Category: Invasive species

Managing Japanese Stiltgrass in NC

On By durhammastergardenersIn Gardening information, invasive plants, Invasive species, Japanese stiltgrass, mulching iwth paper, Uncategorized, weed

By Susan Sharp, NC State Extension Master GardenerSM  volunteer of Durham County

Many NC gardeners know both the joys and the frustrations of managing landscape beds and woodland areas in the summer.  If we’ve done the planting and maintenance (and if a drought hasn’t done too much damage), plants like black-eyed Susan (Rudbeckia hirta), hyssop (Agastache), sage (Salvia), and Stokes’ asters (Stokesia laevis) are providing color and pollinator interest. On the edges, however, invasive summer weeds will be creeping in.  Some will have grown slowly since spring seeding, while others have volatile spreading habits. Here we look at one of the most challenging: Japanese stiltgrass (Microstegium vimineum).

Close-up view of Japanese stiltgrass (Microstegium vimineum) amongst other green foliage.

Late summer appearance of Japanese stiltgrass before flowering – optimum time to control. (Image credit: Andrea Lane CC BY-NC 4.0)

Japanese Stiltgrass – History and Current Status

There are reasons why one of the most popular Horticulture Information Leaflets on the NC State Extension publications website is the one entitled Japanese Stiltgrass Identification and Management. Japanese stiltgrass (Microstegium vimineum), also known as Napalese browntop or bamboograss, is a summer annual in the grass family (Poaceae) that invades both disturbed and undisturbed areas in woodland and landscape settings. Researchers first reported it in the US (Tennessee) around 1919, likely introduced as packing material for fragile items from Asian countries. It now invades at least 26 US states and multiple countries globally, and the NC Invasive Plant Council classifies it as Rank 1 – Severe Threat in NC.

A dense patch of Japanese stiltgrass (Microstegium vimineum) growing in a shaded woodland area, surrounded by trees and underbrush.

Japanese stiltgrass overgrowth in woodland setting (Image credit: Susan Sharp)

Identification and Growth Habit

Japanese stiltgrass germinates in early spring. Key vegetative identification characteristics include rolled vernation and a short membranous ligule1. Additionally, the leaf blades are short and broader than most grasses, around 3 inches long and ½ inch across, often with a distinctive silvery stripe of reflective hairs along the midrib. As the season progresses, the stems grow increasingly wiry, turning color from light green to reddish purple through the summer.

Close-up of Japanese stiltgrass (_Microstegium vimineum_) stem with leaf blades with silver midrib, reddish stem and young flower spike against a light background.

Japanese stiltgrass flower in September (Image credit: Susan Sharp)

The flowers are racemes with branched spikes appearing from late August to September, but they often hide within the leaf sheaths. Seeds then easily spread by multiple means carried by awns2, including wind, water, people and animals, making pre-flowering control a top priority. Plants will wilt to a light tan shade after frost, but some persist throughout the winter, especially in wooded landscapes.

Four samples of grass awns displayed in varying orientations against a blue background, with a scale bar indicating 1 cm.

Japanese stiltgrass awns for seed dispersal (Image credit: Steve Hurst. Provided by ARS Systematic Botany and Mycology Laboratory)

The plant prefers partially shady, moist areas but adapts readily to other conditions and most soil types. It spreads during the growing season by stolons, and each plant can disperse over 1,000 seeds that remain viable for up to four years. Gardeners now find it in woodlands, shaded to partial-sun landscapes, and low-maintenance turf throughout the southeastern US, including Durham County. Unfortunately, it provides little to no food value to animals or insect herbivores, so natural controls on its spread are minimal. If left unchecked, stiltgrass spread can overtake native landscapes in three to five years.

Stiltgrass Control and Management

Controlling Japanese stiltgrass requires persistence and good timing. Mulch is generally ineffective, but denial of light early in the season using blockers like thick cardboard can help in landscape beds. We have experimented with this approach in a home landscape bed this season and have seen less infestation. Hand pulling can help in beds – perfect for meditative weeding, but hard on the gardener’s back. For larger infestations, mowing prior to seeding can reduce spread effectively, and flame weeding works in moist sites when fire hazard is low.

A landscaped area showing a mixture of dried grass and fallen leaves along a pathway, with dense green vegetation in the background.

Roadside Japanese stiltgrass mowed in late August (Image credit: Susan Sharp)

Importantly, timing is crucial: gardeners should complete all manual/mowing control measures by mid to late August, before the flowers become visible, to prevent seed production. If removed or mowed before August, the remains can be left as mulch in woodland or shaded areas. Bag all plant debris for disposal if it’s later in summer near the flowering season.

For chemical control, herbicides that target crabgrass will generally control Japanese stiltgrass as well, both pre-emergent and post-emergent. The NC State Horticulture Information Leaflet publication provides details on proper use and timing. The NC Agricultural Chemicals Manual offers additional product-specific guidance. As always, consulting the herbicide label for usage guidance is essential.

Notes

1– In grassy plants, the ligule is a thin outgrowth found on the inner surface of a leaf where the leaf blade meets the sheath that wraps around the stem. It acts as a protective barrier against pests and other stressors for younger leaf tissue. A membraneous ligule is a thin, translucent outgrowth at the junction of the leaf blade and sheath.

2–An awn is a small, usually bristled or barbed projection often used by grassy plants to boost seed dispersal.

Resources and Additional Information

NC State Extension Plant Toolbox: Microstegium vimineum (Japanese Stiltgrass) | North Carolina Extension Gardener Plant Toolbox

NC Invasive Plant Council on Japanese stiltgrass: Invasive Species

USDA PLANTS Database: USDA Plants Database Plant Profile General

NC State Extension Horticulture Information Leaflet: Japanese Stiltgrass Identification and Management | NC State Extension Publications

2026 North Carolina Agricultural Chemicals Manual: 2026 North Carolina Agricultural Chemicals Manual | NC State Extension Publications

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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

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