Scilla and Taxonomic changes

Lee Poulsen
Wed, 12 Jan 2005 10:29:45 PST
As much as I admire the work done by people like Manning, Goldblatt,  
and other experts in this area (such as Alan Meerow), even though I'm  
no expert nor do I have college course training in this field, I think  
they've pushed the definition of what a species or genus is or is not,  
according to DNA analysis, too far. Who decides the cut-off point in  
DNA similarity beyond which we will say two different plants are  
different species, or different genera? How did these researchers  
decide on their metric? Since there isn't any hard and fast definition  
about what a Genus is or isn't, but there is this sense that  
growers/hobbyists have, analogous to the U.S. Supreme Court justice's  
statement about how to determine if something was obscene or not: "I  
know it when I see it." (See  
obscenity.htm>), it seems that that kind of thing should also be  
included in deciding whether a group of plants ought to be given their  
own genus name or not. Let us know that they are very closely related  
and that we could try hybridizing them. That would be great  
information. But I see no reason why they can't remain separate genera  
in name, since this is a descriptive term as well as an indication of  
some natural relationship. Maybe these DNA researchers ought to  
increase the importance of a Supergenus or Subfamily name so that we  
all begin to use that category as well as Family, Genus, and Species.

I've already stated on some previous occasion my objections to the  
lumping of Homeria, Gynandriris, (and others?) into Moraea and how  
every single site that sells these always puts the original genus name  
in parentheses next to it because people who grow them still separate  
them into different genuses. I do.

With respect to lumping Polyxena into Lachenalia, I grow quite a few  
species of Lachenalia and around 5 species of Polyxena. I never confuse  
the two and I never get them mixed up. It's great to hear that they are  
so closely related and belong to the same supergenus. Maybe there will  
be people who try hybridizing the two together. But I would never  
consider any Polyxena just another Lachenalia. They're different enough  
to not need to be put into the same genus in my opinion.

I'm even more amazed that these experts now consider Albuca, Dipcadi  
and Ornithogalum all the same. Why? Once again it's great to hear that  
they're all part of the same supergenus and again maybe some  
interesting hybrids might appear in the future. But I see no reason why  
I should just "lump" all my Albuca species' pots mixed in with all my  
Ornithogalum species' pots as if they were all permutations of the same  
general genus. I think even my 2-year-old would be able to separate  
those two groups from each other when in bloom.

Given the fact that research on the human genome is showing that there  
isn't a one-to-one correspondence between a gene on the DNA strand and  
a single trait in a human, and that even some of the non-gene parts of  
DNA may play important parts in determining the growth and  
differentiation of traits in any given organism, it seems a little too  
rushed to say that you can do a DNA analysis of only certain  
chromosomes or parts of chromosomes of a set of plants and based solely  
on the differences in those parts of the DNA be able to adequately  
determine quantitatively when two species ought to be classed in the  
same genus or not.

If I have to, I'll do the reverse of what the nurseries do and put the  
lumped genus name in parentheses on my plant labels next to the  
original, and IMHO better, genus name...    ;-)
All my opinion, of course.
--Lee Poulsen
Pasadena area, California, USDA Zone 9-10

On Jan 12, 2005, at 8:09 AM, Mary Sue Ittner wrote:
> Julian and I have been communicating privately about Polyxena as I had  
> a plant (grown as sp. #2) that bloomed and I wanted confirmation for  
> what I thought it might be. I hadn't shared this with the group as I  
> intended to do something with the Polyxena wiki page first and haven't  
> found the time or decided exactly what. Polyxena has been transferred  
> to Lachenalia by Manning, Goldblatt and Fay. Here is the resource:
>  J.C. Manning, P. Goldblatt & M.F. Fay, "A revised generic synopsis of  
> Hyacinthaceae in sub-Saharan Africa, including new combinations and  
> the new tribe Pseudoprospereae", Edinburgh Journal of Botany 60(3):  
> 533-568 (2004).
> Julian wrote to me:
>  "The article discusses an unpublished DNA study by the same authors,  
> and their results suggest a giant taxonomic upheaval for most of the  
> family, and they made the necessary numerous new combinations. Apart  
> from the sinking of Polyxena into Lachenalia: Drimiopsis and Resnova  
> were sunk into Ledebouria; Albuca, Dipcadi, Galtonia, Neopatersonia,  
> and Pseudogaltonia were sunk into Ornithogalum; Litanthus,  
> Rhadamanthus, Rhodocodon, Schizobasis, Tenicroa, Thuranthos, and  
> Urginea were sunk into Drimia; and Whiteheadia sunk into Massonia. At  
> the same time, they recognise the splitting of Scilla, but only for  
> the southern African species; no comment was made on the Eurasian  
> species. I've also noticed a dozen or so taxonomic errors; for  
> example, Dipcadi glaucum was renamed Ornithogalum magnum, which is a  
> name already used for an different species of Ornithogalum. All the  
> new combinations can be found doing an IPNI search  
> <> 
> query_ipni.html, making sure that both IK and GCI extended options are  
> selected."
> I don't know if  South African bulb enthusiasts are going along with  
> all these changes. I suppose I'll need to write a note on some of our  
> wiki pages explaining the proposed changes . Sigh. It is hard to keep  
> up with all of this.

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