A Small Beauty: Purple Milkwort

Posted on August 18, 2017 by Mary Anne Borge

As we walked the path between the woods and the meadow at the Pole Farm section of Mercer Meadows, Wood Nymphs flitted in and out of the foliage, Monarchs flew by, some mating, and a Clouded Sulphur dipped into the path to lay eggs, the tip of her abdomen touching the leaves of White Clover for a split second each.

Monarch butterflies mating

Wood Nymph

Glancing down, I saw a small group of plants that at first glance looked like a type of clover.

Purple Milkwort (Polygala sanguinea).

But it wasn’t clover. The plants had narrow, alternate leaves, and the tiny flowers were tightly packed into a somewhat flat-topped cylindrical cluster. It was Purple Milkwort (Polygala sanguinea).

In profile, the outside of the flowers in the cluster (inflorescence) look like overlapping scales, similar to those on a pine cone. These scale-like structures are sepals, the outermost appendage of a flower. When present, sepals protect the other flower parts as they mature. In Purple Milkwort, two sepals fuse to form these scale-like outer flower parts, each for a separate flower.

Purple Milkwort (Polygala sanguinea), with unknown insect, probably a beetle, investigating its flowers

Viewed from the top, the inflorescence looks like a single very showy flower.

Purple Milkwort (Polygala sanguinea)

A closer inspection tells a different story. The outermost layers of the display look like white petals dipped in purple, but they are the sepals visible when the flower cluster is viewed in profile. Moving inward, there are tube-like structures, in luscious shades of yellow, peach and a deep bright pink, reminiscent of popsicle colors. These tubes are the fused petals of the individual flowers that form this cohesive cluster. At the very center of the inflorescence is a bouquet of buds that have not yet opened. Together these flowers and buds offer an impressive show.

Purple Milkwort (Polygala sanguinea). The fused petals form a tube, initially yellow, then fading to peach and deep pink.

What explains the different colors of the floral tubes? If you look carefully, the yellow flowers are closest to the center of the display. They are the most recently in bloom, open for business, the bright yellow actively beckoning pollinators. The peach flowers have been open longer, and are shutting down. The deep pink flowers have been in bloom the longest, and are no longer seeking pollinators for themselves. This kind of color change is usually a plant adaptation to direct pollinators only to the receptive flowers that have not yet been pollinated. It makes the most efficient use of the pollinator’s efforts from the perspective of both the pollinator and the plant. While the peach and pink flowers are not beckoning pollinators for themselves, they continue to add to the attractiveness of the overall floral display.

This brightly colored display works! It attracts small to medium sized bees and bee-flies with tongues long enough to reach down the floral tube for a nectar reward. The photos below show a Sweat Bee (Halictid bee, Augochlorini tribe) exploring the flowers.

Sweat Bee (Halictid bee, Augochlorini tribe) exploring a Purple Milkwort (Polygala sanguinea) inflorescence

Sweat Bee (Halictid bee, Augochlorini tribe) positioning its proboscis for a drink from a Purple Milkwort (Polygala sanguinea) flower

Mmmm, delicious! Sweat Bee (Halictid bee, Augochlorini tribe) drinking nectar from a Purple Milkwort (Polygala sanguinea) flower

Purple Milkwort can be found in the ground cover layer of meadows, prairies, open fields and woods edges from Nova Scotia west to Ontario in Canada, and in much of the eastern two-thirds of the United States, except Florida. It can grow to a height of four to sixteen inches (1-4 dm). Both the common and scientific names reflect the color of the flowers and the milky sap the plant contains. The genus, Polygala, is derived from Greek words that mean ‘many or much’ and ‘milk’, referring to the sap. The species, sanguinea, is derived from a word that means ‘blood’. Other common names for Purple Milkwort are Blood or Field Milkwort, reflecting its color or habitat. Although common, it’s not always easy to spot this little beauty.

Follow the camera lens to the Purple Milkwort in the shadows in the lower left of the photo.

Resources

Mauseth, James D. Botany An Introduction to Plant Biology. 2014.

