Be Your Own Plant Detective: Spot Invasives

By Lisa Nadler and Martha Keehner Engelke, NC State Extension Master Gardener^SM volunteers of Durham County

Sometimes a plant becomes a rapid spreader working its way into places where you would rather it not go. Coral honeysuckle (Lonicera sempervirens) is an example of this. It is a vigorous twining vine that is native to the eastern United States. It can grow 10-20 feet high in a season. It spreads aggressively. But, because it is native to our ecosystem, it doesn’t displace other native plants in the area. It is not invasive. In contrast, its “cousin” Japanese or Chinese honeysuckle (Lonicera japonica), a native of Asia, is capable of growing over plants and smothering them. It can displace native species by outcompeting them for light, space, water and nutrients.

“The term invasive applies only to non-native plants; invasive implies a negative effect on native plants and animals. On the other hand, native plants that establish quickly in your garden and spread readily are more appropriately termed “aggressive.” Aggressive native plants generally are species adapted to recently disturbed sites where they establish and spread quickly but give way to other native plants within a few years”.¹

So, how do you tell the difference?

Close-up of coral honeysuckle flowers, showcasing elongated yellow blooms surrounded by green foliage.

Close-up view of coral honeysuckle (_Lonicera sempervirens_) with green leaves and white-yellow tubular flowers growing on a tree.

Close-up of coral honeysuckle (_Lonicera sempervirens_) featuring white flowers and green leaves against a blurred green background.

Close-up of bright red and orange tubular flowers of Coral Honeysuckle (_Lonicera sempervirens_), surrounded by green leaves.

Two of the pictures above are Lonicera sempervirens (native) and two are Lonicera japonica (invasive). Can you tell the difference? Answers are at the end of the post. (Image credit: Top left: Debbie Roos; Top Right: Lucy Bradley, CC-BY 4.0; Bottom left: Hope Duckworth CC- BY 4.0; Bottom right: Chris Kreussing CC-BY-NC-ND 2.0)

Lisa Nadler’s adventure to distinguish a native plant from an invasive plant is enlightening. It is an excellent illustration of how two plants that seem similar and are in the same family are vastly different in the impact they will have on your garden.

Plant Detective: Lisa Nadler

On a recent visit to Cocoa Cinnamon Container Garden², Lisa Nadler made a discovery. Invasive Chinese or Sericea Lespedeza (Lespedeza cuneata) was in one of the painted pots. Lespedeza is in the Fabaceae, or bean family.

A close-up of a painted flower pot containing various plants, including invasive Chinese Lespedeza, with two arrows pointing to the identified invasive species. Background features blue and red patio chairs.

A woman wearing a colorful tank top holds a plant with roots in one hand and gives a thumbs down gesture with the other, standing in a garden setting with outdoor tables and chairs.

The picture on the left shows Lespedeza cuneata growing in a pot at Cocoa Cinnamon. In the photo on the right Deb Pilkington holds the plant after it is removed illustrating its long tap root (Image credit: Lisa Nadler)

So, what is Lespedeza and how did they know it is bad? There are both native and invasive Lespedeza plants and they can look similar. So, you need to know what to look for to know which ones to yank and which ones to leave.

Sericea lespedeza (Lespedeza cuneata) is a warm-season, perennial legume with many erect, leafy branches. It also goes by the name of Chinese Bush Clover. It was introduced from Asia in 1896 for erosion control, livestock forage and wildlife cover. But, it has no natural diseases or insects to manage it here and it is now listed as a Rank 1-Severe Threat in NC.

According to the NC Plant Toolbox, it may be allelopathic, producing substances that chemically inhibit the growth of other plants. It forms extensive monocultures and develops an extensive seed bank in the soil, ensuring its long residence at a site. Its high tannin content makes it unpalatable to livestock and most native wildlife. So, not a very good addition for wildlife feed. It can grow up to 6 feet tall and once you know what it looks like, you’ll start seeing it everywhere, especially on road sides.

