What are invasive plants? (from PlantRight.org)

Across California, invasive plants damage wildlands, displace native plants and wildlife, increase wildfire and flood danger, consume valuable water, degrade recreational opportunities, and destroy productive range and timber lands.

Most of the plants used in gardens and landscaping do not invade or harm wildland areas. But a few vigorous species can - and do - escape from cultivation into open landscapes where they cause a variety of ecological problems. They crowd out native plants, insects and animals, clog waterways, and can lead to increased flooding, fire and crop losses.

When an aggressive plant is introduced to a new environment, the predators that would normally limit their growth in their home environment may not be present. This allows them to proliferate, spread, and take over natural habitats. Each invasive plant has its own strategy for growth and dispersal. Some have seeds that are spread by the wind, like pampas grass, whose seeds can be blown up to two miles away. Others have seeds that are carried by water or eaten by birds and animals that deposit them far from the parent plant. There are also species that reproduce vegetatively, like Arundo that sprouts new shoots from fallen stalks and plant fragments.

Invasive species are a leading threat to biodiversity, second only to habitat destruction. And the economic cost is as significant as the ecological cost: in California, more than $85 million goes to fighting invasive plant and animals every year1. A much-cited paper by Cornell researchers including David Pimentel estimates the economic impacts of invasive species to be $120 billion a year. If divided equally through the 50 states, the cost to each state averages $2.4 billion annually — and given California's size and resources, the actual impact is likely greater in our state.

A plant's invasiveness is largely a matter of location and climate. California's regions are organized on this site according to Sunset^® Western Gardening Zones. Select your region using the map on the left for a list of invasive plants in the selected region or click here for the list of the 19 plants that have been identified as invasive by the steering committee for the PlantRight campaign. The list indicates what region the invasive plants occur and their suggested alternatives.

Most of the plants used in gardens and landscaping do not invade or harm wildland areas. But a few vigorous species can - and do - escape from cultivation into open landscapes and cause a variety of ecological problems. They crowd out native plants, insects and animals, and can lead to increased flooding, fire and crop losses.

Visit the PlantRight Library Scientific research has provided the foundation for PlantRight recommendations. To share the wealth of knowledge, this page lists important articles from peer-reviewed journals. We encourage you to learn more about invasive plants by reading these papers and discussing them with your community.

Weed Management Areas (WMAs) are local organizations that bring together landowners and managers (private, city, county, State, and Federal) in a county or multi-county geographical area to coordinate efforts and expertise against common invasive and noxious weed species. The WMA functions under the authority of a mutually developed memorandum of understanding (MOU). The WMA develops a Strategic Plan which helps prioritize eradication, control, and containment projects, as well as other WMA activities. The Strategic plan also identifies what specifically each WMA partners contributes toward the overall cooperative nature of the WMA.

A WMA may be voluntarily governed by a chairperson or a steering committee. To date, groups in California have been primarily initiated by either the leadership of the County Agricultural Commissioner’s Office or Resource Conservation District. WMAs are unique because they attempt to address agricultural (regulatory) weeds and “wildland” weeds under one local umbrella of organization. It is hoped that participation will extend from all agencies and private organizations. The primary goal of WMAs is to institute joint eradication, control, and containment projects. Other activities include: promoting prevention practices, coordinating collaborative mapping, sponsoring education outreach, writing grants to secure resources beyond WMA funds, and improving regional collaboration.

How the Program Works
The California Department of Food and Agriculture (CDFA) administers contracts with local WMAs, An advisory panel reviews proposals from WMAs and makes awards according to guidelines. To receive funding, each WMA must have an MOU between all stakeholder groups in their area, and a strategic plan defining their goals and objectives. For more information, see the CDFA's Weed Management Area page.

