A Thistle Banquet

On a recent walk through a local meadow I spotted a bank of Field Thistle (Cirsium discolor).

Field Thistle (Cirsium discolor)

It was eye-catching for two reasons.  The sight of the plant itself is arresting, with its tall candelabra-like shape topped with purple pompoms of flowers instead of candle flames.  But it was the sight of so many visitors to the flowers, often several on a single flower head, that was really breath-taking.  Bumble Bees, Honey Bees, Clearwing Moths and so many different butterflies moved quickly from flower to flower, pausing briefly to dine.  Field Thistle presents a sumptuous feast for potential pollinators!

At one ‘banquet table’, a Honey Bee, a Thistle Long-horned Bee (Melissodes desponsus) and a Hummingbird Clearwing Moth all dined amiably together.

A Honey Bee, a Thistle Long-horned Bee (Melissodes desponsus) and a Hummingbird Clearwing Moth all drinking nectar from Field Thistle (Cirsium discolor)

At another, several Bumble Bees, Honey Bees and Thistle Long-horned Bees shared a meal.

Bumble Bees, Honey Bees and a Thistle Long-horned Bee (Melissodes desponsus) feeding from Field Thistle (Cirsium discolor)

How is it that one flower head can accommodate so many visitors simultaneously?  Field Thistle is a member of the Aster or Composite (Asteraceae) family.  Each of the purple pompoms consists of a cluster of many long narrow tubular disk flowers.  You can see the individual flowers in the head in the lower part of the photo below.

Field Thistle (Cirsium discolor). Note the individual narrow, trumpet-like disk flowers shown below the bee.

The Long-horned Thistle Bee in the photo below is actively eating both pollen and nectar, and harvesting more to provision her nest for her larvae.  You can see the pollen she has collected packed onto hairs, called scopae, on her hind legs. We know this is a female, because only female bees harvest food for their offspring.  This bee species specializes on pollen from Field Thistle and a few other closely related plants (all of the genus Cirsium) for her larvae.  This makes her an excellent pollinator for Field Thistle, since she won’t be visiting other flowers.  It also means that without these thistles, this bee species would not survive.  It’s the same concept as the Monarch butterfly’s dependency on Milkweeds (Asclepias species) for survival, because Milkweeds are the only food their caterpillars can eat.

Thistle Long-horned Bee (Melissodes desponsus) feeding on Field Thistle (Cirsium discolor). She’ll bring the pollen on her hind legs to her nest. Note the pollen grains all over her body! Some will help with pollination.

Although it appears in the photos above that the various visitors to these flowers are happy to share the wealth of the Field Thistle banquet, I’m sorry to have to report that the Honey Bees actually indulged in bullying behavior.  They were especially hostile to the Thistle Long-horned Bees, trying to chase them away by bumping them.

Honey Bee bullying Thistle Long-horned Bee (Melissodes desponsus) on Field Thistle (Cirsium discolor).

Fortunately, the Thistle Long-horned Bees were undeterred.  They were also respectful of other diners, even those smaller than themselves.

The small bee (possible Eucera species) in the upper left is harvesting pollen. With Thistle Long-horned Bee (Melissodes desponsus) on Field Thistle (Cirsium discolor).

I visited this meadow several times within a few weeks, and each time there were at least a half dozen Hummingbird Clearwing Moths at the thistle.

Hummingbird Clearwing Moths on Field Thistle (Cirsium discolor).

Their close relative, a Snowberry Clearwing Moth, also stopped by for a drink.

Snowberry Clearwing Moth drinking nectar from Field Thistle (Cirsium discolor).

One of the Hummingbird Clearwing Moths shared a thistle banquet table with a female Zabulon Skipper, while a male Zabulon Skipper and Peck’s Skipper dined together at another.

Female Zabulon Skipper and Hummingbird Clearwing Moth drinking nectar from Field Thistle (Cirsium discolor).

Male Zabulon Skipper (left) and Peck’s Skipper drinking nectar from Field Thistle (Cirsium discolor).

These skippers are small butterflies who specialize on various grass species as food for their caterpillars.  Many of these grasses can be found nearby in the meadow.

