In the Intermountain West, the plant's distribution corresponds to river systems and riparian zones which are the primary areas of invasion in most states. However, perennial pepperweed is not limited to riparian zones and is found in waste areas, ditches, roadsides, pastures and residential areas as well. The plant can tolerate high salt concentration in soils, but is not limited to these sites. Perennial pepperweed spreads in many ways. The plant commonly travels in rivers and irrigation systems as seeds and rhizomes from eroded banks.
Flood irrigation carries plant propagules into hay meadows, pastures and other irrigated lands.
Perennial pepperweed is also carried in contaminated topsoil used as fill in construction and landscaping sites. Seeds are transported when they attach themselves to machinery and vehicle tires. Perennial pepperweed threat Perennial pepperweed is a very competitive species that crowds out desirable vegetation and results in dense monocultures and a decrease in biodiversity. When established along rivers and streams, the plant interferes with the regeneration of willows and cottonwoods, reducing cover and food availability for birds. The accumulation of semi-woody stems negatively impacts nesting habitat for wildlife.