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

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

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

Flora of Wisconsin

Illinois Wildflowers

Minnesota Wildflowers

USDA NRCS Plants Database

Blackberries, Butterflies, Bees and Birds

Posted on May 31, 2017 by Mary Anne Borge

Common, or Allegheny, Blackberry (Rubus allegheniensis) brambles are blooming in woodlands and meadows throughout the local areas I frequent in central New Jersey and eastern Pennsylvania. This Rose (Rosaceae) family member can be found from Quebec to Ontario provinces in Canada, south as far as South Carolina and Oklahoma in the United States. It is also present in California and British Columbia.

Common, or Allegheny, Blackberry (Rubus allegheniensis)

At Bowman’s Hill Wildflower Preserve, near New Hope, Pennsylvania, I found masses of Wild Blackberry blooming in the meadow. Traditionally, the entire meadow is mowed during the winter, but this year a new method of meadow maintenance was introduced, one recommended by the Xerces Society. Only part of the site was mowed last year, in order to preserve habitat for overwintering insects, birds, and other animals. This new technique is already paying off, with an impressive display of flowering Blackberry canes, and an equally impressive variety of native pollinators visiting the flowers.

I wasn’t the only one to discover the Blackberries in bloom. From a distance, I could see that at least three Monarch butterflies were already there, flirting and drinking nectar, drawing me in to get a closer look. They were my first certain Monarch sighting of the season.

Monarch on Common Blackberry (Rubus allegheniensis)

The Monarchs weren’t alone. Little Wood Satyrs flitted about, occasionally stopping to drink nectar from the flowers. Little Wood Satyrs are often found where woodlands meet meadow habitat.

Little Wood Satyr on Common Blackberry (Rubus allegheniensis)

Several Red-banded Hairstreaks visited the flowers, along with a few Zabulon Skippers, Eastern Tiger Swallowtails, and Silver-spotted Skippers.

Red-banded Hairstreak hanging out on Common Blackberry (Rubus allegheniensis)

Eastern Tiger Swallowtail drinking nectar from Common Blackberry (Rubus allegheniensis)

Zabulon Skipper drinking nectar from Common Blackberry (Rubus allegheniensis)

Bees and Common Blackberry have a mutually beneficial relationship. Bees are important pollinators for Common Blackberry, and Common Blackberry is an important source of nectar and pollen for the bees. While I watched, Mining Bees, Bumble Bees, Carpenter Bees and Honey Bees worked the flowers.

Mining Bee (Andrena species) with Common Blackberry (Rubus allegheniensis)

A different Mining Bee (Andrena species) with Common Blackberry (Rubus allegheniensis)

Female Bumble Bee (Bombus species) foraging on Common Blackberry (Rubus allegheniensis). Notice the huge orange load of pollen she has harvested to take back to her nest to feed her larvae.

Eastern Carpenter Bee (Xylocopa virginica) with Common Blackberry (Rubus allegheniensis).

A pair of soldier beetles, Pennsylvania Leatherwings (Chauliognathus pensylvanicus) were mating at the same time the female impressively foraged the flowers for food, a pretty common beetle behavior combination.

A pair of soldier beetles, Pennsylvania Leatherwings (Chauliognathus pensylvanicus) mating, at the same time the female impressively forages Common Blackberry flowers for food.

A Flower or Syrphid Fly (Toxomerus geminatus) ate pollen from the flowers, probably not helping very much to pollinate the Blackberries. Flies, bees and even beetles all consume some of the pollen. Only about 2% of pollen is actually used for pollination. The rest serves as an enticement to flower visitors.

A Flower or Syrphid Fly (Toxomerus geminatus) eats pollen from Common Blackberry (Rubus allegheniensis) flowers

A Flesh Fly, and a Robber Fly disguised as a Bumble Bee paused on Blackberry leaves. As a carnivore, the Robber Fly’s mission is to capture and eat other insects. The disguise may help it elude predators and seem harmless to its intended prey.

A Robber Fly ( Laphria flavicollis) pausing on a Common Blackberry (Rubus allegheniensis) leaf

A Flesh Fly (Sarcophaga species) on Common Blackberry (Rubus allegheniensis)

At a woods edge location nearby in New Jersey, a Bumble Bee and Orange Sulphur enjoyed the nectar the Blackberries offered.

Bumble Bee (Bombus species) on Common Blackberry (Rubus allegheniensis).

Orange Sulphur drinking nectar from Common Blackberry (Rubus allegheniensis).

