Formerly, the two species in the genus
Pentarhizidium were considered to be members of
Matteuccia, but genetic analysis has determined that they compose a basal sister clade to the rest of the family. This family has been determined by genetic analysis to be closely allied to the
Blechnaceae, within the clade of families sometimes known as
Blechnales (which includes the athyrioid ferns and asplenioid ferns as well) (this clade is often treated as part of the order
Polypodiales however).
Matteuccia struthiopteris was previously classified under the
Dryopteridaceae, and still is by the
USDA.
Phylogeny The following cladogram for the suborder
Aspleniineae (as eupolypods II), based on Lehtonen (2011), •
Matteuccia •
Matteuccia struthiopteris (ostrich fern) - wide distribution including North America, Europe, and Asia •
Onoclea •
Onoclea sensibilis (sensitive fern) - North America and eastern Asia, with the American and Asian populations being recognized as distinct varieties •
Onocleopsis •
Onocleopsis hintonii - found in a restricted range of wet mountain canyons in southern Mexico and Guatemala; some botanists (especially Masahiro Kato) consider this to be a species of
Matteuccia •
Pentarhizidium •
Pentarhizidium orientale - eastern Asia as far south as the
Himalayas •
Pentarhizidium intermedium - China to India ==References==