Acrostichum
Introduction '''''Acrostichum''''' is a fern genus in the Parkerioideae subfamily of the Pteridaceae. It was one of the original pteridophyte genera delineated by Linnaeus. It was originally drawn very broadly, including all ferns that had sori apparently "acrostichoid", or distributed in a uniform mass across the back of the frond, rather than organized in discrete sori. This led Linnaeus to include such species as ''Asplenium platyneuron'' in the genus, because the specimen he received had sori so crowded that it appeared acrostichoid.Since ''Acrostichum aureum'' is regarded as the type for the genus, it is now narrowly circumscribed only to the natural genus of three species, that are allied to the genus ''Ceratopteris''. They are collectively known as the '''leather ferns''' or '''leather swamp ferns''', genus members commonly being found in swamps. The species of ''Acrostichum'' are massive ferns, with fronds up to  tall, that depend on a semi-aquatic existence. They do not withstand prolonged immersion, but require wet roots. The species ''Acrostichum aureum'' is known to have a high saltwater tolerance, growing in mangroves.
Species Phylogeny of ''Acrostichum''.Nitta et al. 2022 and Fern Tree of lifeOther species:*''Acrostichum preaureum'' fossil plant.
References * World species list for ''Acrostichum'': https://web.archive.org/web/20090921113828/http://homepages.caverock.net.nz/~bj/fern/acrostichum.htm* C. Michael Hogan. 2010.''Fern''. Encyclopedia of Earth. National council for Science and the Environment. Washington, DC