Common Blackberry has high value for other animals. The insect flower visitors will help to ensure a late summer feast of blackberries for birds, and mammals from mice to fox, and even bear. They’re very healthy for humans, too!

Ripe fruit of Common Blackberry (Rubus allegheniensis).

Wild Turkey is one of the many animals that benefit from eating Common Blackberry (Rubus allegheniensis) fruit

During the summer, these Common Blackberry brambles offer the perfect nesting habitat for Indigo Buntings. I saw a flash of blue feathers heading for a nearby tree, so they may already be in the process of establishing their nesting territory.

Male Indigo Bunting in Eastern Red Cedar

Multiflora Rose (Rosa multiflora), another Rose family member, is also in bloom. This species was introduced from Asia for use in hedgerows, especially around farm fields. As is so often the case, it turned out the introduction was a bad idea. Multiflora Rose has since become invasive in much of the United States and Canada. Several states list it as a noxious weed, and some prohibit it.

Plants and even animals that are introduced in a location far from where they evolved often become a problem in their new environment, since the natural predators with which they evolved are not present. In their native locations, these predators help to keep the plant or animal population in balance with other species. Without these natural checks, the introduced species can crowd out the native plant species on which the animals with which they evolved depend. We end up losing both plant and animal species as a result.

There is a family resemblance between Common Blackberry and Multiflora Rose, but it’s fairly easy to tell them apart.

Common Blackberry (Rubus allegheniensis) flowers

Common Blackberry flowers are usually white, about 1-1 ½ inches (2.54-3.8 cm) in diameter. The petals have rounded tips. A large cluster of greenish pistils, the female reproductive flower parts, are visible at the center of the flowers. These pistils together produce an aggregation of tiny fleshy fruits (called druplets) that are what we know as a blackberry. The fruits start out green, turning red and eventually black when they’re ripe. The stamens (male reproductive parts) surround the pistils. They have white filaments topped with brownish anthers from which pollen is released.

Multiflora Rose (Rosa multiflora) flowers

Multiflora Rose flowers are also usually white, or rarely pinkish. They are just a bit smaller, and the tip of each petal is notched, not rounded. There is a single greenish pistil at the center of the flower that produces a single round red berry-like fruit called a hip. The pistil is surrounded by stamens with creamy yellow filaments and darker golden anthers. Multiflora Rose leaves have a distinctive fringe along the sides of the base of the stem. This is not present in Common Blackberry.

Where I have seen Common Blackberry and Multiflora Rose in close proximity to each other, the pollinators always choose Common Blackberry. It may be a small sampling for a scientific study, but it seems like a pretty telling endorsement to me!

Eastern Tiger Swallowtail drinking nectar from Common Blackberry (Rubus allegheniensis)

Related Posts

Indigo Buntings – Living on the Edge!

For Information on Meadow Maintenance from the Xerces Society

http://www.xerces.org/wp-content/uploads/2014/09/PollinatorsNaturalAreas_June2014_web.pdf

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

The Xerces Society

Resources

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

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

Evans, Arthur V. Beetles of Eastern North America. 2014.

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

Marshall, Stephen A. Insects Their Natural History and Diversity. 2006.

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

Illinois Wildflowers

USDA NRCS Database

Lady Bird Johnson Wildflower Center

For Information on Mutiflora Rose

USDA NRCS Database

USDA National Invasive Species Information Center

Center for Invasive Species and Ecosystem Health

Pussytoes and Butterflies

Posted on May 15, 2017 by Mary Anne Borge

Plantain-leaved Pussytoes (Antennaria plantaginifolia)

Plantain-leaved Pussytoes (Antennaria plantaginifolia) bloom in early spring, their flower shoots and leaves emerging from the soil as the temperatures warm and the days lengthen. The common name ‘Pussytoes’ comes from the resemblance of the tight flower clusters to a cat’s paw, especially when the flowers are still in bud. Both the common and scientific (plantaginifolia) names refer to the appearance of the mature leaves of this plant, which resemble those of the Plantains (Plantago species). The leaves remain green throughout the winter.

