White Beardtongue for Pollinators

Posted on June 26, 2016 by Mary Anne Borge

White or Foxglove Beardtongue (Penstemon digitalis) blooms in late spring to early summer, offering nectar and pollen to flower visitors. It’s easy to recognize in fields and along roadsides by its upright habit and its inflorescence of many whitish flowers, all positioned perpendicularly to the stem. The name Penstemon reflects the fact that these flowers each have five male flower parts, called stamens. ‘Foxglove’ and ‘digitalis’ both refer to the shape of the flowers, which resemble those of Foxglove (Digitalis purpurea).

White or Foxglove Beardtongue (Penstemon digitalis)

The white flowers beckon to a variety of bees who are enticed by the possibility of a meal of nectar and pollen, with the purple lines (nectar guides) on the throat of the flower showing them the way.

Bufflehead Mason Bee (Osmia bucephala) on White Beardtongue (Penstemon digitalis)

Sweat Bee on White Beardtongue (Penstemon digitalis)

Bee on White Beardtongue (Penstemon digitalis)

In addition to feeding themselves, female bees also harvest pollen and nectar to provision their nests for their larvae. But if bees are eating and harvesting the pollen, how will the flowers be pollinated? Will there be any pollen left to fulfill the plant’s goal of reproduction?

Female Bumble Bee on White Beardtongue (Penstemon digitalis). Note the harvested food on her hind leg.

Although much of its pollen is used to entice and reward insect visitors, White Beardtongue’s strategy is to deposit pollen on its flower visitors’ bodies in a place that can’t be easily reached for grooming.

The flowers have both male and female parts, but they are sequentially unisexual. The male flower parts, or stamens, mature first, with the anthers at their tips opening up to release pollen. Although White Beardtongue has five stamens, only four are capable of producing fertile pollen. These four stamens are all positioned just below the ‘roof’ of the flower tube, or corolla. The dark brown anthers, which contain the pollen, are at the tips of the stamens, clustering above the center of the entrance to the flower.

White Beardtongue (Penstemon digitalis) in the male phase. The dark brown anthers are clustered just below the center of the ‘roof’ of the flower.

When the flowers are in this phase, a visitor like the Bumble Bee in the photo below may enter the flower, and be brushed with pollen on the top of its head, thorax or even its tongue (proboscis).

Bumble Bee on White Beardtongue (Penstemon digitalis).

After a day or so, the anthers begin to wither and the female flower part begins to mature, the sticky stigma at its tip becoming receptive to pollen. The style extends and curves downward, taking the same position that the anthers once held.

White Beardtongue (Penstemon digitalis) in the female phase. The stigma has replaced the anthers just below the center of the ‘roof’ of the flower.

If a bee carries the pollen to a flower in the female phase, it will generally enter the flower in the same way, depositing the pollen on the receptive stigma. Success! White Beardtongue’s pollination strategy has worked.

Bumble Bee depositing pollen on stigma of a White Beardtongue (Penstemon digitalis) in the female phase.

Some pollen may fall on the ‘floor’ of the flower, where the fifth stamen is positioned. This stamen is sterile; it does not produce its own pollen. It is somewhat hairy, giving the plant its common name ‘beardtongue’. This hairy stamen may catch some of the fallen pollen and deposit it on an insect visitor as it brushes past, a secondary means of pollen dispersal. Some smaller bees may cling upside down while foraging for pollen.

Bee visiting White Beardtongue (Penstemon digitalis), possibly harvesting pollen

Butterflies and even hummingbirds may stop by for nectar. They may not be as effective in pollinating White Beardtongue as the bees are if their anatomy and behavior is not as good a match for the anatomy of the flower. On the plus side, neither butterflies nor hummingbirds harvest pollen, so any that does adhere to them has the possibility of being deposited on another flower.

Hobomok Skipper butterfly visiting White Beardtongue (Penstemon digitalis) for nectar. It may be just the right size to pick up or deliver pollen on its head.

White Beardtongue blooms for a period of about a month in June to early July. It is native in the eastern two-thirds of the United States, and is found in several Canadian provinces. It can tolerate sun to part shade in dry to somewhat moist, well-drained soil, and grows to a height of 2-5 feet (6 – 15 decimeters). It’s a good addition to a natural area or a pollinator garden.

Bumble Bee visiting White Beardtongue (Penstemon digitalis)

Here are some other early summer blooming plants that are important for pollinators:

Milkweed – It’s Not Just for Monarchs

What Good is Dogbane?

Resources

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

Holm, Heather. Pollinators of Native Plants. 2014.

Willmer, Pat. Pollination and Floral Ecology. 2011

Illinois Wildflowers

Lady Bird Johnson Wildflower Center Plant Database

Ontario Wildflowers

USDA NRCS Plant Database

Black Cherry – for Wildlife, and People, too!

