Bewitching Witch-hazel

Posted on December 12, 2017 by Mary Anne Borge

It’s well into December, and American Witch-hazel (Hamamelis virginiana) is still in bloom, brightening our winter shade garden and the woodland understory.

Witch-hazel (Hamamelis virginiana) in bloom, with open fruit capsules

The flowers are arranged in clusters, usually in threes. Each flower has four long, spidery, streamer-like petals. In the center of the flowers, you can see other flower parts that also come in fours. Four stamens (male reproductive parts) are tucked in between the petals, protected from below by the four sepals that protected the flower until it was ready to open. The pistils (female reproductive parts) can be seen in the very center of the flowers.

Witch-hazel (Hamamelis virginiana) flower beginning to bloom. The anthers have not yet open to release pollen.

Witch-hazel (Hamamelis virginiana) flower beginning to bloom. The anthers have opened to release pollen.

Even though Witch-hazel blooms when the weather is cooler, it relies primarily on insects for pollination. Various fly species are the most frequent flower visitors. This is not too surprising, since many flies are active at fairly low temperatures. Several species of bees, small wasps, moths and even beetles have also been documented as potential Witch-hazel pollinators. They are attracted by the color of the petals, a mild (to me, at least) fragrance, and the fact that there is not much else in bloom. If the weather doesn’t cooperate and not enough insects are active, witch-hazel is capable of self-pollination, although cross-pollination with the assistance of an insect is preferred, since this produces a stronger genetic result. Fertilization is delayed until spring, after which fruits begin to develop.

Even during and after our first snowstorm of the season with about 5 inches of wet snow, these tough little flowers hung on, looking as fresh as ever.

Witch-hazel (Hamamelis virginiana), still blooming in spite of the snow.

Such tenacity can pay off. While looking at the flower photos that I took during the storm, I found a moth taking refuge on a branch near the flowers, waiting for the temperatures to warm up enough to become active and search for nectar. That little moth could make a nice snack for a Chickadee and Titmouse searching the seemingly baren winter branches.

A moth sheltering on Witch-hazel (Hamamelis virginiana) during a December snow storm.

The flowers are accompanied by fruit capsules that look like small flowers carved from wood. These fruit capsules are the product of the previous year’s successfully pollinated flowers.

Witch-hazel (Hamamelis virginiana) in bloom, with open fruit capsules

In early October, as the leaves began to turn from green to yellow, the fruit capsules and flower buds were still tightly closed. As this season’s flowers began to bloom, the fruit capsules opened explosively, ejecting the seeds several feet away. The seeds will wait through two winters before they germinate. Ruffed Grouse, Northern Bobwhite, Wild Turkey, as well as some rabbits and squirrels eat the fruit.

Witch-hazel (Hamamelis virginiana) in early fall, with fruit capsules and flower buds still tightly closed

Witch-hazel is well-known for its use as an astringent and anti-inflammatory agent. You may have a bottle in your medicine cabinet now. Witch-hazel is used to treat wounds and hemorrhoids, and it’s an ingredient in some cosmetics. It acts as a styptic to stop bleeding, and reduces bruising and inflammation. It also helps reduce the chances of infection.

It’s not by accident that Witch-hazel has these properties. The tannins found in the leaves and inner bark of Witch-hazel provide these benefits. Witch-hazel produces these compounds as protection from herbivores, and to inhibit the growth of fungi and bacteria that might be harmful to the plant. Fortunately for us, humans can also benefit.

The tannins are not 100% successful in deterring herbivores. There are some insects that specialize on Witch-hazel as their source of food, including the caterpillars of several moth species. There are also two aphid species that produce eye-catching galls. (A gall is a growth that is the plant’s reaction to being used as a source of food and shelter by an organism such as an insect, fungus or bacteria. Galls seldom cause any harm to the plant, and they may stimulate the plant to produce more protective chemicals.)

Witch-hazel (Hamamelis virginiana) in bloom, with spiny Witch-hazel bud galls

The spiny witch-hazel bud gall aphid (Hamamelistes spinosus) is named for the appearance of the gall the plant produces from bud tissue in response to being used as a home by the developing aphids. At this time of year, the gall looks woody. At a quick glance it might be mistaken for a fruit capsule, until you notice the spines.

Earlier in the season, the spiny witch-hazel bud gall is green and fleshy.

Spiny Witch-hazel bud gall, with ants. What’s the attraction?