Plantain-leaved Pussytoes (Antennaria plantaginifolia) in bud

Plantain-leaved Pussytoes are Aster (Asteraceae) family members. Each toe-shaped inflorescence (flower cluster) consists of small tubular ‘disk’ flowers typical of this family. Somewhat less common in an herbaceous plant (one that’s not woody) is the fact that Plantain-leaved Pussytoes have male and female flowers on separate plants. As the flowers open, they reveal their sex. In the male flowers, the stamens (the male reproductive parts) emerge above the tubular corolla, transforming the inflorescence’s appearance from pussytoe-like to more of the look of a white-iced cupcake covered with birthday candles. In a close-up, a stamen also resembles a box of popcorn (at least to me), with the emerging pollen playing the role of the popcorn spilling out of the box.

Plantain-leaved Pussytoes (Antennaria plantaginifolia) with male flowers beginning to open. Note the stamens emerging from the flowers.

The female flowers look like tiny pompoms, with white hair-like projections (pappus) jutting well past the tube of fused flower petals. After a flower is successfully germinated, the pappus will transform to a light, fluffy appendage attached to the ripe fruit, helping it to disperse with the wind. The genus ‘Antennaria’ refers to the antenna-like appearance of the pappus.

Plantain-leaved Pussytoes (Antennaria plantaginifolia) with female flowers in bloom.

Like most plant species, Plantain-leaved Pussytoes would prefer to be cross-pollinated. This requires the assistance of insects who visit the flowers and transfer pollen on their bodies from male to female plants. But if flower visitors aren’t timely enough, Plantain-leaved Pussytoes can also self-fertilize to produce seed. It may not be as strong a genetic result, but it’s better than failing to reproduce.

Plantain-leaved Pussytoes can also reproduce vegetatively through horizontal ground-level stems, called stolons. Through this method, Pussytoes can form a spreading colony of shoots, all sharing the same genetics, and all of the same sex.

A colony of Plantain-leaved Pussytoes (Antennaria plantaginifolia) with male flowers.

On a warm spring afternoon, I watched while pollinators visited two separate but near-by colonies of Plantain-leaved Pussytoes, one male, the other female.

Flies were the predominant visitors to the female flowers, both flesh flies and Tachinid flies, although there was also an ant visiting for nectar.

A flesh fly (Sarcophaga species) foraging on Plantain-leaved Pussytoes (Antennaria plantaginifolia) with female flowers

Adult flesh flies often drink nectar from flowers, but their offspring have different needs. The larvae of many species live in and eat carrion, an adaptation that gives this genus (Sarcophaga) its common name. This important service helps to speed the decomposition of dead animals, and can be used in determining time of death in crime scene investigations.

A Tachinid Fly (Gonia species) feeding on Plantain-leaved Pussytoes (Antennaria plantaginifolia) with female flowers

In addition to pollination, Tachinid flies also work a second job, helping to keep other insect populations in check. Their larvae develop within an insect host, eating it from the inside. They keep the host insect alive by eating its vital organs last, finishing just as the larva completes its own development. This particular Tachinid Fly (Gonia species) specializes on owlet moth caterpillars.

Tachinid flies and Cuckoo Bees visited the male flowers while I watched.

A Tachinid Fly (Gonia species) feeding on Plantain-leaved Pussytoes (Antennaria plantaginifolia) with male flowers

A Cuckoo Bee (Nomada species) feeding on Plantain-leaved Pussytoes (Antennaria plantaginifolia) with male flowers

A Cuckoo Bee (Nomada species) feeding on Plantain-leaved Pussytoes (Antennaria plantaginifolia) with male flowers. Do the flower clusters look like pussytoes or cupcakes with candles?

A Cuckoo Bee (Nomada species) feeding on Plantain-leaved Pussytoes (Antennaria plantaginifolia) with male flowers. The red-striped stamens with yellow pollen at the top look a bit like a box of popcorn.

Since the Tachinid Flies were the only species I saw foraging on both male and female flowers, they are the most likely to have helped this particular colony of Plantain-leaved Pussytoes with pollination.

American Lady butterflies specialize on some Aster family members as food for their caterpillars, including Plantain-leaved Pussytoes, other Antennaria species, Pearly Everlastings (Anaphalis margaritacea), and a few others.

American Lady butterfly

Plantain-leaved Pussytoes with male flowers can grow to a height of about 8 inches (20 cm). The flower stalks of plants with female flowers are taller, with a maximum height of about a foot (30 cm).

