Some of the West's worst invasive plants were actually introduced intentionally. Many were planted as ornamentals for landscaping and herbal gardens; purple loosestrife, salt cedar, knotweed, and policeman's helmet are just a few examples of these intentional introductions. Other invasive species, including pests, have also shown up unintentionally as contaminates in wildflower mixes, animal feed, and potting soil. These species include: oxeye daisy, houndstongue, yellow toadflax and Japanese beetle. Unfortunately, many invasives either escaped containment or invaded unnoticed, and are now widespread in Idaho's roadsides, agricultural lands, waterways, and natural areas.
In the past, many of these invasive plants were introduced to serve a function - Purple Loosestrife is a medicinal herb, Dyers Woad had been used to manufacture blue dye, and Yellow Flag Iris & Water Hyacinth were desired for their beautiful and showy displays. Early immigrants didn't know that the introduction of these species would end up negatively impacting their way of life. They were crossing oceans to a land unknown and wanted to take with them the plants they were used to seeing each day - much like travelers pack supplies for long outings.
We know that humans are the main dispersers of plants, but we also know that plant introductions have set the very foundation of modern agriculture and horticulture. Not all introductions are bad. In fact, it is only a small proportion of introduced plant species that become invasive and cause significant problems that threaten wildlife habitat, native ecosystems, agriculture and our economy.
For more information about invasive species found in Idaho visit here!