Partnership is the foundation of work conducted by WMAs. Many diverse entities participate in WMAs, including:

• Private partners-utilities, land trusts, forest industry, pest control operators, ranchers, farmers, nurseries;
• County agencies-Agricultural Commissioners, Resource Conservation Districts, Parks, Public Works, Farm Bureau, Master Gardeners, school districts, municipalities;
• State agencies-CalTrans, Fish and Game, Food and Agriculture, Forestry, Parks and Recreation, University of California Cooperative Extension, Regional Water Quality Control Boards, Department of Water Resources;
• Federal agencies-US Forest Service, National Resource Conservation Service, National Park Service, Bureau of Land Management, US Fish and Wildlife Service, US Army Corps of Engineers;
• Nonprofit organizations-Audubon Society, Sierra Club, California Native Plant Society, Cal-IPC.

Accomplishments
California's WMAs have proven to be an efficient and effective instrument for controlling the spread and impact of invasive weeds throughout the state. The program has grown to include (from CDFA program report) 48 WMAs covering all 58 counties. Because they are local efforts that involve all land management stakeholders, their work has strong local support.

The program's accomplishments to date include (from CDFA program report):

• Permanent eradication of 2,015 populations of high priority weed infestations;
• Effective treatment of more than 128,421 acres of high priority weed infestations;
• Distribution of $5.6 million to 48 WMAs covering 58 counties (AB1168 & SB1740);
• Leveraging a 3-to-1 match from outside grant funding and in-kind donations and services;
• Development of new local partnerships between public agencies, private landowners, agriculturalists and conservationists, with outreach programs reaching 88,803 people; and
• Attendance by 6,781 people at regular weed management meetings throughout the state.

Find local Weed Management Area contacts

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Aquatic nuisance species (ANS) are nonindigenous species that threaten the diversity or abundance of native species, the ecological stability of infested waters, and/or any commercial, agricultural, aquacultural , or recreational activities dependent on such waters. ANS include  nonindigenous species that may occur within inland, estuarine, or marine waters and that presently or potentially threaten ecological processes or natural resources. The term ANS is often used interchangeably with aquatic invasive species, the preferred term of Federal and State managers. An aquatic invasive species is defined as a species not native to the ecosystem under consideration whereby introduction of this species does or is likely to cause economic or environmental harm or threaten human health.
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By: Mandy Tu, Callie Hurd & John M. Randall
Invasive non-native plants are a serious threat to native species, communities, and ecosystems in many areas around the world. They can compete with and displace native plants, animals, and other organisms that depend on them, alter ecosystem functions and cycles significantly, hybridize with native species, and promote other invaders. The good news is that many plant invasions can be reversed, halted or slowed, and in certain situations, even badly infested areas can be restored to healthy systems dominated by native species. In most instances this requires taking action to control and manage those invasive plants. This handbook provides you with detailed information about the tools and techniques available for controlling invasive plants, or weeds, in natural areas. Whenever possible, language familiar to natural area managers is used, and unfamiliar terms and jargon borrowed from other fields are defined.
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By: R.J. Pawlitz and K.D.David
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By: Daniel Simberloff, Ingrid M Parker, and Phyllis N Windle
Introduced species represent an accelerated global change, and current efforts to manage them, though effective in particular situations, are not controlling the general problem. In the US, this failure is the result of insufficient policy, inadequate research and management funding, and gaps in scientific knowledge.
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By: U.S. Fish & Wildlife Service
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By: U.S. Fish & Wildlife Service
The negative consequences of invasive species are far-reaching, costing the United States billions of dollars in damages every year. Compounding the problem is that these harmful invaders spread at astonishing rates. Such infestations of invasive plants and animals can negatively affect property values, agricultural productivity, public utility operations, native fisheries, tourism, outdoor recreation, and the overall health of an ecosystem. Read More »


By: M. Brooks and M. Lusk
Fire management can help maintain natural habitats, increase forage for wildlife, reduce fuel loads that might otherwise lead to catastrophic wildfire, and maintain natural succession. Today, there is an emerging challenge that fire managers need to be aware of: invasive plants. Fire management activities can create ideal opportunities for invasions by nonnative plants, potentially undermining the benefits of fire management actions. This manual provides practical guidelines that fire managers should consider with respect to invasive plants. Read More »


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Back in 2006 the California Invasive Plant Council (Cal-IPC) published The California Invasive Plant Inventory to catalog and categorize the invasive non-native plants that threaten California's Wildlands.

