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2021 Top 25 Invasive Plants Expanding in Missouri

by Tina Casagrand

The Missouri Invasive Plant Task Force’s (MoIP) 2021 List of Expanding Invasive Plants draws data from MoIP’s statewide assessment that was compiled and reviewed by experienced field biologists in Missouri. In addition to identifying invasive plant abundance and assessing the severity of the plants’ impact on natural communities, biologists estimated how rapidly the species’ ranges will expand to form new occurrences throughout each of Missouri’s primary ecological regions over the next 10 years. The results follow here.

Because of their vigorous expansion, the species on the 2021 Top Invasive Plants Expanding in Missouri list are particularly important to identify and control. See below for links to resources on how to identify and control each plant.

Click to download the 2021 MoIP flier listing top 25 expanding invasive plants in Missouri.

This assessment will be updated every several years based on additional and ongoing in-the-field observations and reviews.

1. Callery pear

Pyrus calleryana

Representative photos of Callery pear:

2. Garlic mustard

Alliaria petiolata

Representative photos of garlic mustard:

3. Sericea lespedeza

Lespedeza cuneata

Representative photos of Sericea lespedeza:

4. Invasive privets

Ligustrum spp.

Representative photos of some invasive privets:

5. Reed canary grass

Phalaris arundinacea

Representative photos of reed canary grass:

6. Japanese stiltgrass

Microstegium vimineum

Representative photos of Japanese stiltgrass:

7. Invasive bush-honeysuckles

Lonicera spp.

Representative photos of invasive bush-honeysuckles:

8. Himalayan blackberry

Rubus armeniacus

Representative photos of Himalayan blackberry:

9. Autumn olive

Elaeagnus umbellata

Representative photos of autumn olive:

10. Japanese chaff flower

Achyranthes japonica

Representative photos of Japanese chaff flower:

11. Japanese honeysuckle

Lonicera japonica

Representative photos of Japanese honeysuckle:

12. Japanese hops

Humulus japonicus

Representative photos of Japanese hops:

13. Wintercreeper, climbing euonymus

Euonymus fortunei

Representative photos of wintercreeper:

14. Teasels

Dipsacus spp.

Representative photos of teasels:

15. Sweet autumn virginsbower

Clematis terniflora

Representative photos of Sweet autumn virginsbower:

16. Smooth brome

Bromus inermis

Representative photos of smooth brome:

17. Invasive wisterias

Wisteria floribunda and Wisteria sinensis

Representative photos of invasive wisterias:

18. Oriental bittersweet

Celastrus orbiculatus

Representative photos of Oriental bittersweet:

19. Spotted knapweed

Centaurea stoebe subsp. micranthos

Representative photos of spotted knapweed:

20. Japanese knotweed

Fallopia japonica

Representative photos of Japanese knotweed:

21. Burning bush

Euonymus alatus

Representative photos of burning bush:

22. Birdsfoot trefoil

Lotus corniculatus

Representative photos of birdsfoot trefoil:

23. Johnson grass

Sorghum halepense

Representative photos of Johnson grass:

24. Old-world bluestems

Bothriochloa spp.

Representative photos of old-world bluestems:

25. Common reed

Phragmites australis

Representative photos of common reed:

Why some common invasive plants did not make this particular list

Plants listed above may be expanding rapidly in some Missouri regions, but not in others.

Some readers may be surprised to see that some commonly known invasive plants, such as multiflora rose (Rosa multiflora) or ground ivy/creeping charlie (Glechoma hederacea) are not listed. That is because this “Top 25” list emphasizes expansion of range/abundance. According to the assessment, multiflora rose shows only a “Gradual Increase” in all regions with sufficient data. That resulted in multiflora rose scoring much lower on this list than many other species that show more vigorous expansion.

Do you have an observation to share?

You may report observations of invasive plants in your area any time using the Mapping MO Invasives app or EDDMapS Midwest. These real-time mapping systems for documenting invasive species distribution are fast, easy to use and important for early detection and rapid response to invasive species before they become unmanageable problems.

State verifiers review all data to ensure accuracy. The data are made freely available to scientists, researchers, land managers, land owners, educators, conservationists, ecologists, farmers, foresters, state and national parks.

