Phylum Pteridophyta (classification modified)

Ken Kinman kinman2 at YAHOO.COM
Sun Mar 13 18:42:23 CST 2005

     Of course, your right!  I should have realized that Pterophyta was just an inflated Pteropsida.  But even without Pterophyta, that still leaves us with 6 names for true ferns (Filicophyta, Polypodiophyta, Pteropsida, Filicopsida, Polypodiopsida, and Pteridopsida).  Class Pteridopsida (true ferns) is actually probably a better choice than Filicopsida!!!  So this wasn't totally the fault of the strict cladists after all----they just took advantage of the confusion to more easily get rid of another paraphyletic group (namely, the traditional Pteridophyta, encompassing seedless vascular plants).  Very clever!!  Anyway, substitute Class Pteridopsida for Filicopsida in my just posted classification of Phylum Pteridophyta.  Thank you Curtis, that is an improvement.

     As for the zosterophyllophyte-trimerophyte split, my classification reflects that perfectly.  Zosterophyllophytes at the base of Class Lycopsida, and Trimerophytes at the base of the Euphyllophyte clade.  What's the problem?  The coding shows Lycopsida to be sister group to everything below it (euphyllophytes).  You can mark the euphyllophyte clade in the margin of the classification if that makes my coding easier for you to understand.

     And if you want to group Archaeopteris with Cycas, that's great.  I actually did that in my 1994 classification by shifting Class Progymnospermopsida into Phylum Pinophyta (as the basalmost Class).  It's the same cladistic topology, but just shifted the dividing line (between Pteridophyta and Pinophyta) up one branch (or down a branch, depending on how your cladogram is oriented).  I asked a prominent paleobotanist whether that was a good idea, and he said either approach would have its advantages.  Anyway Curtis, thanks for that observation too, and perhaps I will leave it that way afterall (and glad to know that what I did in 1994 corrected such an egregious error).  The only thing I regret is having used Pteropsida instead of Pteridopsida for the true ferns (but like you said, it's the same word).
   ---Many thanks,
            Ken Kinman
Curtis Clark wrote:
     This is just stupid. Pteridophyta and Pterophyta are the same word, based on a disagreement on whether the genitive of Pteris (a latinized Greek word) is Pteris or Pteridis. (Pteris is by the way a leptosporangiate fern). Because Phylum names are not covered by priority in the ICBN, they can be and have been used interchangeably. While the ranking of true ferns as a phylum is certainly subject to legitimate debate, calling that phylum Pterophyta or Pteridophyta has been the norm in basic botany textbooks for a decade or so (Raven et al., _Biology of Plants_, only separated the bryophyte phyla in the mid-1990s, but Pter(id)ophyta has been used for the ferns as far back as I can remember).
(And totally aside from cladistics, I am a proponent of naming taxa on types even when it is not required, so I would call your Filicopsida "Pteropsida" [or Pteridopsida] instead.)
It's one thing to support paraphyly; I understand the arguments, although I disagree with them. It's another thing altogether to ignore the bountiful evidence from palaeobotany (the trimerophyte- zosterophyllophyte split), morphology, and molecular studies that the lycophytes are sister to the rest of the extant vascular plants. And it is especially egregious to group together Lepidodendron and Archaeopteris in a taxon that excludes Cycas.

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