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Subject: European frogbit expands range to include eastern Michigan (U.S.A.)
Date posted: December 05, 2001
Source: United States Geological Survey Nonindigenous Species Reports
European frogbit, Hydrocharis morsus-ranae, was reported in late 2000 as new to the state of Michigan from marshes along Lake St. Clair and the Detroit River. This species was introduced to Ottawa, Canada as an ornamental in the 1930's and is now found throughout southeastern Ontario and western Quebec, along the north shores of Lake Ontario, Lake Erie, and the St. Lawrence River, as well as northern New York and Vermont, including Lake Champlain. Hydrocharis morsus-ranae is an annual, free-floating aquatic herb native to temperate Eurasia that prefers quiet, open water in marshes, ditches and swamps. It relies on rapid vegetative growth for reproduction, which results in the development of dense, floating mats of intertwined plants on the water's surface. These mats impede boat traffic, by which the species often spreads, inhibit recreational activities and wildlife movements, and limit light penetration and availability for other aquatic plants. Hydrocharis morsus-ranae presents a potentially immediate threat to the entire Great Lakes region and northeastern states and provinces. See http://infoweb.magi.com/~ehaber/factfrog.html for more information.