But how can you tell it from the native Bush clover species, Lespedeza virginica and Lespedeza capitata? Here are some clues.

Bloom Color (which wasn’t helpful in this case because it wasn’t in bloom.)

Lespedeza cuneata has white blooms with a touch of purple. The native Lespedeza virginica has purple flowers. But… (isn’t there always a but…) the other common native, Lespedeza capitata, has white flowers but with a redder touch.

Close-up of white and purple flowers of Lespedeza cuneata, a perennial legume with leafy branches.

Close-up of a pink flowering plant with small clusters of flowers, surrounded by green foliage in a natural setting.

The picture on the left is Lespedeza cuneata which is invasive. In the middle is Lespedeza virginica, a native and on the right is Lespedeza capitata, another native. (Image credit: Anita 363 CC-BY-NC 2.0; CC-BY-SA-2.0; CC-BY-SA 2.0)

Leaves

Okay, so now look at the leaves. The Lespedeza cuneata (the bad guy) has leaves that are more rounded at the end with a single tooth. Also, the veins are straight and easily visible. The leaves of the Lespedeza virginica and Lespedeza capitata (the good guys) are pointier at the end, usually have a less prominent tooth and the veins are curvier (I’m sure there is a specific botanical name for that…).

Close-up of elongated green leaves with droplets of water, surrounded by a small green plant, potentially illustrating the invasive Lespedeza cuneata.

Left to right: Lespedeza cuneata; Lespedeza virginica; Lespedeza capitata (Image credit: Hamilton Native Outpost; Bonnie Semmling CC-BY-4.0; Missouri plants. com).

There are other plant families that include both native and invasive species so it is important to always be on the lookout. The Poaceae family includes invasive and native grasses. The aquatic common reed (Phragmites australis), is native to Europe but very invasive in NC. It spreads rapidly and forms dense stands. Within the Rosaceae family we find native plants but also the highly invasive Multiflora Rose (Rosa multiflora). Plants in the Oleaceae Family are popular ornamentals and there are some natives but invasive species like Autumn Olive (Elaeagnus umbellata) and Russian Olive (Elaeagnus angustifolia) should not be planted. Autumn olive was introduced for wildlife habitat and ornamental purposes but has become invasive. Finally, we have the Fabaceae family. While Wisteria frutescens is a native, Chinese Wisteria (Wisteria sinensis) and Japanese Wisteria (Wisteria floribunda) are invasive vines in North Carolina.

So be on the lookout and be your own plant detective!

Answers to quiz: The picture on the upper left and lower right are native (Lonicera sempervirens) the other two are Invasive (Lonicera japonica).

Note 1: This article by Christoper Moorman and Dr. Lucy Bradley, summarizes the differences between aggressive and invasive plants. https://gardening.ces.ncsu.edu/how-to-create-wildlife-friendly-landscapes/why-landscapes-for-wildlife/invasive-species/

Note 2: Cocoa Cinnamon is a demonstration garden located at 420 West Geer Street, Durham, NC 2770. The Durham EMGs provide oversight and it has been an amazing source of information on best practices for growing plants in containers. Here are a few examples of previous posts inspired by the Cocoa Cinnamon project:

Winter pruning of “Little Miss Figgy”: https://wp.me/p2nIr1-5Xr

“Little Miss Figgy in the City” https://wp.me/p2nIr1-50Z

Give a thought to the pot: https://wp.me/p2nIr1-4sZ

Pot Luck: Adventures in Urban Container Gardening: https://wp.me/p2nIr1-2jZ

Pot Luck: A Wildlife Ecosystem in the Middle of a City? : https://wp.me/p2nIr1-2tn

Another series on invasive plants and alternatives by Jeanne Arnts, was recently published on the blog:

From Beloved to Invasive: How does it happen? https://wp.me/p2nIr1-5l3

Replacing Invasive Plants: Suggestions for Beneficial Alternatives https://wp.me/p2nIr1-5CJ

