Two Exuberant Native Shrubs in the August Garden

Author’s note: This essay first appeared under the title “August-Flowering Native Shrubs” in The New England Gardener’s Year by Reeser Manley and Marjorie Peronto (2013, Tilbury House Publishers, Thomaston, Maine).

Garden-worthy native shrubs that flower or fruit in August, like summersweet clethra and staghorn sumac, are rare. Both are found in the wild throughout New England, but only the clethra has found its way into the hearts of gardeners. Staghorn sumac is too exuberant for many and mistakenly labeled invasive by some – only a non-native species can be called invasive, but perhaps I can convince those who shun it that staghorn sumac has merit and can be managed with success.

Summersweet Clethra

Summersweet clethra 'Hokie Pink'  in August.

Summersweet clethra ‘Hokie Pink’ in August.

Summersweet clethra, Clethra alnifolia, is a native plant success story, a favorite shrub among the many gardeners who grow it for its spicy fragrant summer flowers and golden yellow fall foliage. Also called sweet pepperbush for its peppercorn-like fruit, white alder for the similarity of its foliage to that of the true alders, and “poor man’s soap” because the flowers produce lather when crushed in water, summersweet has been in cultivation for over 200 years. It is an essential plant in the pollinator garden, attracting butterflies, bees, and hummingbirds, and it is ignored by deer, a draw for many New England gardeners.

Clethra's blossoms are a magnet for pollinators, including bumblebees.

Clethra’s blossoms are a magnet for pollinators, including bumblebees.

Borne in dense narrow spikes, the blossoms can fill the summer air of the garden with a spicy scent for several weeks in late July and August. Following the bloom are small rounded seed capsules, each one-eighth inch in diameter and containing several seeds, all packed into the same dense spikes of their forebears. These tan-colored capsules persist into autumn, gradually darkening in color and adding textural depth to fall foliage that varies from light yellow to gold.

The autumn foliage of summersweet clethra ranges from yellow to gold.

The autumn foliage of summersweet clethra ranges from yellow to gold.

While the species has white blossoms, many new cultivars of summersweet have been introduced in recent years, including ‘Hokie Pink’, the cultivar that grows in Marjorie’s garden. And while the species can reach heights up to ten feet in the garden, newer cultivars selected for compact habits top out at three to four feet.

Staghorn Sumac

“In summer, Staghorn Sumac lifts its immense panicles of vivid flowers among the great frond-like pinnate leaves, and in autumn the brilliant fruits, the most variously brilliant foliage, shout out their color to the dying year. Flaunting orange, war-paint vermilion, buttery yellow, or sometimes angry purple may be seen all together on a single tree. More, it commonly happens that half of a compound leaf, or even half of a leaflet, may retain its rich, deep, shining green, in calm contrast to the flaming autumnal hues. And at all times the lower surface of the foliage keeps its pallid, glaucus cast that, when early frost has brushed it, turns silver. Probably no tree in the country, perhaps in the world, may exhibit so many and such contrasting shades and tints, such frosty coolness with its fire.”

–Donald Culross Peattie, A Natural History of Trees of Eastern and Central North America, 1948

Staghorn sumac in fruit.

Staghorn sumac in fruit.

You know this tree, the staghorn sumac (Rhus typhina), its common name derived from the fine felt-like hairs on young stems, giving them the texture of a deer’s antlers. You know it, if only from the window of your car, those roadside colonies of tropical foliage with wine-red pyramidal fruit clusters encircled by long, dark green, pinnately compound leaves. If you are really observant, you’ve noticed that some colonies sport these showy fruit clusters while others lack them. Some colonies are female, some are male.

Actually, each colony can be considered a single multi-trunked tree, each trunk derived from a suckering shoot that likely originated from a single bird-dispersed seed. The shoot that started it all may have long since died, leaving behind a group of suckers that are all the same sex and that, in time, will produce more suckering shoots. And so the colony grows, old stems dying, a multitude of young suckering shoots taking their place.

Old colonies of staghorn sumac can cover an extensive area. I recall a two-acre hayfield divided in half by a colony of 20-foot-tall fruiting branches, a beautiful sight in August when the colony was fruiting, in October when the leaves were turning, and in winter when the persistent fruits were dusted with snow.

Staghorn sumac’s vegetative growth habit makes it a difficult plant to bring into some gardens. When I recommend its use as both a lovely ornamental and a valuable wildlife plant, I’m likely to hear the term “invasive” tossed into the discussion. But no, a native plant, by definition, cannot be considered invasive. Aggressive it is, for sure. In the right place, in the right garden, I like “exuberant”.

It comes down to a matter of placement. The suckering habit of staghorn sumac can be controlled by mowing, paving, and water. For example, I recall a colony of fruiting plants in Orono, Maine, growing between the banks of the Penobscot River and a paved road, their spread controlled by water on one side, asphalt on the other. In Orono, I lived next door to a colony of sumac in a neighbor’s back yard, its spread limited by the lawn mower.

Staghorn sumac’s shallow, wide-spreading roots make it ideal for soil stabilization along slopes, streams, or pond-side, wherever its suckering habit can be tolerated or controlled and drainage is good. Because of its tolerance of salt, it is also an excellent plant for seashore and roadside plantings.

Each "fruit" of the staghorn sumac is actually a cluster of berries.

Each “fruit” of the staghorn sumac is actually a cluster of berries.

The berries of staghorn sumac, small fleshy drupes covered with fine red hairs and borne in cone-shaped clusters, are eaten by ruffed grouse, eastern phoebe, common crow, northern mockingbird, gray catbird, American robin, wood thrush, hermit thrush, eastern bluebird, and over 30 other bird species. Because the fruit persists through the winter, it is an excellent emergency source of food for these creatures.

Staghorn sumac’s spring flowers, greenish-yellow and borne in conical clusters, provide nectar for bees and several butterfly species, including banded and striped hairstreaks. It is also a larval host for the luna moth and the spring azure butterfly. In late August, its leaves are riddled with the chewing of these caterpillars.

For those who can manage its exuberance, staghorn sumac belongs in the wildlife garden where it will nourish a host of birds and insects. And it belongs in the ornamental garden where the gardener can watch it change in texture and color through the seasons.

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About Reeser Manley

I was born in Laramie Wyoming but moved to the southeast at an early age. I was educated through my B.S. in Biology in the Columbus, Georgia area, then crossed the Chattahoochee River to earn my M.S. in Botany at Auburn University. For the next ten years, I worked as Horticultural Manager for the George W. Park Seed Co. in Greenwood, S.C. At 40 years of age, I decided to return to graduate school and in 1994, I earned a Ph.D. in Horticultural Science from Washington State University, Pullman, Washington. Fast forward through 10 years at university (7 at UMaine, Orono) and you find me teaching high school science in Eastport, Maine, the edge of the world, and writing a weekly garden column for the Bangor Daily News. My new book, The New England Gardener's Year, a Month-by-Month Guide for Maine, New Hampshire, Vermont, Massachusetts, Rhode Island, Connecticut, and Upstate New York”, will be published later this year by Cadent Publishing. You can learn more about the book by visiting its Facebook page: http://www.facebook.com/pages/The-New-England-Gardeners-Year/187285218055676.)