Polypodiales

Polypodiales
Polypodium californicum
Scientific classification
Kingdom:	Plantae
Division:	Pteridophyta
Class:	Polypodiopsida/Pteridopsida (disputed)
Order:	Polypodiales Link (1833)
Families
See text.

See text.

The order Polypodiales encompasses the major lineages of polypod ferns, which comprise more than 80% of today's fern species. They are found in many parts of the world including tropical, semitropical and temperate areas. The characteristics of this group include: sporangia with a vertical annulus interrupted by the stalk and stomium; indusia laterally or centrally attached (or lost); gametophytes green, chordate, and surficial.

Polypodiales may be regarded as one of the most evolutionarily advanced orders of monilophytes (ferns), based on recent genetic analysis. They arose and diversified about 100 million years ago, probably subsequent to the diversification of the angiosperms.

In the molecular phylogenetic classification of Smith et al. in 2006, the Polypodiales were placed in the leptosporangiate ferns, class Polypodiopsida. Fifteen families, including members of the eupolypods, comprising two unranked clades, were recognized: Lindsaeaceae, Saccolomataceae, Dennstaedtiaceae, Pteridaceae, eupolypods I (Aspleniaceae, Thelypteridaceae, Woodsiaceae, Blechnaceae, and Onocleaceae), and eupolypods II (Dryopteridaceae, Lomariopsidaceae, Tectariaceae, Oleandraceae, Davalliaceae, and Polypodiaceae). While many of these families had previously been recognized with similar superscriptions, the authors noted that Dryopteridaceae was more narrowly bounded than in historical circumscriptions, which had included their Tectariaceae, Onocleaceae, and Woodsiaceae. The circumscription of Lomariopsidaceae changed dramatically, most historical genera of that family (except Lomariopsis and Thysanosoria) being moved to Dryopteridaceae, while Cyclopeltis and Nephrolepis were added. Saccolomataceae were removed from the dennstaedtioids. Cystodium was tentatively placed in Lindsaeaceae, away from its historical position with the tree ferns. Woodsiaceae was acknowledged to be of uncertain circumscription and perhaps paraphyletic; the inclusion of Hypodematium, Didymochlaena, and Leucostegia perhaps also rendering Dryopteridaceae paraphyletic. The grammitids were included in Polypodiaceae to render that family monophyletic.

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