Some weeds escape mainly in gardens. Others may be weeds in gardens, or may not, but are able to grow in undisturbed, or relatively undisturbed wild habitats. A prime example is Algerian Ivy, which can cover the ground under redwood trees and climb them, sometimes causing them to die. Most plants not native to the redwood forest woudn't be able to grow there, but this one, from North Africa and the nearby Canary Islands, just takes over.
As the information about these pest plants gets out, gardeners who want to do the right thing begin to check whether a plant could be a wildland invasive before they plant it. This is a good thing, but going online to check can be tricky. If a search for the plant's name with the word "invasive" or "wildland weed" turns up a lot of hits, you still may not be clear whether the plant is invasive where you live.
In California, the best site to check for this information is the California Invasive Plant Council. Here is a link to their site:
www.cal-ipc.org California Invasive Plant Council. This nonprofit seeks to reduce the escape of non-native invasive plants into California’s wildlands. The entire book Invasive Plants of California’s Wildlands, with both text and photos, is available on their site.
If what you want to do is find out where wildland weeds are being combatted near you, with the thought you might volunteer to help, this next link is for you:
http://www.ice.ucdavis.edu/nrpi/ This is the Natural Resource Project Inventory. If you scroll down and click on "county" and then select your county and click on "submit" you will find out where the nearby action is. These projects welcome volunteers and can be fun and a good place to make new friends.