It’s interesting that there are so many ants swarming this gall. If the gall were open and the aphids were available, the ants would likely be milking them for delicious ‘honeydew’ (excrement). But the aphids have not reached maturity, they are still safely encased inside the gall.

Ants are often very beneficial to plants. They disperse the seeds of many spring blooming wildflowers, for one thing. Ants also provide protection from herbivores like caterpillars who might eat a plant’s leaves, flowers or buds, because other insects are an important part of an ant’s diet. Plants often emit a chemical call to arms to alert ants and other predators to the availability of insect food. The plant may offer an additional reward and reason to stick around in the form of nectar not associated with flowers (extra-floral nectaries) or resins, specifically aimed at payment to their protectors.

It’s a mystery to me what caused the ants in this photo to visit. Maybe this Witch-hazel detected the presence of a new generation of insect eggs (not visible to me), and sent out a distress signal to the ants. Any other ideas?

Pristine leaves unfold in spring, but they are often quickly put to use as food and shelter by another aphid (Hormaphis hamamelidis), the Witch-hazel leaf or cone gall aphid. This gall resembles a cone, or a witch’s hat.

Witch-hazel (Hamamelis virginiana) leaves in spring

Witch-hazel (Hamamelis virginiana) leaf with Witch-hazel cone gall, caused by an aphid (Hormaphis hamamelidis)

Both of these aphids spend part of their life cycle on birch trees.

Witch-hazel branches have been used as divining rods to find underground water sources, a practice sometimes referred to as ‘water witching’. In theory at least, the branch would point or bend towards the ground when it detected water. The ‘Witch’ in ‘Witch-hazel’ is based on an Anglo-Saxon word, ‘wych’, that means ‘bending’.

Witch-hazel is a multi-stemmed shrub that can grow to a height of about 16 feet (5 meters), and can tolerate shade. It is native in the Eastern half of the United States, and Ontario, Quebec, New Brunswick and Nova Scotia in Canada.

Enjoy these bright blossoms while they last!

Witch-hazel (Hamamelis virginiana) in bloom

Will Work for Food – Extra-floral Nectaries

Resources

Capon, Brian. Botany for Gardeners. 2005

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.

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

Williams, Ernest H. Jr. The Nature Handbook – A Guide to Observing the Great Outdoors. 2005.

Clemson Co-operative Extension – River Birch Aphid

Illinois Wildflowers

USDA NRCS Plant Database

USDA FEIS

Crayon-colored Hickories

Posted on November 12, 2017 by Mary Anne Borge

Mockernut Hickory (Carya tomentosa)

The compound leaves of Hickory (Carya species) trees still clinging to their branches are displaying colors that remind me of crayons: yellow-green, yellow-orange, lemon-yellow, chestnut, burnt umber. Together with the reds and browns of Oaks, the tans and peach of American Beech, they are part of the mid-fall forest pallette. Shagbark (Carya ovata), Mockernut (C. tomentosa) and Bitternut (C. cordiformis) are the Hickories I encounter most often.

Mockernut Hickory (Carya tomentosa).

Those Hickory leaves may have supported up to 200 different species of butterflies and moths as food for their caterpillars, all without any negative impact on the appearance of the trees. Some of the species Hickories support are Banded and Hickory Hairstreak butterflies, and many moths, including Hickory Tussock, Yellow-shouldered Slug, and the dramatic Hickory Horned Devil, the largest of our native North American caterpillars.

Banded Hairstreak on Indian Hemp (Apocynum cannabinum). Banded Hairstreak caterpillars eat Hickory leaves, as well as some other woody species.

Hickory Tussock Moth Caterpillar

Yellow-shouldered Slug

The aptly named, acrobatic Hickory Horned Devil caterpillar.

The aptly named, athletic, Hickory Horned Devil caterpillar.

All of those caterpillars are fair game for birds, looking for food for themselves and their growing offspring. Insects, especially caterpilIars, are an important source of food for birds. It can take thousands of caterpillars to raise a hungry clutch of baby birds.

Wood Thrush at the nest with babies

Some caterpillars may fall victim to other predators, like spiders, predatory wasps or flies, and assassin bugs.

Brown Assassin Bug (Acholla multispinosa) on Bitternut Hickory bud.

Hickory nuts also supply food for animals, including people. The husks have four sections that split open to reveal the hard shell protecting the nut ‘meat’ inside.

Shagbark Hickory (Carya ovata) nuts

Mockernut Hickory (Carya tomentosa) nuts split partially open, like this one.

