Time for Cranberries!

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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

 

Love Blueberries? Thank a Native Bee!

It’s blueberry season in New Jersey!  There are plenty of delicious deep blue orbs ripening for use on cereal, in pancakes, pies, crisps, cobblers, muffins, or just for snacking.  The blue color reflects the presence of anthocyanins, antioxidants with anti-inflammatory, anti-viral, and anti-cancer properties. Blueberries are not only tasty, but good for you.

A Bowl of Blueberries

For anyone who loves blueberries, you should know that some of our native bees are the most effective pollinators of this flavorsome fruit.

Blueberries are the fruit of deciduous shrubs that generally bloom in spring.  Most commercial blueberries in this region are cultivars of native blueberry species, usually Highbush Blueberry (Vaccinium corymbosum).  Lowbush Blueberry (Vaccinium angustifolium) is a species whose fruit is commonly harvested and sold in New England.  If the flowers are pollinated, the fruit ripens in mid to late summer, depending on their growing conditions.

Lowbush Blueberry (Vaccinium angustifolium)

An essential partner in the production of blueberries are the bees that are the primary pollinators for blueberry flowers.  While commercial growers may use Honey Bees to pollinate their crops, there are several species of native bees that are much more efficient blueberry pollinators.

How could that be?  Honey Bees pollinate flowers for a living.  Many are shipped from farm to farm specifically to pollinate crops.  (I think of them as the migrant workers of the insect world.)  How could there be bees that are more efficient pollinators?

Flowers come in all shapes and sizes, and they store and dispense their nectar (if they produce any) and pollen in many different ways.  Blueberry flowers are bell-shaped, with a narrow opening that allows access to the flowers’ nectar from the bottom of the hanging blossom.

Highbush Blueberry (Vaccinium corymbosum) Flowers

Lowbush Blueberry (Vaccinium angustifolium) Flowers

The pollen is most efficiently dispensed from the flowers’ anthers through a process called sonication, or ‘buzz’ pollination.  Buzz pollination is a process of releasing pollen by which the pollinator clings to the flower and vibrates its wing muscles without moving its wings.  This sets up enough of a vibration for the anthers to discharge a dusting of pollen on the flower visitor.  The wing vibration makes a buzzing sound, which gives this technique its name.  (Buzz pollination is the bee equivalent of ventriloquism!.)  Some of the pollen will be carried from flower to flower to enable pollination, while the rest is a pay-off for this service, and will be eaten by the bee and her larvae.  Bees drink nectar, but pollen is also a very important food source for them.

Honey Bees are not capable of buzz pollination, but several families of native bees are, including bumble bees, large carpenter bees, mining (Andrenid) bees, many sweat bees, some mason (Osmia) bees and Melitta bees.  Highbush and Lowbush Blueberry shrubs evolved with these bees who are native to the same region and habitats.  These native bees are able to handle the flowers more quickly and dispense and carry more pollen than the Honey Bees who lack this athletic skill.  Mason bees generally are very swift and efficient pollinators, able to process flowers many times more quickly than Honey Bees.

Mining Bee (Andrenid) visiting Lowbush Blueberry (Vaccinium angustifolium) Flower

Some of the native bees who are able to buzz pollinate specialize on visiting the flowers of blueberries; they and their larvae can only digest pollen from blueberry plants.  This is a great benefit to the blueberries, since these bees spend all of their foraging time visiting blueberry flowers, and there is no risk of pollen being dropped off on the wrong species.  It’s a risk for the bees, however.  If no blueberry flowers are available when the bees are active, the bees have no back-up plan; they could starve.  On the other hand, if blueberry flowers are available, it’s like assembly line processing. The bees know how to handle the flowers very efficiently to get the nectar and pollen they need to survive.

Mason Bee (Osmia) visiting Lowbush Blueberry (Vaccinium angustifolium) Flower

Blueberries are not the only crop that is most efficiently pollinated through sonication.  Cranberries, tomatoes, tomatillos, potatoes, peppers and eggplant are some of the other crops that have a higher rate of pollination when native bees with this skill are available to help pollinate their flowers.

A love of blueberries is not exclusive to people. Many other mammals and birds also enjoy the tasty fruit. Black bears are probably second to humans as consumers of blueberries, but fox, rabbits, raccoons, mice and many more eat their share, too.

Red Fox are among the animals that love blueberries.

Ruffed and Spruce Grouse relish the bounty blueberries provide,

Spruce Grouse

as do many other birds including Bluebirds, Catbirds, Scarlet Tanagers, Tufted Titmice, Veeries, Robins, and Brown Thrashers.

Eastern Bluebirds love blueberries

Veery in Fringtree (Chionanthus virginicus) Veeries are among the many birds who eat blueberries.

Butterflies and moths depend on blueberries, too, but in a completely different way.  Many species use the leaves and flowers as their caterpillar food.  The Natural History Museum’s Database of the World’s Lepidopteran Hostplants (HOSTS) lists 32 species that use Highbush Blueberry as caterpillar food, 42 that use Lowbush Blueberry.

Spring Azure butterfly. Highbush and Lowbush Blueberry shrubs are a caterpillar food plant for Spring Azures.

Saddleback moth caterpillar. Highbush and Lowbush Blueberry shrubs are a caterpillar food plant for Saddlebacks.

Caterpillars are an important part of the diet of many birds and other animals, so feeding caterpillars means that these other species will have the food they need, too.

