Raffi at 04:58, 8 April 2007

2007-04-08T04:58:11Z

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'''Fern ally''' is a general term covering a somewhat diverse group of [[vascular plant]]s that are not [[flowering plant]]s and not true [[fern]]s. Like ferns, these plants reproduce by shedding [[spore]]s to initiate an [[alternation of generations]]. There are three or four groups of plants considered to be ''fern allies''. In various classification schemes, these may be grouped as classes or divisions within the plant kingdom. The more traditional classification scheme is as follows (here, the first three classes are the "fern allies"):

*Kingdom: [[Plant]]ae
**Division [[vascular plant|Tracheophyta]] (vascular plants)
***Class [[Lycopodiophyta|Lycopsida]], (''fern-allies'') the [[clubmoss]]es and related plants
***Class [[Equisetophyta|Sphenopsida]] or Equisetopsida, (''fern-allies'') the [[horsetail]]s and scouring-rushes
***Class [[whisk fern|Psilopsida]], (''fern-allies'') the [[whisk fern]]s
***Class [[fern|Filices]], the true ferns
***Class [[Spermatopsida]] (or sometimes as several different classes of seed-bearing plants)

A more modern or newer classification scheme is:

*Kingdom [[Plant]]ae<br>Subkingdom [[vascular plant|Tracheobionta]]
**Division [[Lycopodiophyta]]
***Class [[Lycopodiopsida]], the clubmosses
***Class Selaginellopsida, the [[spikemoss|spikemosses]]
***Class Isoetopsida, the [[quillwort]]s
**Division [[Equisetophyta]], the [[horsetail]]s and scouring-rushes
**Division [[Psilotophyta]], the [[whisk fern]]s
**Division [[Ophioglossophyta]], the [[Ophioglossum|adders'-tongues]] and [[moonwort]]s
**Division [[fern|Pteridophyta]], the ferns
**Division [[Spermatophyta]] (or as several different divisions of seed-bearing plants)

Note that in either scheme, the basic subdivision of the fern allies is preserved, with the exception that the [[Ophioglossophyta]] (Ophioglossopsida), once thought to be true ferns, are now generally regarded by many to be a distinct group of fern allies.

Another way of looking at it is:

Several groups of plants were considered "fern allies": the [[clubmoss]]es, [[spikemoss]]es, and [[quillwort]]s in the [[Lycopodiophyta]], the [[whisk fern]]s in [[Psilotaceae]], and the [[horsetail]]s in the [[Equisetaceae]]. More recent genetic studies have shown that the Lycopodiophyta are only distantly related to any other [[vascular plant]]s, having radiated evolutionarily at the base of the vascular plant [[clade]], while both the whisk ferns and horsetails are as much true ferns as are the Ophioglossoids and Marattiaceae. In fact, the whisk ferns and Ophioglossoids are demonstrably a [[clade]], and the horsetails and Marattiaceae are arguably another clade. (Traditionally, three discrete groups of plants had been considered [[fern]]s: the [[Ophioglossum|adders-tongues]], [[moonwort]]s, and [[grape-fern]]s ([[Ophioglossophyta]]), the [[Marattiopsida|Marattiaceae]], and the [[sporangium|leptosporangiate]] ferns. The Marattiaceae are a primitive group of tropical ferns with a large, fleshy rhizome, and are now thought to be a sibling taxon to the main group of ferns, the leptosporangiate ferns.)

==External links==
*[http://www.borealforest.org/ferns.htm Common Ferns and Fern-Ally Species]
*[http://www.jaknouse.athens.oh.us/ferns/classfra.html A Classification of the Ferns and Fern-Allies] (uses frames)
*[http://www.cas.vanderbilt.edu/bioimages/pages/non-seed-plants.htm Non-seed plant images at bioimages.vanderbilt.edu]
*Lord, Thomas R. (2006). Ferns and Fern Allies of Pennsylvania. Indiana, PA: Pinelands Press [http://www.paferns.com]

[[Category:Cryptogams]]
[[Category:plant taxonomy]]

Fern ally - Revision history

Raffi at 04:58, 8 April 2007