Back in April, Ilsa Setziol of Rambling LA had a really great series on the Los Angeles Times Home blog about nonnative invasive plants. If you're at all interested in gardening or the preservation of natural habitats, I encourage you to check it out. Ilsa runs down a list of the plants commonly found in garden centers that can do serious damage when they get out of the garden and into the wild.
One of the posts discusses fountain grasses, which have spread through Southern California open space and parkland and pushed out the native chaparral. I'm sad to admit that, after reading the article, I realized that I have some in my front yard. I planted two clumps of purple fountain grass several years ago. I think it's probably sterile, because I haven't noticed it spreading, but I am considering removing it after reading Ilsa's article.
I also realized that my front yard had been invaded by another variety of invasive grass: Mexican feathergrass. It showed up among my native plants last year, and grew into two or three smallish clumps. Informed by the invasive plant series, I removed the grass last month and threw it in the garbage, rather than the green bin, so hopefully it won't spread. Since then, I've noticed the feathergrass in other peoples' yards and in public landscaping. Hopefully those gardeners will hear about the danger of nonnative fountain grasses and take their invasive species out as well.
Last Christmas, I was up in the Russian River Valley in Northern California, and I noticed large clumps of pampas grass growing among the redwoods. It looked really weird on the otherwise woody hillsides, and I know this aggressively-spreading grass is a pretty serious problem up and down the California coast. It was kind of a bummer to see the obviously out-of-place pampas grass among the gorgeous redwoods. If we're lucky, the park service will beat it back before it chokes out the native vegetation.
Hopefully, the more people are aware of problems with invasive nonnatives, the more they will turn to the just-as-attractive native plants. The California Native Plant Society has a good list of nurseries here. Many of the plants in my front yard, including native grasses, are from Matilija Nursery in Moorpark.