Echte Farne. Die Echten Farne (Polypodiopsida, =Filicopsida) sind eine Klasse innerhalb der Farne. Sie umfasst die leptosporangiaten Farne, während die früher als eusporangiat bezeichneten Farne heute in die Klassen Marratiopsida und Psilotopsida gestellt werden. Die Klasse umfasst rund 11.000 Arten. Merkmale[Bearbeiten] Die Merkmale der Farne treffen auch auf die Echten Farne zu.
Die Sporangien der Echten Farne entwickeln sich aus einer einzelnen Zelle. Die Sporangien sitzen in großer Zahl an der Unterseite der photosynthetisierenden Blätter (Sporotrophophylle). Die Prothallien (der Gametophyt) sind kurzlebig. Verbreitung[Bearbeiten] Sie sind weltweit verbreitet, ihr Schwerpunkt liegt allerdings in den Tropen, wo sie Formen von nur wenigen Millimetern Größe (Didymoglossum) bis zu 20 Meter große Schopfbäume entwickelt haben.
Systematik und Evolution[Bearbeiten] Die Echten Farne werden nach der hier verwendeten Systematik von Smith et al. (2006)[1] wie folgt untergliedert: Literatur[Bearbeiten] Pteridophyte. Pteridophytes or Pteridophyta, in the broad interpretation of the term (or sensu lato), are vascular plants (plants with xylem and phloem) that reproduce and disperse via spores. Because they produce neither flowers nor seeds, they are referred to as cryptogams. The group includes ferns, horsetails, clubmosses, spikemosses and quillworts. These do not form a monophyletic group, because ferns and horsetails are more closely related to seed plants than to lycophytes (clubmosses, spikemosses and quillworts). Therefore, pteridophytes are no longer considered to form a valid taxon, but the term is still used as an informal way to refer to ferns (monilophytes) and lycophytes, and some recent authors have used the term to refer strictly to the monilophytes.
Pteridophyte classification[edit] In addition to these living groups, several groups that are now extinct and known only from fossils are considered to belong to pteridophytes. Pteridophyte life cycle[edit] See also[edit] References[edit] Polypodiopsida. Polypodiopsida. [edit] Main Page Regnum: Plantae Phylum: Tracheophyta Divisio: Pteridophyta Classis: Polypodiopsida Ordines: Cyatheales - Gleicheniales - Hymenophyllales - Osmundales - Polypodiales - Salviniales - Schizaeales - †Zygopteridales Name[edit] Polypodiopsida Cronquist, Takht.
& Zimmerm. Synonyms[edit] FilicopsidaGleicheniopsida DoweldPteridopsida Ritgen References[edit] Vernacular names[edit] dansk: bregne (bregner)Deutsch: Farn (Farne)English: fern (ferns)español: helecho (helechos)français: fougere (fougeres)magyar: PáfrányokNederlands: varen (varens)日本語: ウラボシ綱, シダ綱norsk bokmål: bregnenorsk nynorsk: blom, bregnepolski: Paprocieportuguês: feto (fetos)русский: ПапоротниковыеTiếng Việt: Lớp Dương xỉ中文: 真蕨綱. Leptosporangiate fern. Leptosporangiate ferns are the largest group of living ferns, comprising some 9000 species worldwide. They comprise the subclass Polypodiidae,[1] but are often considered to be the class Pteridopsida or Polypodiopsida,[2] although other classifications assign them a different rank.[3] The leptosporangiate ferns are one of the four major groups of ferns, with the other three being the Eusporangiate ferns comprising the marattioid ferns (Marattiidae, Marattiaceae), the horsetails (Equisetiidae, Equisetaceae), and whisk ferns and moonworts.[1][2] There are approximately 9000 species of living leptosporangiate ferns, compared with about 300 for all other ferns put together.[4] Almost a third of leptosporangiate fern species are epiphytes.[4] Classification[edit] Leptosporangiates include the vast majority of extant ferns.
Only groups that branched off early from the fern lineage, which retain a eusporangium, are not included. Phylogenic relationships[edit] References[edit] External links[edit]