Posted on June 3, 2016 by Mary Anne Borge

Black Cherry or Wild Black Cherry (Prunus serotina) is a bountiful tree for wildlife, and an important species for humans, too. It blooms in spring, with a profusion of long, slender, densely packed flower clusters.

Black Cherry (Prunus serotina) in bloom

The flowers offer nectar and pollen as enticements to a variety of bee and fly species who need this food to survive. The insects become Black Cherry’s unsuspecting pollination partners. In return for the food provided to these insect floral visitors, the flowers benefit by having some of their pollen transported on the insects’ bodies and deposited advantageously for pollination on other Black Cherry flowers. Successful pollination will result in fruit that ripens in late summer and fall.

A broad spectrum of animals eat Black Cherry’s fleshy fruit. Many thrushes, woodpeckers, sparrows, bluebirds, tanagers, orioles, and Cedar Waxings are among the dozens of bird species that eat the fruit.

Wood Thrush

Red-bellied Woodpecker

Mammals as diverse as fox, squirrels, chipmunks, mice and even Black Bears eat Black Cherry’s fruit.

Eastern Chipmunk

The fruit has evolved to lure animals to help Black Cherry spread its seeds. In exchange for the meal, the seeds are ‘dispersed’ after traveling through the animals’ digestive tracts.

Hundreds of insect species depend on Black Cherry for food, and in some cases, shelter.

In spring, finger galls caused by a mite (Eriophyes cerasicrumena) are conspicuous on Black Cherry leaves. A gall is a plant’s reaction to being used as food and shelter by an insect. The mite will feed on the tissue inside the gall until the mite matures and emerges from the gall.

Finger galls caused by a mite (Eriophyes cerasicrumena) on Black Cherry (Prunus serotina) leaves

You may be used to seeing Eastern Tiger Swallowtail butterflies feeding on nectar from a variety of plants.

Eastern Tiger Swallowtail nectaring at Wild Bergamot (Monarda fistulosa) flowers

But Eastern Tiger Swallowtail caterpillars have a completely different diet. They depend on the leaves of several woody plants species as their food source, including Black Cherry.

Eastern Tiger Swallowtail caterpillar in Black Cherry leaf

Eastern Tiger Swallowtails are just one of 456 species of butterflies and moths whose caterpillars eat the leaves of Black Cherry and other Prunus species, according to research from Douglas W. Tallamy and the University of Delaware. These caterpillars are in turn an important source of food for birds, especially when they are raising their young.

Tufted Titmouse – one of many bird species that harvest caterpillars from Black Cherry

Tent caterpillars favor Black Cherry, a practice that gardeners usually view unfavorably.

Tent Caterpillar egg mass in winter

But even Tent caterpillars have redeeming qualities, since they are an important food source for both Yellow- and Black-billed Cuckoos.

Yellow-billed Cuckoo

Adult butterflies and moths may also become food for birds or other insects, and in the case of night-flying moths (including Tent caterpillars that survive to become adult moths), for bats.

In addition to the nectar offered by its flowers, Black Cherry provides nectar from glands on its leaf stems. These nectaries are not targeting pollinators. Instead, they are there to lure a mercenary army of ants to protect the tree from herbivores, especially caterpillars. The nectaries entice ants to visit the trees for a drink. While there, the ants may also help to keep the caterpillar population in check, since ants also need insect protein as part of their diet.

Black Cherry (Prunus serotina) in bloom

People benefit directly from Black Cherry trees. In addition to the beauty of its flowers, fruits and foliage, Black Cherry’s wood is an important timber crop, primarily for use in furniture and cabinet making. Black Cherry’s fruit is used to flavor brandies and to make a liqueur called cherry bounce. The fruit is somewhat bitter, but with added sugar it can be used to make jellies. Eating the raw fruit is not advisable, since the seeds can be toxic. Medicinally, Black Cherry’s inner bark has been used in cough suppressants.

Black Cherry can grow to a maximum height of 80-100 feet (24-30 meters). Its range is primarily eastern North America, from Canada through the United States and south into Mexico, although it is an adaptable species and may also be found in some areas of the Pacific Northwest.

Providing beauty, timber, food and medicine for humans, food for birds, mammals, pollinators and hundreds of other insects, Black Cherry is among our most productive native trees.

Black Cherry (Prunus serotina) in bloom

Resources

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

Eiseman, Charley; Charney, Noah. Tracks & Sign of Insects and Other Invertebrates. 2010.

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.

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

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

Tallamy, Douglas W. Bringing Nature Home, 2007,

Illinois Wildflowers

USDA Plant Database

A Tale of Two Spring Beauties

Posted on May 19, 2016 by Mary Anne Borge

Spring Beauty (Claytonia virginica) is one of the earliest of the spring wildflowers to appear in New Jersey, where I live. Its grass-like leaves emerge first, finding their way through their warm winter blanket of leaf mulch.