Hickory nut on the right, empty husk pieces on the left

Eastern Chipmunks, Red, Gray, Fox and Flying Squirrels, Raccoons, and rabbits all eat Hickory nuts. Squirrels may bury some of the nuts rather than eating them right away. This habit helps to disperse the Hickories if the squirrels don’t come back and eat the nuts at a later date.

Eastern Chipmunk (with full cheeks!)

Gray Squirrel

Fox may also eat Hickory nuts, or they may eat the smaller animals who eat the nuts.

Red Fox eating Gray Squirrel

Wild Turkeys, Bobwhites, Red-bellied Woodpeckers, Blue Jays, Rose-breasted Grosbeaks and even Wood Ducks are among the birds that consume the tastier species of Hickory nuts.

Red-bellied Woodpecker

Male Wood Duck in non-breeding plumage

Hickory trees provide food and building material for humans, too. Shagbark is the species whose nuts are most often sold commercially. As you might guess from its name, Bitternut Hickory is not sought after for its nuts. Pecans (Carya illinoinensis) are in this same genus and are an important commercial crop. Hickory sap can be used to make syrup or other sweeteners.

Shagbark is also the species whose wood is most often used commercially for making handles, ladder rungs, wheel spokes, flooring, and a hickory-smoked flavor for cooking. Named for its shaggy strips of bark, Shagbark Hickory stands out from the crowd.

Can you pick the Shagbark Hickory (Carya ovata) out of the crowd?

The bark offers warm, dry accommodations for insects and others trying survive the winter.

Spider web on Shagbark Hickory (Carya ovata)

Eastern Comma butterflies survive the winter as adults, if they can find a warm dry shelter like a space under the loose bark of Shagbark Hickory (Carya ovata).

Mockernut Hickory also has distinctive bark, but in a completely different way. Its gray, smooth-looking, corky exterior forms sinuous ridges along the length of the trunk.

Mockernut Hickory (Carya tomentosa). Notice the curved ridges in the bark, especially in places where branches have fallen off.

Look for Hickory trees even after their leaves fall. You may be able to identify them by their bark and their buds. Hickories typically have a single large end bud at the tip of their branches that is usually quite distinctive, different for each species. There are smaller buds spaced alternately along the length of the branches.

Mockernut Hickory buds are somewhat rounded, echoing the curved pattern of the bark ridges.

Mockernut Hickory (Carya tomentosa) branch in winter. Notice the large end bud with rounded sides.

Shagbark Hickory usually retains contrasting bud scales, which you might think of as being reminiscent of the shaggy bark.

Shagbark Hickory (Carya ovata) bud. Notice the bod scales hugging the sides.

Shagbark Hickory (Carya ovata) bud. Notice the scales hugging the sides of the bud.

Bitternut Hickory buds are a bright mustard color that is difficult to mistake for anything else.

Bitternut Hickory (Carya cordiformis), showing its distinctive mustard-colored buds.

As winter turns to spring, watch for these buds to swell and unfold like flowers.

Mockernut Hickory (Carya tomentosa) leaves unfolding in spring.

Shagbark Hickory (Carya ovata) in spring

The range for Shagbark and Bitternut Hickory includes much of the eastern two-thirds of the United States, and Ontario and Quebec provinces in Canada. Mockernut’s range is similar, but it does not include the Canadian provinces, or some of the northern tier of the United States.

Enjoy the colorful foliage while it lasts!

Mockernut Hickory (Carya tomentosa)

American Beech

In Praise of Black Walnut Trees

Resources

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

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

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

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

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

Tallamy, Douglas W. Bringing Nature Home. 2007

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

Illinois Wildflowers
http://www.illinoiswildflowers.info/trees/plants/btnt_hickory.html
http://www.illinoiswildflowers.info/trees/plants/mock_hickory.html

Tallamy, Douglas W. Bringing Nature Home

USDA NRCS Plant Database
https://plants.usda.gov/core/profile?symbol=CAOV2
https://plants.usda.gov/core/profile?symbol=caco15
https://plants.usda.gov/core/profile?symbol=CAAL27

The Wood Database

White Snakeroot, and a Bit of a Paradox

Posted on October 17, 2017 by Mary Anne Borge

White Snakeroot (Ageratina altissima) provides food for late summer and fall visitors, primarily small critters. Its button-like clusters of tiny tubular flowers offer nectar to a variety of potential pollinators, and flower buds and leaves provide food for other insect diners.

White Snakeroot (Ageratina altissima)

In my shade garden in central New Jersey, Bumble Bees and Small Carpenter Bees (Ceratina species) drink happily from the flowers.

