Fern

The ferns are a group of vascular spore plants that form the sister group of seed plants. The ferns include all vascular spore plants except the Bärlapppflanzen: horsetails, fork -leaved plants, snake tongues, Pteridopsida and Marattiaceae. They are often referred to as Monilophyten, but the numbers are not valid Moniloformopses Monilophyta or taxon designations.

There are around 12,000 species worldwide. In Europe, some 171 species, is home to some 101 species in Central Europe.

History

In the Carboniferous ( approximately 360-300 million years ago ) formed ferns ( in larger form than today, usually called tree ferns ) together with horsetails and Bärlapppflanzen huge forests and created the basis for today's coal deposits. The oldest fossil finds come from the lower Devonian ( about 400 million years ago). Ferns are therefore probably older than the seed plants, which first appeared in the Upper Devonian.

Features

The ferns have all the characteristics of the vascular cryptogams. You have a special form of vascular bundles: The protoxylem is restricted to certain lobes of the Xylemstrangs. Hence the name comes Monilophyta: Latin moniliformis means " collar -like". All extant representatives also have a specific insertion in the plastid gene rps4 of nine nucleotides.

Dissemination

Ferns are distributed worldwide. They occur almost exclusively in shady and moist places in the forest, in wall cracks, crevices and ravines, on stream banks or the like from a few light- loving species. The distribution area have the ferns in the tropics. Thus one finds in the tropical rain forest, for example, the largest Ferns, the tree ferns.

System

The ferns are in the scheme of Smith et al used here. (2006 ) are divided into four classes, all of which are monophyletic:

• Class Psilotopsida order Ophioglossales Family adder's tongue plants ( Ophioglossaceae ) (incl. Botrychiaceae, Helminthostachyaceae )

• Family Fork -leaved plants ( Psilotaceae ) (incl. Tmesipteridaceae )

• Order Equisetales Family horsetails ( Equisetaceae )

• Order Marattiales Family Marattiaceae (including Angiopteridaceae, Christenseniaceae, Danaeaceae, Kaulfussiaceae )

• Order Osmundales
• Order Hymenophyllales
• Order Gleicheniales
• Order Schizaeales
• Order Salviniales
• Order tree ferns ( Cyatheales )
• Order Polypodiales

Fossil groups that are at the basis of today's existing ferns, are:

• Cladoxylopsida Pseudosporochnales
• Iridopteridales

• Rhacophytales
• Coenopteriden
• Stauropteridales
• Zygopteridales

Gallery

Meadow Horsetail ( Equisetum pratense)

Sori on the underside of leaves of the tree fern Dicksonia antarctica

Fronds before rolling out

Documents

The article is based on the following documents:

• Peter Sitte, Elmar Weiler, Joachim W. Kadereit, Andreas Bresinsky, Christian Körner: textbook of botany for colleges. Founded by Eduard Strasburger. 35th edition. Spektrum Akademischer Verlag, Heidelberg 2002, ISBN 3-8274-1010- X.
• Alan R. Smith, Kathleen M. Pryer, Eric Schuettpelz, Petra coral, Harald Schneider, Paul G. Wolf: A classification for extant ferns. In: taxon. Volume 55, No. 3, 2006, ISSN 0040-0262, pp. 705-731, Abstract, PDF file.
• Nele Wellinghausen: Ferns. Identification keys for all native ferns, horsetails and Bärlappartigen. German youth club for nature observation ( DJN ), Hamburg 1997, ISBN 3-923376-13-8.