small family aquatic semi aquatic sight physically resemble group commonly known family water family leaves genus resemble leaves leaf flowering plant leaves substitute leaves family contains genera species belonging natural history members aquatic semi aquatic plants grow dense mud shores ponds streams grow submerged shallow water leaves extending float water surface grow wet habitats survive winter dry season losing leaves producing hard resistant reproductive structures living genera family majority species belong genus grows worldwide warm temperate tropical regions distinguished genera presence leaf species occasionally produce leaf second genus includes single living species grows southern brazil neighboring parts argentina leaf genus grows widely temperate regions northern southern leaves slender tapered point overlooked mistaken grass species known closest relatives aquatic families float freely surface ponds lakes instead soil mud close relationship groups supported molecular analysis discovery intermediate fossil named general better fossil record recently oldest fossil member known preserved containing spores found india discovery cretaceous eastern north_america announced fossils assigned species pushed known history oldest fossil known upper lower cretaceous japan fossils include leaves visible veins morphology share basic structural characteristics common differences noticeable similarities species family long slender beneath ground leaves grow distinct clusters wide leaf clusters result plants appear stem leaf unlike roots grow primarily leaves grow locations roots noteworthy containing vessel elements vessels found species vessels evolved independently vessels groups plants leaves easily observed characteristic long slender leaf stalk ending zero occasionally number differs genera identification leaves narrowly cylindrical point leaves bear broad leaves bear tip leaf borne equally instead borne pairs pair attached slightly higher developing leaf folded like wings butterfly like leaves develop pattern begin small tight leaf matures maturity held erect leaves blade temperate species deciduous losing leaves winter tropical species lose leaves dry season leaves produce food plant aquatic species especially growing submerged leaves leaves grow surface water look like leaves species growing water plants produce leaves shorter leaf long reach surface remain underwater leaves different cellular characteristics better suited submerged environment addition sterile species produce fertile spore producing near base leaves reproductive portion looks functions differently portion leaves life cycle like members produce spores seeds reproduce unlike spores family produced inside short shaped structures usually diameter hardened outer covering outer covering tough resistant drying allowing spores inside survive unfavorable conditions winter frost summer despite open readily water conditions favorable specimens successfully stored years growing season typically develops near base leaf species occasionally resemblance gives family common modified shorter inside modified bear consists covered thin hood tissue includes mix types type producing kinds spores center developing produce single large female surrounding edge developing later produce small male produce kinds spore kinds called norm plants seeds flowering plants conifers rare groups plants plants produce kinds different places plant grow kinds single cluster differ plants regard spores remain dormant inside unfavorable conditions conditions suitable wet splits halves allowing tissue inside internal tissue swells water pushes halves hard outer covering apart emerges long gelatinous worm like bearing structure unique extend times length inside extension carries numerous spore producing attached water human uses species cultivated garden pools indigenous australians called contain toxic levels careful preparation methods order safe consumption
Marsileaceae