White Snakeroot (Ageratina altissima) with Small Carpenter Bee (Ceratina species)

On a late September Sunday at Garden in the Woods in Framingham, Massachusetts, I watched while Bumble Bees and Honey Bees took advantage of White Snakeroot’s abundant nectar.

White Snakeroot (Ageratina altissima) with Bumble Bee (Bombus species)

White Snakeroot (Ageratina altissima) with Honey Bee (Apis mellifera)

In a sunny woods-edge location at Bowman’s Hill Wildflower Preserve near New Hope, Pennsylvania, several butterfly species found needed nourishment in the nectar White Snakeroot flowers offered.

Painted Ladies and Sachem helped themselves to White Snakeroot’s sustaining beverage. These butterflies have been around much of the summer and fall, drinking from the flowers in bloom, moving from one species to the next as the season changed.

Painted Lady butterfly drinking nectar from White Snakeroot (Ageratina altissima)

Sachem drinking nectar from White Snakeroot (Ageratina altissima)

I was excited to see a Fiery Skipper, a butterfly that is rare in Pennsylvania, but a common resident in the southern United States. Fiery Skippers are among the butterfly species that regularly attempt to push the envelope of their range by emigrating to the north. White Snakeroot’s refreshing nectar rewarded this individual for its exploration efforts.

Fiery Skipper drinking nectar from White Snakeroot (Ageratina altissima)

Meanwhile, a Monarch fueled up for a flight in the opposite direction, heading south towards its winter territory in Mexico.

Monarch drinking nectar from White Snakeroot (Ageratina altissima)

If these potential pollinators do the job for which White Snakeroot has enticed them to visit its flowers, pollination occurs, and a type of fruit, called an achene, develops. The achene looks like a seed with a tiny hair-like parasol attached, designed to be dispersed by the wind to a favorable place for another White Snakeroot plant to germinate and grow.

White Snakeroot (Ageratina altissima), ready to disperse its fruit

At Bowman’s Hill Wildflower Preserve, an insect that looked a bit like a stink bug turned out to be the opposite – Harmostes fraterulus, one of the scentless plant bugs. Pennsylvania is thought to be the northern edge of Harmostes fraterulus’s range. Scentless plant bugs are a group of true bugs that lack glands to produce an unpleasant smell, quite unlike stink bugs who are named for their ability to do this. Harmostes fraterulus feeds on the flowers of several Aster (Asteraceae) family members, of which White Snakeroot is one.

Harmostes fraterulus on White Snakeroot (Ageratina altissima)

It’s interesting that this small insect is able to eat parts of White Snakeroot, since this plant contains potent toxins evolved to prevent herbivores from consuming it. These toxins are so effective that they can be fatal to mammals. As you might guess, deer do not eat this plant. If cows graze on a sufficient amount of White Snakeroot, the milk they produce is toxic to humans. In the nineteenth century, many people became sick or even died as a result of drinking this tainted milk, most famously, Abraham Lincoln’s mother.

While this plant’s chemical defenses are potent enough to sicken or even kill large mammals, some tiny insects have successfully adapted to use this plant as their food source (host plant). A type of small fly species, a midge named Schizomyia eupatoriflorae, specializes on White Snakeroot buds. The larvae of this midge live inside the plant tissue, prompting the plant to produce a rounded gall that the developing midge uses for both food and shelter until it is ready to emerge as an adult.

White Snakeroot (Ageratina altissima) with galls caused by the plant’s reaction to being used by a midge, Schizomyia eupatoriflorae

Flowers often have a lower concentration of a plant’s chemical defenses than do the other plant parts such as leaves and stems. But there are even insects who have evolved to specialize on White Snakeroot’s leaves. The one of which I most often see evidence is a leaf miner, Liriomyza eupatoriella, a type of fly. The larvae of Liriomyza eupatoriella develop between the outer layers of the leaf, feeding on the tissues inside.

White Snakeroot (Ageratina altissima) with leaf mines caused by a leaf mining fly, Liriomyza eupatoriella

Mammals have plenty of other food alternatives (at least for now) without having to evolve a tolerance for White Snakeroot’s toxins. But tiny insects may gain an advantage if they can specialize on food that few others can consume (and live to tell the tale!), especially a relatively common food source like White Snakeroot.

Despite its toxicity, several Native American tribes found medicinal uses for White Snakeroot, often using the root, but other plant parts as well. Some sources say that a poultice to treat snakebites was made from the root, resulting in the common name, White Snakeroot.

