[Wikipedia] Native to the steppe and desert zones of the Caucasus, Central A: Invasive and noxious weed In certain locations, the plant is classified as a non-native and invasive weed. It is listed as a noxious weed by the agriculture departments of several states in the western United States: Arizona, California, Colorado, Idaho, Montana, Nevada, New Mexico, Oregon, Utah, Washington, and Wyoming. In Montana, it has been the target of an extensive, and largely successful, eradication attempt. (link added by Mary Ann Machi)