[Taxacom] Pteridophyta

Peter Stevens peter.stevens at mobot.org
Sat Jul 25 10:40:09 CDT 2009

Curious discussion... I don't think paraphyletic groups are  
meaningless; they often tell you a lot about evolution if you look at  
characters at the nodes/along the internodes (e.g. ANITA grade in  
angiosperms).  Naming is a separate issue. One can extract all sorts  
of information from phylogenies if you do not get hung up over  
classifications.  But pteridophytes are curious; I always think first  
of ferns when somebody says "pteridophytes" (cf. Wikipedia), and they  
would be monophyletic f the include the assemblage of taxa that they  
have recently incorporated - Psilotum, Equisetum, etc.  Ultimately it  
is well supported trees that matter, or an understanding of why there  
is poor support and/or conflict, and oodles of lovely morphology s.l.

To invoke the great unwashed out there - a.k.a. Google - is a  
difficult one.  As a "scientist", my classifications are for my  
peers, and why I should worry about what are au fond folk  
classifications I have never understood. There may be things of  
interest in them, but they have their own particular spheres of  
applicability.  Also, I am a firm believer in the ultimate  
educability of "the public", even if it happens only gradually;  
Google is mapping the present and the past, but we may reasonably  
think of a future.  We have found out so much over the last thirty  
years or so, with the possibility of thinking in new (to most of us)  
conceptual frameworks, that changes will inevitably be in order  
(please, I do not want to hear about what people of  
moderation/"sensible"people might do). End of sermon!

And who is to say what is hogwash and propaganda? I might think that  
of some of the pronouncements of the evolutionary school, and there  
is indeed h. & p. by taxonomists of all persuasions out there, but it  
does little for understanding to try and tar what you think of as  
your opponents with it - even with the caveat "strictly cladistic".


On Jul 24, 2009, at 10:30 PM, Kenneth Kinman wrote:

> Hi Jim,
>       Phylogenetically the taxon Phylum Pteridophyta is indeed not a
> single clade, but to call it "meaningless" just because it is
> paraphyletic is frankly just another case of strictly cladistic  
> hogwash
> and propaganda.  You call people wrong to consider Pteridophyta a good
> taxon in which to express their interest.  But those "heaps of people"
> would consider you equally wrong in criticizing them for studying a
> paraphyletic taxon just because it happens to exclude that taxon's
> spermatophyte descendants.
>        Consider the fact that before spermatophytes evolved,
> pteridophytes were the only tracheophytes in existence.  In other  
> words,
> pteridophytes were a clade before one of them happened to give rise to
> spermatophytes.  Therefore it is hardly a meaningless taxon.  It is
> really no different than criticizing people who specialize in studying
> reptiles just because Reptilia happens to be paraphyletic.
>         --------Ken Kinman
> --------------------------------------------------------------
> Jim Croft wrote:
> There are heaps of people around the world who profess an interest in
> 'pteridophytes', even 'Pteridophyta'.  Even though based on compelling
> evidence, it seems to be phylogenetically quite meaningless, dare I  
> say
> 'wrong', to do so.  But, as a concept it is meaningful to them in  
> their
> context.
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