Date: Tue, 24 Feb 1998 08:24:25 From: SCHLAUER@chemie.uni-wuerzburg.de To: cp@opus.hpl.hp.com Message-Id: <aabcdefg732$foo@default> Subject: Re: On Cultivars (and Taxa)
Dear Richard,
> I think this is analagous to why F1 hybrids are quite consistent
> in appearance while F2 hybrids will have much greater variation.
This is correct. Nevertheless, the variation is still within given
limits (it does not reach *beyond* the species involved). This is the
essential point for taxonomic considerations.
> >> Is this
> >> one of those cases where there is a lot of "theoretical variation"
> >> but in practice all (for example) (S. x mitchelliana) x (S. x
> >> formosa) crosses look pretty much the same?
> >
> >You do not talk about cultivars in this case. Both hybrids are taxa,
> >and at least theoretically, the complex hybrid is again a taxon. This
> >latter taxon will include all intermediates between the species
> >involved (_S.leucophylla, minor, psittacina, purpurea_).
>
> True, I am not talking about cultivars in this case (or above). And
> I think I am questioning the usfullness of giving a name to a group
> of plants that includes all intermediates between those 4 species.
But this is essentially what a taxon of the given parentage would do
(whether sensible or not).
> If my understanding of cultivar is correct, there should
> be no genetic variation of cultivars (or the only genetic variation
> should be from spontaneous mutation of the cells that allow asexual
> reproduction?)
In an ideal world, this would be correct. There is no life without
genetic variation, however.
> >> On a related note. Are many of the morphologic characters of
> >> Nepenthes sex linked? If they are, then it seems that having
> >> different names for essentially the same cross (only by opposite
> >> sexed parents) makes sense.
> >
> >Not at all if they are treated as taxa. In this case, the direction
> >(and any repetitions) of the cross is entirely immaterial.
>
> Perhaps this example will elucidate my confusion: Are
> N. x wrigleyana and N. x coccinea examples of taxa or cultivars
> or neither? I was thinking these were considered taxa and the
> only difference between them was the sex of the parents.
Both belong to the same taxon (not cultivar) and are later synonyms of
N. * stewartii.
Kind regards
Jan
This archive was generated by hypermail 2b30 : Tue Jan 02 2001 - 17:31:29 PST