Why Sell It, If Itís Invasive?
"French Broom," Genista monspessulana, was sold as a beautiful, yellow-flowered landscape shrub before it became a noxious weed in California. In fact, according to Scott Oneto, Farm Advisor and UC Cooperative Extension Director for Tuolumne, El Dorado, Calaveras and Amador Counties, "85% of invasive woody plants in the US were introduced through ornamental trade. 53% of California's most invasive plants are from the ornamental industry."
Brooms-French, Spanish, and Scotch-are notorious for developing solid stands of growth that contribute to high wildfire risk. They also outgrow native vegetation and push their way into forested areas. At least one county in California is now considering an ordinance barring all ornamental broom plant sales from the county.
Currently, a pretty, little, yellow-flowered "sterile" broom known as "Sweet Broom" is available from nurseries and garden centers in Tuolumne County. Unfortunately, research conducted by UC Davis indicates that sweet broom is a member of the same genus, Genista, as French broom. Genetic evidence shows that many sweet broom and French broom plants share some of the same genes, indicating that sweet broom may have hybridized into wild, invasive populations.
So why do garden centers sell plants that are invasive? Most nurseries and big box stores have contracts with growers to provide plants for the shelves in retail stores. Growers may propagate plants as many as three years in advance, based on corporate office-approved product lists. Plants are replaced based upon consumer purchases. They will sell what you buy.
But in the meantime, it's up to each consumer to educate themselves. Remember, we all vote with our dollars. If you like an invasive plant's appearance, the California Invasive Plant Council (Cal-IPC) can help you find a replacement http://www.cal-ipc.org/landscaping/dpp/index.php
PlantRight is a voluntary partnership helping gardeners and the horticultural industry proactively address the problem of invasive plants in the trade. They host an information website, with a list of alternative plants that will provide the same color as the attractive, problem plant being offered http://www.plantright.org/map.
The California Invasive Plant Council (Cal-IPC) also offers a series of brochures called "Don't Plant a Pest." The brochures contain full-color photos and descriptions of both "thug" plants and their better-mannered replacements, http://www.cal-ipc.org/landscaping/dpp/brochures.php. There's also a wallet card to print, requesting your local store stop selling invasive plants.
Rebecca Miller-Cripps works in the UC Cooperative Extension office in Sonora; she is part of the Natural Resources Program of UCCE Central Sierra.