Hydrocharis morsus-ranae

Frogbit is a spectacular aquatic plant.


Frogbit is a free-floating aquatic plant with rosettes of leathery, heart-shaped leaves that rest on the water’s surface. The flowers grow out above the water and have three white, crumpled petals that narrow towards the base, leading to a yellow centre. Flowers can be seen from July-August. In winter, the dormant buds (turions) of Frogbit settle underwater until spring when they begin to grow.


Frogbit is found in sheltered areas of ponds, ditches, lakes, and swamps where the water is slow-moving, calcareous, and has a pH of 6.5 – 7.8. This species can tolerate the cold due to its winter dormancy stage in its life cycle.

Distribution and threats

Frogbit is declining in Britain due to the conversion of grazing marshes to arable land and due to eutrophication within its preferred habitats. It is therefore listed as vulnerable in the Red Data Book for Great Britain. It is also listed as locally scarce within Oxfordshire and since 2010, it has only been recorded at one site within the county.