A colony of Plantain-leaved Pussytoes (Antennaria plantaginifolia) with female flowers.

Plantain-leaved Pussytoes can be found in open woods, fields and rocky banks from Maine to Minnesota (except Michigan), south as far as Louisiana and the Florida panhandle. One source, the Flora of North America, says it can be found in Manitoba, Nova Scotia, New Brunswick and Quebec provinces in Canada.

Plantain-leaved Pussytoes (Antennaria plantaginifolia) with A Tachinid Fly (Gonia species)

Related Posts

Asters Yield a Treasure Trove

New England Asters – A Hotbed of Activity!

Feasting on Green-headed Conefower

Resources

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

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

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

Marshall, Stephen A. Insects Their Natural History and Diversity. 2006.

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

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

Bugguide.net

Flora of North America

Illinois Wildflowers

NC State Extension

USDA NRCS Plant Database

Hepatica’s Survival Strategy

Posted on April 17, 2017 by Mary Anne Borge

Early spring blooming wildflowers are typically small, lovely, and very delicate looking. But looks can be deceiving. Most are actually very tenacious, often with multiple strategies geared to enable them to survive and reproduce. Take the Hepaticas (Anemone americana, A. acutiloba) for example.

They are among the earliest blooming spring wildflowers, starting as early as mid-March in the southern part of their range to as late as May in the northernmost areas. The flower stalks emerge from their blanket of fallen leaves and bloom well before the new season’s leaves unfurl on the trees above them.

Round-lobed Hepatica (Anemone americana, synonym Hepatica nobilis var. obtusa) emerging from its blanket of leaves

Hepatica is able to get a head start on the blooming season because its leaves remain viable throughout the winter, gathering energy and photosynthesizing when the conditions permit. When the warmer spring days arrive, Hepatica is ready to go full steam ahead with photosynthesis. The overwintering leaves may be green, or mottled with maroon.

Round-lobed Hepatica (Anemone americana, synonym Hepatica nobilis var. obtusa); note its evergreen leaves

Hepatica produces bright flowers in shades from white to deep blue-violet, perfect for enticing pollinators to assist with cross-pollination. The flowers contrast well with the browns and tans of the decomposing leaf mulch surrounding them, beckoning to early flying solitary bees and flies.

Round-lobed Hepatica (Anemone americana, synonym Hepatica nobilis var. obtusa); with whitish flowers and mottled leaves

Round-lobed Hepatica (Anemone americana, synonym Hepatica nobilis var. obtusa); with deep violet flowers

Hepaticas have a short blooming season, at a time of year when weather can be unpredictable. It’s more difficult to photosynthesize in cool temperatures, so plants have to be very efficient about how they allocate their energy. The early flying solitary bees and flies that are their likely pollination partners are interested in nectar, but they need pollen even more. Many bees and flies consume pollen for the nutrients it provides, and female bees also harvest pollen to feed their larva. Pollen is a very effective reward to attract these visitors, so effective that Hepaticas have evolved not to put any energy into producing nectar.

Round-lobed Hepatica (Anemone americana, synonym Hepatica nobilis var. obtusa); with bee harvesting pollen

The bee moves on to another flower. Round-lobed Hepatica (Anemone americana, synonym Hepatica nobilis var. obtusa); with bee harvesting pollen

Round-lobed Hepatica (Anemone americana, synonym Hepatica nobilis var. obtusa); with bee harvesting pollen

Hepatica does hedge its bets a little. It protects its pollen by closing its flowers at night, and on rainy days. Cross-pollination with the assistance of an insect is preferred, since a stronger genetic result is more likely. But if that doesn’t happen, Hepaticas are able to self-pollinate. It’s better than not reproducing at all.

Regardless of how pollination is achieved, ants disperse Hepatica seeds, as they do for about 30% of spring blooming plants in the forests of the northeast. They are enticed to do this by the nutritious food packets, called elaiosome, that are attached to the seeds. Ants take the seeds back to their nests, eat the elaiosome, and discard the seed, usually in a location that is rich in soil nutrients and safe from seed-eating birds.

