Category: invasive plants

Be Your Own Plant Detective: Spot Invasives

On By durhammastergardenersIn container gardening, endemic plants, gardening NC, invasive plants, Invasive species, native plant list for Piedmont NC, native plants, Native plants of NC

By Lisa Nadler and Martha Keehner Engelke, NC State Extension Master GardenerSM 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.
Close-up view of clusters of white flowers with pink markings, with a blue butterfly perched on the blooms.

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…).

A close-up image of three leaves held by a finger, showcasing the different shapes and textures of the leaves for identification.
Close-up of elongated green leaves with droplets of water, surrounded by a small green plant, potentially illustrating the invasive Lespedeza cuneata.
A hand holding a sprig with three green leaves, displaying fine venation and elongated shapes, indicative of a Lespedeza plant.

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

From Beloved to Invasive: How does it happen?

On By durhammastergardenersIn benign non-native plant, bird friendly habitat, bugleweed, conservation, crape myrtle, Durham NC, ecological sustanability, ecology, gardening, Gardening information, gardening NC, heavenly bamboo, hellebore, how plants become invasive, Invasive Atlas of the United States, invasive plants, Japanese stiltgrass, lenten rose, lesser threat invasive plant list, liriope, monkey grass, nandina, native ecology, native ecologynative plant ecology, native plants, Natives, NC biodiversity, NC conservation, NC Native Plants, New Hope Bird Alliance, non-native plants, ox-eye daisy, perennials, polyculture, privet, protecting native plants, Rose of Sharon, Russian olive shrub, sustainable garden design, sustainable gardening, sustanability, Uncategorized, urban garden, urban gardening, watch list for invasive plants

By Jeannie Arnts , North Carolina Extension Master GardenerSM volunteer of Durham County

I have volunteered as a recorder for the New Hope Bird Alliance (formerly Audubon) Bird Friendly Habitat (BFH) team since 2018. The BFH team, consisting of a plant expert and a recorder, visits homeowners’ yards to identify native and invasive plants and make recommendations for improvements to achieve an ecologically beneficial habitat for birds, insects, and other wildlife. Since I have joined the group, plants previously recognized as non-native, non-invasive plants have been moved onto the “Watch List” or “Lesser Threat Invasive” list. Other plants previously considered lower threat have been moved to a higher threat category. The question arises, “What is it that changes a benign non-native into an invasive?

When is a Plant Determined to be Invasive?

Plants are categorized as invasive once they disrupt the ecology of intact, functioning eco-systems, leading to loss of biodiversity and habitat degradation. This results in huge economic damage valued in the billions of dollars to agriculture, forestry, and personal property. Invasive plants compete with our natives for critical and often limited resources like sunlight, water, nutrients, soil, and space. Anyone who has ridden the train at the Museum of Life and Science in Durham and seen the Russian olive shrubs (Elaeagnus sp) overtaking the landscape along the tracks or been on a hiking trail in many Triangle forests and seen the stiltgrass (Microstegium vimineum) engulfing the entire ground cover of the forest floor can easily see the impact of invasive species.

Russian olive shrubs (left) out-compete native plants and dominate riparian areas primarily in central and western USA. Japanese stiltgrass (right) was accidentally introduced into Tennessee around 1919 as a result of being used as packing material for porcelain from China.  it has invaded many woodlands in North Carolina. (Image credit: NC State Cooperative Extension)

What Factors Influence a Plant to Become Invasive?

Biologists have been “vexed for decades” by the question of what causes some plants, once thought to be benign, non-invasive exotics, to become a risk to our eco-systems due to their invasive characteristics. The ecologist, Charles Elton, wrote the book, The Ecology of Invasions by Plants and Animals, in 1958 and, more than 100 years earlier, Charles Darwin pondered this question during his voyage on the Beagle (1831-1836). Johnny Randall, former Director of Conservation Programs at the NC Botanical Garden, noted that one reason plants become invasive is that in their new environment, they no longer have natural controls, such as pests, pathogens, and herbivores. This gives them an advantage over native plants that have been part of a region’s ecology for millennia; consequently, the invasives often out compete the natives.1

In addition, a plant’s propensity to become invasive is a function of the plant’s own biology, including a relatively short generational period, large seed production, its ability to reproduce asexually (without the need for fertilization), and having large fleshy fruits, such as those produced by Autumn or Russian olive trees (Elaeagnus sp), privet (Ligustrum sp.) and heavenly bamboo (Nandina sp.) With this latter trait, birds will eat the berries and deposit the seeds far from the original location of the plant.