Peck’s Skipper drinking nectar from Field Thistle (Cirsium discolor).

Peck’s Skippers were ubiquitous, sipping nectar alone and in the company of others, including Spicebush Swallowtails and Great-spangled Fritillaries.

Spicebush Swallowtail and Peck’s Skipper drinking nectar from Field Thistle (Cirsium discolor).

Two courting Great-spangled Fritillaries and Peck’s Skipper on Field Thistle (Cirsium discolor).

Eastern Tiger Swallowtails also visited the flowers for nectar.

Eastern Tiger Swallowtail drinking nectar from Field Thistle (Cirsium discolor).

All of these large butterflies specialize on plants found in the adjacent woodlands as food for their caterpillars.  Spicebush Swallowtails require Spicebush (Lindera benzoin), their namesake plant, or Sassafras (Sassafras albidum);  Great-spangled Fritillaries need violets; and Eastern Tiger Swallowtails use various tree species, including Ash (Fraxinus species), Tuliptrees (Liriodendrun tulipifera), and Black Cherry (Prunus serotina).

It was very encouraging to see that there were many Monarch butterflies partaking of the thistle feast.  Both Common (Asclepias syriaca) and Swamp Milkweed (Asclepias incarnata) were available in the meadow for egg-laying.

Monarch butterfly drinking nectar from Field Thistle (Cirsium discolor).

Even Ruby-throated Hummingbirds visited the thistles for nectar, but they didn’t stay long enough for a photo op.

Field Thistle’s strategy to protect itself from being eaten is to have very spiny leaves and branches.  This works well in deterring mammals from munching the plant; Field Thistle is not a species that deer are likely to browse.  But caterpillars are a different story.  Painted Lady butterflies as well as Common Loopers and some other moth species use this plant as food for their caterpillars.

Painted Lady on White Snakeroot (Ageratina altissima). Field Thistle (Cirsium discolor) is one of the plant species that Painted Lady butterflies can use as food for their caterpillars.

Common Looper Moth on New England Aster ( Symphyotrichum novae-angliae). Common Looper Moths caterpillars also eat the leaves of Field thistle (Cirsium discolor).

After all of this help with pollination, Field Thistle produces seed-like fruits called achenes.  They have a light, white fluff (called pappus) attached, enabling their dispersal by the wind. But these fruits are also desirable food and nesting material for Goldfinches and other birds.

Eastern Goldflinches harvesting seeds from Field thistle (Cirsium discolor)

Field Thistle is native from Saskatchewan to Quebec provinces in Canada and in much of the eastern half of the United States, although it is less common in the southeastern states and absent from Florida.  The flower color can vary from purple to pinkish, and is occasionally white.  Field Thistle is a biennial or short-lived perennial, replacing itself by producing seeds.  It can grow to a height of five to seven feet (1.5 – 2.1 meters).  Unlike some non-native thistles, Field Thistle is not invasive.

There is a non-native thistle, Bull Thistle (Cirsium vulgare), that closely resembles the native Field Thistle.  Some differences in their characteristics that can help tell them apart include:  Field Thistle leaves have consistently white felt-like or woolly undersides, Bull Thistle leaves are green to greenish-white below;  Bull Thistle has winged stems where the leaves meet them, Field Thistle does not;  Field Thistle usually has a ring of leaves pointing upward hugging the base of the inflorescence (flower head), like a very pointy stand-up collar, Bull Thistle may have one or two leaves below the inflorescence.

Field Thistle (Cirsium discolor) with great-spangled Fritillary butterfly. Note the stand-up leaf collar hugging the base of the flower head.

Field Thistle isn’t traditionally used in gardens, but in the right location in a sunny garden, it could really make a statement, and bring so many visitors!

Field Thistle (Cirsium discolor)

 

Related Posts

A Butterfly garden that Embraces the Shade

Asters Yield a Treasure Trove

Black Cherry – for Wildlife and People, Too!

For Great-spangled Fritillaries, Leave the Leaf Litter

Spicebush or Forsythia?

Resources

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

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

Newcomb, Lawrence.  Newcomb’s Wildflower Guide.  1977.

