Phylum Pteridophyta (classification modified)

Ken Kinman kinman2 at YAHOO.COM
Mon Mar 14 10:01:06 CST 2005

Dear All,
      Two small changes to my classification posted over the weekend.  First, as I have stated, I am substituting Pteridopsida for Filicopsida.  The other is just a coding change for Phylum Bryophyta.  Instead of coding Bryopsida as sister group to Tracheophyta, note that I now code a combined Hepaticopsida-Bryopsida clade as sister to Tracheophyta.  Either way, the content of Bryophyta remains the same, and the coding absorbs the change in topology.  I just hope the strict cladists haven't insisted on formally naming the Hepaticopsida-Bryopsida clade, because it doesn't seem absolutely necessary and certainly isn't a done deal.  I will answer Curtis Clark's latest post further below.


 1  PHYLUM Bryophyta% (mosses and liverworts)
       1  Anthocerotopsida
       2  Hepaticopsida
       B  Bryopsida
       3  {{Tracheophyta}}
           (= Pteridophyta + Spermatophyta)

_1_ PHYLUM Pteridophyta%
       1  Horneophytopsida
       2  Plesion Aglaophyton
       3  Rhyniopsida
       4  Lycopsida (club mosses)
       5  Trimerophytopsida
       6  Cladoxylopsida
       B  Sphenopsida (horsetails)
       C  Pteridopsida (true ferns)
       7  Plesion Pertica
       8  Progymnospermopsida%
      _a_ {{Spermatophyta}}
            (= Pinophyta + Magnoliophyta)

     Sorry Curtis, but your latest suggestions won't work.  Combining Horneophytopsida, Aglaophyton, and Rhyniopsida into a single plesion would just make that plesion paraphyletic (which I'm sure you don't want).  In fact, to totally cladify Pteridophyta, you would have to raise all the listed clades to Phylum level.  Furthermore, Phylum Pinophyta is paraphyletic with respect Phylum Magnoliophyta, so you would also have to raise all the Pinophyte classes to phylum level.  One of the major drawbacks of strict cladism is that it inevitably destroys the ranking system, and then they have the gall to blame the system of ranks when it can't properly handle the abuse.  Ranks work just fine if you don't abuse them.  Anyway, I am quite happy with the above classification, although considering your suggestion, I just might slide Progymnospermopsida back into the base of Phylum Pinophyta (as I did in 1994).  It depends on which of the two options is supported by the most clear-cut synapomorphy (and if that is congruent with your "less egregious" criterion, all the better).
  ---Cheers, Ken Kinman

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