Sudden Oak Death confirmed in Missouri

Consumers should properly dispose of infected rhododendrons and lilac plants

[link to release]

JEFFERSON CITY, Mo. – The Missouri Department of Agriculture, in coordination with USDA Animal and Plant Inspection Service, has detected ramorum blight on rhododendron plants shipped to some retail nurseries in Missouri. The disease is more commonly known as Sudden Oak Death when it infects oak trees. The rhododendrons were shipped to Wal-Mart and Rural King stores throughout Missouri, as well as the Springfield Home Depot, Stark Bros. Nursery Garden Center and Fort Leonard Wood PX.  

Consumers who purchased rhododendrons or lilac plants of the known infected varieties labeled Park Hill Plants from these stores between March and June of this year should dispose of the plants immediately. Consumers who are unsure of their plant’s variety should look for wilting or browning leaves, leaf spots and twig dieback. If consumers notice these symptoms, they should contact the Department’s Plant Pest Control team at (573) 751-5505 and begin the disposal process.    

Varieties that have been infected should be disposed of immediately to prevent further spread of the disease. Plants may be destroyed by burning, deep burial or by double-bagging the plant with its root ball in heavy duty trash bags for disposal into a sanitary landfill (where allowable). Consumers should not mulch, compost or dispose of the plant material in municipal yard waste. Garden tools used to dig up any affected plants should also be sanitized before they are used again.

Sudden Oak Death is a form of ramorum blight and is caused by a fungus-like pathogen known as Phytophthora ramorum. Since the 1990s, the plant disease has caused mortality in some types of oak trees in California and Oregon, but it has not established itself in the Midwest. The disease has a host list of more than 100 species of trees and shrubs, including rhododendrons.

Since early June, the Department has worked alongside USDA-APHIS to visit more than 113 retail locations to collect samples and place potential host plants under quarantine. USDA-APHIS has worked with Wal-Mart to organize a voluntary recall of the impacted plants, while other locations have isolated or destroyed affected plants. Any remaining plants confirmed with ramorum blight, and any host species comingled with the confirmed positive plants, will be destroyed.

Shipment of these rhododendrons has been successfully traced back to Park Hills Plants in Oklahoma and may have originated from nurseries in Washington State and Canada. Plant varieties identified during the investigation, which is still partially ongoing, were shipped to at least 18 states.      

Specific varieties of rhododendrons that have tested positive in destination states include:

  • Cat Cunningham Blush
  • Firestorm
  • Holden
  • Nova Zembla
  • Percy Wiseman
  • Roseum Elegans
  • Wojnars Purple.

Specific varieties of lilac that have tested positive in destination states include:

  • Common Purple
  • Persian Lime

To learn more about the Missouri Department of Agriculture or its programs, visit Agriculture.Mo.Gov.

Nominations Open for Invasive Plant Action Awards

Contact: Tina Casagrand, [email protected]


New awards program of the Missouri Invasive Plant Task Force to recognize exemplary work in invasive plant early detection and control.


JEFFERSON CITY (May 13, 2019)—As public awareness grows about the harmful effects of invasive plants, the Missouri Invasive Plant Task Force (MoIP) seeks to recognize individuals and groups performing outstanding work controlling invasive plant species on property in Missouri. Nominations for Invasive Plant Action awards are open now through July 1, 2019.

Nomination categories are for individual landowners, group collaborators, and researchers. Self-nomination is welcome; a recommendation by a natural resource professional is required to be eligible.

“There are many individuals and groups carrying out impressive invasive species control in every corner of the state,” says Carol Davit, chair of MoIP and executive director of the Missouri Prairie Foundation. “We want to recognize those doing exemplary work and present them with an aware at an event of the awardee’s choice to be honored in front of their peers.”

By definition, invasive plants are those not native to a region whose abundance and/or rapid spread  harm economic and environmental resources. The Action Awards seek to demonstrate how control the spread of  invasive plants on Missouri farms, forests, woodlands, prairies, , gardens, roadsides and along waterways is wise stewardship.

Members of MoIP will evaluate nominations. MoIP is a resource of the Grow Native! program and the Missouri Prairie Foundation.

For more information and to submit nominations, please visit http://moinvasives.org/moip-invasive-plant-action-awards/

# # #

The Missouri Invasive Plant Task Force (MoIP) is a resource of Grow Native!—a 19-year-old native plant marketing and education program serving the lower Midwest. Grow Native! is administratively housed by the nonprofit Missouri Prairie Foundation. For more information about MoIP, visit www.moinvasives.org or call 417-299-1794; for more on the Grow Native! program at grownative.org or for more on the Missouri Prairie Foundation visit moprairie.org.