Additional Reading and Resources

For more information on plant diversity check out this article from the NC Botanical Gardens. https://ncbg.unc.edu/2025/03/06/what-are-the-most-diverse-plant-families-and-why-part-one-the-asters

The NC Native Plant Society has good information on identifying native vs. invasive plants. https://ncwildflower.org/invasive-exotic-species-list/

How do invasive plants affect our forests? Here is the answer: ttps://content.ces.ncsu.edu/invasive-plants-and-your-forests

Article Short Link: https://wp.me/p2nIr1-68z

Bringing Plants of the Piedmont back to Downtown Durham

On August 28, 2024August 27, 2024 By durhammastergardenersIn bees, beneficial insects, birds, cover crops, CPTED, crime prevention through environmental design, Downtown Durham, NC, drought tolerant plants, Durham NC, garden design, gardening, Gardening calendar, Gardening information, gardening NC, green mulch, ground covers, ground covers for living mulch, how to improve soil, insects, landscaping for wildlife, living mulch, native plant list, native plant list for Piedmont NC, native plants, Natives, NC Native Plants, Perennial, phenology calendar, Piedmont Prairie Garden at Rotary Plaza, pollinator gardening, polyculture, renewable gardening, soil, soil health, sustainability, sustainable garden design, sustainable watering, sustanability, Uncategorized, urban challenges in landscaping, urban garden, urban gardening, urban heat islands, urban planning, urban prairie garden, urban wildlife, uuban service benefits in landscapes, water wise plants, wildlife

By Eric Wiebe, NC State Extension Master Gardener^SM volunteer of Durham County

A once neglected site, Rotary Plaza in downtown Durham comes alive in July 2021 with sunflowers that produce seeds for wildlife. Millet, a grain used here in the design and novel to many urban dwellers, also serves as a great food source for gold finches and other birds. (Image credit: Ben Bergmann)

Have you noticed changes to the plantings in downtown Durham over the past few years? If not, you need to head on down, walk around, and appreciate the transformation of the many of the city-owned green spaces. This transformation, and the strategies behind it, point to a new way of thinking about our relationship to the landscape, both in urban settings like downtown, but also in our own yards.

I had the pleasure of both walking around downtown Durham with and then sitting down and talking to Ben Bergmann, the architect of this transformation. Ben was hired by City of Durham in September 2020 and charged with re-envisioning and elevating horticulture in downtown Durham, including creating a Downtown Horticulture Crew within Landscape Services. Ben brought a widely varied background to this position, trained with BS, MS, and PhD degrees in plant sciences, and working as everything from small business owner and farmer to tropical agroecologist and research scientist. One thing all this work has in common is plants and his great love of them. Ben feels this broad range of experiences has helped prepare him for a job that has him applying both the art and science horticulture to a municipal government position with its many constraints and opportunities and multitude of stakeholders.

“When I started, I realized I needed a mission statement to clearly and concisely communicate to my supervisors and the public what I and my unit in government is doing.” He stated that his landscape design and management are guided by the goal of enhancing

Environmental sustainability
Programmatic stability
Aesthetic appeal
Service benefits

He notes that it is important to recognize that these categories are not mutually exclusive, but each has a role to play in his horticultural work supporting the living landscape in downtown Durham.

Designing Sustainably

Ben explains that a crucial re-orientation is to start planning a landscape by thinking about how it can best align with the ecosystem, and that means starting with native plants that can be used. “For urban contexts some people would say that there is nothing native to these downtown spaces, and they will use this as an ‘out’ to plant whatever they want. I don’t embrace this–something was native, originally, in these spots. Many times these native plants can and will grow and thrive in these spaces.”

When Ben thinks about which native species to use, he first looks for plants native to the North Carolina Piedmont and secondarily to the larger Piedmont of eastern U.S. He notes, however, that it is very important to select plants with a long-range vision. That is, when accounting for global climate change, plants that are going to be here in 20 years may very well be in an environment that looks more like the southern Piedmont, our coastal plains, or South Carolina.