White Snakeroot is a plant of woods and woods edges. It prefers light shade but can tolerate partial sun, with moist to slightly dry soils. In Canada it is native in Ontario and Quebec provinces and the Northwest Territories, and in the United States from Maine to eastern North Dakota, south to Texas and the Florida panhandle, although it is much less widespread in the southeastern U.S.

American Goldfinch, taking refuge on White Snakeroot (Ageratina altissima)

Resources

Brock, Jim P.; Kauffman, Ken. Kaufman Field Guide to Butterflies of North America. 2003.

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

Coffey, Timothy. The History and Folklore of North American Wildflowers. 1993.

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

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.

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

Illinois Wildflowers

USDA NRCS Plant Database

Harmostes fraterulus:

Maryland Biodiversity Project

Wheeler, A. G. Jr.; Miller, Gary L. Harmostes Fraterculus (HEMIPTERA: RHOPALIDAE): Field History, Laboratory Rearing, and Descriptions of Immature Stages. 1983.

Wheeler, A. G. Jr. Harmostes reflexulus (Say) (Hemiptera: Rhopalidae): New Western U.S. Host Records, Analysis of Host-Plant Range, and Notes on Seasonality. 2013.

Partridge Pea Puzzles

Posted on September 5, 2017 by Mary Anne Borge

Bright yellow Partridge Pea (Chamaecrista fasciculata) flowers peek out from between the stems of taller grasses and flowering forbs in meadows, prairies, stream banks and other open areas from July through early September.

Partridge Pea (Chamaecrista fasciculata)

Partridge Pea’s flowers are tucked in the leaf axils down the length of the stem.

Partridge Pea (Chamaecrista fasciculata)

Each flower has five yellow petals, with one much longer than the other four, and another partially curled toward the center of the flower, where its reproductive parts are located. A 1992 study showed that the curved petal directs floral visitors to the flower’s reproductive parts, first to the pistil (female reproductive part), and then the stamens (male reproductive parts).[1] The red smudges on the petals are part of the visual allure to pollinators.

Partridge Pea (Chamaecrista fasciculata)

In the Partridge Pea flower in the photo above you can see the three evenly sized petals at the top, one petal in the lower left that curls toward the center of the flower, and an over-sized petal at the lower right. The stamens are mostly clustered at the middle of the flower. The pistil resembles a hook projecting from beneath the right-most stamen. It is visible at the top of the over-sized petal. Imagine a pollinator coming in for a landing using the over-sized petal as a runway, guided by the curved petal, with the red smudges on the petals as beacons. The pollinator brushes first against the receptive stigma at the tip of the pistil, depositing pollen from the last flower visited, then moves on to harvest pollen from the stamens.

Bumble Bee harvesting pollen from Partridge Pea (Chamaecrista fasciculata) flower. Bumble Bees are adept at buzz pollination.

Partridge Pea flowers offer pollen as a reward to their visitors, but they don’t produce nectar. As a result, bees that collect pollen are the most likely visitors of the flowers. But the bees have to have skills in order to harvest Partridge Pea’s pollen, since it requires special handling in order to access it. The pollen is dispersed through a slit at the tip of the stamen’s anther. Pollen can be shaken out of the anther as a result of buzz pollination, a technique in which a bee clings to the flower while vibrating its wing muscles without actually moving its wings. ‘Milking’ the anther with a series of strokes is another method of successfully harvesting Partridge Pea’s pollen.[2]

Honey Bee harvesting pollen from Partridge Pea (Chamaecrista fasciculata) flower. Honey Bees can’t perform buzz pollination, so may be using the ‘milking’ technique.

Eastern Carpenter Bee harvesting pollen from Partridge Pea (Chamaecrista fasciculata) flower.

Butterflies aren’t interested in Partridge Pea flowers, since they don’t offer nectar. But several butterfly species use Partridge Pea as a food plant for their caterpillars, including the Sleepy Orange and Cloudless Sulphur.

Sleepy Orange drinking nectar from Winged Loosestrife (Lythrum alatum)

Cloudless Sulphur

Gray Hairstreak and caterpillar on Partridge Pea (Chamaecrista fasciculata). Can you see the tiny caterpillar clinging to a leaf in the lower left of the photo?

When I saw a Gray Hairstreak butterfly spending time walking around a Partridge Pea plant, it seemed possible that this was a female laying eggs. Gray Hairstreaks use some Pea family members as caterpillar food, including clovers and tick-trefoils, although I haven’t seen any confirmation that they would use Partridge Pea.

