The distribution of transformer plant species, defined as harmful species that substantially modify ecosystems, was generally localized in Tallgrass Prairie National Preserve, Kansas (TPNP). Surveys for transformer species were conducted along line transects (n=301) in September 2006. Nine of 16 transformer plant species (81.8%) revealed significant positive associations with riparian forests or with cultivated land. These preferences are likely confounded in that the soils most suitable for cultivation lie in the vicinity of riparian forests. In contrast, a single transformer species revealed a significant positive association with roads. Agricultural areas and riparian forests appear to be more highly invaded than annually burned and grazed prairie in TPNP. Consequently, targeting early detection efforts in or near agricultural areas and riparian forests rather than the more extensive prairie will likely yield higher detection rates of transformer species.