According to the Cal-IPC this document "represents the best available knowledge of invasive plant experts in the state".

Download the Inventory from the Cal-IPC website (1.8 MB PDF) or use the links below to view Cal-IPC's descriptions of the individual sections. A Cal-IPC Publication 2006-02, California Invasive Plant Council: Berkeley, CA.

• The Inventory
• Definitions
• Criteria for Listing
• Inventory Categories
• Uses and Limitations
• Providing Input for Future Revisions
• Summary of the Criteria
• References
• Inventory Review Committee
• Acknowledgments
• Financial Support
• Related Links

Get the 2007 Updates (PDF) here.

Access the inventory database hosted by the best authority on invasives in the state, the California Invasive Plant Council. Select a region on the map to show only plants found in that region.

The California Invasive Plant Inventory Database is produced, published and updated by California Invasive Plant Inventory. Cal-IPC Publication 2006-02. California Invasive Plant Council: Berkeley, CA.

The California Native Plant Society (CNPS) is dedicated to Preserving and Protecting California Native Plants and Their Habitats.

The native plants of California are unlike any other in the world. From the richly colored expanse of spring wildflowers in the desert to groves of Monterey cypress on the coast, California's wild gardens are immensely diverse and awe-inspiring in their beauty. They define the landscape and offer Californians a sense of place, pride and stability, and they provide habitat for endemic wildlife species that exist no place else on earth.

Since 1965, CNPS has worked hard to protect California's native plant heritage and preserve it for future generations. CNPS actively promotes the use of science in land use and management decisions through our Online Rare Plant Inventory and essential reference book: Manual of California Vegetation, 2nd Edition, both of which are the most advanced resources available for identifying and managing critical habitat in California. We work closely with decision-makers, scientists, and local planners to advocate for well-informed and environmental friendly policies, regulations, and land management practices.

Originally formed in 1965 in the east bay region, the California Native Plant Society (CNPS) is a statewide non-profit organization of amateurs and professionals with a common interest in California's native plants. Our nearly 10,000 members work to promote native plant appreciation, research, education, and conservation through our five statewide programs and 33 regional chapters in California. Through membership in CNPS, Californians of all walks of life are able to support and engage in opportunities to experience and learn about native plants and their habitats, gardening and landscaping with native plants, restoration of habitat areas, and conservation issues throughout the state.

Local Chapters
Numerous CNPS activities are organized at the chapter level where the varied interests of local members directly influence programs and projects. Common activities include plant sales, field trips, demonstration gardens, and speaker programs. Many chapters also engage in weed eradication, conservation projects, rare plant monitoring, plant community sampling, and educational outreach. Each activity brings members together with shared goals under the CNPS mission.

The CNPS Inventory of Rare and Endangered Plants (The Inventory) has served as a resource for information about California's rare plants for over 35 years. The Inventory is a credible and widely-recognized resource that plays a significant role in promoting scientific research, conservation planning, and the effective enforcement of environmental laws that deal with plant conservation. The Inventory also helps to build a foundation for stewardship and conservation by celebrating the unique richness of, and facilitating education about California's rare plants. CNPS published the first edition of its Inventory of Rare and Endangered Plants in 1974. The Inventory was published in print form a total of 6 times (the last print version, the 6th Edition was published in 2001).

Check out the The 8th Edition of the Inventory, released online December of 2010.

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Do you want to connect your audiences to conservation messages but don’t know where to start? Conservation plans, based on extensive biological research, will help prioritize your efforts. 

This resource sheet will help you:

• Link your education programs to priorities in bird conservation plans; 
• Find relevant bird conservation plans in your area of focus; 
• Extract key information to guide education program development; and 
• Involve scientists in the development of your education programs.

