Source: California Invasive Plant Council

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General Invasive Plant Information

Ivy in Trees
Ivy climbs up and over trees in the San Fransisco Bay Area

This page is for people seeking introductory information on invasive plants, and for people who are still working on their "elevator message." If you are just learning about invasive plants, and you want to find out once and for all what these plants are, what they do, and more, this is the page for you. And what is an elevator message, you may be asking? Here's the situation: You're a long-time weed worker, but today you're at the bank, riding the elevator up to the 45th floor. The person riding next to you turns to you and says, "So what do YOU do?" It's not always easy to know what to say, especially to someone who may never have thought about invasive plants before. This section provides short, practical answers to help you talk about what we do.

My question is...

  1. What is an invasive plant?
  2. What is the problem with invasive plants?
  3. How can I identify an invasive plant?
  4. What should I do when I find an invasive plant?
  5. How can I find someone to speak to my organization about invasive plants?
  6. How do I know what plants are OK to put in my garden or on my property?

What is an invasive plant?

Non-native plants are plants that have been brought to a place (like California, for example) either intentionally or unintentionally by people. But most non-native plants aren't invasive!* Invasive plants are the few non-native plants that are able to grow unassisted in California's natural areas, and have a negative impact on these places. The reason I work with invasive plants is that I want to protect California's unique natural areas, and I have a real concern for the survival of the native plants, animals, birds, and insects that invasive plants can displace.

*This is an important distinction. "Non-native" and "invasive" aren't interchangeable words!

What is the problem with invasive plants?

Clogged arundo breaks through a bridge

A common feature of all invasive plants is that they have a negative impact in the area where they grow. Here are some examples of the damage these plants cause:

  • Some invasive plants grow quickly, and form dense stands or mats. This happens on land, and also in the water, in the case of invasive aquatic plants. These types of plants are usually very strong growers and can crowd out other plants, animals, birds, fungus and insects that can't compete.
  • Some very invasive plants can completely change the area that they invade. Just ask Florida, where invasion of the "Punk Tree" changes marshes in the Everglades into swamp forests.
  • Other invasive plants cause damage in more subtle ways. They alter the composition of the soil, making it difficult for other plants, insects, and microbes to live there. They can increase the fire danger and change the natural fire cycle of some areas. Some invasive plants increase or decrease the erosion of soil.
  • Even more microscopic: some invasive plants can breed (or "hybridize") with native plants. Over time, this can completely wipe out the native plant.
  • If you're not yet convinced about the damage caused by invasive plants, we have more reasons just for YOU! Click here to see why specific people should be concerned about invasive plants.
  • Download a copy of Cal-IPC's "Biological Pollution" brochure, or order a set on-line at the Cal-IPC shop. This brochure covers what you should know about invasive plants in California.

How can I identify an invasive plant?

OK! You've convinced me! Now how do I know when I'm looking at an invasive plant?
It will only take a little time and experience for you to be a regular invasive plant identifier. Some are hard to miss, once you know what you're looking for. Here's a list of resources that will help you get to know the plants in your area.

What should I do when I find an invasive plant?

  • Tell Someone! Contact your county Agricultural Commissioners and Sealers Department. All county Ag departments have employees who specialize in invasive plants. Click here to find your Ag Department contact info.
  • Get Involved! Now that you've seen it, you know that it's a problem where you live. No matter where you are, there are local groups working to get rid of these plants. Find out how you can help! Coming soon: a list of regional groups engaged in the invasive plant issue.

How do I know what plants are OK to put in my garden or on my property?

This is a good question, because some invasive plants are sold in nurseries and grown in gardens.

  • To find out about invasive garden plants, and to find a list of planting alternatives, check out our Don't Plant a Pest! Brochures.
  • Visit the Cal-HIP webpage at Find lists of invasive plants in your area, and non-invasive alternatives to these plants. Cal-HIP is a collaborative effort dedicated to finding alternatives to invasive garden plants, and to working together with the nursery and garden industry to protect California's natural areas.
  • Visit the California Native Plant Link Exchange. Search by plant name, bioregion, county, nursery availability, plant community, and more! If a plant name appears shaded pink AND has a red exclamation point next to it, this plant is invasive in California.
  • Contact your local chapter of the California Native Plant Society. This is a state-wide organization with all the know-how about gardening with native, non-invasive plants. CNPS' members and employees can provide you with plenty of options for safe garden plants. Travel to the CNPS webpage and click on "local chapters," in the top navigation bar.