Date: Sun, 2 Aug 1998 18:34:31 From: SCHLAUER@chemie.uni-wuerzburg.de To: cp@opus.hpl.hp.com Message-Id: <aabcdefg2566$foo@default> Subject: Re: Albino capensis
Dear Phil,
Although your message was perhaps intended for Barry's eyes only, I
am (and some others may be) interested in the contents as well:
> Attached is a copy of the original article describing the albino D.
> capensis.
Unfortunately, nothing was attached to the message I received.
> I'm not sure how this leaves the impending paper describing
> the plant as a cultivar but to me it looks as if the plant has already
> been described in this article.
I cannot tell much (as I have not seen the paper) but if the white
flowered plant was described as a *taxon* in the mentioned article
(you can recognize this easily if the text switches to Latin language
all of a sudden), still nothing can stop anyone describing such
plants as *cultivars* after that. A cultivar always *belongs to* a
taxon but it *is not* a taxon in the sense defined in the
International Code of Botanical Nomenclature (ICBN). The
International Code for the Nomenclature of Cultivated Plants (ICNCP)
calls cultivars, chimaeras, and cultivar groups "taxa" but these
items are not what a taxonomist would call taxa; this bit of
confusion will probably be eliminated in the next revision of the
ICNCP.
NB: All listeners who consider naming cps in the future and who are
not yet familiar with the provisions of the ICBN and the ICNCP are
kindly requested to take note of the rest of this message. All
listeners who are already fed up with nomenclatural details,
please skip the rest of this message.
Let me explain the difference (cf. also my article in CPN 27:27-28,
1998) between a taxon and a cultivar.
A taxon is a group of individuals which are considered to share a
common phylogenetic origin. Taxa are considered to reflect stages in
the natural process of the development of species.
A cultivar is the product of human efforts to select, maintain, and
improve particular plants because of desired traits. Cultivars have a
meaning for the horticultural market, they are not considered as
naturally occurring items of taxonomic significance.
Taxa are described and named scientifically according to the ICBN. A
scientific description consists of the full Latin name of the taxon
indicating its rank (species, subspecies, genus, etc.) and its
author, a Latin description or diagnosis highlighting the
distinguishing features of the new taxon, and the citation of a type
specimen, which must be a conserved individual or set of individuals
permanently stored and accessible to other scientists. The type
specimen must belong to the taxon but it does not need to (and it
realistically cannot) be representative of all individuals belonging
to the taxon. The description must be published effectively in a book
or journal generally accessible to Botanists.
Cultivars are described and named according to the ICNCP. A cultivar
description consists of the name of the cultivar composed of the
"denomination class" (usually a genus) to which the cultivar belongs,
the cultivar epithet (a fancy name in a modern language, included in
single quotes and beginning with a capital letter), a description of
the cultivar distinguishing it from all other described cultivars in
a modern language, and some additional data required for registration
by an International Registration Authority (IRA, the ICPS is the
forthcoming IRA for all cp cultivars). A standard has to be selected,
which must display all characteristics required for the unambiguous
identification of the cultivar. For cps, the standard must be a high
quality colour photograph or set of photographs.
Whether taxon or cultivar, the first published name for a plant has
to be used. A name already in use for a taxon or a cultivar may not
be applied to a different taxon or cultivar. A specific epithet must
not be re-used within a genus, a cultivar epithet must not be re-used
within a denomination class.
In taxa, *all* individuals fitting into the circumscription of the
taxon, irrespective of their resemblance to the type specimen belong
to the taxon including the type specimen (the species _Drosera
peltata_ belongs to the genus _Drosera_, of which the type is _D.
rotundifolia_; the subspecies _Sarracenia rubra subsp. gulfensis_
belongs to the species _S. rubra_).
In cultivars, *only* those individuals that match the cultivar
description and the standard belong to the cultivar (an anthocyanin-
containing plant derived by whatever means from an anthocyanin-free
individual belonging to _Darlingtonia_ ' Othello ' is no longer part
of the cultivar because ' Othello ' is defined to contain only
anthocyanin-free individuals).
If differences within a given taxon appear to justify the recognition
of separate entities, taxa at lower rank under the original taxon can
be defined (genera in a family, subspecies in a species, etc.).
If a cultivar proves to contain distinguishable individuals or groups
of individuals, a cultivar-group can be defined to contain all
individuals formerly recognized as the initial cultivar (if this is
considered useful). The separate entities can then be distinguished
as cultivars within this cultivar-group. Since all cultivars are
considered to be of *equal* rank, no nested classification of
cultivars (except grouping them in cultivar-groups) is possible.
Cultivar-groups may be overlapping (cultivars may be assigned to more
than one cultivar-group), no nested classification of cultivar-groups
is possible.
There is (or there should be) no conflict between taxonomic and
cultivated plant nomenclature because of the above mentioned
differences. If a given taxon is transferred to another taxon, this
does not have an effect on the cultivars belonging to that taxon:
If _Drosera_ ' Kansai ' was an established cultivar name, transfer of
_Drosera spatulata subsp. tokaiensis_ (to which _D._ ' Kansai '
could belong) to the taxon _D. * tokaiensis_ (because it is in fact
not a subspecies of _D. spatulata_ but a hybrid involving _D.
spatulata_) would not change anything for the cultivar, the name of
which would remain _Drosera_ ' Kansai '.
Returning to the initial problem, if a _Drosera capensis f. alba_ was
described as a taxon, this would contain also individuals that have
pink flowers but that are in all other features identical with the
form (if flower colouration was the *only* feature to distinguish
it, such a form would be of no taxonomic value, anyway). A truly
white-flowered individual belonging to the form could then be
selected as a cultivar, e.g. _Drosera_ ' White Angel '. This
cultivar could (but would not need to) be named more precisely _D.
capensis f. alba_ ' White Angel '. Since ' White Angel ' would
in this case constitute a cultivar epithet in the denomination class
_Drosera_, no other cultivar of any other taxon belonging to the
genus _Drosera_ could be given this epithet. Neither the description
of forms (or other infraspecific taxa) of _Drosera capensis_ nor the
establishment of other (distinguishable) cultivars precludes
establishment and use of ' White Angel '.
Kind regards
Jan
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