Although it may seem simple, working one-on-one with plants across the Arboretum landscape since high school has taught me a symbolic life lesson—the importance of taking a minute out of the day to slow down and admire something captivating in nature. One of the plants I’ve come to admire but might otherwise be overlooked is winged sumac (Rhus copallinum). These deciduous shrubs (and, as you will see, trees) are native to eastern North America and offer interest to landscapes throughout the seasons. The Arboretum’s collection offers visitors the opportunity to observe this species at different growth stages, and see how they grow depending on differing planting locations and conditions.
In early September I helped plant out three new accessions of R. copallinum (298-2019*C, D, & E) among the cosmopolitan mix of hardy perennials growing in the landscape of the Arboretum’s Weld Hill Research Building. As Horticulturalist Brendan Keegan and I planted these specimens we were entranced by their newly emerging fall foliage as well as their vigorous red roots with their cinnamon aroma. Winged sumac was a great choice for combating erosion along this hillside, since winged sumac spreads by root suckers to form large, thick masses. Because of this tendency to colonize, however, it may not be a good choice for smaller gardens.
My Arboretum colleagues Andrew Gapinski, Sean Halloran, and Jared Rubinstein collected 200 seeds of winged sumac during the first North American expedition of the North America-China Plant Exploration Consortium (NACPEC) in 2019. Harvested from the Charles Eulett Wilderness Preserve on the edge of the Appalachian Mountains in Ohio with NACPEC partners Dr. Tao Deng and Dr. Xinfen Gao of the Chinese Academy of Sciences and Dr. Kang Wang of the Beijing Botanical Garden, the seeds were shared among the participating institutions. It will be interesting to see how this plant performs for our collecting partners, as overall the species shows little tendency for uniform growth, a quality that makes it so distinct in larger landscape settings. As horticultural guru Michael Dirr describes it, R. copallinum is “irregular and picturesque as it ages.” Another fine accession of R. copallinum (Accession 288-97) at the Arboretum growing near the summit of Peters Hill offers an example of this, showing how the species can perform in maturity as an individual tree.
The large compound leaves typical of the genus display an identifying feature of this species suggested by one of its common names—stems are winged, with flat, leafy extensions along the midrib. Another common name for R. copallinum is flameleaf sumac, which conjures its vibrant fall color shades of reds, purples, and oranges which should begin soon in our landscape. Complementing its fall color, the pollinated female flowers of the plant produce clusters of pubescent drupes which ripen to maroon as autumn progresses, making for a showy winter feature that also provides a food source for wildlife.
Near these specimens, you can observe the wide-ranging characteristics of the other eight species of Rhus in the Arboretum’s collection. Historically, plants in this genus have been used as medicine by North American indigenous people, from derivatives of its roots to treat colds and fevers to the dust from its berries to treat cold sores or ringworm. Although it may not be curing illness in present day, the ripened fruits of its relative R. typhina (staghorn sumac) can add flavor to pies a lemonade-type beverage.
The next time you find yourself amongst the over 16,000 accessioned plants that the Arboretum is home to, I encourage you to take a minute out of your stroll to explore some of our hidden gems, like Rhus copallinum. Every plant has its moment to shine, and the next few weeks will reward visitors to this vibrant member of the cashew family.