ABSTRACT
Invasive plants are species or genotypes that can thrive and spread aggressively outside their natural range. They cause problems in wetlands and other habitats worldwide by displacing native ora, reducing biodiversity, impeding boat trafc, and degrading wetland habitat values (Jakubauskas et al. 2002; Madden 2004). Some plants are intentionally introduced and become invasive in the absence of the natural pests that controlled their spread in their natal range. Other invasive plants are unintentionally introduced and escape and spread by competitive dispersal mechanisms, such as the copious seed production of purple loosestrife (Lythrum salicaria) (Galatowitsch et al. 1999). Submersed aquatic invasives including common watermilfoil (Myriophyllum spicatum) can be spread by fragments that cling to boat trailers, taking advantage of human mobility (Johnson et al. 2001). Wetland invaders generally have high productivity under nutrient enrichment that allows them to take advantage of disturbed conditions (Zedler and Kercher 2004).
