European Frog-bit

European frog-bit is a free-floating aquatic plant with leathery, heart-shaped leaves and small white flowers with three petals. The root system is well developed, but does not normally anchor the plant to the substrate (Environment Canada, 2003).

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 (Ontario, 2018).

• The plant can float free or put down roots up to 50 cm long in shallow water.
• It produces a single white flower up to two cm wide with three rounded petals and a yellow centre.
• Leaves are 2.5-5 cm wide (about the size of a Canadian loonie) and round/heart-shaped. They form a rosette up to 6 cm wide.
• The leaf bottom is purple-red with a spongy coating along the middle vein of the leaf that allows it to float on the water.

In 1932, this plant was brought over from Europe to the Central Experimental Farm in Ottawa, Ontario, as a potential ornamental plant, where it escaped into the Rideau Canal by 1939.

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, Lake Huron along St. Joesph’s Island, 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 (Ontario, 2016).

(Range map provided courtesy of the USDA website and is displayed here in accordance with their policies)

The free-floating form of this plant can lead to densely-tangled floating mats, which can crowd and shade out native aquatic vegetation.  It can dominate wetlands where it occurs, and the dense mats may affect wildlife as well as native plants (Environment Canada 2003).

European frog-bit grows rapidly and 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 (Ontario, 2016)