Hepaticas employ two strategies to protect themselves from being eaten by browsing insects or larger animals. Like many members of the Buttercup (Ranunculaceae) family, their leaves are toxic. The newly emerging flower stems, bracts and leaves, as well as the fruits (achenes) that develop later, are all hairy, a characteristic that discourages herbivores, and may also help to keep the plant’s tissues warm during cool spring days and nights.

Hairy fruit capsules and bracts of Round-lobed Hepatica (Anemone americana, synonym Hepatica nobilis var. obtuse)

Hepatica gets its name from its resemblance to a human liver, both in shape and in the maroon color often seen in its leaves. ‘Hepatica’ is derived from a Greek word that means ‘the liver’. Other common names for Hepatica are Liverleaf and Liverwort.

There was a period during which it was thought that if a plant resembled a body part, it would be effective in treating diseases of that body part (the ‘Doctrine of Signatures’). As a result, the Hepatica (Hepatica nobilis) native to Europe was used in preparations for treating liver ailments for many years, but more recent scientific testing of Hepatica has refuted its efficacy.

There are two Hepaticas in North America, Round-lobed Hepatica (Anemone Americana, synonym Hepatica nobilis var. obtusa) and Sharp-lobed Hepatica (Anemone acutiloba, synonym Hepatica nobilis var. acuta). They are named for the shape of the lobes of their leaves. Aside from that, they look the same. They are so similar to each other and to the European Hepatica (Hepatica nobilis), that some experts consider the North American species are sub-species of Hepatica nobilis.

Sharp-lobed Hepatica (Anemone acutiloba, synonym Hepatica nobilis var. acuta); Notice the maroon leaves from the previous season; the pointed lobes distinguish this species from Round-lobed Hepatica. The new leaves, flower stems, bracts, and even the flowers are hairy.

Hairy fruit capsules and pointed bracts of Sharp-lobed Hepatica (Anemone acutiloba, synonym Hepatica nobilis var. acuta)

Both the North American Hepaticas can be found in rich woodlands, often on dry upland slopes. Sharp-lobed Hepatica has a preference for rocky soils that have a higher calcium content. Both can be found in Manitoba, Ontario and Quebec provinces in Canada. In the United States, Round-lobed Hepatica may be found from Minnesota to Maine, south to Arkansas and the Florida panhandle, but it is more common in the northern and eastern part of its range. Sharp-lobed hepatica has a similar U.S. range, it is more common in the northern and central parts of its range. It has not been reported in New Jersey or Florida.

So Hepatica’s survival strategy includes winter-hardy leaves to enable winter and early spring photosynthesis, hairy, toxic foliage to deter herbivores, produce flowers that entice pollinators, but self-pollinate if necessary, and partner with ants for seed dispersal. Seems pretty comprehensive!

Round-lobed Hepatica (Anemone americana, synonym Hepatica nobilis var. obtuse)

Resources

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

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.

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

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

Illinois Wildflowers

USDA NRCS Plant Database

https://www.plants.usda.gov/core/profile?symbol=HENOO

https://plants.usda.gov/core/profile?symbol=HENOA

Bountiful Blue Wood Aster

Posted on November 27, 2016 by Mary Anne Borge

Blue Wood or Heart-leaved Aster (Symphyotrichum cordifolium) began its seasonal bloom in late September, and amazingly, at the end of November it’s still possible to find some blossoms.

Blue Wood Aster (Symphyotrichum cordifolium) with Sweat Bee (Halictus species)

Like all Aster (Asteraceae) family members, each flower ‘head’ of Blue Wood Aster consists of many tiny flowers that bloom gradually over a period of several weeks, offering nectar and pollen to a variety of flower visitors. Each Blue Wood Aster flower head has an outer ring of ice blue petal-like ray flowers designed to advertise this feast. Tiny tubular disk flowers form the center of the display; this is where Blue Wood Aster makes its bountiful food available in hope that while dining, visitors will pick up pollen and transfer it to another plant of the same species, enabling pollination to occur.

Blue Wood Aster’s disk flowers are pale yellow when they’re in bud and when they first open. They turn pink or magenta as they age, and when they have been successfully pollinated. This color change is a signal to pollinators, directing them to the receptive yellow flowers which are not yet pollinated and that will reward them with nectar, and steering them away from blossoms that are already satisfactorily pollinated and will not produce a nectar reward. This evolutionary adaptation makes the most efficient use of both the plant’s and the potential pollinator’s efforts.

