Staghorn Sumac (Rhus typhina) is a popular ornamental shrub or small tree chosen for its striking appearance, which includes velvety branches that resemble deer antlers in velvet and vibrant scarlet-orange fall foliage. The plant produces upright, fuzzy clusters of red fruit that persist through the winter, offering year-round visual interest. However, its inclusion in landscapes frequently leads to confusion over its ecological status. This article will clarify the distinction between the plant’s aggressive growth habit and true invasive status.
Defining Aggressive Growth Versus Invasive Status
Staghorn Sumac is definitively not an invasive species in North America because it is native to the continent. Its natural range spans from southeastern Canada down to Georgia and across to the midwestern United States. The term “invasive” is specifically reserved for non-native species whose introduction causes or is likely to cause economic or environmental harm.
The source of the confusion is the plant’s highly aggressive nature, which causes it to be labeled as “weedy.” This aggressive habit allows it to rapidly colonize open areas, forming dense thickets that quickly outcompete other vegetation in a domestic setting. While it is a native species, its vigorous tendency to spread in the landscape is what leads many gardeners to mistakenly classify it as invasive. The plant is well-suited for erosion control on slopes or in naturalized areas where its spread is desired.
Biological Mechanisms of Rapid Spreading
The rapid lateral spread of Staghorn Sumac is driven by its extensive underground root system, which produces structures called rhizomes. These rhizomes are horizontal, modified stems that can extend far from the main parent plant. Along the length of these underground stems are buds that generate new vertical shoots, known as root suckers, sometimes several feet away from the original trunk.
Over time, this process results in a single genetic individual forming a large, dense colony or clone, with the oldest, tallest stems typically found at the center. This clonal growth allows the sumac to establish itself quickly and dominate an area.
The plant’s survival mechanism is triggered by damage to the root system or the main stem. When the main trunk or established suckers are cut, mowed, or otherwise damaged, the plant interprets this as a threat and responds by vigorously stimulating the growth of new suckers. This means that simply mowing over new sprouts or cutting down the main plant without follow-up treatment often exacerbates the problem, as energy reserves stored in the extensive root network fuel this burst of replacement growth.
Management and Control of Unwanted Growth
Managing the aggressive spread of Staghorn Sumac requires a multi-pronged approach that targets the root system rather than just the above-ground growth.
Mechanical and Physical Control
For mechanical control, cutting down unwanted suckers must be a continuous effort to consistently deplete the plant’s stored energy reserves. Mowing new sprouts frequently throughout the growing season can weaken the overall clone, but it is unlikely to eliminate it entirely.
For long-term landscape containment, physical barriers are an effective preventative measure. Installing a deep root barrier, such as a specialized, non-permeable membrane, vertically into the soil can prevent the rhizomes from spreading into cultivated areas. These barriers should be placed at a depth of at least 18 to 24 inches to block the lateral growth of the roots.
Chemical Control
When mechanical removal is insufficient, chemical control may be necessary, involving the application of a systemic herbicide that moves through the plant to the roots. Herbicides containing active ingredients like glyphosate or triclopyr are effective against woody plants like sumac. The most targeted application method is the “cut-stump” treatment, where the herbicide is immediately brushed onto the fresh cut surface of a stem or sucker. This minimizes the risk of harming surrounding desirable vegetation, which is a concern with broad foliar sprays.