any of numerous flowerless and seedless vascular plants having true roots from a rhizome and fronds that uncurl upward; reproduce by spores

any of several water ferns of the genus Marsilea having four leaflets

European water fern found around margins of bodies of water or in wet acid soil having small globose sporocarps

small latex-containing aquatic fern of southern Brazil

free-floating aquatic ferns

small free-floating aquatic fern from the eastern United States to tropical America; naturalized in western and southern Europe