Invasive Species
One of the top three threats to native ecosystems
The California Invasive Plant Council (Cal IPC) defines invasive plants as those that are “not native to an environment, and once introduced, they establish, quickly reproduce and spread, and cause harm to the environment, economy, or human health.”
A plant isn’t invasive only by being non-native. A plant is invasive when it is both non-native and threatens native habitat with the specific aggressive characteristics.
Plants like black mustard (Brassica nigra), pampas grass (Cortaderia selloana), and French broom (Genista monspessulana) are common examples of invasive plants that can spread quickly into farmland and undeveloped natural areas.
You can help by recording the locations of invasive plants in either CalFlora or iNaturalist. This creates data that helps experts recognize new invaders, create regional priorities for control, and provides data for invasion biologists who study the movements and ecology of non-native weeds.
Unchecked growth
Invasive plants are free from the controls on growth they experience in their place of origin. Unchecked by animals or climate, invasive plants become a nightmare for land stewards and a financial drain for farmers, government, and consumers. In natural landscapes, animals lose out on habitat and resources. Gardeners spend hours and money controlling weeds. Wildfire risk increases as invasive weeds take over and crowd out native vegetation. The costs to manage the problem are staggering. California spends over $80 million dollars a year dealing with invasive plant species.
What you can do
- Before buying a plant from a nursery or big-box store, check to see if it’s an invasive species.
- Stay on designated roads and trails. Clean your boots, gear, pets, and vehicle to keep from bringing invasive species to new areas.
- Moving firewood can spread invasive species. Buy your firewood where you burn it.
- If you can no longer care for a pet, find it a new home instead of releasing it into the wild.
CNPS Policy on Invasive Plants
Get Involved and Learn More
CNPS Orange County Chapter: Emergent Invasive Plant Program
This program prioritizes potentially invasive plants that pose significant environmental threats to wildlands. The Orange County Chapter looks for and monitors detections of new, small populations, before they become widespread. They then work with local land managers and agencies to create effective management.
California Invasive Plant Council (Cal-IPC)
The mission of Cal-IPC is to protect California’s environment and economy from invasive plants. They do this by assessing invasive plants and providing information on management; supporting land managers and volunteers, coordinating landscape-level strategic mapping planning, and implementation; advocating for funding and policy initiatives; and reducing invasive plants introduced through gardening.
California Department of Fish and Wildlife: Native Plants and Invasive Species
California has over 1,000 non-native plants that now reproduce naturally in the state. Learn how you can help stop invasive plants by not buying ones commonly sold by plant nurseries and get information on how invasive plants have already changed California’s landscape.
Science-based Monitoring and Management of Invasive Plants
This session from the CNPS 2026 Conference focused on how invasive plants are affecting native plants and plant communities.
CNPS Policy on Wildland Invasive Plants, Integrated Weed Management
This policy explains that CNPS supports the use of Integrated Weed Management (IWM) to control invasive plant (weed) infestations and protect vulnerable wildlands and corridors from invasive plants
“While the invasion of invasive plants can seem overwhelming, well-designed projects and community action can go a long way toward protecting our native biodiversity.“
– Steve Schoenig, CNPS Board of Directors
