Downy Skullcap and the Amorous Skippers

Posted on August 3, 2020 by Mary Anne Borge

Apparently I planted some Downy Skullcap (Scutellaria incana) in our garden last year and then promptly forgot, so it was a delightful surprise when the vivid blue flowers began to bloom in long stalks above gray-green foliage.

Downy Skullcap (Scutellaria incana) with Flower (Syrphid) Fly

Each long tubular flower has an entrance with a hood- or cap-like overhang at the top, and a floor with a white pathway beckoning to visitors who might help pollinate the flowers.

Downy Skullcap (Scutellaria incana) Flower

The almost sapphire blue flowers are especially attractive to bees, and are thought to be most often pollinated by Bumble Bees (Bombus species) but they entice other pollinators as well, including flower flies, bee flies, and small butterflies.

I watched for visitors to the flowers in our garden and at another near-by site, Bowman’s Hill Wildflower Preserve. At both locations, bees were the most frequent visitors on days when I checked, and of the bees, Small Carpenter Bees (Ceratina species) were the most common.

Downy Skullcap (Scutellaria incana) with Small Carpenter Bee (Ceratina species)

Don’t be put off by the fact that they are called carpenter bees. These tiny bees won’t be drilling holes in the deck, siding or wood trim of your home. They nest in the stems of dead or broken twigs, excavating nesting cells by chewing through the pith, the softer tissue inside the stem. Small Carpenter Bees are pollinators of many plants, especially those with small flowers.

Each bee crawled inside the flower, disappearing down the throat until they reached the nectar reward at the bottom.

Downy Skullcap (Scutellaria incana) with Small Carpenter Bee (Ceratina species) crawling down the throat of the flower to reach the nectar reward

But it wasn’t just nectar they were after. Bees need a balanced diet. They wanted pollen, too, for the protein and lipids it provides. The flowers’ reproductive parts, the stamens and pistils, are hidden under the hood at their entrance. After emerging from drinking nectar at the depths of a flower, each bee then checked under the hood for pollen, which is dispersed from the anthers at the stamens’ tips. Some bees even went straight for the pollen without bothering with the nectar. Hopefully some of that pollen was later deposited on the stigma of another flower, the female flower part where pollen must be placed in order for pollination to occur.

Downy Skullcap (Scutellaria incana) with Small Carpenter Bee (Ceratina species) emerging from the flower

Downy Skullcap (Scutellaria incana) with Small Carpenter Bee (Ceratina species) harvesting pollen

Much larger relatives of these tiny bees, Eastern Carpenter Bees (Xylocopa virginica), also visited the flowers. Although these bees can be excellent pollinators, it pains me to tell you that in the case of Downy Skullcap, Eastern Carpenter Bees are thieves. They can’t access the flowers’ nectar by going through the inviting entrance, thus interacting with the flowers’ reproductive parts and helping with pollination. So instead, they bite through the floral tube near its base, directly accessing the nectar, doing nothing in return to assist the plant in its reproductive goals. Interestingly, a Honey Bee tried to discourage the Eastern Carpenter Bees from this dishonest activity by trying to chase them away, with some success. And yes, regrettably, Eastern Carpenter Bees might choose to nest in the wood of your home.

Downy Skullcap (Scutellaria incana) with Eastern Carpenter Bees (Xylocopa virginica) robbing the flower of nectar by biting through the floral tube to drink it.

While looking for Downy Skullcap flower visitors in our garden, I spotted a male Zabulon Skipper drinking nectar.

Male Zabulon Skipper drinking nectar from a Downy Skullcap (Scutellaria incana) flower

A moment later, I noticed a female Zabulon Skipper, doing the same.

Female Zabulon Skipper drinking nectar from a Downy Skullcap (Scutellaria incana) flower. Notice the bee disappearing into the flower above hers.

Then the male flew over to the female and suggested a ‘hook up’.

Female (top) and male (bottom) Zabulon Skippers, negotiating a hook up. Their wings are a little out of focus because both were vibrating them energetically as a lead-up to an agreement.

She was apparently persuaded by his pitch. They went off to a more secluded spot, and stayed there beyond the limits of my attention span.

Zabulon Skippers, mating

These small butterflies are common in gardens and natural areas, specializing on many grass species as food for their caterpillars, including Purpletop (Tridens flavus), Purple Love Grass (Eragrostis spectabilis), and other related species.

Purpletop (Tridens flavus), a caterpillar food for Zabulon Skippers

When the flowers have finished blooming and drop away, a cap-shaped calyx, the set of sepals that act as bud scales remains, providing the inspiration for the common name ‘skullcap’.

Cap- or dish-like calyxes of Downy Skullcap (Scutellaria incana)

‘Downy’ in the common name and ‘incana’ in the scientific name, which means hoary or quite gray, refer to the short soft hairs present on the flowers and stems of this plant. Hoary Skullcap is another common name for the species.

Downy Skullcap is native in the United States from New York west to Wisconsin, south as far as Texas and the Florida panhandle. It can tolerate full sun to full shade, dry to moist soil. Blooming in mid-summer, it makes a dramatic addition to a garden. Add it to yours and wait for the real drama (food foraging, bee face-offs, theft, flirtation, sex!) to begin.

Downy Skullcap (Scutellaria incana) with Small Carpenter Bee (Ceratina species)

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

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

Willmer, Pat. Pollination and Floral Ecology. 2011

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

Illinois Wildflowers

Lady Bird Johnson Wildflower Center Plant Database

Missouri Botanical Garden Plant Finder

USDA NRCS Plants 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

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Tag Archives: Ceratina

Downy Skullcap and the Amorous Skippers

Hepatica’s Survival Strategy

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