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Weed Warriors

A unique approach to managing invasive plants in Montgomery County

What's the Problem? | How to Help | Know Your Invasive Plants | Links & More info

By whatever name you call them, non-native invasive plants, alien invasive plants, or exotic invasive plants - the key word is invasive.

These plants did not evolve in North American ecosystems and they have become too successful at reproducing.They are threats to native flora, fauna, soils, and water regimes throughout the United States and they have become a region-wide problem in recent years.

In Montgomery County Parks (a system of almost 34,000 acres) non-native invasives (NNIs) have begun to invade park edges, woodlands and shady forests, meadows and other open spaces, trail corridors, and waterways. NNIs compete with desirable plants for light, water, and nutrients. They have been introduced into an environment that is free of the vast and complex array of natural controls present in their native lands (including herbivores, insects, parasites, and pathogens) that would otherwise limit their reproduction and spread.

In response to this problem, the Montgomery Parks forest ecologist Carole Bergmann created Weed Warriors in 1999 to educate citizens about identification and management of NNIs.

The program now has two components - Certified Weed Warriors and Special Project Weed Warriors.

  • Certified Weed Warrior volunteers must complete a two-part online course and participate in a two-hour field training session with the forest ecologist.
  • Certified Weed Warriors are authorized to work anywhere on M-NCPPC parkland on their own schedules and at their own pace.
  • Certified Weed Warriors, who have logged to date more than 23,000 hours, make a valuable contribution to the control of non-native invasive vegetation in county parks. 

Our newest component—Special Project Weed Warriors—was added in 2007. It will enable citizens to learn about and work on invasive plants in their parks without making the commitment to become full-fledged Weed Warriors. Special workdays, under the supervision of a staff specialist, will take place throughout the year in small and large parks throughout Montgomery County.

For more information about becoming a Certified Weed Warriors and Special Project Weed Warriors follow the QuickLinks above.

What's the Problem?

Why non-native invasive plants are such a problem? Most natural communities support a great variety of native plants and animals. Such biodiversity is threatened when a few plant species take over and dominate the herbaceous, shrub, and canopy layers of a forest.

Overly successful NNIs can alter the complex webs of plant/animal associations that have evolved over thousands of years to such a degree plants and animals once familiar to all of us are eliminated. In edge and meadow areas, for example, non-native invasive plant (NNI) monocultures can reduce or destroy butterfly populations that can no longer find the native host plants on which their survival depends. Recent research has shown that pure monocultures of NNIs can alter soil chemistry or disrupt the growth of the mycorrhizal fungi on which healthy forests depend.

Coupled with plant predation by over-abundant herds of white-tailed deer and disturbance caused by such activities as development, erosion, and storms, NNIs are causing significant changes in the composition, structure, and ecosystem function in natural areas.
Non-native species threaten two-thirds of endangered species worldwide, and are considered by most experts to be the second most important threat to biodiversity after outright habitat destruction.

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How to Help: A Comprehensive Approach

Natural Resources Stewardship staff of the Montgomery County Department of Parks has been aware of the problems posed by non-native invasive plants (NNIs) for many years, and has developed several strategies to deal with them. We have been:

  • Developing long-range management plans that will enable us to take back parkland from the encroachment of NNIs.
  • Building staff and financial resources that will enable us to implement those plans.
  • Using staff and contract resources to conduct mechanical, chemical, and cultural control efforts in our best natural areas, as well as in highly visible and urbanized natural areas.
  • Training park managers and maintenance personnel to recognize and deal with the invasive plant problem as part of their regular work programs.
  • Using GIS technology to locate and map heavy NNI infestations and particularly troublesome plants (such as Japanese knotweed, kudzu, and tree-killing vines).
  • Developing prioritized lists of treatment sites concurrent with our mapping efforts.
  • Implementing reforestation and habitat restoration projects that include a site preparation phase where NNIs are removed.

The Certified Weed Warrior volunteer force and Weed Warrior Special Project workdays are crucial components of our comprehensive approach to reclaiming parkland.

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Know Your Invasive Plants

Some non-native plants that became invasive were introduced to the United States by accident (such as stilt grass, which was used as packing material for Chinese porcelain); but most were brought here because they were attractive landscape plants (Japanese knotweed, porcelain berry, Oriental bittersweet); they were familiar food or medicinal plants for settlers and immigrants (garlic mustard, beefsteak plant, mugwort); they provided quick growing pest free erosion control (kudzu), visual screening (running bamboos), windbreaks (autumn olive), or wildlife food (multiflora rose). Some invasives fit several of these categories.

A typical non-native invasive plant (NNI) has some or all of the following characteristics::

  • Grows fast and matures early.
  • Spreads quickly over large areas; thrives in many habitats.
  • Reproduces profusely by seed and/or vegetative structures.
  • Survives and produces seeds under adverse environmental conditions.
  • Has few known diseases or pests, and is difficult to remove or control.
List of the non-native invasive plants

These plants present the most serious threats to natural areas in Montgomery County, including parkland owned and managed by Montgomery Parks:

  • Autumn olive – Elaeagnus umbellata
  • Bush honeysuckles – Lonicera spp.
  • Canada thistle – Cirsium arvense
  • English ivy – Hedera helix
  • Garlic mustard – Alliaria petiolata
  • Japanese honeysuckle – Lonicera japonica
  • Japanese knotweed – Polygonum cuspidatum or Fallopia japonica
  • Japanese or Vietnamese stilt grass – Microstegium vimineum
  • Japanese barberry – Berberis thunbergii
  • Kudzu – Pueraria montana var. lobata
  • Lesser celandine – Ranunculus ficaria
  • Mile-a-minute or Devil’s tearthumb – Polygonum perfoliatum
  • Multiflora rose – Rosa multiflora
  • Oriental bittersweet – Celastrus orbiculatus
  • Porcelain berry – Ampelopsis brevipedunculata
  • Tree-of-heaven – Ailanthus altissima
  • Wineberry – Rubus phoenicolasius
  • Wintercreeper or climbing euonymus – Euonymus fortunei
  • Running bamboos – various species

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Links and More Information about Invasive and Native Plants

Contact Weed Warriors

Certified Weed Warriors Program or to Register for Training

  • Email -  mcp-weedwarriors@mncppc-mc.org
  • Phone - 301-942-4709  - Volunteer Coordinator/Certified
  • Mail -  Weed Warriors/Certified, M-NCPPC- Natural Resources Stewardship Section, 2000 Shorefield Rd. Wheaton, MD 20902

Special Project Weed Warriors Program

  • Email -  Lynette.Scaffidi@mncppc-mc.org
  • Phone -  301-949-0223 - Volunteer Coordinator/Special
  • Mail -  Weed Warriors/Special Projects, M-NCPPC- Natural Resources Stewardship Section, 2000 Shorefield Rd. Wheaton, MD 20902

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