Peterson, Roger Tory; McKenny, Margaret.  A Field Guide to Wildflowers of Northeastern and Northcentral North America. 1968.

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

Illinois Wildflowers

Invasive Plant Atlas of the United States: Bull Thistle

USDA NRCS Plant Database

USDA NRCS Plant Fact Sheet

 

 

 

Encounter with a Bluebird Family

As I approached a place where a meadow meets a narrow strip of woods, I noticed some movement in the shadows cast by a Tuliptree (Liriodendron tulipifera).  The light was low, so I had to use binoculars to be able to see that the bird flying from the ground to a low branch was an immature Eastern Bluebird.

Immature Eastern Bluebird

This is just the kind of habitat Eastern Bluebirds prefer, open meadows or even lawns with trees nearby for perching and nesting.  Bluebirds nest in cavities, using natural cavities and abandoned woodpecker holes in trees. This kind of real estate is in high demand, so Bluebirds also use nesting boxes.  The male brings materials to the nesting site, including grasses, spent plant stems and pine needles for the outside of the nest, finer grasses and sometimes animal hair for the inside.  The female is in charge of construction, building the nest inside their chosen cavity.

This youngster was apparently already learning and practicing a common Bluebird food foraging behavior, that of sitting on a low branch and flying down to capture an insect meal.  As is the case with most birds, insects and spiders are an important part of a Bluebird’s diet. Bluebirds eat quite a variety, including beetles, grasshoppers, crickets, and caterpillars.

Grasshopper – A good meal for a hungry Bluebird!

Tulip Tree Beauty – Nothing beats a caterpillar as a tasty treat!

In fall and winter fruit is added to this insect diet.

In fall and winter, Bluebirds add fruit like that offered by this Flowering Dogwood (Cornus florida) to their diet.

While I focused on this young bird, someone else entered my line of sight.  It was a vividly colorful mature male Bluebird.  He landed in a low bare branch of the Tuliptree, the remnants of last year’s fruit only slightly obscuring my view of him.

Male Eastern Bluebird in Tuliptree (Liriodendron tulipifera)

This dazzling male seemed intent on mesmerizing me with his beauty so that I would forget about his offspring in the shadows behind him.

Male Eastern Bluebird in Tuliptree (Liriodendron tulipifera)

His strategy was pretty effective.  While I didn’t forget about the young bird, I couldn’t take my eyes off its father.

Male Eastern Bluebird in Tuliptree (Liriodendron tulipifera)

But eventually my peripheral vision picked up some movement behind this stunning male.

A female Eastern Bluebird was flying from a nesting box in the meadow, to the far edge of the tree line.  She flew back and forth, until the young bluebird finally followed her and they disappeared together through the trees.  When I looked again for the male, he had also taken off.

I walked to the lawn on other side of the wood line toward the place where the Bluebirds had escaped from my view and found lots of activity.  The female, now with two immature Bluebirds, flew back and forth from the lawn to the trees.  Practice flights?  One of the youngsters decided to stay in the grass, poking at the ground in search of insect food.  Mom stayed for a while, coaching her young student.

Female Eastern Bluebird (left) with tutoring her young offspring

Eventually Mom flew back to the shelter of the trees.  After a moment, the young bird followed the rest of its family, disappearing into the trees.

Young Eastern Bluebird

 

Resources

Eastman, John.  Birds of Forest, Yard, and Thicket.  1997.

Harrison, Hal H.  Eastern Birds’ Nests.  1975

Sibley, David Allen.  The Sibley Guide to Bird Life and Behavior.  2001.

Cornell Lab of Ornithology All About Birds

 

Goldthread

On a recent trip to Vermont, we spotted the bright white flowers of Goldthread (Coptis trifolia) dotting the forest floor’s green carpet.  We saw it growing in mossy areas, and often in the company of Canada Mayflower (Maianthemum canadense) and ferns.

Goldthread (Coptis trifolia), Canada Mayflower (Maianthemum canadense) and ferns

Our timing was perfect to see these tiny flowers, since each half inch diameter blossom is typically only in bloom for about a week.  Each flower is perched about six inches (15 cm) from the ground on its own straight stem.

