Pteridopsida

Taxobox
name = Pteridopsida ~ Modern Ferns


image_width = 240px
image_caption = Tree fern
regnum = Plantae
divisio = Pteridophyta
classis = Pteridopsida/Polypodiopsida
subdivision_ranks = Orders
subdivision =
* Osmundales
* Hymenophyllales
* Gleicheniales
* Schizaeales
* Salviniales
* Cyatheales
* Polypodiales
* Blechnales

The Pteridopsida is a class of plants in the Division Pteridophyta that includes all the leptosporangiate ferns. In the recent 2006 classification by Smith et al. the class is renamed Polypodiopsida. This recent reclassification of Monilophyte (ferns) is based on multiple molecular studies published since 1994 that have clarified some of the confusion of the placement and relations among fern families.Smith, A. R., K. M. Pryer, et al. (2006). "A classification for extant ferns." Taxon 55(3): 705-731] Polypodiopsida is one of four classes of Monilophytes (an Infradivision, this rank is not recognized by the "International Code of Botanical Nomenclature"), the other three being Marattiopsida, Equisetopsida, and Psilotopsida.

Classification

The classification scheme proposed by Smith et al.(alternative names in brackets):

*Order Osmundales
**Family Osmundaceae
*Order Hymenophyllales
**Family Hymenophyllaceae (incl. Trichomanaceae)
*Order Gleicheniales
**Family Gleicheniaceae (incl. Dicranopteridaceae, Stromatopteridaceae)
**Family Dipteridaceae (incl. Cheiropleuriaceae)
**Family Matoniaceae
*Order Schizaeales
**Family Lygodiaceae
**Family Anemiaceae (incl. Mohriaceae)
**Family Schizaeaceae
*Order Salviniales
**Family Marsileaceae (incl. Pilulariaceae)
**Family Salviniaceae (incl. Azollaceae)
*Order Cyatheales
**Family Thyrsopteridaceae
**Family Loxomataceae
**Family Culcitaceae
**Family Plagiogyriaceae
**Family Cibotiaceae
**Family Cyatheaceae (incl. Alsophilaceae, Hymenophyllopsidaceae)
**Family Dicksoniaceae (incl. Lophosoriaceae)
**Family Metaxyaceae
*Order Polypodiales
**Family Lindsaeaceae (incl. Cystodiaceae, Lonchitidaceae)
**Family Saccolomataceae
**Family Dennstaedtiaceae (incl. Hypolepidaceae, Monachosoraceae, Pteridiaceae)
**Family Pteridaceae (incl. Acrostichaceae, Actiniopteridaceae, Adiantaceae, Anopteraceae, Antrophyaceae, Ceratopteridaceae, Cheilanthaceae, Cryptogrammaceae, Hemionitidaceae, Negripteridaceae, Parkeriaceae, Platyzomataceae, Sinopteridaceae, Taenitidaceae, Vittariaceae)
**Family Aspleniaceae
**Family Thelypteridaceae
**Family Woodsiaceae (incl. Athyriaceae, Cystopteridaceae)
**Family Blechnaceae (incl. Stenochlaenaceae)
**Family Onocleaceae
**Family Dryopteridaceae (incl. Aspidiaceae, Bolbitidaceae, Elaphoglossaceae, Hypodematiaceae, Peranemataceae)
**Family Lomariopsidaceae (incl. Nephrolepidaceae)
**Family Tectariaceae
**Family Oleandraceae
**Family Davalliaceae
**Family Polypodiaceae (incl. Drynariaceae, Grammitidaceae, Gymnogrammitidaceae, Loxogrammaceae, Platyceriaceae, Pleurisoriopsidaceae)

Discussion of Molecular Classification

There has been some challenge to the recent molecular studies, claiming that these provide a skewed view of the phylogenetic order because the studies don't take into account fossil representatives [Rothwell, G. W. and K. C. Nixon (2006). "How does the inclusion of fossil data change our conclusions about the phylogenetic history of euphyllophytes." Int. J. Plant Sci 167(3): 737-749] . However, the molecular studies have clarified relations among families that were thought to be non-monophyletic before the advent of molecular information, which were left in their non-monophyletic ranks because there was not enough information to do otherwise [Kramer, K. U. (1990). Notes on the Higher Level Classification of the Recent Ferns. The Families and Genera of Vascular Plants: Pteridophytes and Gymnosperms. K. Kubitzki, K. U. Kramer and P. S. Green. New York, Springer-Verlag. 1: 49-52] . The reclassification of ferns using multiple molecular studies, which have generally supported each other, is not any different from classifications of the past--it is the definition of the relations utilizing the all the information available. It does not discourage the further study and clarification of the groups, and does not mean that if further study proves the classification wrong, it will not be changed.

References