Callery Pear Buy-back Event in St. Louis, MO — April 26, 2019

Do your part to reduce this highly invasive tree that threatens native wildlife and causes difficulties for private and public landowners, and receive a free native tree!

Jefferson City, MO (April 15, 2019)—Homeowners with an invasive tree in their yard can celebrate Arbor Day in a special way this year: by cutting it down.

To spread awareness about how the invasive Callery pear causes harm to economics and environment, MoIP will partner with Forest ReLeaf and Forrest Keeling Nursery for a Callery Pear “Buy-back” offering on April 26. People who supply photos of themselves with a cut-down, in-bloom Callery pear tree in their yards will receive a free native tree to replace it. The offer is limited to one native tree per photo proof of cut-down tree. Participants are invited to pick up their trees at Forest Releaf CommuniTree Gardens Nursery, located in Creve Coeur Park (2194 Creve Coeur Mill Rd SOUTH, from Hwy 141/Maryland Heights Expressway) from 9 a.m. to 4 p.m., while supplies last.     

“People once planted Callery pear trees for the beauty of their spring blossoms,” says Carol Davit, director of Missouri Prairie Foundation (MPF) and chair of the Missouri Invasive Plant Task Force (MoIP). “We now understand that when non-native Callery pear cultivars cross pollinate, the hybrid offspring become invasive, and are already causing harm to properties across the state.”

An inter-agency and inter-organizational resource of MPF’s Grow Native! program, MoIP’s principal goal is to make early detection and control of invasive plants a higher statewide priority. The MoIP website offers resources on how to control highly invasive species; and provides resources on native alternative trees to plant instead of Callery pear. “We don’t want to merely encourage landowners to keep invasive species from spreading; we want to teach people how to plant beneficial native species in place of invasive plants,” Davit says. “We are excited to partner with Forest ReLeaf, whose mission is to restore and sustain urban forests by planting trees and enriching communities.”

Native, noninvasive trees with white flowers blooming in April include serviceberry, wild plum, and dogwoods. This web page from the City of Columbia offers photos of native trees for comparison.

Callery pear (Pyrus calleryana) is native to China. Several cultivars of the tree are offered commercially, including ‘Aristocrat’, ‘Autumn Blaze’, ‘Bradford’ (which is the commonly planted “Bradford pear”), ‘Capital’, ‘Cleveland,’ ‘Chanticleer’, ‘Redspire’, and ‘Whitehouse’.

Callery pear limbs generally grow vertically, forming a pyramid or egg shape. In early April, very dense clusters of white flowers cover the tree before leaves form. In maturity, they reach heights of 30 to 40 feet. Property owners are encouraged to cut the trees during spring (when they are easy to identify) as a means to reducing populations from spreading in unwanted areas.  (For details on how to treat cut stumps with herbicide, visit MoIP’s management page.)

Photo courtesy Missouri Department of Conservation

These cultivars are generally themselves unable to produce fertile seeds when self-pollinated, or cross-pollinated with another tree of the same cultivar. However, if different cultivars of Callery pears are grown in proximity (for instance, neighboring homes or strip malls), thanks to insect pollination, they often produce fertile seeds—carried by birds—that can sprout and establish wherever they are dispersed. Each year, older trees in urban landscapes produce viable seeds that contribute to growing infestations. Breaking this cycle begins with choosing native alternatives for future plantings, and controlling existing invasive populations.

Participants in the “Buy-back” will have the opportunity to receive one of the following trees native to Missouri: Bur Oak, Northern Red Oak, Shumard Oak, Roughleaf Dogwood, Buttonbush, and hackberry. Four hundred trees are available, each in 3-gallon containers and between 4 and 5 feet tall.

Availability is on a first-come, first-served basis and may go fast; call ahead to 417-299-1794 or 314-956-2561 to confirm availability. To be eligible for a free tree, participants must either bring a photo of themselves next to their cut-down Callery pear or email the photo ahead of time to [email protected]

Frequently Asked Questions

Q: I cut down my callery pear in the last year–can I still get a native tree to replace it?