A non-native, is especially prone to invasion when it sets its roots in a “matched habitat” similar from which it came, i.e., their native ranges tend to have similar temperature extremes, precipitation levels, and seasonal cycles. Stiltgrass (Microstegium vimineum) is an example of a plant that meets most of the criteria for becoming invasive. It is an annual that produces up to 1000 seeds per year, has no natural controls, reproduces asexually, and its seeds are distributed by the wind. In addition, the seed bank may take up to five years to germinate. Many gardeners who think they have eliminated stiltgrass on their property one year are befuddled to find a number of plants from the seed bank sprouting the next summer. The good news is that if you continue to manage the stiltgrass, you will have fewer plants each year.

Beloved Plants that Become Invasive

I think we can all agree that we want stiltgrass eliminated from our property, but there are non-native plants that have been beloved by gardeners for generations that are being added to the invasive lists, much to the consternation of gardeners. One example is the lenten rose (Helleborus orientalis).

Some hellebores  have started to escape into woodland areas and are able to stifle our favorite native understory flowers. They prevent seedlings of other plants from getting established as dense mats of their offspring grow. (Image credit: NC Extension Toolbox, Bob Gutowski CC-BY-NC-SA-2.0; Jim Robbins CC-BY-NC-4.0).

There are many good reasons that hellebores are such a beloved plant: they bloom over the winter months when very few other plants are blooming; they require little care; they are deer and rabbit resistant; they tolerate a wide range of light conditions; including light shade; and they survive even deep frosts. Unfortunately, they meet many of the conditions that place them at risk to become invasive in our region: they have no natural pests or pathogens; they can successfully fertilize themselves (although bees will seek nectar and pollen from the plants); and they produce a multitude of fertile seeds. While there is not a perfect native substitute for hellebores, the gardener may consider planting a matrix of sedges (Carex species), coral bells (Heuchera americana), and ferns, many of which are host plants, to provide winter interest .

While not yet on the invasive lists in N.C, another beloved plant that is of concern is the crape myrtle (Lagerstroemai indica). Its spread is being tracked in Southern states by the Invasive Atlas of the United States and the plant’s spread is being watched with caution by conservationists in N.C. Each flower of the crape myrtle produces a prodigious number of seeds that are carried or blown far from the mother plant. I have had a crape myrtle in my yard for probably the past 40 years and it has only been recently that I have seen it sprouting up elsewhere in my yard and ¼ acre woods.


Crape myrtles are seen along roadways and in gardens in North Carolina but conservationists have raised concerns because it outcompetes many native plants (Image credit: NC Plant Toolbox, skdavidson)

Liriope (Liriope muscari and L. spicata), bugleweed (Ajuga reptens), Rose of Sharon (Hibiscus syriacus), and ox-eye daisy (Leucanthemum vulgare) are all common ornamental plants that have been added to the NC Invasive Plant list as “Low Threat” species. While they have the potential to harm our local ecology, they are not yet doing so.

Liriope (Liriope muscari), bugleweed (Ajuga reptens), Rose of Sharon (Hibiscus syriacus), and ox-eye daisy (Leucanthemum vulgare) are plants that many of us have in our garden. They are considered to be “Low Threat” to native plants of North Carolina. (Image credit: North Carolina Toobox, Manuel-CC-BY-2.0; Jim Robbins-CC-BY-NC-ND; Frank Mayfield, CC-BY-SA-2.0)

As gardeners, we can control the spread of potentially invasive plants in our own yards or we can choose to remove them and plant a native that supports our native ecology. A follow-up blog will suggest options to consider for replacing invasive plants with natives that power our ecosystems.

Notes

  1. Personal communications Peter Schubert, NC Invasive Plant Council, October, 2024 and Johnny Randall, former Director of Conservation Programs, NC Botanical Garden, October 2024.

Resources and Additional Information

NC Invasive Plants List adopted by NC-IPC, November 16, 2023NC Invasive Plant Council
https://nc-ipc.weebly.com/uploads/6/8/4/6/6846349/invasive_plant_list_-_ranked_-_2023-11-16.pdf

Grzędzicka, E., Assessment of Habitat Selection by Invasive Plants and Conditions with the Best Performance of Invasiveness Traits, February, 2023. https://www.mdpi.com/1424-2818/15/3/333

Invasive plant Atlas of the United States University of Georgia-Center for Invasive Species and Ecological Health, October 2018 https://www.invasiveplantatlas.org/index.cfm

Jones, M., Gaster, R. Invasive Species, NC Cooperative Extension, Lee County, July 30, 2019 https://lee.ces.ncsu.edu/2019/07/invasive-species/

Moony, H.A., Cleland, E.E., The Evolutionary Impact of Invasive Species, Proceedings of the National Academy of Sciences. May 2001, 98(10) 5446-5451 https://www.pnas.org/doi/full/10.1073/pnas.091093398

Moorman, C, Megalos, M, Douglas, K. Invasive Plants and Your Forests, NCSU Extension Publication. Revised September 11, 2024. https://content.ces.ncsu.edu/invasive-plants-and-your-forests

Article Short Link: https://wp.me/p2nIr1-5l3