To share in the bounty offered by Blue Wood Aster, I invite you to a virtual time-lapse visit to our garden in central New Jersey. You can see the last Blue Wood Aster blossoms for this year, and a selection of the many of the visitors that this lovely plant hosted throughout the season. Notice that the potential pollinators are generally visiting the yellow disk flowers, those that are still open for business, not the pinkish flowers that have shut down their nectar production.

Bumble Bees are the most frequent visitors.

Bumble Bee (Bombus species) drinking nectar from Blue Wood Aster (Symphyotrichum cordifolium)

An athletic Eastern Carpenter Bee drinking nectar from Blue Wood Aster (Symphyotrichum cordifolium).

But many species of Sweat Bees (Halictid bees), and even Honey Bees dine on Blue Wood Aster nectar and pollen.

Sweat Bee (Halictus species) with Blue Wood Aster (Symphyotrichum cordifolium)

Sweat Bee (Halictus species) drinking nectar from Blue Wood Aster (Symphyotrichum cordifolium)

A gang of Sweat Bees (Halictus species) drinking nectar from Blue Wood Aster (Symphyotrichum cordifolium)

Sweat Bees (Halictid bees) of two different species visiting Blue Wood Aster (Symphyotrichum cordifolium)

A Sweat Bee (Halictid bee) drinking nectar from Blue Wood Aster (Symphyotrichum cordifolium)

A Sweat Bee (Augochlorella species) investigating Blue Wood Aster (Symphyotrichum cordifolium)

A Honey Bee (Apis mellifera) nectaring from Blue Wood Aster (Symphyotrichum cordifolium)

A Mason Wasp stopped by for nourishment.

A Mason Wasp (Ancistrocerus species) drinking nectar from Blue Wood Aster (Symphyotrichum cordifolium)

Many fly species paused to drink, most disguised as bees or wasps in an attempt to appear threatening to potential predators.

A Syrphid or Flower fly drinking nectar from Blue Wood Aster (Symphyotrichum cordifolium)

A Syrphid or Flower Fly (Toxomerous geminatus) drinking nectar from Blue Wood Aster (Symphyotrichum cordifolium)

A Syrphid or Flower Fly (Syrphus ribesii) drinking nectar from Blue Wood Aster (Symphyotrichum cordifolium)

A Syrphid or Flower Fly (Sericomyia chrysotoxoides) drinking nectar from Blue Wood Aster (Symphyotrichum cordifolium)

A Syrphid or Flower Fly (Eristalis tenax) drinking nectar from Blue Wood Aster (Symphyotrichum cordifolium)

Greenbottle Fly (Lucilia sericata) drinking nectar from Blue Wood Aster (Symphyotrichum cordifolium)

Even late season butterflies and moths were able to refuel on Blue Wood Aster nectar.

A Clouded Sulphur butterfly drinking nectar from Blue Wood Aster (Symphyotrichum cordifolium). Notice the heart-shaped leaves that are characteristic of this species.

A Pearl Crescent butterfly drinking nectar from Blue Wood Aster (Symphyotrichum cordifolium). Not only do these butterflies benefit from the nectar, but their caterpillars dine on the foliage of several aster species.

A Corn Earworm Moth drinking nectar from Blue Wood Aster (Symphyotrichum cordifolium).

A Yellow-collared Scape Moth (Cisseps fulvicollis) and Bumble Bee on Blue Wood Aster (Symphyotrichum cordifolium).

Meanwhile, a Brown-hooded Owlet Moth caterpillar dined on the leaves and spent flowers of Blue Wood Aster.

Brown-hooded Owlet caterpillar eating Blue Wood Aster (Symphyotrichum cordifolium) leaves and flowers.

Blue Wood Aster is native in much of the eastern half of the United States, and in British Columbia, Manitoba, Ontario, Quebec, Prince Edward Island and Nova Scotia in Canada. It can be found in a variety of habitats, including woodlands, meadows and roadsides. There may still be some blooming near you!

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Resources

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

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

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

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

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

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

USDA NRCS Plant Database

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Bountiful Blue Wood Aster

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