Hemidictyum is a genus of ferns with a single species, Hemidictyum marginatum, commonly known as the marginated half net fern.[3] In the Pteridophyte Phylogeny Group classification of 2016 (PPG I), it is the only genus in the family Hemidictyaceae.[4] Alternatively, the family, along with Aspleniaceaesensu stricto, may be placed in a much more broadly defined family Aspleniaceae as the subfamily Asplenioideae.[5]
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.[6]
Phylogenetic relationships
Hemidictyaceae is considered to be a sister family to Aspleniaceae s.l., believed to have diverged during the Cretaceous period.[7][8] The following cladogram for the suborder Aspleniineae (as eupolypods II), based on Lehtonen (2011),[9] and Rothfels & al. (2012),[10] shows a likely phylogenetic relationship between the Hemidictyaceae and the other families of the clade.
There is currently only one accepted Hemidictyum species, Hemidictyum marginatum.[2]
Distribution
Hemidictyum is a native neotropical fern, found in Mexico, the Caribbean, Costa Rica, Guatemala, Honduras, Nicaragua, Panama, French Guiana, Suriname, Brazil, Venezuela, Puerto Rico, Bolivia, Colombia, Ecuador, and Peru.[3][11]
^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
