Spicebush or Forsythia?

Posted on April 16, 2014 by Mary Anne Borge

For the past few weeks, Spicebush (Lindera benzoin) buds looked like they couldn’t wait to open. Over the weekend when the temperatures reached 80°F in the latest round of weather whiplash, the buds burst open, resulting in a display of bright yellow starbursts lighting up the forest understory.

Spicebush (Lindera benzoin) in bloom, with ant seeking nectar

Spring temperatures have a big influence on the exact timing, but where I live in the mid-Atlantic United States, Spicebush typically blooms in late March or early April, at about the same time as forsythia. Forsythia is also lovely for the ten days or so that it’s in bloom, but then it’s a little, well, boring, when compared to Spicebush.

Sometimes called Northern Spicebush or Common Spicebush, this shrub is native in the north from Maine to Ontario, Michigan, Iowa and Kansas, then its range extends south to Texas and throughout the southeastern United States to Florida. It can generally be found in woodlands, but works well as a landscape plant, too. Spicebush gets its common name from the spicy aroma emitted from its leaves and young branches when they are rubbed or crushed.

Where Spicebush is native, it has important relationships with animals that have evolved with it over the centuries. Many insects, including early butterflies, visit the flowers for nectar, but early solitary bees and flies are the primary pollinators.

Spicebush (Lindera benzoin) with Spring Azure butterfly nectaring

The flowers bloom before the leaves unfurl, making it easy for pollinators to find them. Spicebush has male and female flowers on separate plants.

Male Spicebush flowers; note yellow pollen like little balls at tips of stamens

Female Spicebush flowers; note pistils protruding beyond the petals

So if you are using them in your landscape, you will want a male to pollinate the female plants in order to see the bright red fruits that complement this shrub’s yellow fall foliage.

Spicebush (Lindera benzoin) fall fruit and foliage

Many birds eat the fruit, but Veeries

Veery

and Wood Thrushes,

Wood Thrush

birds that are often found in the same habitat as Spicebush, are especially partial to them.

Spicebush Swallowtail butterflies are often seen nectaring on flowers in sunny locations,

Spicebush Swallowtail nectaring on Wild Bergamot (Monarda fistulosa)

but they can also be found in the woods in the vicinity of their namesake plant, Spicebush. This is because the primary food plants for Spicebush Swallowtail caterpillars are Spicebush (Lindera benzoin and in the southern U.S., also L. melissifolia) and the related Sassafras (Sassafras albidum), which is usually found in the same type of habitat. Without these plants we wouldn’t have this lovely butterfly, since its caterpillars can only survive on the leaves of a few plant species.

Female Spicebush Swallowtails lay their eggs singly on the underside of a leaf.

Spicebush Swallowtail egg

After the caterpillars hatch from the eggs, they depend on the leaves of these plants for both food and shelter. Each caterpillar eats a few leaves of a Spicebush during its development.

Spicebush Swallowtail caterpillar; notice the evidence of feeding on the leaf in the lower right corner

Looking for holes in leaves is one way to find these caterpillars. But we’re not the only creatures who have figured out this strategy for locating them. Caterpillars and other insects are an important source of food for birds, especially when the birds are raising their young. Some bird species also know enough to look for partially eaten leaves to point them to a tasty meal of caterpillar protein.

Tufted Titmouse, looking for a meal

So the caterpillars have evolved to protect themselves by destroying the evidence of their dining experience. While I watched, this caterpillar crawled to the stem of the leaf it had been eating. It chewed through the stem, and the incriminating evidence, the partially eaten leaf, fell to the ground.

Spicebush Swallowtail caterpillar, destroying the evidence of its presence by chewing through the leaf stem

Spicebush Swallowtail caterpillars have other strategies to protect themselves from predators. In their earliest growth stages they look like bird droppings, a clever disguise to deter birds from eating them. As they grow, they take on the appearance of a snake, with false eye spots above their real head. This snake disguise is an effective deterrent to at least some of the birds that might otherwise eat the caterpillars, since snakes are the birds’ predators in their wintering grounds.