(Left to right) By selecting plants that can cope with a warming environment, Bergmann installed dwarf palmetto (Sabal minor), a plant typically associated with climates in the native ranges east and south of Durham, NC, and shown in green on the USDA’s zone map. (Image credit: Ben Bergmann; https://plants.usda.gov)

While native species take the lead when planning bed renovations, Ben states that non-native plants can still play a role. Returning to his guiding principles, non-natives can help fill functional gaps that might be hard to resolve in the short run with native species. Similarly, there are times that a spot planting of a non-native will help achieve a particular aesthetic goal by providing highlight color, texture, or architecture.

(Left to right) Before, a non-imaginative flag pole bed at Durham Parks and Recreation building included a highly invasive and exotic species: Nandina domestica. After a re-imagining, the same bed demonstrates there is a place for non-native plants alongside natives, especially during transition phases. (Image credit: Ben Bergmann¹

Because the legacy plantings downtown were almost 100% non-native, it means that during a bed’s transition period, some non-natives may be left to help visually and functionally stabilize the bed until new, native plants can get established and then take over. Among other things, the non-native plants retained just for the transition can provide shelter from the sun and wind during establishment.

(Left) The process of establishing an urban prairie at the Rotary Plaza began in September 2020 with beds filled with weeds and remnants of long past garden attempts. (Middle) In March 2020, the the beds are full of cover crops: crimson clover, a nitrogen fixer that is great for pollinators in early spring, and winter rye, which has high biomass production and deeply penetrating roots. The intricate planting pattern reflects intentionality and provides visual interest. (Right) By July 2022 the Piedmont Prairie Garden at Rotary Plaza is realized and chock-full of sustainable native plants. (Image credit: Ben Bergmann)²

Even given how much he has achieved is such a short time, Ben still takes the long view when planning and planting. For example, cover crops have been used in very purposeful ways in areas such as the Rotary Garden. During the initial transition of this space, cover crops were planted and maintained in ways that not only helped build the soil, but created visual interest. Over time, the cover crops matured and eventually replaced with native perennials, creating an evolving horticultural narrative in this space. As Ben said, “Some [landscape] designers shy away from transitions–they want to ‘put a tarp over it’ until it has reached its final phase. I don’t shy away from transitions; they are an important part of my plans.”

Ben notes that using select non-native plants, cover crops, and other annuals allows him to more easily use seeds, plugs, and small plants in the beds. In the case of herbaceous perennials and woody plants, besides being less expensive, younger, smaller plants will typically develop more robust root systems and quickly outgrow their bigger counterparts.

Addressing Urban Challenges

Ben was quick to remind me of the many contextual limitations and challenges the Downtown Horticulture Crew faces daily that home suburban gardeners rarely have to contend with. For example, CPTED (Crime Prevention Through Environmental Design), is an important set of guiding heuristics that often preempts other design considerations. In addition to making sure plantings do not screen illicit activities, it also disallows designs that interfere with security cameras or impair pedestrian safety, including driver site lines at street crossings.

The center of the Chapel Hill Street parking lot is a perfect example of an urban heat island with even hotter microclimates where landscapes are needed. (1) In January of 2022, the lot was cleared of weeds and other unhealthy, dated, and non-native landscape plants. (2-5) The view in 2024, after Bergmann and his team revitalized the area with an assortment of heat-tolerant natives. (Image credit: Ben Bergmann)³

Most of the beds Ben and his crew manage are surrounded by heat absorbing asphalt and concrete and buildings with glass that intensify solar radiation by reflecting light onto them. This creates heat islands much hotter than in surrounding communities. In addition, tall buildings funnel wind through these spaces and block rain, further desiccating plants.

Humans also are unhelpful, by walking on, driving over, or otherwise physically challenging plantings. Some soils are more like landfill or construction sites, and many have the negative impact of overuse by dogs on their walks. Even with these challenges, Ben has identified quite a few native species that are up for environmental extremes while still fulfilling functional and aesthetic goals. Not surprisingly, he is currently exploring the possibility of a demonstration xeriscape-inspired bed. This one may very well include some non-native plants more typically found in desert environments.

