lovely fragrance that even humans can detect wafts many feet away from the flowers.  When the air temperature is cooler, you can still catch the fragrance if you bring your nose right up to a flower and sniff.

Leatherwood (Dirca palustris). Bud scales act as a furry hood that protect the flowers.

The sunburst-like flowers of Spicebush (Lindera benzoin) are blooming, beckoning pollinators to visit, and promising fruit for birds in the fall.

Spicebush (Lindera benzoin) blossom, male. Spicebush have male and female flowers on separate plants.

Hepatica, like Leatherwood, wears fur for warmth and to deter herbivores.  Depending on where you live, two species are possible, Round-lobed Hepatica (Anemone americana syn: Hepatica nobilis obtusa, Hepatica americana) and Sharp-lobed Hepatica (Anemone acutiloba syn: Hepatica nobilis acuta, Hepatica acutiloba).

Hepatica in bloom

The earliest of the Trilliums to blossom, Snow Trillium (Trillium nivale), has entered its short bloom season.  As you might guess, it is named for the fact that its flowers may open when snow is still present.  The Latin name nivale means ‘snow white, or growing near snow’.

Snow Trillium (Trillium nivale)

Bloodroot (Sanguinaria canadensis) has opened its blossoms, hoping for insect visitors to help it with cross-pollination, but if all else fails it will self-pollinate.

Bloodroot (Sanguinaria canadensis)

The lovely Dutchman’s Breeches (Dicentra cucullaria) is just starting to bloom, luring Bumble Bees to be their pollination facillitators.  This plant’s delicate appearance gives no hint of its narcotic-packed foliage, a reliable deterrent to herbivores that would otherwise be tempted to eat it.

Dutchman’s Breeches (Dicentra cucullaria)

The first Spring Beauty (Claytonia virginica) flowers are open, the beginning of several weeks of a floral display from this species.  There are specialist bees that depend on the pollen of this species as the only food that their larvae can digest. In return, these bees are very efficient and reliable pollination partners for Spring Beauty.

Spring Beauty (Claytonia virginica)

Spring Beauty (Claytonia virginica), with Toadshade (Trillium sessile) behind it, in bud

So many other species are waiting in the wings to be the next to bloom, including Virginia Bluebells (Mertensia virginica).

Virginia Bluebells (Mertensia virginica)

Everything changes so quickly in spring, from one day to the next and from morning until afternoon.  Visit a natural area often so that you don’t miss anything.  And to give your immune system a boost.  You might even learn something!  Just avoid people.

The author, out for a walk in the woods.

Related Posts

Spicebush or Forsythia?

Bloodroot

Dutchman’s Breeches and Squirrel Corn

A Tale of Two Spring Beauties

Photo Locations

Bowman’s Hill Wildflower Preserve

Goat Hill Overlook, New Jersey

Rockhopper, New Jersey

Resources

All About Birds

National Wildlife Federation Educational Resources

US Forest Service Plant of the Week, Snow Trillium

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

Stearn, William T. Stearn’s Dictionary of Plant Names.  1996

 

 

Holiday Gift Ideas for Your Wild Neighbors

American Robin with Winterberry Holly (Ilex verticillata) at Bowman’s Hill Wildflower Preserve, New Hope, PA

Looking for the perfect holiday gifts for the birds, butterflies, bees and other wildlife neighbors outside your windows?

The answer is simple.  Give them plants that are native to where you live.  Plants and animals have evolved together over many centuries in such a way that they depend on each other for their survival.  Animals depend on native plants for food, shelter, nesting sites and materials.  Plants in turn depend on animals to help disperse their seeds, and in many cases for essential assistance in reproduction, as their pollination intermediaries.

You’ll be doing yourself a favor, too, since native plants, once established, typically don’t require fertilizer, watering or other special care.

The American Robin shown here with Winterberry Holly (Ilex verticillata) was one member of a flock of Robins that swooped down to devour the bright winter-time fruit.  Winterberry Holly has fruit high in carbohydrates and low in fats, a recipe for being ignored during migration season in fall, but devoured during the cold days of winter when birds need those carbohydrates. In exchange for this winter feast, birds ‘disperse’ the seeds complete with fertilizer after the seeds move through a bird’s digestive system.

If you live in North America, here are a few resources to help you learn which plants are native where you live:

Lady Bird Johnson Wildflower Center

Audubon

North American Native Plant Society

Also check with your local state or province native plant society.

For the birds, another great gift idea is a heated bird bath.  Birds need to drink and bathe even in winter.

What else can you do? Less:

  • Leave the fallen leaves in your planting beds.  They provide habitat for overwintering insects, and the insects are food for birds.
  • Don’t use pesticides or herbicides
  • Reduce your lawn size if possible
  • Chop up leaves on your lawn with a mulching mower to create a natural chemical-free fertilizer

Happy holidays!

Related Posts

A Wildlife, Family and Pet-friendly Lawn

Red-banded Hairstreaks Need Sumacs and Leaf Mulch

For Great Spangled Fritillaries, Leave the Leaf Litter

American Robin with Winterberry Holly (Ilex verticillata) at Bowman’s Hill Wildflower Preserve, New Hope, PA

Time for Cranberries!

