Editing Azolla (section)

==Reproduction==
{{more citations needed section|date=January 2025}}
[[File:Azolla megaspore Postglacial Galapagos Islands TEM longitudinal section 1.jpg|thumb|Transmission electron micrograph of a megaspore of the genus ''Azolla'' from postglacial sediments of Laguna El Junco, Galápagos Island of San Cristobal<ref name="Kem">{{cite journal |last1=Kempf |first1=E.K. |year=1976 |title=Low Magnifications - A Marginal Area of Electron Microscopy |journal=ZEISS Information |volume=21 |issue=83 |pages=57–60}}</ref>]]
''Azolla'' reproduces sexually, and [[asexual reproduction|asexual]]ly by splitting.

Like all ferns, sexual reproduction leads to [[spore]] formation, but unlike other members of this group, ''Azolla'' is [[heterosporous]], producing spores of two kinds. During the summer months, numerous spherical structures called [[sporocarp (ferns)|sporocarps]] form on the undersides of the branches. The male sporocarp is greenish or reddish and looks like the egg mass of an insect or spider. It is two millimeters in diameter, and bears numerous male [[sporangia]]. Male spores (microspores) are extremely small and are produced inside each [[microsporangium]]. Microspores tend to adhere in clumps called massulae.<ref name=Arnold1955/>

Female sporocarps are much smaller, containing one sporangium and one functional spore. Since an individual female spore is considerably larger than a male spore, it is termed a [[megaspore]].

''Azolla'' has microscopic male and female gametophytes that develop inside the male and female spores. The female [[gametophyte]] protrudes from the megaspore and bears a small number of [[archegonia]], each containing a single egg. The microspore forms a male gametophyte with a single [[antheridium]] which produces eight swimming sperm.<ref>{{cite book |author1=Scagel, Robert F. |author2=Bandoni, Robert J. |author3=Rouse, Glenn E. |author4=Schofield, W.B. |author5=Stein, Janet R. |author6=Taylor, T.M. |year=1965 |title=An Evolutionary Survey of the Plant Kingdom |place=Belmont, California |publisher=Wadsworth Publishing}} 658&nbsp;pp.</ref> The barbed [[glochidia]] on the male spore clusters cause them to cling to the female megaspores, thus facilitating fertilization.