Educating the Community

Ben understands that an important part of his job is educating not only the workers and residents of downtown Durham but all city residents and visitors as to a new way of envisioning landscapes. Landscapes that, while they exist in a human-built environment, much more clearly reflect real ecosystems of the NC Piedmont. This means not only planting predominantly native species but planting them in soil nourished by natural mulches created by the plants themselves rather than imported, dyed wood chips. He also allows the plants to go through full cycles, creating visual landscapes that sometimes predominate in browns, grays, and blacks, as much as greens, yellows, and reds.

(Left to right) The Piedmont Prairie Garden at Rotary Plaza in early January with the last vibrant colors and in late February, when the remaining plants still create an almost black-and-white picture. (Image credit: Ben Bergmann)⁴ (Below) By designing a phenology calendar for his plantings, Bergmann pays careful attention to nature’s timing. This tool helps gardeners know when to plant, specific bloom times, and when colors, textures, and other elements are present throughout the seasons. For a closer view, click on the link for an electronic version of the calendar in our Resources and Additional Information section below.

He is heartened that there is a growing critical mass of professionals helping him in this educational work. The City of Raleigh and Wake County has been hard at work creating plantings that reflect this same vision. He also has strong allies at Duke Gardens, where Annabel Renwick, has provided both inspiration and plants for some of the bed designs. Ben recognizes that it will take a while both for his beds to reach the final stages of their design vision and for Durham residents to embrace this new look, but he has already received lots of positive feedback for his renovated beds. It will also be up to Durham Master Gardeners, and committed gardeners everywhere, to help continue to educate the public and support this work.

Plant lists for featured Downtown Durham Sites

1–The planting design at the Parks and Recreation administration site include a mix of natives (*) and non-native plants: threadleaf coreopsis* (Coreopsis verticillata), creeping phlox* (Phlox subulata), eastern ninebark* (Physocarpus opulifolius), panicle hydrangea (Hydrangea paniculata), lantana (Lantana camara), coleus (Solenostemon scutellarioides).

2–Plants in the Piedmont Prairie Garden at Rotary Plaza include swamp milkweed (Asclepias incarnata), blue mistflower (Conoclinium coelestinum), purple coneflower (Echinacea purpurea), Joe-Pye weed (Eutrochium fistulosum), Spotted Joe-Pye weed (Eutrochium maculatum), common sunflower (Helianthus annuus), scarlet rosemallow (Hibiscus coccineus), larger blue flag iris (Iris versicolor), cardinal flower (Lobelia cardinalis), switch grass (Panicum virgatum), garden phlox (Phlox paniculata), hoary mountain mint (Pycnanthemum incanum), brown-eyed Susan (Rudbeckia triloba).

3–Center of Chapel Hill Street parking lot showcases the following native plants: sedge (Carex bicknellii), purple love grass (Eragrostis spectabilis), Elliott’s lovegrass (Eragrostis elliottii), scarlet rosemallow (Hibiscus coccineus), swamp rosemallow (Hibiscus moscheutos), Virginia sweetspire (Itea virginica), tulip poplar (Liriodendron tulipifera), black-eyed Susan (Rudbeckia hirta).

4–The Piedmont Prairie Garden at Rotary Plaza in late February still offers color, texture, and winter interest. They include climbing aster (Ampleaster carolinianus), scarlet rosemallow (Hibiscus coccineus), switch grass (Panicum virgatum), hoary mountain mint (Pycnanthemum incanum), white goldenrod (Solidago bicolor), showy goldenrod (Solidago speciosa)–with touches of hopeful green, beardtounge (Penstemon digitalis), eastern beardtounge (Penstemon laevigatus), stoke’s aster (Stokesia laevis), adam’s needle yucca (Yucca filamentosa).

5– See below for Bergmann’s list of natives that are tried-and-true performers for Durham and central North Carolina.