Hydrocharis is a genus of aquatic plants in the family Hydrocharitaceae described as a genus by Carl Linnaeus in 1753. Species range across much of Europe and Asia, northwestern and central Africa, New Guinea, and the Americas from the eastern and central United States to Argentina and Chile. Species are naturalized in parts of California, northeastern North America, southern tropical Africa, and Australia.

The best known species is Hydrocharis morsus-ranae, commonly called common frogbit or European frog's-bit, and occasionally water-poppy.

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