European frogbit

Scientific Name: Hydrocharis morsus-ranae

Dave Brenner (Michigan Sea Grant)Copyright Info

Identification: European frogbit is a free-floating aquatic plant with leathery, heart-shaped leaves and small white flowers with three petals. Its root system is well developed but does not normally anchor the plant. The species spreads by sending out runners, which are stems that grow horizontally, from which new plants can develop. This species is also known as common frogbit.

Size: The leaves vary in size, but they are typically less than 2.5 inches (6.3 cm) across.

Native Range: European frogbit is native to Europe and northern Asia.

Table 1. Great Lakes region nonindigenous occurrences, the earliest and latest observations in each state/province, and the tally and names of HUCs with observations†. Names and dates are hyperlinked to their relevant specimen records. The list of references for all nonindigenous occurrences of Hydrocharis morsus-ranae are found here.

Full list of USGS occurrences

State/ProvinceYear of earliest observationYear of last observationTotal HUCs with observations†HUCs with observations†
Michigan1996201915Au Gres-Rifle; Detroit; Huron; Kawkawlin-Pine; Lake Erie; Lake Huron; Lake St. Clair; Lone Lake-Ocqueoc; Lower Grand; Ottawa-Stony; Pigeon-Wiscoggin; Raisin; Saginaw; St. Marys; Thunder Bay
New York1974201517Ausable River; Black; Chaumont-Perch; Grass; Headwaters St. Lawrence River; Indian; Irondequoit-Ninemile; Lake Champlain; Lake Ontario; Lower Genesee; Mettawee River; Oak Orchard-Twelvemile; Oneida; Oswegatchie; Salmon-Sandy; Seneca; St. Regis
Ohio200420194Black-Rocky; Cedar-Portage; Huron-Vermilion; Lake Erie
Vermont199320112Lake Champlain; Mettawee River

Table last updated 9/30/2019

† Populations may not be currently present.

* HUCs are not listed for areas where the observation(s) cannot be approximated to a HUC (e.g. state centroids or Canadian provinces).

Means of Introduction: This species was planted in 1932 in arboretum ponds beside Dow’s Lake in Ottawa, Canada. It escaped from these ponds and was found in the St. Lawrence River from Montreal to Lake St. Peter by 1967. It has been known from the Canadian shoreline of Lake Erie since 1976, and has also spread into Lake Ontario and localities in New York. Plant dispersal to United States waters was aided by motor boats entering from Canada.

Status: European frogbit was first introduced to North America in Ottawa, Canada, and has been recorded along the Canadian shoreline of Lake Erie since 1976. It has spread into Lake Ontario, as well as inland lakes and streams in New York, Vermont, and Michigan. It is also established in Washington, Ontario, and Quebec.

Remarks: European frogbit is endangered in Switzerland and is threatened in parts of its native range.

Author: Illinois-Indiana Sea Grant

Contributing Agencies:
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Revision Date: 9/25/2012

Citation for this information:
Illinois-Indiana Sea Grant, 2019, European frogbit: U.S. Geological Survey, Nonindigenous Aquatic Species Database, Gainesville, FL, and NOAA Great Lakes Aquatic Nonindigenous Species Information System, Ann Arbor, MI,, Revision Date: 9/25/2012, Access Date: 10/13/2019

This information is preliminary or provisional and is subject to revision. It is being provided to meet the need for timely best science. The information has not received final approval by the U.S. Geological Survey (USGS) and is provided on the condition that neither the USGS nor the U.S. Government shall be held liable for any damages resulting from the authorized or unauthorized use of the information.