Spring Beauty (Claytonia virginica) leaves emerging from their winter blanket of leaf mulch.

When temperatures are warm enough, flowers begin to bloom, offering an enticement to early spring pollinators.

Spring Beauty (Claytonia virginica) with bee

I knew there was another Spring Beauty species, Carolina Spring Beauty (Claytonia caroliniana), but I never encountered it until a recent trip to Stowe, Vermont.

Carolina Spring Beauty (Claytonia caroliniana)

The flowers of the two Spring Beauty species look identical. Both have 5 white to pinkish petals, with nectar guides that vary from almost white to deep pink, striping the petals like the insect equivalent of airport runway lights, showing the way to a meal instead of a terminal.

Spring Beauty (Claytonia virginica) flowers, with bee

Carolina Spring Beauty (Claytonia caroliniana) flower, with flower fly

It’s the foliage of the two Spring Beauties that set them apart. In contrast to the long, narrow leaves of Spring Beauty,

Spring Beauty (Claytonia virginica)

Carolina Spring Beauty has a pair of paddle or spatula shaped leaves with very distinct petioles (leaf stems).

Carolina Spring Beauty (Claytonia caroliniana)

The leaves are succulent, helping the plants through any periods of moisture shortages in the upland habitats where they are most likely to be found, according to their USDA wetland status.

Carolina Spring Beauty (Claytonia caroliniana)

Carolina Spring Beauty’s firm leaves are the perfect solar panels for this plant, gathering energy from the sun during the few weeks they appear above ground each spring.

Carolina Spring Beauty (Claytonia caroliniana)

The leaves help Carolina Spring Beauty to make the most of the short spring of its native range, which is primarily northerly or in upland areas, from Ontario to Newfoundland and Nova Scotia in Canada, south to the New England states, through the Appalachian mountains as far south as Alabama and Georgia, and in northern Michigan, Wisconsin and Minnesota. They are not found in the places I frequent in New Jersey or southeastern Pennsylvania, so it was pretty exciting to see them.

Carolina Spring Beauty (Claytonia caroliniana)

The other Spring Beauty (Claytonia virginica) has a more southerly range. It is native in Canada only in Nova Scotia and southern Quebec and Ontario provinces, then south through the United States as far as Texas in the west and Georgia in the east. The ranges of these two species rarely overlap.

Spring Beauty (Claytonia virginica) with bee

Look for these Spring Beauties for a few more days, before they disappear underground until they emerge again with the first warm days next spring.

Spring Beauty (Claytonia caroliniana) with bee

Signs of Spring – Mining Bees

Late Spring in Stowe, Vermont

Resources

Clemants, Steven; Gracie, Carol. Wildflowers in the Field and Forest. 2006.

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

USDA Plants Database – Carolina Spring Beauty

USDA Plants Database – Spring Beauty

Evergreen Native Plant Database

Spring Azures

Posted on April 26, 2016 by Mary Anne Borge

Spring Azures spent the winter as pupa, cozy in their chrysalises, poised to take the final step to adulthood when spring conditions were right, with longer days and warmer temperatures. Their fluttering flight showing flashes of azure began lighting up woodlands and gardens earlier than usual this year, when unseasonably warm March temperatures encouraged them to complete their metamorphosis and emerge as early as the last week of March.

Spring Azure butterfly

Nectar was scarce in those early days of emergence, especially when weather whiplash sent the temperatures in the opposite direction, dropping below normal. During the lean times, Spring Azures got their nourishment from a variety of mineral sources, including mud puddles, rocks, leaves, and even bird droppings.

Spring Azure getting nutrients from bird droppings

As temperatures soared again, nectar supplies became plentiful.

Spring Azure dringing nectar from Wild Plum (Prunus americanus) blossoms

Now their priority is reproduction – making sure their species has a future. After mating, female Spring Azures look for plants appropriate for egg-laying, plants whose leaves their caterpillars can eat and on which they will thrive. Spring Azures evolved to use the newly emerging leaves, flowers and buds of a variety of woody plants as their caterpillars’ food, including viburnums, dogwoods (Cornus species), and New Jersey Tea (Ceanothus americanus). For the past week, I’ve watched Spring Azures flitting from plant to plant, and from leaf to bud of Maple-leaf Viburnum (Viburnum acerifolium), taking only seconds to lay each egg.

Spring Azure laying an egg on Maple-leaf Viburnum (Viburnum acerifolium) flower buds

The eggs will hatch and caterpillars will emerge, nibbling on the newly developing leaves and buds. Not all of the caterpillars will complete metamorphosis to fly as butterflies, however. Caterpillars are very vulnerable to predators, including other insects, spiders and birds. Caterpillars are an essential source of food for birds, especially when they are feeding their young. It may take thousands of caterpillars to feed a hungry clutch of growing birds.

