FROGBIT
frogbit, frog's-bit, Hydrocharis morsus-ranae
(noun) European floating plant with roundish heart-shaped leaves and white flowers
Source: WordNet® 3.1
Etymology
Noun
frogbit (plural frogbits)
Hydrocharis morsus-ranae, with roundish leaves and small white flowers, that floats on still water and propagates itself by runners.
An American plant, Limnobium spongia, with similar propagation.
A South American plant, Limnobium laevigatum.
Source: Wiktionary
Frog"bit`, n. (Bot.)
(a) A European plant (Hydrocharis Morsus-ranæ), floating on still
water and propagating itself by runners. It has roundish leaves and
small white flowers.
(b) An American plant (Limnobium Spongia), with similar habits.
Source: Webster’s Unabridged Dictionary 1913 Edition