"The problem of plants invading natural areas in North America, especially species originating in Eurasia, dates back to the earliest days of European settlement. Purple loosestrife ( Lytbrum salicaria) arrived very early and was so well established along the eastern seaboard that early American botanists considered the plant to be native to North America (Thompson, 1991; Thompson et al.. 1987). As time passed more and more plants became invasive in the steadily shrinking area of natural landscape"--Introduction, page 2.