A: Rules still apply: bring or email a photo of the downed tree or cut stump, preferably with you in it. Tree availability is on a first-come, first-served basis .

Q: I don’t have a chainsaw. Where can I get help having my Callery pear professionally removed?

A: Please refer to the Grow Native! Resource Guide listings for Arborists and Land Care & Landscape Services to find professionals in your area who can assist with tree removal. These companies are on board with the Grow Native! mission to protect and restore biodiversity.

Q: Can I have a voucher to pick up my tree?

A: If you email [email protected] ahead of time, we will log your photos, but we unfortunately are not equipped to keep track of orders ahead of time. Trees will be available on a first-come, first-served basis from 9 a.m. – 4 p.m. on April 26, 2019. We have 500 native trees available, but they may go fast; you may call ahead day-of to 417-299-1794 or 314-956-2561 to confirm availability.

Q:  I have 2 “Cleveland” Pear trees, would they be eligible?

A: Yes, absolutely, Cleveland Select is one of 26 cultivars of the Callery pear!

Q: I cannot transport a tree to Forest ReLeaf.

A: We’re not asking that people bring in a Callery pear tree itself – a simple photo of yourself with one cut on your property will do!  

Q: I live too far from St. Louis to make the trade worth it. Are any other cities doing a Buy-back?

Our hope is that the St. Louis Callery pear Buy-back is a smashing success so we can make a case for taking the program to other parts of the state in 2020.

However, the event in St. Louis is our only pilot location for the Buy-back model. 

As a task force, we are working to get invasive plants in more conversations. Our task force chair maintains a good relationship with the Missouri Municipal League, and she will present on the Buy-back and other MoIP projects at their upcoming conference in September. We also have many members and stakeholders tasked with sharing our information in their parts of the state.

Q: I wish Missouri’s county governments and the state would cut down their invasive pear trees on road sides and government land. They are contributing more than a homeowner with 1 tree. We all need to be part of the fight to support native trees.

A: Great point! We are working to get invasive plants in more conversations and out of more land–private and public alike.

As we explore ways to have an impact statewide, a common answer from government entities is that they need to hear from more citizens themselves who are concerned with issues such as invasive plants on public land. Any advocacy you and people in your circle can do will go far.

And there is a lot of good news! For instance, in 2018 Missouri State Parks released a comprehensive invasive species management plan for each of their parks. The Army Corps of Engineers is doing a lot of invasive plant work, as is Mark Twain National Forest. That’s only naming a few.

In fact, we are compiling a web page highlighting the commitments and work different state agencies are doing to address invasive plants. We hope to have this online before our next quarterly meeting July 9, 2019. Stay tuned, and thanks for your interest!

Q: I want to remove Callery pear from my property. What is the best way to ensure it does not grow back?

A: Please see Effective Control of Callery Pear – instructions by Dr. Reid Smeda, MU Extension, for the Missouri Invasive Plant Task Force

# # #

The Missouri Invasive Plant Task Force (MoIP) is a resource of Grow Native!—a 19-year-old native plant marketing and education program serving the lower Midwest. Grow Native! is administratively housed by the nonprofit Missouri Prairie Foundation. For more information about MoIP, visit www.moinvasives.org, email info or call 417-299-1794; for more on the Grow Native! program at grownative.org or for more on the Missouri Prairie Foundation visit moprairie.org.

Forest ReLeaf of Missouri is an independent, nonprofit organization dedicated to inspiring volunteer efforts in planting and caring for our trees and forests, particularly those in our cities and towns. Since 1993, the organization has provided over 200,000 native trees for plantings throughout the region. www.moreleaf.org

Missouri Invasive Plant Task Force Unveils Statewide Invasive Plant Assessment Feb. 7, 2019

by Tina Casagrand

New online tool will help prioritize invasive plant management efforts throughout Missouri

Jefferson City, MO (February 8, 2019)—Yesterday, at the Missouri Natural Resources Conference in Osage Beach, MO, Dr. Quinn Long, a member of the Missouri Invasive Plant Task Force (MoIP), presented a statewide comprehensive invasive plant assessment during the workshop organized by MoIP, Invasive Species Collaboration: Informing the Masses, Building the Armies, Stemming the Flow, and Turning the Tide

“One of the biggest threats to Missouri’s—and the nation’s—native plants and animals, and to many facets of our economy, are invasive plants,” said Carol Davit, MoIP Chair and Executive Director of the Missouri Prairie Foundation. “Invasive plants and animals—including that small percentage of non-native plants that, intentionally or accidentally, have been introduced here and have spread rapidly—are second only to outright habitat destruction in the loss of native biodiversity, can have negative impacts on our cattle, timber, and outdoor recreation industries, cause headaches for private landowners, and nationally, cost billions of dollars in control efforts annually.” 

