Synonyms for Floating Fern (same or very similar meaning)
WordNet sense 1 (pantropical aquatic fern):
Ceratopteris thalictroidesWordNet sense 2 (aquatic fern of tropical America often used in aquariums):
water sprite, Ceratopteris pteridioidesWordNet sense 3 (small free-floating aquatic fern from the eastern United States to tropical America; naturalized in western and southern Europe):
mosquito fern, Azolla caroliniana, Carolina pond fernFrom the ODE community, based on WordNetadd/edit