See the attached identification of the invasive European Frog-bit.
European frog-bit is an invasive aquatic plant native to Europe and parts of Asia and Africa. In 1932 the plant was brought from Europe to the Central Experimental Farm in Ottawa for possible commercial use as an ornamental plant. In 1939 it was found in the Rideau Canal. Since then it has spread to several rivers, Lake Ontario, Lake Erie and other inland waters.
European frog-bit grows rapidly and forms dense, floating mats. It can be found in slow-moving waters such as sheltered inlets, ponds, slow- running rivers and ditches. Large areas of frog-bit that die in the fall and decompose may lead to reduced oxygen levels in the water that can affect aquatic life. New plants can grow from stem fragments, seeds and winter buds known as turions that can be spread to new waters by boats and wildlife.
Outside its native range, European frog-bit is found in the Rideau and Ottawa river systems, the St. Lawrence River, Lake Ontario, Lake Erie, the Kawartha Lakes, and other lakes and rivers in southcentral and southwestern Ontario. The plant has also been introduced to some American states, including New York, Vermont, Michigan and Washington.