classification

Janice M. Glime jmglime at mtu.edu
Thu Apr 6 16:21:03 EST 2000


Plant-edders,
  I need your help in understanding the rationale for the names currently
in textbooks for the divisions/phyla of plants.  While the International
Code of Botanical Nomenclature does not require that the type concept be
followed up to the phylum/division level, they do recommend it, and it
makes more sense and is more stable.  However, introductory textbooks seem
to be following a system for which I cannot find the rationale.  On the
one hand, I do not mind using descriptive names like Coniferophyta or
Anthophyta, but I do not understand the origin of the following: 

Lycophyta
  This is not the traditional descriptive name, which is Microphyllophyta,
nor is it based on the type concept using Lycopodium as the root genus of
the phylum, which would be Lycopodiophyta.  What is its origin and what is
the rationale for using it?

Sphenophyta
  Same problem.  The traditional descriptive name is Arthrophyta.  The
type genus (without using fossils) is Equisetum, providing the phylum
name Equisetophyta. What is the rationale for using Sphenophyta? 

Pterophyta
  Again, why not Polypodiophyta or Pteridophyta.

  Why Psilophyta instead of Psilotophyta (except for those putting in in
Pterophyta).

  I know where the bryophyte phyla names came from, and have discussed
Hepatophyta, Marchantiophyta, and Jungermanniophyta with liverwort
systematists.  There seems to be a preference among the experts and recent
publications for Marchantiophyta, based on Marchantia as the type genus,
as well as being widely known.  However, textbooks are using Hepatophyta.

  Since the general biology and general botany books now seem to be
switching to divisions (now that the International Code says Phylum is an
allowable equivalent term) and switching to the names above, I find this
to be a more difficult presentation to make to students because I cannot
justify it.  I'd love to hear the thoughts of other teachers of plant
science and to hear why these non-type non-descriptive names have emerged
in current textbooks.

Thank you all,
Janice
***********************************
 Janice M. Glime, Professor  
 Department of Biological Sciences
 Michigan Technological University
 Houghton, MI 49931-1295
 jmglime at mtu.edu
 906-487-2546
 FAX 906-487-3167 
***********************************


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