Use of the rank of forma

[Zdenek Skala]

Hi all,
There is no formal stabilization of the rank forma (nomenclatural
code of course has nothing to do with this), so it can be stabilized
by taxonomical practice only. However, I feel that there exist
situations which deserve use of this rank - as far as we want to
manage biological diversity by *naming* it. Forma is traditionally
applied to deal with the variation on the individual level. Since there
exist species which have enormous individual variation (not
necessarily in single characters - see e.g. Erodium cicutarium that
possess complex individual variation) forma is a good tool for
"typology" of such individuals. Even more is this approach useful
when the "formae" represent some well-defined extremes of the
variation continuum. Overview of such typologies (esp. as some
simple charts) are better descriptions of the complex variation
patterns than description in the common language, in my opinion.
Best!
Zdenek

Date sent:              Sun, 1 Oct 2000 22:44:35 +0000
Send reply to:          Jacques Melot <jacques.melot at ISHOLF.IS>
From:                   Jacques Melot <jacques.melot at ISHOLF.IS>
Subject:                Re: Use of the rank of forma
To:                     TAXACOM at USOBI.ORG

>  Le 1/10/00, à 17:53 -0400, nous recevions de John McNeill :
>
> >Like Richard Jensen, I have never felt that there was a biological
> >situation for which the rank of forma was useful; "white-flowered
> >variant" or "glabrous glumed plants" are more informative than
> >"forma alba" or "forma glabra" (in that the white or glabrous organ
> >is indicated).  I cannot remember, however, any proposal to remove
> >the rank from coverage by the International Code of Botanical
> >Nomenclature.  Personally, I think its main period of use has passed and
> >was for single-character (and often single-gene) distinguished
> >individuals that "caught the eye", and that had its heyday before the
> >advent of the International Code for the Nomenclature of Cultivated
> >Plants.  Now, if the human eye is caught in a way that makes cultivation
> >of the variant desirable, the cultivar category under the ICNCP is
> >clearly the appropriate one to use Ø particularly as it let's one
> >distinguish all sorts. say, of different white heathers, with different
> >foliage features, flower size etc. Ø whereas all might be accommodated as
> >_Calluna vulgaris_ f. _alba_
> >
> >But the ICBN, like the ICZN, does not seek to influence taxonomic
> >practice, merely to provide the mechanism for unambiguous naming of
> >taxonomically recognized groups.  If, some day, use of "forma" has
> >totally atrophied, it may be removed from the Code, but whether
> >included or excluded, the decision on usage is a taxonomic not a
> >nomenclatural one.  [Of course, the zoological Code does not
> >regulate any rank below subspecies Ø except indirectly to declare
> >that early varieties are to be treated as subspecies].
> >
> >John McNeill
> >
> >---------------------------------------------------------------------
> >-------------------------- John McNeill, Director Emeritus, Royal Ontario
> >Museum;
> >    Honorary Associate, Royal Botanic Garden, Edinburgh.
> >Mailing address:
> >Royal Botanic Garden, Edinburgh, EH3 5LR, Scotland, U.K.
> >Telephone:    +44-131-248-2862;  fax: +44-131-248-2901
> >Home office:  +44-162-088-0651;  fax: +44-162-088-0342
> >e-mail:  jmcneill at rbge.org.uk or johnm at rom.on.ca
> >---------------------------------------------------------------------
> >---------------------
>
>
>
>     Le rang de forme est encore tres utilise en mycologie (les
> nomenclaturistes non mycologues ont trop tendance a oublier ce
> domaine de l'histoire naturelle!).
>
>     De plus, la suppression du rang de forme serait peu compatible -
> dans l'esprit et a la lettre - avec l'art. 4.3:
>
> 4.3. Further ranks may also be intercalated or added, provided that
> confusion or error is not thereby introduced.
>
>     En realite, si le rang de forme (ou un autre) n'est plus utilise, il
> n'est pas necessaire a priori de le supprimer du Code. De plus, il est
> necessaire que le Code indique comment traiter les formes deja publiees.
>
>     Jacques Melot (Reykjavik, Islande)
>
>
>
>
>
> > >>> Michael Chamberland <chamb at U.ARIZONA.EDU> 09/29/00 05:40pm >>>
> >I'm under the impression that the continued use of the rank of forma in
> >botany is generally discouraged.  Especially so for the "classic"
> >application of naming sporadic flower color mutants (usually
> >white-flowered individuals in typically red or purple-flowered plant
> >populations, the white flowers presumably the result of blockage of
> >anthocyanin production).
> > I can think of some arguments for not naming such plants as forma. 1) as
> >defined by a single character, white-flowered plants cropping up in any
> >population of the species may be referred to under this forma epithet,
> >even when the lack of anthocyanin expression may have been independently
> >derived or under different genetic control.  2) Anthocyanin-lacking forms
> >have been described in genera through much of the plant kingdom, and are
> >to be expected to be noticed among most flowers conspicuously colored
> >with this pigment.  3) The host of different forma epithets applied for
> >these plants are more confusing than referring them in the common
> >vernacular as "white-flowered forms".
> >
> >My question is, should we continue to use the rank of forma for the
> >occasional sports which differ from the norm on the basis of one
> >character such as the loss of red pigmentation, loss of spination, loss
> >of hairiness, etc.?  Are there arguments for continuing to use this
> >taxonomic rank for such plants?  If not as forma, what would be the best
> >nomenclature to use for these plants, while avoiding confusing them with
> >cultivar names?  I have heard that attempts were made to remove the rank
> >of forma from the botanical code but these were unsuccessful.
> >
> >Thanks,
> >
> >Michael Chamberland
> >Assistant Curator
> >University of Arizona Herbarium (ARIZ)
>


++++++++++++++++++++++
] Zdenek Skala
] e-mail:
] skala at incoma.cz