An important component of the vascular flora of Missouri is the aquatic community of springs, lakes, sloughs, and streams. The aquatic vascular flora of Missouri is comprised of native species, rare and endangered taxa, and invasive, non-indigenous species (Yatskievych 1999, Yatskievych and Turner 1990, Missouri Natural Heritage Database 1997). Because many aquatic species, in particularly non-native species, have the potential to create serious weed problems, it is imperative to detect their initial presence in the flora and document their spread if control measures are to be successful (Westbrooks and Eplee 1996, Padgett and Crow 1993). Currently, Missouri is home to at least eight introduced, potentially problematic, aquatic species of flowering plants (Yatskievych 1999, Yatskievych and Turner 1990).