Goldthread (Coptis trifolia) flowers

From a human’s eye view, the showiest parts of the flower are white petal-like sepals.  The primary function of sepals is to protect the other flower parts while the flower is developing, but in some plants, including Goldthread, they are also a showy part of the floral display to help attract pollinators.

From a pollinator’s eye view, additional flower parts come into focus, and offer some surprises.  Working in from the sepals, the unconventional petals make up the next whorl of flower parts. They are much smaller than the sepals, spoon-shaped, with bright yellow, rounded, concave tips.  Not only are these bright yellow petal tips attractive to pollinators because of their color, but also because they produce nectar, an extra enticement for a pollinator’s visit.

Next are the many stamens, the male reproductive parts. Goldthread stamens mature a few at a time, starting from the outside of their cluster.  As the stamens mature they release pollen from the anthers at their tips.  At the very center of the flower are the green pistils (or carpels), the female reproductive parts.  Pollen must be deposited on the stigmas at their tips in order for pollination to occur.

Goldthread (Coptis trifolia) flower. Only some of the stamens have matured.

Goldthread (Coptis trifolia) flowers. (One with a tiny mystery visitor.) All of the stamens are open for business.

Goldthread (Coptis trifolia) flower, When all of the stamens are mature, as they are in this specimen, they make a perfect rounded cluster.

While we watched, a flower fly (Megasyrphus laxus) visited the flowers.  This little fly seemed to be focused on harvesting pollen.  Flies drink nectar, but they also need to eat pollen for its protein.  Everyone needs a balanced diet!

A flower fly (Megasyrphus laxus) hovering over a Goldthread (Coptis trifolia) flower. This group of flies is also called hover flies, or Syrphid flies.

A flower fly (Megasyrphus laxus) eating pollen from a Goldthread (Coptis trifolia) flower. Its proboscis (mouth parts) are directly touching one of the anthers.

If the flowers are pollinated, fruit capsules develop.

Goldthread (Coptis trifolia) fruit capsules

Goldthread leaves are evergreen. In spring dark green leaves from the previous season are visible, and new leaves emerge concurrently with the flowers blooming.

Goldthread (Coptis trifolia). The dark green leaf is from the previous season, the light green leaves have recently emerged.

Goldthread’s scientific name is based on the shape of its leaves, with ‘Coptis’ referring to their deeply cut appearance, and ‘trifolia’ to the three leaflets of each leaf.  The common name Goldthread refers to the plant’s golden colored thread-like underground rhizomes.

Goldthread is a member of the Buttercup (Ranunculaceae) family.  Like some other family members, Goldthread contains berberine, a compound that has anti-fungal, anti-bacterial and anti-tumor properties, among other things.  Plants produce these properties to protect themselves from invaders and consumers.  Although it can be toxic, in the proper doses, Native Americans have found many medicinal uses for this plant.

Goldthread has a northerly distribution. It is native in Alaska, most of Canada except the Northwest and Yukon Territories, the northern tier of the United States from Minnesota east to Maine, and south in the east along the coast as far as North Carolina (except Delaware!).  It can also be found in a few counties in Oregon.  Its preferred habitat is rich, moist woods, and also bogs and swamps.

Goldthread (Coptis trifolia), Canada Mayflower

Related Posts

Rue Anemone and a Bee Fly

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Resources

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.

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

Minnesota Wildflowers

USDA NRCS Plant Database

Flora of North America

 

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

 

 

Rue Anemone and a Bee Fly

Within the space of a day, Rue Anemone (Thalictrum thalictroides) grows from being invisible to attaining its full height.  Walk a trail one day and it is nowhere to be seen, the next day it’s up with its first flower opening, starting the race to reproduce. Rue Anemone blooms, produces fruit, then the above ground parts die back, all before the leaves in the trees above them finish opening for the season.

Rue Anemone (Thalictrum thalictroides)

Before opening, Rue Anemone’s flowers resemble tiny rose buds.  Pale pink sepals enclose the flowers’ reproductive organs, but quickly open for business.

