European frog-bit is now also found as far downstream on the St. Lawrence River as Quebec City and is present in the Eastern Townships of Quebec. In recent years, it has spread to adjacent northern New York State at scattered points along the southeastern shore of Lake Ontario and at various inland sites just south of the St. Lawrence River. It was found in Lake Champlain in 1993, near Grande Isle, Vermont, and by 1999 had extended southward along Lake Champlain to Benson, Orwell and West Haven, Vermont. European frog-bit was first identified from Lake St. Clair in 1996. Biology E uropean frog-bit is an annual, aquatic herb that reproduces both sexually and asexually.
Plants have unisexual, male or female flowers.
Although these attract a variety of insect pollinators, sexual reproduction by seed may be limited or non-existent in some populations. Where only male or female plants are present, no seed production is possible. Low seed production may also occur in mixed sex populations because there tends to be a high male sex ratio. Sexual reproduction is only of minor importance considering the rapid vegetative growth and production of new plantlets from the ends of the long cord-like stolons produced by each floating plant. By mid summer, extensive vegetative growth results in the formation of dense floating mats of intertwined plants.