Image

Cranberries, especially in the form of relishes and baked goods, are a Thanksgiving tradition made possible by Cranberry (Vaccinium macrocarpon), a low-growing, creeping, evergreen shrub native to North American bogs and fens. Cranberry lends itself well to cultivation for commercial use, making cranberry based dishes possible throughout the year.

Cranberry (Vaccinium macrocarpon)

The flowers of this native shrub bloom in early to mid-summer, a prerequisite for the fruit that will come later in the season.

Cranberry (Vaccinium macrocarpon) in flower

In order to produce the tart but luscious and festive fall fruit, Cranberry’s flowers must be pollinated with assistance from insects, primarily bees.

Cranberry (Vaccinium macrocarpon) flowers

The flowers are most efficiently pollinated by bees who are capable of sonication, or buzz pollination.  In the case of Cranberries, this process is performed by bees that are able to hang upside down from the bottom edge of the flower’s corolla (collection of petals) and vibrate their wing muscles without moving their wings.  This sets up just the right motion to release pollen from the flower like salt from a shaker dusting the bee’s underside.  When the bee moves on to the next flower, its pollen-dusted abdomen brushes the flower’s stigma (female reproductive part), depositing pollen from the previous flower.

It’s not every bee that has this special talent.  Honey Bees don’t have the skills necessary to buzz pollinate.  The best Cranberry pollinators are the native bees with which it has evolved, and who can sonicate (buzz pollinate), including several species of Bumble Bees, Sweat Bees (Halictidae) and Mining Bees (Andrenidae).  The presence of these native bees significantly increases the yield of commercial cranberry operations.

Bumble Bee getting in position to buzz pollinate a Shooting Star (Dodecatheon Meadia) flower. The structure of this flower is very similar to those of Cranberry (Vaccinium macrocarpon).

Other food we eat, including blueberries, tomatoes, eggplant, and peppers are produced by plants whose flowers are also most effectively pollinated through buzz pollination.

With the help of the bees, this tough little shrub produces abundant fruit that ripens in the fall and resists spoiling, perfect timing for inclusion in a late fall or winter feast.

Cranberry (Vaccinium macrocarpon)

In addition to being tasty and nutritious, Cranberry has medicinal value. Consumption of cranberries or unsweetened cranberry juice can help prevent urinary tract infections.

Humans are not the only consumers of cranberries.  Birds including Sharp-tailed and Ruffed Grouse, Bobwhites, Mourning Doves and American Tree Sparrows are known to eat cranberries,

Ruffed Grouse

American Tree Sparrow

as are Chipmunks.

Eastern Chipmunk

Cranberry hosts the caterpillars of several moths who can only eat the leaves of this and a few related species.  The Bog Copper butterfly is also a specialist on Cranberry and the closely related Small Cranberry (Vaccinium oxycoccus).

Cranberry is indigenous in the United States from Maine to Minnesota, south from northeastern Illinois to Delaware, and from there reaching as far south as Tennessee and North Carolina primarily through the Appalachians; it can also be found in coastal Washington state and Oregon, and Nevada county in California.  In Canada it is native from Newfoundland to Ontario, in British Columbia and the Northwest Territories.  The top five states in commercial cranberry production are Wisconsin, Massachusetts, New Jersey, Oregon and Washington.  British Columbia and Quebec are the top cranberry producing provinces in Canada.

Why is the range of this plant primarily in northern latitudes and higher elevations?  The answer lies in the fact that Cranberry is much less successful in producing flowers and fruit unless it goes through a sufficient period of dormancy induced by day length change and cold temperatures.  To successfully break dormancy, the plants must experience a cumulative number of ‘chill hours’, usually defined as temperatures between 32 and 45 °F (0 – 7.2 °C), during the winter months.  A study done by University of Wisconsin researchers found that 1500 chill hours seemed to be in the optimal range for successful bloom of cranberry flowers.  As the climate changes and night time temperatures warm, the geographic range where these optimal conditions can be met may shrink.

Enjoy those cranberry dishes while you can!

Manoff’s Apple Cranberry Chutney!

Related Posts

The Buzz about Shooting Star

Love Blueberries?  Thank a Native bee

Resources

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

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

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

Foster, Steven; Duke, James A.  A Field Guide to Medicinal Plants and Herbs of Eastern and Central North America.  2000.

Hoffmann, David.  Medical Herbalism.  2003.

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

Biobest Sustainable crop Management

Illinois Wildflowers

https://illinoiswildflowers.info/plant_insects/plants/vaccinium_macrocarpum.html

http://www.illinoiswildflowers.info/flower_insects/plants/lg_cranberry.htm

Lady Bird Johnson Wildflower Center Plant Database

The Canadian Encyclopedia

University of Wisconsin Extension; Cranberry Crop Management Journal

University of Massachusetts, Natural History of the American Cranberry (Vaccinium macrocarpon)

USDA NRCS Plants Database

USDA REEIS Cranberry Cold Hardiness in Relation to Dormancy and Bud Development; Source: University of Wisconsin

United States Department of Agriculture National Agricultural Statistics Service New Jersey Field Office – Cranberry Highlights

US Forest Service – What is a Fen?

WisCONTEXT: Pollinators Provide Extra Buzz To Wisconsin’s Cranberry Crop

https://www.wiscontext.org/pollinators-provide-extra-buzz-wisconsins-cranberry-crop