Use of the rank of forma

[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 ― particularly as it let's one distinguish all sorts. say, of different white heathers, with different foliage features, flower size etc. ― 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 ― except indirectly to declare that early varieties are to be treated as subspecies].

John McNeill

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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
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>>> 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)