''Hemidictyum'' is a

genus Genus ( plural genera ) is a taxonomic rank used in the biological classification of extant taxon, living and fossil organisms as well as Virus classification#ICTV classification, viruses. In the hierarchy of biological classification, genus com ...

of ferns with a single species, ''Hemidictyum marginatum'', commonly known as the marginated half net fern. In the

Pteridophyte Phylogeny Group The Pteridophyte Phylogeny Group, or PPG, is an informal international group of systematic botanists who collaborate to establish a consensus on the classification of pteridophytes ( lycophytes and ferns) that reflects knowledge about plant relatio ...

classification of 2016 (PPG I), it is the only genus in the family Hemidictyaceae. Alternatively, the family, along with

Aspleniaceae The Aspleniaceae (spleenworts) are a family of ferns, included in the order Polypodiales. The composition and classification of the family have been subject to considerable changes. In particular, there is a narrow circumscription, Aspleniaceae ...

'' sensu stricto'', may be placed in a much more broadly defined family Aspleniaceae as the subfamily Asplenioideae.

Taxonomy

The name ''Hemidictyum'' was derived from the terms ''hemi'' (half) and ''diktyon'' (net), from the veins being netted only half-way across the pinnules.''The Fern Manual, being a description of all the best stove, greenhouse and hardy ferns'' by contributors to the ''Journal of Horticulture'' p.69, London, 1863

Phylogenetic relationships

Hemidictyaceae is considered to be a sister family to Aspleniaceae ''s.l.'', believed to have diverged during the

Cretaceous The Cretaceous ( ) is a geological period that lasted from about 145 to 66 million years ago (Mya). It is the third and final period of the Mesozoic Era, as well as the longest. At around 79 million years, it is the longest geological period of th ...

period. The following cladogram for the suborder

Aspleniineae Aspleniineae is a suborder of ferns in the order Polypodiales. It is equivalent to the clade eupolypods II in earlier systems; it is also treated as a single very broadly defined family Aspleniaceae. The suborder generally corresponds with the o ...

(as eupolypods II), based on Lehtonen (2011), and Rothfels & al. (2012), shows a likely

phylogenetic In biology, phylogenetics (; from Greek φυλή/ φῦλον [] "tribe, clan, race", and wikt:γενετικός, γενετικός [] "origin, source, birth") is the study of the evolutionary history and relationships among or within groups o ...

relationship between the Hemidictyaceae and the other families of the clade.

Species

There is currently only one accepted ''Hemidictyum'' species, ''Hemidictyum marginatum''.

Distribution

''Hemidictyum'' is a native

neotropical The Neotropical realm is one of the eight biogeographic realms constituting Earth's land surface. Physically, it includes the tropical terrestrial ecoregions of the Americas and the entire South American temperate zone. Definition In bioge ...

fern, found in Mexico, the Caribbean, Costa Rica, Guatemala, Honduras, Nicaragua, Panama, French Guiana, Suriname, Brazil, Venezuela, Puerto Rico, Bolivia, Colombia, Ecuador, and Peru.

References

Polypodiales Monotypic fern genera Ferns of the Americas Flora of Central America Flora of the Caribbean Flora of South America Ferns of Brazil Ferns of Mexico Plants described in 1836 Taxa named by Carl Borivoj Presl {{Polypodiales-stub