Black-Throated Blue Warblers may be put off by a snake-like disguised caterpillar

When they’re not eating, Spicebush Swallowtail caterpillars hide in leaf shelters that they create for themselves by spinning silk to pull two sides of a leaf together.

Spicebush Swallowtail caterpillar using its silk to create a leaf shelter

Spicebush is also a food plant for the caterpillars of a moth called the Tulip-tree Beauty,

Tulip-tree Beauty caterpillar on Spicebush (Lindera benzoin)

and one of the giant silk moths, the Promethea Moth.

Promethea Moth Caterpillars on Spicebush

Winter is a good time to look for Spicebush Swallowtail chrysalises and Promethea Moth cocoons, since these species overwinter as pupae.

Forsythia on the other hand, primarily a native of Asia, doesn’t support any of our native insects and birds in this way. So I’m opting for Spicebush.

Spicebush (Lindera benzoin)

Resources

Butterflies and Moths of North America
http://www.butterfliesandmoths.org/

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

Illinois Wildflowers http://www.illinoiswildflowers.info/trees/plants/spicebush.htm

Natural History Museum Database of Leipidoptera Hostplants
http://www.nhm.ac.uk/research-curation/research/projects/hostplants/

In Praise of Black Walnut Trees

Posted on November 22, 2013 by Mary Anne Borge

If you go for a walk in the woods any time soon, you may still encounter black walnuts or the remains of their hulls on the ground.

Fallen Black Walnuts

The nuts usually remain on the tree until after the leaves fall, reminding me of a Charlie Brown Christmas tree. Then all the nuts fall within a short time of each other. These nuts are sweet tasting and highly nutritious. Studies show that eating them helps prevent cardiovascular disease, diabetes and cancer. Walnuts have as much protein as an equal weight of beef, but they also contain essential fatty acids that are necessary for healthy brain development and function. Any aging brains out there? Eat walnuts!

Black Walnut (Junglans nigra)

Mammals other than humans like them, too: squirrels, mice and voles, for example.

Eastern Gray Squirrels eat and help disperse Walnuts

Red Squirrels also enjoy many tree nuts, including Walnuts

These animals aid in the spread of Walnut trees when they overlook some of the nuts they have hidden away for later use, effectively planting them.

In turn, these animals are food for larger animals, like fox

Red Fox

and raptors.

Red-shouldered Hawks, as well as most other raptors, hunt and eat small mammals

According to Douglas Tallamy in Bringing Nature Home, the leaves of Black Walnut (Juglans nigra) trees and the closely related Butternut (Juglans cinerea) provide food for the caterpillars of over 100 species of moths and butterflies, including Luna Moths and Banded Hairstreaks.

Banded Hairstreak on Butterflyweed. Their caterpillars feed on the leaves of Black Walnut and other woody species

The Walnut Caterpillar specializes on Black Walnut and relatives such as Butternut. This means the leaves of these trees are the only food these caterpillars can eat.

Walnut Caterpillar (Datana integerrima)

Since they are an important source of food for birds, not all caterpillars will see life as an adult butterfly or moth.

Tufted Titmouse

Black Walnut trees have a reputation for not playing well with other plants. That is, many plants won’t grow successfully in close proximity (within the drip-line or reach of the roots) of a Black Walnut. The reason is more complex than shade and competition for water. Black Walnuts contain juglone, which is an anti-fungal chemical. In order to derive nutrients from the soil, the vast majority of plants partner with underground mycorrhizal fungi (think mushroom, not the mold in your shower). Unless the fungi on which the plant depends is resistant to juglone, or the plant doesn’t require this partnership to obtain its nutrition, that plant won’t do well. Of course, some plants and their fungi partners have evolved in exactly this way. Click here for some suggestions from The Mortem Arboretum for plants that can co-habit successfully with Black Walnut trees.

It’s of benefit to Black Walnut trees to produce juglone, since it does reduce competition for resources, and protects the trees from fungal invaders that might do them harm. Juglone also has sedative properties that may aid animals in dormancy. It can even have a calming effect on people.

Black walnut trees contain another compound called ellagic acid in both their nuts and leaves. This compound is thought to help prevent cancer in people who consume the nuts. The ellagic acid in the leaves is effective in removing carcinogenic hydrocarbons from the air, helping to reduce the effects of air pollution.

As if that weren’t enough, Black Walnut’s wood is valuable for furniture and cabinet making, and the nut hulls can be used to make a dye.

Black Walnut with hull partially removed

These are just some of the known benefits of Black Walnut trees. Just imagine what we don’t know yet! No wonder ‘juglans’ is sometimes translated as ‘nut of Jupiter’, or ‘nut of the gods’.

Black Walnut Tree (Juglans nigra)

Resources

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

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

Tallamy, Douglas W. Bringing Nature Home. 2007

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

Butterflies and Moths of North America

Natural History Museum Database of Leipidoptera Hostplants

Embracing the Shade: Summer and Fall

Posted on October 30, 2013 by Mary Anne Borge

Is it possible to have a perennial shade garden with continuous bloom throughout the summer and fall? By June, the trees are fully leafed out, sheltering our home from the summer sun’s strong rays. That means that the garden is in the shade, too. Will anything be blooming? You bet.

Spicebush Swallowtails nectaring on Bottlebrush Buckeye

Some spring bloomers, like Heartleaf Foamflower (Tiarella cordifolia) and Virginia Goldenstar (Chrysogonum virginianum), also called Green and Gold, may continue their display into the summer months. While not yet blooming, the leaves of White Wood Aster (Eurybia divaricata) join the violets, ferns, and Spreading Sedge (Carex laxiculmis) to form a ground cover blanketing much of the garden. Arching four to five feet above them are long sprays of Goat’s-beard (Aruncus dioicus) a.k.a. Bride’s Feathers’ tiny white flowers, lighting up the deep shade. June brings Rosebay Rhododendron (Rhododendron maximum) and Wild Hydrangea (Hydrangea arborescens) blossoms, too.

Bottlebrush Buckeye (Aesculus parviflora) is part of the shrub layer in the woods behind our house. In July, this reliable bloomer with its large palmately compound leaves and tall spikes of white tubular flowers attracts Ruby-throated Hummingbirds in addition to Spicebush and Eastern Tiger Swallowtails.

Dark form Eastern Tiger Swallowtail nectaring on Bottlebrush Buckeye

Last summer we were surprised to see dark morph Tiger Swallowtails nectaring on the Bottlebrush Buckeye. By adopting this Pipevine Swallowtail-like coloration disguise, the Tiger Swallowtails gain some protection from being eaten by birds and other predators who have learned of the Pipevine Swallowtail’s toxicity. The dark morph occurs most frequently in areas where Pipevine Swallowtails are present. Maybe Dutchman’s Pipevine (Aristolochia macrophylla) and its namesake swallowtail are increasing in our area!

Courting Zabulon Skippers on Purple Giant Hyssop

July is also the beginning of Purple Giant Hyssop’s (Agastache scrophulariifolia) long bloom, lasting well into September. We have it in both deep shade and a spot that gets a few hours of afternoon sun, blooming dependably in both locations. This herbaceous plant is a great choice for a woodland garden, with a growth form that is similar to Butterfly Bush. In our garden, butterflies from the smallest skippers to the largest swallowtails love Purple Giant Hyssop. Bees love it, too, and even hummingbirds may drink from the nectar-packed purple flowers.

Eastern Tiger Swallowtail nectaring on Purple Giant Hyssop

Pollinators can’t resist Mountain Mints.

Sweat Bee (Lasioglossum species) on Short-toothed Mountain Mint

I decided to try Short-toothed Mountain Mint (Pycnanthemum muticum), also called Clustered Mountain Mint, the only one of the Mountain Mint (Pycnanthemum) species I thought could tolerate some shade. I put it in the one location that gets about four hours of afternoon sun, and I got lucky. While not as robust as it would be in a sunnier spot, it’s doing well, its tiny magenta and white blossoms enticing the smaller butterflies like azures and skippers throughout July and August.

Summer Azure nectaring on Short-toothed Mountain Mint

As summer progresses, False Sunflower (Heliopsis helianthoides) radiates bright yellow sunbursts at the wood’s edge from July well into September.

Sweat Bee (Agapostemom species) on False Sunflower (Heliopsis helianthoides)

Eastern Tiger Swallowtails and Bumble Bees are frequent diners at Great Blue Lobelia (Lobelia siphilitica), open for business during August and September. Even Ruby-throated Hummingbirds will stop here for a drink.

Eastern Tiger Swallowtail nectaring on Great Blue Lobelia

Also in August, after gathering energy from the sun from the earliest spring days when its leaves begin to emerge, White Wood Aster blinks on its light show of white blossoms, illuminating the dense shade through October. The delicate blue disk flowers of Carolina Elephantsfoot (Elephantopus carolinianus) provide a complementary offset in August and September.

White Wood Aster

Butterfly traffic slows by September, but Black Swallowtails may still lay eggs this late, sometimes on my cooking herbs (parsley and dill).

Black Swallowtail caterpillar eating parsley

Last fall we hosted a chrysalis on a hot pepper plant.

Black Swallowtail chrysalis on pepper plant

More aster family members begin their fall performance now, including Blue Wood Aster (Symphyotrichum cordifolium),

Blue Wood Aster with Bumble Bee

Wreath Goldenrod (Solidago caesia),

Wreath Goldenrod

and Zigzag Goldenrod (Solidago flexicaulis), in bloom and offering nectar through October or early November. Like White Wood Aster, all of the foliage of these species emerged in early spring from the winter’s leaf cover.

All of these summer and fall blooming species have a reproductive strategy that includes clusters or spikes of flowers that bloom gradually over a period of many weeks, increasing each plant’s chances of pollination by bees, butterflies, and others, and resulting in a long colorful garden display.When successfully pollinated, Purple Giant Hyssop, Carolina Elephantsfoot and Woodland Sunflower offer Chickadees, Goldfinches and other birds a fall bounty of food.

Goldfinch eating Elephant’s Foot seeds

Resident and migrant birds dine on the bright red fruit of Spicebush (Lindera benzoin) and Flowering Dogwood (Cornus florida) and the dark blue fruit of Sassafras (Sassafras albidum) and Blackhaw Viburnum (Viburnum prunifolium). This is after a busy season of acting as caterpillar food plants – Spicebush and Sassafras for Spicebush Swallowtails, Flowering Dogwood and Blackhaw for Spring Azures.

Flowering Dogwood fruit

In October and November, Witch-hazel’s (Hamamelis virginiana) spidery yellow blossoms complement the fall foliage.

Witch-hazel flowers and fruits

The bright red fruits of Winterberry Holly (Ilex verticillata) may last until late winter, when hungry birds finally eat them.

Winterberry Holly berries

Little maintenance is required in this woodland garden. Because the plants have filled in to form a ground cover in most places, there is little weeding to do. We primarily use naturally fallen leaves as mulch, although we may supplement with a bit of prepared leaf compost around the front edges, in deference to our homeowners’ association’s sensibilities.

When we were trying to grow lawn in the shade, it was sparse, and we had problems with standing water after a heavy rainfall. Not anymore. The trees, shrubs and other plants in the garden, as well as the leaf litter, help the soil to absorb rainfall. The shade keeps the soil from drying out too quickly. So once these plants are established, watering is only required when drought conditions become extreme.

Not a bad performance for a woodland garden. And it brings so much pleasure!

Notes:

This is part 3 of a 3 part series. To see parts 1 & 2, see A Butterfly Garden That Embraces the Shade and A Butterfly Garden That Embraces the Shade – Spring.

This post was adapted from an article that was originally published in the Summer 2013 issue of Butterfly Gardener, a publication of the North American Butterfly Association.

Butterflybush – Are there better alternatives?

Posted on September 11, 2013 by Mary Anne Borge

About a year ago I was asked by the editor of Butterfly Gardener, a publication of the North American Butterfly Association, to take the ‘con’ side in a debate about whether to use Butterflybush. I knew it was invasive, but until I started to research the article, I didn’t realize the extent of its reach.

It’s all about the next generation: The Caterpillars

There’s no denying that Butterflybush (Buddleja davidii), also called Orange Eye Butterflybush, can be a lovely plant. In a sunny location it has attractive flowers, blooms for a long period of time, and may draw a variety of species of adult butterflies for nectaring. What more could a butterfly gardener want? What else is there to know?

What about caterpillars?

Pipevine Swallowtail Caterpillar on Dutchman’s Pipevine (Aristolochia macrophylla)

In Butterflies Through Binoculars, Jeffrey Glassberg says “The most important factor contributing to the decline of butterfly species is habitat loss.” Glassberg also states “For many uncommon butterflies the easiest way to locate colonies is to search for sites where the foodplant is common.” By food plant, he means the plant(s) on which the next generation, the caterpillars, can feed and thrive. Perpetuation of butterfly species requires habitat that will support a butterfly’s full life cycle, not just the adult stage.

Kenn Kaufman, in his Field Guide to Butterflies of North America, states “A butterfly’s most important relationship is with the plants eaten by its caterpillars”. Butterflies of the East Coast: An Observer’s Guide by Rick Cech and Guy Tudor notes “the most important single determinant of butterfly distributions, as well as many other aspects of their lives” are the butterfly’s “host plants”, the food plants that caterpillars need to survive.

None of these sources identify Butterflybush as a food plant for butterfly caterpillars. Does it provide food for the hungry caterpillars of any species of butterflies or moths native to North America? A search of the Natural History Museum’s database of known host plants yields only one species of Lepidoptera present in North America as using Butterflybush as a food plant, the Buddelja Budworm Moth, present only in urban areas of California and thought to be introduced there. So it’s not a known caterpillar food plant. Even if a caterpillar is spotted on Butterflybush, more study would be necessary to see if it gets sufficient nutrition to successfully become an adult.

Isn’t it enough that Butterflybush is a good nectar source?

It would be, except for one thing.

The Orange Eye Butterflybush Plant Fact Sheet from the USDA Natural Resources Conservation Service includes a bright red warning, “Caution: This plant may become invasive.” The USDA lists it as naturalized in 20 states, British Columbia, and Puerto Rico. This means it has escaped from gardens to surrounding natural areas, with the potential to crowd out native vegetation that is essential to wildlife, including butterflies and birds. And is difficult to remove once it has established itself.

According to the USDA, Butterflybush (except for a few sterile cultivars) is prohibited for entry, transport, purchase, sale or propagation in the state of Oregon. It is prohibited from being propagated, released, displayed or sold in New Zealand, is listed as one of the top 20 weeds in Western Europe, and in 2007, the US Fish and Wildlife Service Bayscapes program listed it as a plant that should no longer be used for landscaping. (Soure: The Invasive Buddleja davidii (butterfly bush).(Report), The Botanical Review, September 1, 2009, Tallent-Halsell, Nita G.; Watt, Michael S.)

It’s not that Butterflybush is inherently a bad plant. It is native to China, not North America, Europe or New Zealand. The insects, birds and other residents with which it evolved in China and that depend on it for food there aren’t present in the areas in which it was introduced. So there are no species here that will naturally keep it in check. This is always a potential danger when a species is introduced in an environment in which it is not native, where its food web partners are missing.

A sterile cultivar might be worth a try, but they have a tendency to evolve back into a fertile state over time, so they may become a problem further down the road. Is it worth the risk? (See Developing Sterile Invasives by Ellen Susa )

There are better alternatives

The good news is that there are lots of great alternatives to Butterflybush.

For caterpillar food plants, consider trees and shrubs like Black Cherry (Prunus serotina), Tuliptree (Liriodendron tulipifera), Oaks, Northern Spicebush (Lindera benzoin), blueberries (Vaccinium corymbosum, V. augustifolium), Gray Dogwood (Cornus racemosa), Ninebark (Physocarpus opulifolius), Hoptree (Ptelea trifoliata) and Pipevine (Aristolochia species), and herbaceous perennials including American or Maryland Senna (Senna hebecarpa, S. marilandica), Blue False Indigo (Baptisia australis), violets, milkweeds and asters.

Azure laying eggs (ovipositing) on Ninebark (Physocarpus opulifolius)

Red Admiral Nectaring on Ninebark

For nectar, in addition to the plants listed above, you can’t beat Mountain Mints, Common Buttonbush (Cephalanthus occidentalis),

Indian Skipper and Bumble Bee nectaring on Buttonbush (Cephalanthus occidentalis)

and Coastal Sweetpepperbush (Clethra alnifolia). What thirsty butterfly could resist pink clouds of Joe-Pye-Weed (Eutrochium species),

Eastern Tiger Swallowtails and Peck’s Skippers nectaring on Joe-pye-weed (Eupatoriadelphus species)

bold purple New York Ironweed (Vernonia noveboracensis),

Zabulon Skipper nectaring on New York Ironweed (Vernonia noveboracensis)

Northern Blazing Star (Liatris scariosa),

Monarch on Northern Blazing Star (Liatris scariosa)

Purple Giant Hyssop (Agastache scrofulariifolia), or sunburst yellow coneflowers?

Green-headed Coneflower (Rudbeckia laciniata) with American Copper and Bumble Bee

From late summer through fall, the shimmering yellows of goldenrods

Common Buckeye and Potter Wasp on Goldenrod

and the many bright hues of asters are a prolific source of food for hungry butterflies and native bee species, while hosting many other insects that provide essential food for birds.

Orange Sulphur nectaring on Aster

Listed above and pictured here are just a few of my personal favorites. Good sources of information about plants that will work well in your area include Attracting Native Pollinators by Mader, Shephard, Vaughan, Black and LeBuhn; Bringing Nature Home by Douglas W. Tallamy, the North American Butterfly Association website, and your state or regional native plant society.

Most of us (except in places where prohibited, like Oregon and New Zealand!) are free to choose. Would you like to have a chance to watch butterfly species successfully raise new generations on your property, and protect their habitat in the natural areas near you? Choose well, and you will also have a continuously changing display of colorful blossoms to host adult butterflies from early spring through late fall.

Note: This is adapted from an article that appeared in the Summer 2012 issue of Butterfly Gardener, a publication of the North American Butterfly Association.

Ruby-throated Hummingbirds are Back!

Posted on June 3, 2013 by Mary Anne Borge

In late April we started to have occasional visits from Ruby-throated Hummingbirds, once every few days. Male hummers were first on the scene,

Male Ruby-throated Hummingbird

followed by visits from females about a week later. Continue reading →

The Natural Web

Exploring Nature's Connections

Category Archives: Gardening for Wildlife

Spicebush or Forsythia?

In Praise of Black Walnut Trees

Embracing the Shade: Summer and Fall

Butterflybush – Are there better alternatives?

Ruby-throated Hummingbirds are Back!

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