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Discusses pathogens and parasites, genetic alterations, and genetically modified organisms.
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A must-read for any responsible aquaculturist contemplating non-native species production.
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Strategies and cost estimates for various forms of frightening programs and exclusion ro barrier methods of control.
A list of all Southern Regional Aquaculture Center factsheets (more than 150) are available at https://srac.tamu.edu/index.cfm/event/viewAllSheets/ Read More »

BMPs oriented more specifically toward water quality, farming & agriculture, energy efficiency and wildlife habitat management are also available.

The following news articles are provided by the Google News service and do not reflect the views or imply an endorsement by the California Conservation Center and its affiliates. We cannot guarantee the relevance of the content of this page or any links that may be followed from the articles herein.

Registration Deadline For Conservation Authorities Invasive Plant And ... NorthumberlandView.ca The event will demonstrate how some garden plants can be invasive, and how the Grow Me Instead program of the Ontario Invasive Plant Council promotes non-invasive alternatives. “But this workshop goes further,” according to Mr. Towle, “by setting a ...

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USC Dornsife Scientific Diving: An Analysis of Sargassum Horneri Ecosystem ... Scientific American (blog) S. horneri and S. filicinum, once thought to be two different strains but recently proven to be both classified as the horneri species by Uwai et al. in 2009, is an invasive seaweed found along the coasts of Southern California, the Channel Islands ...

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New units to help keep invasive aquatic species out of province Winnipeg Free Press These steps can prevent the introduction or reduce the further spread of aquatic invasive species. For more information on aquatic invasive species in Manitoba or to report a sighting, visit www.manitoba.ca/StopAIS or phone 1-877-867-2470 (toll-free).

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Showy Primrose Helps to Beautify our Highways and Byways (Harvey Cotten) The Birmingham News - al.com Some people call it invasive but by the true definition of the term it is not invasive since it is native to areas of the United States but it is definitely aggressive and some might even call it weedy. I often look at a gardening website ... The first ...

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Group strives to manage invasive species The Guardian Charlottetown One local group that is keeping tally on these plant and animal invaders and their impact on Prince Edward Island is the P.E.I. Invasive Species Council, the mandate of which is to raise awareness about invasive species and focus on building a ...

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Green guide North Shore News The exhibit consists of 19 interpretative panels, each representing a species of tree, that explore how trees in the garden are adapting (or not) to the climatic changes in southwestern B.C. Info: sue. watts@ubc.ca. Eat Your (Micro) Greens: A program ... and more »

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College student snares record long Burmese python near Miami Sarnia Observer He then reported the find through Florida's “IveGot1” program, which connects callers to wildlife researchers. The Burmese python is an invasive species in Florida. Native to the region from India to lower China, the species has been documented to grow ... Largest Burmese Python caught in Miami-Dade CountyCatholic Online Man captures and kills 18-foot long pythonMyFox Atlanta all 89 news articles »

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Gardeners to gather this weekend The Sudbury Star For more about the Sudbury Gardening Festival, go to www. sudburygardening festival.ca. ... The festival will kick off Friday at 7 p.m. with a talk by Martha Scott on the topic Control and Management of Invasive Non-Native Plants for Home Gardeners ...

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Seven Days

State Entomologist Alan Graham Tries to Prevent Mosquito-Borne Diseases Seven Days Graham studies hundreds, if not thousands, of insect species, both native and invasive. However, he pays particularly close attention to those that ... California and Florida also have enormous programs. In Vermont, the program is minuscule, and the ... and more »

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UC Berkeley Tree Cutting Proposal Slammed By Environmentalists Huffington Post ... Oakland Fire Danger , UC Berkeley Trees , San Francisco News. A proposal by UC Berkeley and a collection of local government agencies to cut down over 85,000 trees in Berkeley and Oakland to reduce fire danger has drawn the ire of Northern ...