Rue Anemone (Thalictrum thalictroides) in bud

There may be up to five flowers per plant, arranged in a whorl radiating from the main stem of the plant, with a whorl of leaves directly below the flowers.

Rue Anemone (Thalictrum thalictroides) in bloom

The flowers open one at a time, beginning soon after the plant emerges.  The petal-like sepals form the outermost circle of each floral display.  They may be pure white or retain the hint of pink they showed before the flowers opened.  Moving toward the center of the flower, numerous stamens (the male reproductive parts), comprise the next ring in the floral structure. Starting from the outside of this ring and gradually moving inward, the anthers, located at the tips of the stamens, open a few at a time to release their pollen.  At the very center of the flower, there is a cluster of female reproductive parts called carpels, or collectively, pistils. The whitish stigmas at the tips of the carpels are receptive, advertising their availability for a pollen deposit.

Rue Anemone (Thalictrum thalictroides) in bloom. The petal like sepals form the outer ring of the floral display. The next ring are the stamens, with the anthers of the outermost beginning to open to release their pollen. A cluster of carpels forms the center of the floral display.

Within a few days, all of the flowers on the plant open, each at a slightly different stage of development as a result of their staggered opening.

Rue Anemone (Thalictrum thalictroides) in bloom

Rue Anemone partners with early flying bees and flies to assist with cross-pollination.  Like some other early spring wildflowers, including Hepaticas (Hepatica nobilis) and Bloodroot (Sanguinaria canadensis), Rue Anemone has evolved to provide only pollen as an enticement to these flower visitors.  Pollen is an important part of a bee’s diet, and female bees also harvest it to feed to their larvae.  Flies of many species also consume pollen; the females of some species require the protein in pollen to enable egg development.

I watched while a Greater Bee Fly (Bombylius major) darted in and out of a Rue Anemone flower.  Bee flies have a very long proboscis (mouth parts), perfectly suited to reach and sip nectar that might be out of range for some other flower visitors.  Knowing that Rue Anemone doesn’t offer nectar, I assumed the Bee Fly was harvesting pollen, and I was curious to see how she did it.

Greater Bee Fly (Bombylius major) visiting a Rue Anemone (Thalictrum thalictroides) flower. Note the long proboscis (mouth parts)

In the photos below, it appears that the Bee Fly is harvesting pollen with its proboscis.  Once pollen is at the tip of its proboscis, a bee fly then mixes the pollen with fluids and sucks it up through its straw-like mouth parts.

Greater Bee Fly (Bombylius major) visiting a Rue Anemone (Thalictrum thalictroides) flower. Note she is opening the tips of the proboscis, apparently to harvest some pollen.

In exchange for the meal, the Bee Fly’s hairy body may pick up pollen and deposit it on another Rue Anemone, enabling cross-pollination.

Greater Bee Fly (Bombylius major) visiting a Rue Anemone (Thalictrum thalictroides) flower. Note she is opening the tips of her proboscis to harvest some pollen.

After pollination occurs, fruits develop at the center of the flower.  Ants disperse the seeds, enticed by the nutritious food packet, called an elaiosome, that is attached.

Rue Anemone (Thalictrum thalictroides). Note the green fruit capsules beginning to develop at the center of the largest flower.

Rue Anemone (Thalictrum thalictroides) in fruit.

Rue Anemone is a delicate looking perennial of wooded understories, usually about 6-8 inches (1 – 2 dm) tall, but its height can range from 4 to almost 12 inches, depending on growing conditions.  It is a member of the Buttercup (Ranunculaceae) family, and like other members of this family, the foliage produces a burning sensation if eaten, a survival strategy that discourages herbivores from consuming the plant.

Rue Anemone is native in the eastern half of the United States, and in the province of Ontario in Canada.

Rue Anemone (Thalictrum thalictroides)

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Resources

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

Hoffmann, David.  Medical Herbalism.  2003.

Marshall, Stephen A. Flies The Natural History and Diversity of Diptera. 2012.

Newcomb, Lawrence.  Newcomb’s Wildflower Guide.  1977.

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

Illinois Wildflowers

USDA NRCS Plant Database