Gray Hairstreak on Partridge Pea (Chamaecrista fasciculata).

A closer look showed that the butterfly was visiting Partridge Pea for nectar after all, but it was nectar that is made available through extrafloral nectaries on the base of the stem of each leaf. This was a great benefit for the butterfly, but not much help for the plant, since the butterfly offered no services in return.

Gray Hairstreak drinking nectar from an extrafloral nectary on Partridge Pea (Chamaecrista fasciculata)

When present, extrafloral nectaries are generally a plant’s adaptation to entice insects that are predators of herbivores to visit and protect the plant. Ants are especially important in this role, since caterpillars are a very desirable food for them. Some wasps and lady beetles are also potential protectors of plants. While they are interested in nectar for themselves, they are also on the hunt for insects to feed to their larvae. The wasps and lady beetles may rid the plant of the caterpillars or other insects who would eat it. Nectar is provided in exchange for this protection.

Partridge Pea’s extrafloral nectaries look like tiny open pots, glistening with nectar, an open invitation to thirsty insects cruising through, not all of whom will offer services to the plant.

The two round pot-like appendages near the base of the Partridge Pea (Chamaecrista fasciculata) leaf stems are the extrafloral nectaries. Notice the glistening drops of nectar oozing from them.

While I have seen ants working Partridge Pea extrafloral nectaries, I was surprised at the variety of insects I saw drinking from them at one location I visited. It makes me wonder whether the cost of providing this nectar is worth the protection gained from them. In addition to the Gray Hairstreak, I watched while a Bumble Bee spent more time visiting the extrafloral nectaries than the flowers.

Bumble Bee drinking nectar from a Partridge Pea (Chamaecrista fasciculata) extrafloral nectary.

After visiting several extrafloral nectaries, the Bumble Bee moved on to a flower.

I saw several Paper Wasps visit the nectaries. Since these wasps hunt caterpillars to feed their larvae, they do have the potential to provide a service in exchange for a tasty drink.

Paper Wasp (Polistes species) drinking from an extrafloral nectary on Partridge Pea (Chamaecrista fasciculata)

‘That was tasty!’ Paper Wasp (Polistes species) on Partridge Pea (Chamaecrista fasciculata)

Some accounts of Partridge Pea say that the leaves will sometimes fold up when they are touched. I’ve tried it several times, but I have never had Partridge Pea respond to my touch. However, I have seen Partridge Pea plants with their leaves folded, so I’m guessing the plant folds its leaves in response to some stimuli, but I haven’t found an explanation for what it might be. Maybe it’s a mechanism to prevent excessive water loss on hot, dry, or windy days. Or maybe the plant responds to the touch of a butterfly laying eggs, and wants to minimize the leaf surface available to her. I wish I knew!

Partridge Pea (Chamaecrista fasciculata) with leaflets folded. What prompted this?

If the name didn’t give away its family heritage, the fruits identify Partridge Pea as a member of the Pea or Bean (Fabaceae) family. These fruits are an important winter source of food for birds, especially Bobwhites and Greater Prairie Chicken.

Partridge Pea (Chamaecrista fasciculata) with fruits typical of the Pea (Fabaceae) family.

Partridge Pea is an annual, but reseeds itself readily. It likes sun, and can tolerate poor, dry soils. It helps to fertilize soils through its release of nitrogen, and is sometimes used in stream bank stabilization. Partridge Pea is native from Rhode Island to Minnesota in the north, south as far as southeastern New Mexico, and from Texas to Florida.

Partridge Pea (Chamaecrista fasciculate)

Cloudless Sulphurs Are on the Move

Sleepy Orange Butterflies are Back

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.

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

Illinois Wildflowers

USDA NRCS Plant Database

USDA NRCS Plant Guide – Partridge Pea

[1], [2] Pollination and the Function of Floral Parts in Chamaecrista fasiculata, Andrea D. Wolfe and James R. Estes, 1992.

Natural Selection on Extrafloral Nectar Production in Chamaecrista Fasciculata: The Costs and Benefits of a Mutualism Trait

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

The Natural Web

Exploring Nature's Connections

Category Archives: Gardening for Wildlife

Bewitching Witch-hazel

Crayon-colored Hickories

White Snakeroot, and a Bit of a Paradox

Partridge Pea Puzzles

A Small Beauty: Purple Milkwort

Share this:

Like this:

Share this:

Like this:

Share this:

Like this:

Share this:

Like this:

Share this:

Like this: