Native Viburnums: Form and Function in the Landscape

In a finely-timed spring ritual, a vibrant host of warblers, tanagers and other songbirds have ridden the wave of emerging caterpillars northward to arrive--much to our delight-- in our local woods, fields and yards.

Yet as Doug Tallamy, author of Bringing Nature Home and The Living Landscape has so succinctly put it: we feed the birds in winter, but starve them in spring and summer. We put out seeds and suet, but we may not be providing them with what 96% of songbird species need to migrate or raise the next generation: caterpillars. Even those we think of as seed-eaters—chickadees, for example, or cardinals—feed their young almost exclusively on caterpillars.

Azalea sphinx caterpillar on blackhaw viburnum.

Successful leaf-munching entails adapting to the defensive chemicals created by plants—and readapting once the plants have responded in turn by tweaking those chemical defenses. This ancient process of coevolution between plant and caterpillar accounts for the limited range of food or “host” plants available to a caterpillar species, even within its native ecosystem. Nonnative plants that have not been a part of this adaptation process rarely participate in the propagation of native moths or butterflies. Among shrubs, for instance, the Asian Budleia, or butterfly bush, may provide nectar for adult lepidoptera, but offers exactly nothing to their larvae. This is the crux of the reason for including a variety of native plants in our gardens and landscapes.

Happily, there are plenty of shrubs indigenous to Indiana that provide not only leafy food for caterpillars, but nectar for pollinators, protective cover for wildlife, nesting sites for birds, and fruits that are relished by gamebirds, songbirds and mammals. Native shrubs in the genus Viburnum are among the most valuable for the amount of wildlife they support.

Viburnums are host plants for many caterpillars: spring azure and Baltimore checkerspot butterflies; the rose hook-tip moth (which eats only viburnum); two large pollinator moths, the hummingbird clearwing and azalea sphinx; and numerous little moths with appellations such as common pug, horrid zale, intractable Quaker-- ones we consider nuisances around the porch light in their adult forms, but which as larvae are the mainstay of bird diets in spring and summer.

Human aesthetics need not be sacrificed to function here--all our native viburnums feature conspicuous, frothy heads of white flowers in April or May. Their leaves come in a variety of attractive forms, and in autumn take on brilliant reddish hues, contrasting in most species with blue-black fruits. Nine viburnum species occur in Indiana, with the following four found in many counties throughout the state.

Southern arrowwood is adaptable to most soil types and a range of light conditions. Its coarsely serrate, deeply veined leaves make the shrub attractive even when not in full flower. An upright shrub that suckers freely from the base, its dense, “limby” structure makes it ideal for nesting birds, and the fruits are savored by wildlife.

Blackhaw is tolerant of many soil types and grows in both sun and shade. The leaves of this robust viburnum are notable for their bright red petioles and vivid fall color. This tall, handsome shrub is fast-growing and may sucker widely to form large thickets, so give it lots of room.

Nannyberry (above) is another tall, suckering viburnum. Its charming name comes from the resemblance of the bluish black fruits to goat droppings, i.e. nannyberries. This viburnum will adapt to upland sites, but is a good choice for poorly drained or wet areas, and can be grown in either shade or sun. It may be susceptible to mildew if not given adequate air circulation.

Mapleleaf viburnum is a lower-growing shrub that spreads slowly to form clonal thickets. Often found on wooded ridgetops, it tolerates dry shade, but adapts to a variety of soil and sun exposures. Its striking maple-like leaves are as downy-soft to the touch as a kitten’s ear; autumn tints range from apricot to rose. Its growth form makes it a good shrub for wildlife cover and nesting birds.

Of my viburnums, deer seem to browse arrowwood the most heavily. They also sampled nannyberry leaves when the shrubs were young, but there’s been nary a cervine nibble on the blackhaw. That’s just in my garden, however, and is in no way a guarantee of what deer may find palatable in the shrubbery next door! A new threat to be aware of is the European viburnum beetle, which can defoliate and kill native viburnums (remember the coevolution lesson above—our viburnums lack a chemical defense against these recently introduced insect larvae).

Carolina Chickadees feed their nestlings almost exclusively on caterpillars

and other insect larvae.

A sweet cacophony of bird song outside provides my soundtrack as I write this. It reminds me that even the tiny chickadees require over 9,000 caterpillars to raise a single brood, and that a native viburnum in the landscape greatly enhances their chances for success.

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Life Among the Red-cedars: Beautiful and Bizarre

As I strolled along my road this winter, I admiring a row of Eastern Red-cedars dark against the snowfield behind them, I startled a mixed flock of cardinals and chickadees that had been busy in the conifers’ branches. They flitted noisily across my path to more cedars on the opposite verge. Red-cedars often take advantage of our landscapes of neglect: roadsides, fence rows, old scruffy fields. The birds, who plant them there, reap many benefits from Indiana’s only common, widespread native conifer—as do a host of other creatures.

Members of the Cypress family, Red-cedars (Juniperus virginiana) are cousins to the more northerly Common Junipers that make up so many overgrown foundation shrubberies. Wandering through my neighborhood Red-cedars, I see that most of them are female, bearing the waxy blue fruits that we refer to as juniper berries, but that are actually fleshy cones (look closely and you can see the tightly overlapping scales). I also spot a male tree here, bearing innumerable minute pollen cones—so many that they give the tree an overall tawny cast.

Unlike the acid-loving pines and spruces we plant in southern Indiana, which often die prematurely because they’re ill-suited to our alkaline clay soil and climate, Red-cedars thrive here. Hardy and adaptable, they can be found in swamps and under deciduous trees, but are sun-loving and drought-tolerant. They grow not only in old fields, but in challenging environments such as limestone glades or atop limestone cliffs.

Indeed, if you have a prairie or meadow planting, or you maintain a glade ecosystem, Red-cedars may become the woody encroachers you love to hate. They are tough pioneer trees, leaders in the succession from meadow to forest. On prairies they were once kept down by frequent wildfires—unlike most other conifers, many of which are fire-dependent, Red-cedars are not even fire-resistant.

The Eastern Red-cedar is home to many captivating critters. Amid the dense boughs of this roadside hedgerow I find an empty praying mantis case adjacent to the curious marvel of a cedar bagworm house, a tapered silk cocoon shingled with leaf bits cut from the tree. The grub-like female bagworm never leaves this camouflaged chamber, not even to mate: conjugation with the winged male transpires through the bag’s door flap.

Behind these insect wonders a coppery growth clasps a shoot: the fascinatingly grotesque and aptly-named cedar-apple rust, now shuttered in dormancy. Warmer, wetter months stir it into weird life: gelatinous orange tentacles (telial horns) protrude and lengthen, releasing spores that damage apple and crabapple trees. If you grow these fruit trees, it’s best to avoid planting the Red-cedar nearby. If Red-cedars exist in your area already, do some research on rust-resistant apple tree varieties before planting your orchard. Otherwise, take some time to examine this funky, freaky fungus.

Cedar apple rust, in winter dormancy (above). In warm wet weather the dimples will become openings through which spore-bearing telial horns, gelatinous when fresh, emerge. Thanks to Jan Thornhill for the image below, and for her fascinating blog on fungi:

https://weirdandwonderfulwildmushrooms.blogspot.com/

The Eastern Red-cedar also supports pretty birds and butterflies, if that’s your thing.

If you espy a dainty green-flecked butterfly nectaring at your flowers in summer, you can thank the Red-cedar for providing the food for its larvae, the Juniper Hairstreak caterpillar. But good luck locating this cat; it so cunningly mimics the green hue, scale pattern and attitude of the cedar shoots that it virtually disappears among them. Even more cryptic is the Curve-lined Angle moth caterpillar; visually searching for it, reads one field guide, “is essentially futile”. Other caterpillars hosted by Red-cedars are the Variegated Midget and the jauntily-named Juniper Geometer.

Juniper Hairstreak caterpillar and butterfly. Thanks to Jim McCormack for use of these photos. Check out his informative and entertaining blog on Ohio wildlife: http://jimmccormac.blogspot.com

If you hear a bustling in the juniperous hedgerow, it may be juncos settling in amongst the boughs for a winter’s night. Red-cedars stand up well to wind and snow, and their erect, dense forms provide vital shelter for overwintering birds and small mammals; come spring, they harbor songbird nests. In the breeding season I hear the ascending buzz of the prairie warbler as I pass these trees; the diminutive black-streaked yellow birds nest not in open prairie but in shrubby old fields and glades, and Red-cedars are often indicative of their presence.

Male Prairie Warbler. Photo by William H. Majoris, Wikimedia Commons

Now, back to those juniper “berries”: plenty of birds not only relish them, but rely on them in wintertime--including turkeys, robins, bluebirds, and yes, the breathtaking Cedar Waxwing. Twelve days in the gut of a waxwing, followed by a lie-in over the next winter, and the juniper seeds are scarified, stratified, and good to go.

A Cedar Waxwing forages for Red-cedar fruits.

Cedar waxwings pass fruit back and forth--in this case a juniper "berry"-- as part of their bonding activity. Thanks to Mark Reinig for permission to use his cedar waxwing images; view more of his wildlife photos at

http://www.onthemarkphotos.com

There are many Juniperus cultivars available, but the best support for wildlife is the straight, wild species endemic to your local region. Just be aware of the caveats mentioned above, and that Eastern Red-cedars are fast-growers that require elbow room. Smaller trees transplant more successfully, and it is recommended that you plant during the warmer months, so the tree has time to develop roots before a frost. Otherwise, the needles, unable to receive adequate moisture, may suffer from freeze damage.

Meanwhile, consider an outing to Cedar Bluffs or The Cedars, two wonderful nature preserves just south of Bloomington, and enjoy Indiana’s signature conifer.

