Saturday, 24 November 2007

Chocolate teapots and cultivars

The continued use of the term x hortensis when describing Canna cultivar names must be the most useless naming convention in existence. It is apparently used to identify a variety as being a horticultural creation and not a wild species. I have not been able to identify a formal definition, although I have seen it attributed to a Professor André Guillaumin, and it is reasonable to assume that he must have defined it's usage in a learned journal at sometime.

However, it is well beyond its sell-by date, just consider it being used on a cultivar, such as Canna x hortensis
'Moonbeam'. The fact that the name Moonbeam is non-italic and surrounded by inverted commas tells us immediately that it is a cultivar. Why use a made-up species-type name to indicate that it is a cultivar? That is not only belt and braces, but string as well! A totally useless convention, only used by people trying to impress the uninitiated. As much use as a chocolate teapot!

Canna (Crozy Group) 'John Layden', shown here for no good reason; other than I like it, and wanted to share it!

Then we should consider the two garden species names invented by the great Professor Liberty Hyde Bailey. Following the practise of the day he resolved to solve the problem of accurately categorising Cannas by creating two separate garden species names, namely:

  • Canna x generalis, which is a hybrid shorthand for C. glauca x C. indica x C. iridiflora
  • Canna x orchiodes, which is a hybrid shorthand for C. flaccida x C. generalis

These hybrid shorthands were formally defined in the following learned journals:
  • Canna x generalis. Hortus, 118 (1930); cf. Standley & Steyerm. in Fieldiana, Bot., xxiv. III.204 (1952).
  • Canna x orchiodes. Gentes Herb. (Ithaca), 1 (3): 120 (1923).
Following the convention of the day, these two names are describing the internals of the plant, its genetic make-up, or genotype. But we cannot see DNA and we don't know if the term is being used correctly by visual inspection of the plant, i.e. the phenotype. The use of such garden species names for cultivars has long been deprecated. Inevitably, cultivars of both types became crossed, and people were not sure which term to use, and confusion reigned.

Then we had the absurd suggestion made in a gardening book that as we are all confused, we should simply drop the use of x orchiodes altogether, and just use the term x generalis for all cultivars instead. It simply isn't acceptable to informally redefine an accepted scientific term in that manner. But, even more important, it brings us full circle. Somebody has just created a competitor for x hortensis! That is like creating a competitor for a chocolate tea pot! The name Canna x generalis 'Moonbeam' is just as pointless as Canna x hortensis 'Moonbeam', unless you are sure that Moonbeam contains only the DNA of C. glauca, C. indica and C. iridiflora.

If we want to achieve what Bailey attempted to create, i.e. a workable categorisation mechanism, then the International Code of Nomenclature for Cultivated Plants (ICNCP) gives us a far superior and more understandable mechanism, i.e. the cultivar group. The species behind our modern cultivars are so confused that attempts to identity them visually by the genome are doomed to failure. Humans classify things by what they see and creating a group of similar cultivars is the only thing that can possibly work, unless somebody created a group resulting in Canna (Cultivar Group) 'Moonbeam', another chocolate teapot!

A link to the Wikkipedia definition of cultivar groups:

Incidentally, the term cultivar was created by Professor Bailey, one of my all-time heros, from the joining together parts of the two words CULTIvated VARiety. Not many people know that.

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