ABSTRACT We examined the potential allelopathic effect of American lotus (Nelumbo lutea) on two submerged plant species common to Great Lakes coastal wetlands: Eurasian watermilfoil (Myriophyllum spicatum) and sago pondweed (Potamogeton pectinatus). Whole N. lutea seedlings and aqueous leaf extracts were employed as sources of putative allelochemical agents. N. lutea seedlings had no effect on the growth of target plants over seven-day exposures. Aqueous extracts at both 2% and 10% titers significantly stimulated (P < 0.05) shoot growth rates in M. spicatum compared with extract-free control plants. N. lutea extracts were ineffective in altering P. pectinatus growth rates. These findings suggest that, at natural plant population densities, it is unlikely that N. lutea allelopathy plays a significant role in watermilfoil or sago pondweed population dynamics.