Dr. Quinn Long, botanist, Director of Shaw Nature Reserve, and MoIP member, worked since 2015 to lead the MoIP working group that assembled and analyzed invasive plant data for the assessment. “This assessment—complete with maps for each of the 142 species assessed—will provide a valuable tool for landowners, land managers, and natural resource planners to focus their efforts on invasive plant management,” said Long. The assessment maps depict abundance, impact, and rate of spread of these plants in the state. 

“MoIP is a dedicated group of representatives from land-holding agencies and natural resource management professionals from across the state,” said Davit. “We are pleased to present this important new tool, which is critical to assertive, prioritized invasive plant management efforts. Many individuals have worked very hard to make this assessment possible, including more than 25 reviewers; Phillip Hanberry, contractor with the Missouri Department of Conservation who generated the assessment maps; and Tina Casagrand, MoIP contractor who loaded and linked all maps to the MoIP website, where they are available for all to consult and use.”MoIP is housed and administered by Grow Native!, a native plant education and marketing program of the Missouri Prairie Foundation. The purpose of MoIP—working as a united, supportive front—is to review, discuss, and recommend actions related to managing known and potential non-­native invasive plant species that pose threats in Missouri and elsewhere in the lower Midwest. For more information about MoIP, definitions of invasive plants, and many other resources, visit www.moinvasives.org.

Missouri Invasive Plant Action Awards

by Tina Casagrand

Do you know an individual or group who performs outstanding work related to controlling invasive plant species on property in Missouri? If so, please nominate them for an Invasive Plant Action Award!

New in 2019, the nominations will be evaluated by members of the Missouri Invasive Plant Task Force (MoIP), a resource of the Grow Native! program and the Missouri Prairie Foundation.

How to Nominate:

Use our online form: Nominate via Google Form.

Download & email form: Download and complete a Microsoft Word nomination form and email to [email protected] You may also download the PDF.

a few people cutting invasive plants among a winter woodland landscape

Honeysuckle Hack 2017, photo submitted by Jay Doty, Magnificent Missouri

– – – – –

We will present one award in each category:

    1. Single Landowner – (e.g., a private landowner, a corporation, school, or other single entity that has demonstrated progress in reducing invasive plants over at least two years)
    2. Group Collaborators – a collaborative network (e.g., homeowners, city park, school, business) working together to fight the spread of invasive plants in a particular geographic area that includes multiple landowners.
    3. Researchers – An individual or group who has published research on invasive plant management.

To submit a nomination for the Missouri Invasive Plant Action Award, please submit this form by July 1, 2019

*If for some reason you cannot use Google forms, please download and complete a Microsoft Word nomination form and email to [email protected] You may also download the PDF.

Our intention for the 2019 awards is for a MoIP representative to present the awards at  events of the winners’ choice (for example, a municipal or industry conference), so they can be honored in front of their peers and thus lead by example.

– – – – –

Requirements for Single Landowners and Group Collaborators:

    • Self-nomination is allowed.
    • Nomination must be submitted by or include a recommendation letter from a natural resources professional (this may include Missouri Department of Conservation Private Land Conservationist, staff of other agencies who work with private landowners, private contractors, or professional staff working for the single landowner)
    • 1-page narrative about the “before and after” work of the collaboration or group
    • For Group Collaborators, application describes work on multiple properties as part of a group
    • Evidence of a long-term invasive plant management plan
  • We ask that the nominee(s) has/have been active in their leadership for two or more years.

Requirements for Researchers:

  • 1-page description of the nominee’s research, including background, methods, results and discussion, and how this research applies to invasive plant control and management?
  • Link to published papers, if available.

– – – – –

To Nominate:

Submit nominations by July 1, 2019.

Use our online form: Nominate via Google Form.

Download & email form: Download and complete a Microsoft Word nomination form and email to [email protected] You may also download the PDF.

Please direct questions to Tina Casagrand at [email protected]