[pbs] Taxonomic Changes
Mary Sue Ittner
msittner at mcn.org
Tue Jul 1 12:40:14 EDT 2003
Dear All,
Yesterday I got my IBSA (Indigenous Bulb Association of South Africa) Bulb
Chat #36 which I always find fascinating. This issue is a collaborative one
so I don't know if the article below was written by Alan Horstmann, the
current editor, or Andries de Villiers, the previous one. I'd suspect
Andries, but it doesn't have his name on it so I could be wrong. Perhaps
Rachel could help me to give credit where it is due. I don't see a
copyright anywhere so I hope it is o.k. to include this with the source
information.
Background: A couple of years ago the Manning-Goldblatt team reduced
Homeria, Gynandriris, Hexaglottis, and Galaxia into Moraea, an already
large genus. The IBSA members were especially unhappy about Galaxia as it
more than any other of the disappearing genera resembled Moraea the least.
There were protests and editorial comments. It is perhaps because of this
that in the new Color Encyclopedia although all these are now listed under
Moraea the key in the back of the book divides them into subgroups by the
former genera. Although the article below may still be a bit too scientific
for some of us gardener types I thought there are members of this group who
are also unhappy with some of the changes who would appreciate it, so am
copying it below as written in BULB CHAT.
Mary Sue
THE TAXONOMIC REVOLUTION
We are living through a revolution. For 250 years we have been loyal to the
Linnaean concept of cognate species grouped together into genera. A genus
comprising those species which shared a common or several common
characteristics based primarily on a set of morphological characteristics
could be described and defined to distinguish it from any other genus. In
comparatively recent years a genus could be drawn as a cladogram to
demonstrate the mutations that must have occurred in the course of
evolution to produce the separate species. It was a tidy, logical and
understandable progression not interrupted by specimens of other genera.
Now we are being subjected to a taxonomy based on DNA analysis, a science
still in its infancy, which discards morphology as the determinant of
relationship and substitutes genetic proximity. We in IBSA were first
subjected to it by the revision of the genus Moraea which sunk the genus
Galaxia into the middle of Moraea. None of us liked it but few of us
realized the implications. Now if we were to draw a diagram of relationship
we would have to extend a straight line or several straight lines along
which species of different genera are interspersed. We would be creating a
complex but, unlike a genus, the component species would have no common
identifiable characteristics. Such a complex could not be defined. Genus
was an inclusive concept, the component species all and only those which
shared the determining characteristics. A DNA complex would include many
components which had diverse characteristics and, moreover, would separate
similar species by utterly different ones. When DNA taxonomy is applied to
Lachenalia, Polyxena and who knows what else we will find various
Lachenalia and Polyxena mixed helter skelter along the lines of relationship.
We need to remember one of the abiding features of a revolution. The
generation which begins it is not the generation which refines and
developes it. A younger generation takes over and introduces new and
exciting applications. At present the Botanists who are leading the
revolution are still imbued with the Linnaean concept and will try to apply
generic names to non generic complexes. They will try to make definitions
of disparate specimens. No doubt a new generation will devise a taxonomy to
take care of it all but it is doubtful whether any of us will live to see
it. Meanwhile we must stick to names that we can understand. To us a
Galaxia is still a Galaxia."
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