Source : WordNet®

floating fern
     n 1: pantropical aquatic fern [syn: {Ceratopteris thalictroides}]
     2: aquatic fern of tropical America often used in aquariums
        [syn: {water sprite}, {Ceratopteris pteridioides}]
     3: small free-floating aquatic fern from the eastern United
        States to tropical America; naturalized in western and
        southern Europe [syn: {mosquito fern}, {Carolina pond fern},
         {Azolla caroliniana}]