Winter Sowing Bee at Fish Creek Preserve

On a frigid Friday in December, folks have gathered at Myriam Wood's Fish Creek Preserve to start the plants of future springs and summers. It is the annual winter seed-sowing at Myriam’s home-away-from-Bloomington, a property adjacent to Owen-Putnam State Forest, and now placed in a conservation easement with Sycamore Land Trust.

It’s darned cold outside, but some of us have just returned from taking the dogs for a ramble through woods that have reclaimed most of this land. We now assemble in Myriam’s garage and get down to business: mixing and potting up soil; sifting out seeds from dried flower heads; dispersing seeds among numerous, carefully labelled flats. False indigo, beebalm, liatris, coneflower; blue-eyed grass, goldenrod, alumroot, penstemon: these are just some of the seeds harvested from native plants that grow at Fish Creek. Some were purchased and put in by Myriam; others simply recovered their place here, as this land was allowed to ease back toward its natural state.

Native plant seeds harvested from Myriam's land. Photo by Gillian Harris

Like most of southern Indiana, the land was once farmed, the soil eroded and depleted. Now under Myriam’s stewardship, botanical diversity is returning, and with it the insects, birds and other animals that make up a living landscape. It has taken decades of learning, experimentation, and strenuous labor to get to this point, to the collection of seed-filled jars on the garage windowsill. When Myriam and her husband Jim came to this place in 1973, their first impulse was to replicate their Bloomington landscape, and they set about planting conventional ornamentals around the new cottage.

But while teaching state history at University School, Myriam became interested in Indiana prairies. She also noticed how pollinators thronged to the Joe-Pye Weed growing in her creek bottomlands, and began to seek out other native plants to attract and sustain wildlife. When she retired, Myriam was able to fully devote herself to rejuvenating the ecosystem of Fish Creek. She called upon Spencer Goehl of Eco-logic (a former student), who walked the property with her, drew up a list of native plants for butterflies, and facilitated her purchase of large flats of plants to kick-start her project. She now employs two groundskeepers/gardeners, Anthony Bizzari (another former student) and Andy Marrs, to keep the endeavor growing.

Ramsey Harik, Dottie Warmbier, and Andy Marrs prepare the stratification beds.

Photo by Gillian Harris

And she calls on friends, who are only too happy to be a part of the process. A few especially cold-hardy souls have now left the garage to prepare the winter garden bed. They dig shallow troughs in soil that was covered to protect it from freezing, footprints of the flats we sowed indoors. The pots are transferred from their flats and nestled into these depressions. Here the seeds will bide, undergoing the cold stratification necessary for most wild plants, until the longer days of spring stir them into germination.

Lizz Robb and Myriam Wood mix potting soil. Photo by Gillian Harris

Mary Weeks and Kathy Ruesink sow stratification flats. Photo by Gillian Harris

Just as we run out of pots, Myriam announces that soup is ready, and shedding boots and winter layers, we trail into the house to enjoy the spread she has laid out for us. As we finish, she sets two binders down amongst the empty bowls and Christmas cookies, and we leaf through pages of photos, garden lists, nursery receipts and germination notes. Eschewing herbicides, Myriam has taken a measured approach to planting her clearings, creating “pocket prairies”-- areas small enough to be prepared with a weed-smothering layer of cardboard and mulch, and more easily managed throughout the seasons.

After lunch we follow Myriam as she guides us through the landscape surrounding her house. The ornamentals of yesteryear have been largely supplanted with native flowers and shrubs that support a diversity of wildlife. The scarlet fruit of winterberry pops against a muted December pallet. Neon green moss carpets logs gathered as seedling nurseries, as well as cover for small critters. Since a marbled salamander was discovered in the leaf litter, leaves are no longer “cleaned up” but left to provide free mulch as well as the foundation of a living landscape.

Myriam in one of her shade beds, describing how the fire-pinks (Selena virginica) she planted years ago have thrived and spread. Inset: Fire-pinks in bloom attract hummingbirds. Photos by Gillian Harris

Myriam’s enthusiasm and dedication is infectious. She is constantly amazed at what the land has “in its belly,” as she puts it--if it is only encouraged, or even left to its own devices. She recalls the purple fringeless orchids that dotted the meadows last summer, and the day that her gardener went out to plant bottle gentians newly acquired from Eco logic, only to discover that gentians had already, and freely, emerged on their own.

As we leave, we joke that if our seeds germinate successfully, we may benefit from Myriam’s generosity in sharing extra plants. Ever the teacher and mentor, Myriam has also shared what she has learned from her years at Fish Creek, welcoming to the preserve school-bus-loads of children, surveying botanists, local plant and conservation groups, and, today, a community of friends—to partake in the ongoing work of bringing plant diversity, ecological function, and life back to the landscape.

Midsummer pay-off: One of the pocket prairies in bloom. Photo by Dottie Warmbier

Hit the slider arrow below to see more native Indiana plants at Fish Creek Preserve, a Sycamore Land Trust conservation easement in Owen County, Indiana.

Thank you to Myriam Wood for her hospitality, generosity, and enthusiastic dedication.

(all photos © Gillian Harris).

Dobbie, in the creek. Photo by Gillian Harris