The European annual plants Salsola iberica. Sisymbrium altissimum, Descurainia sophia, and Bromus tectorum invaded southern Idaho about 1900 and spread very rapidly into native plant communities damaged or eliminated by binning, abusive grazing, and agricultural clearing. Historic photographs reveal that the sites of initial invasion were waterway margins, railroad rights-of-way, road shoulders, city streets, agricultural areas, and construction sites. By 1915, these plants were widespread and abundant. Burning and grazing fostered their spread and dominance on millions of acres in southern Idaho.
Yensen, Dana L.
"The 1900 invasion of alien plants into southern Idaho,"
Great Basin Naturalist: Vol. 41
, Article 2.
Available at: http://scholarsarchive.byu.edu/gbn/vol41/iss2/2