Female Common Yellowthroat with Caterpillar

Blueberries are great landscape plants.  Not only do they provide food for our many animal neighbors (and us, if we’re quick!), but they are beautiful throughout the seasons, with their spring flowers, summer fruit, fabulous fall color and winter architectural structure and slightly shredding bark.  Why would anyone plant the non-native, invasive Burning Bush (Euonymus alatus) for its brief flash of color, when they could have blueberries instead?

Lowbush Blueberry (Vaccinium angustifolium) with Lichen in Fall

Highbush Blueberry is native primarily in the eastern third of the United States and Canada, but also in Washington state and British Columbia.  It is common in dry to wet woods, in thickets and on stream banks.  It can grow to a height of about 13 feet (4 meters).  Lowbush Blueberry is native from Manitoba to Newfoundland and Labrador provinces in Canada, and south as far as Tennessee and North Carolina (except Kentucky) in the United States. It can be found in dry woods and barrens, where its partnership with mycorrhizal fungi helps it to get the nutrients it needs from the soil.  It is a low growing plant, usually to a maximum height of about 2.5 feet (.75 meters).

The USDA NRCS Plant Database lists 25 species of blueberries that are native in different regions in North America.  Find one that’s native where you live, and add it to your landscape to enjoy its beauty and bounty.

A Bowl of Blueberries

A Bowl of Blueberries

Related Posts

Nutritious Fall Foliage – What Makes Leaves So Colorful?

The Buzz About Shooting Star

Partridge Pea Puzzles

Resources

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

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

Eastman, John.  The Book of Field and Roadside.  2003.

Holm, Heather.  Bees An Identification and Native Plant Forage Guide.  2017.

Mader, Eric; Shepherd, Matthew; Vaughan, Mace; Black, Scott Hoffman; LeBuhn, Gretchen.  Attracting Native Pollinators: Protecting North America’s Bees and Butterflies.  2011.

Martin, Alexander C.;  Zim, Herbert S.; Nelson, Arnold L.  American Wildlife & Plants A Guide to Wildlife Food Habits.  1951.

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

Tallamy, Douglas W.  Bringing Nature Home.  2007

Wagner, David L.;  Caterpillars of Eastern North America, 2005.

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

Illinois Wildflowers

Natural History Museum’s Database of the World’s Lepidopteran Hostplants – Vaccinium corymbosum

Natural History Museum’s Database of the World’s Lepidopteran Hostplants – Vaccinium angustifolium

 

The Buzz About Shooting Star

Shooting Star (Dodecatheon meadia) is an herbaceous perennial named for the shape of its flowers and the flowers’ curved stems, which together look a bit like a shooting star with a tail following it through the sky.

Shooting Star (Dodecatheon meadia)

Shooting Star blooms in spring over a period of several weeks. Each flower shoot produces multiple flowers, each flower with its own curved stem (or tail).  The flowers can be white or pink.

Shooting Star (Dodecatheon meadia)

Shooting Star (Dodecatheon meadia)

If the flowers are pollinated, fruit capsules take their place and along with the leaves remain visible for many weeks in the summer.

Shooting Star (Dodecatheon meadia) fruit capsule

Shooting Star requires a partner with special skill to help achieve successful pollination,  an insect with the athletic ability to hang from below the flower and vibrate its wing muscles without moving its wings, in order to shake pollen loose from the flower.  This is called buzz pollination, because the vibration makes a buzzing sound.  Queen Bumble Bees have this ability, and they are the perfect unsuspecting collaborator in Shooting Star’s pollination.

Queen Bumble Bee on Shooting Star (Dodecatheon meadia)

When a female Bumble Bee like the one shown here clings to a Shooting Star flower from below, her abdomen touches the plant’s stigma, the place on the pistil (female reproductive part) where pollen must be deposited if pollination is to take place.  If pollen is present on the bee when she arrives at a flower, it will be brushed from her abdomen onto the flower’s stigma, possibly with some assistance from static electriciy.  As the Bumble Bee clings to the flower she vibrates it, causing a dusting of pollen to be releases onto her abdomen.  She then carries the pollen to the next flower she visits.

Queen Bumble Bee on Shooting Star (Dodecatheon meadia). The flower’s stigma is touching the bee’s abdomen. Notice the dusting of pollen that is beginning to accumulate.

Honey bees don’t have this special skill. Only native bees like Bumble Bees and some others are able to buzz pollinate.  Blueberries, cranberries, tomatoes, eggplants and peppers also require buzz pollination.  If we didn’t have these bees, we wouldn’t have this food!

Shooting Star doesn’t produce nectar, so why would bees keep visiting these flowers?  They don’t do it altruistically, they need some incentive.  Bees visit the flowers for pollen, a food source high in the protein and lipids bees need. After she has visited enough flowers, the Bumble Bee will groom herself, eating some of the pollen and storing the rest on her legs to carry back to her nest to feed her larvae.

Queen Bumble Bee on Shooting Star (Dodecatheon meadia). She has collected pollen on her rear legs to take back to her nest to feed her larvae.

Other small bees may visit the flowers to harvest pollen, but because of the way these smaller bees handle the flowers, the chances are lower that they will encounter the stigma and deposit pollen.

Shooting Star is native in Manitoba in Canada, and much of the eastern half of the United States except the New England states, New Jersey and Delaware.  It is most commonly found in some of the mid-western states.  Shooting Star likes shade to part shade and can be found in open woods.

Resources

Spira, Timothy A.  Wildflowers & Plant Communities of the Southern Appalachian Mountains & Piedmont.  2011.

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

Willmer, Pat.  Pollination and Floral Ecology. 2011

Illinois Wildflowers

USDA Plant Database