Hungry young Tufted Titmouse looking for food

Normally, ants would be among the insects that would love to eat a tasty caterpillar treat. Even when fully grown Azure caterpillars are small, the perfect snack size for an industrious ant on the hunt. To protect themselves, Azure butterflies have developed a way to enlist the ants to protect them rather than eat them. Azures produce delicious honeydew that ants love. The ants guard the Azure caterpillars, palpating them to trigger the honeydew payment.

Ant guarding/palpating an Azure caterpillar for honeydew. They’re on New Jersey Tea (Ceanothus americanus).

Ants will work for the highest bidder, and in this case they help some of those caterpillars live to become butterflies.

Spring Azure butterfly on Maple-leaf Viburnum (Viburnum acerifolium)

‘Will Work for Food’ – Extra-floral Nectaries

Maple-leaf Viburnum

Gray Dogwood for Butterlies, Bees and Birds

Resources

Butterflies and Moths of North America

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

Slippery Elm in Bloom

Posted on March 25, 2016 by Mary Anne Borge

Color is slowly easing back into the deciduous woods. Branches that were bare all winter are beginning to show the subtle reds, greens and yellows of early blooming trees and shrubs.

Slippery Elm (Ulmus rubra) in Bloom

Slippery Elm (Ulmus rubra) is among the early flowering trees, often blooming sometime in March. Before blooming, its rusty colored, fuzzy-hairy flower buds are visible throughout winter.

Slippery Elm (Ulmus rubra) Buds

Slippery Elm blooms before its leaves appear, making it easier for the wind to carry Slippery Elm’s pollen to another flower, helping this species to achieve successful pollination. Wind pollination is a good evolutionary adaptation for an early blooming tree, since wind is a more reliable pollination partner in the usually cool blustery days of March than insects are. (Although this spring is exceptionally warm in the Northeastern United States!)

Slippery Elm (Ulmus rubra) in Bloom

Flowers that are successfully pollinated produce fruits that many birds eat, including Carolina Chickadees, Rose-breasted Grosbeaks, and Purple Finches.

Female Purple Finch. Purple Finches are among the birds that eat elm seeds

Squirrels and other small mammals also eat Slippery Elm seeds.

Red Squirrel – a consumer of elm seeds

Slippery Elm leaves are large and rough, with distinctly toothed edges.

Slippery Elm Leaf

These leaves provide food for many insects that in turn provide pollination services for other plants, or food for other animals. Over 200 species of butterfly and moth caterpillars (Leipidoptera), including those of Mourning Cloak, Question Mark and Eastern Comma butterflies and Polyphemus moths may eat the leaves of Slippery Elm and its close relatives.

Eastern Comma Butterfly

Polyphemus Moth caterpillar, looking for a place to pupate. What a plump, juicy treat for a hungry bird!

Birds depend on these insects as protein for themselves and their growing offspring.

Male Black-throated Blue Warbler. Warblers, Chickadees, Titmice and most other birds depend on insects for a large percentage of their diet.

Cavity nesting birds or small mammals may find a suitable home site in Slippery Elm, while other birds, like Baltimore Orioles, may build their nests in its branches.

Natural cavity in a Slippery Elm. Some strings of nest material are draped below the opening.

Slippery Elm gets its name from its inner bark (the phloem) which is part of the vascular system that transports food throughout the tree. Slippery Elm’s inner bark is mucilaginous (thick, sticky) and fibrous. Indigenous North American peoples used the inner bark fibers to make rope or other cordage.

Slippery Elm’s inner bark has also been used to make a tea that is easy to digest and high in nutrients; it was given to people who had difficulty consuming food. The inner bark was also dried and ground to make a flour high in nutritional value.

Slippery Elm has many medicinal uses. As a demulcent it is well suited for treatment of inflamed mucous membranes throughout the digestive tract. It also has anti-inflammatory and astringent properties, and has been used externally to treat skin problems including wounds, ulcers and boils. Slippery Elm is available as an over the counter supplement, and has been approved by the Food and Drug Administration for use in throat lozenges. Even plant-derived supplements can have unwanted side effects, so careful research or consultation with a physician should take place before consuming Slippery Elm.

Slippery Elm can be found in much of the eastern two-thirds of the United States and Canada, often in moist woods, stream banks, and woodland edges. Look for it blooming now in a natural area near you.

Slippery Elm (Ulmus rubra) in Bloom

Resources

Beresford-Kroeger, Diana. Arboretum America: A Philosophy of the Forest. 2003

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

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

Tallamy, Douglas W. Bringing Nature Home, 2007,

Illinois Wildflowers

USDA Database

The Natural Web

Exploring Nature's Connections

White Beardtongue for Pollinators

Black Cherry – for Wildlife, and People, too!

A Tale of Two Spring Beauties

Spring Azures

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