Taxonomy of cacti

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habanerocat
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Taxonomy of cacti

Post by habanerocat »

Who has the final say in this? I'm a bit confused.......
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Acid John
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Re: Taxonomy of cacti

Post by Acid John »

Nobody!
You can make your own choice of which system you use.
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Terry S.

Re: Taxonomy of cacti

Post by Terry S. »

Acid John is spot on, but it might help to elaborate. Anybody can create a new taxon, for example a family, genus or variety, but it has to been done in accord with a thick set of rules called "International Code of Nomenclature for algae, fungi, and plants" for it to be valid. Once created a species can be moved between genera provide the move is again done in accord with those rules. As a consequence we can end up with a number of different but equally valid names for the same plant. Different botanists or amateur botanists can have quite different ideas about how plants are grouped together and proposals for name changes have multiplied in recent years as botanists have got new insights into plants' relationships by exploring their DNA. For the purpose of BCSS publications, the Society tends to stick with the nomenclature used in the "New Cactus Lexicon" and the "Illustrated Handbook of Succulent Plants", but in some respects these are becoming increasingly outdated as new information, particularly from DNA sequencing becomes available.

But please don't think that DNA analysis is infallible. The actual sequencing of the DNA does give a definitive result and one can identify the differences in the sequences for various plants. However this information then has to undergo a complex computer analysis to try and identify the order in which these changes might have occurred and this is the weakness, particularly since the botanists are likely to have little understanding of the algorithms that they are using.
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habanerocat
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Re: Taxonomy of cacti

Post by habanerocat »

Thanks for the replies.

I'll hardly be forking out for the New Cactus Lexicon any time soon. So would the Handbook Of Shows, available here, be a good starting point?

Sites like llifle.com and cactiguide.com seem to be good reference sites. What brought up this question is there seems to be a lot of mention of Aylostera around this place again. A name I thought was dead and buried many years ago.
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Tony R
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Re: Taxonomy of cacti

Post by Tony R »

habanerocat wrote: Mon Jun 24, 2019 12:18 pm ... Aylostera ... A name I thought was dead and buried many years ago.
See Ivor Crook's article in ESR for a good starting point and further references re. Rebutias et al.
https://www.essexsucculentreview.org.uk ... h-2015.pdf
If this link does not work for you, go to the ESR Home Page and follow the links (back issues, 2015) from there.
https://www.essexsucculentreview.org.uk
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ragamala
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Re: Taxonomy of cacti

Post by ragamala »

Terry S. wrote: Mon Jun 24, 2019 9:14 am For the purpose of BCSS publications, the Society tends to stick with the nomenclature used in the "New Cactus Lexicon" and the "Illustrated Handbook of Succulent Plants", but in some respects these are becoming increasingly outdated as new information, particularly from DNA sequencing becomes available.
Returning to the "hobby" after a couple of decades I was surprised to see how Hunt's naming was adopted, as the lumping process based apparently on morphology rather than newer scientific method (as you suggest) is in stark contrast to the feelings of many growers such as myself. I have a regard for scientists when they go by evidence, not so much when they go by predetermined bias. I can only assume Hunt's personal reputation in the UK played some part in this.

I still go by Backeberg. That's what I grew with, and what I understand.

But Habanerocrat don't worry. If you are like me, many of your plants will have through force of circumstance lose their labels anyway over some decades. Appreciate them for what they are, not for how they are named.

Unless you want to show......
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habanerocat
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Re: Taxonomy of cacti

Post by habanerocat »

One of the most difficult and time consuming parts of this hobby is naming and labelling plants and seeds that I've bought.
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KarlR
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Re: Taxonomy of cacti

Post by KarlR »

To me it seems that cactus taxonomy is muddier and more confused than ever with the "schools" of Backeberg (continued today by Lodé) and Hunt completely at odds with each other.

It's all well and good to say use whichever taxonomy you prefer, but when big online sites usually tend to apply one or the other it does matter for anyone looking online for identification and advice. Or when nurseries use one or the other taxonomy I'm sure it's confusing for anyone who hasn't paid much attention to the development of cactus taxonomy over the past decades. The same goes for reference books or specialist monographs on certain genera.

If you have a Neochilenia that you're uncertain about the identity of, how will you figure out what to call it? Calling it a Neochilenia is a bit outdated as that genus name is invalid. But is it a Neoporteria or Eriosyce? Or perhaps it fits Horridocactus or Thelocephala better? Both of those genus names are valid, but neither Hunt nor Lodé accepts them as good genera.

Or what about if you have an old Brasilicactus graessneri? According to Hunt that is a Parodia, while Lodé calls it Acanthocephala. The old name is fine to use (though when I think about it, it might be invalid according to Lodé), but as time goes by more and more people will probably know it as something else - as with Normanbokea or Neogamesia. It's practical to use the names that are most commonly accepted so you don't have to explain the name or add "formerly known as".

I do hold high hopes for DNA-based taxonomy, but for the amateur grower and collector, I do think a balance between DNA and morphology would be best. Right now it seems that the trend in morphology based taxonomy is the view by Hunt et.al. to look for similarities rather than differences, and to try to lump if possible. Whereas DNA-based taxonomy seems to argue very much in favour of splitting and resurrecting "old" generic names - almost following Backeberg.

Lodé is currently working on a continuation of his taxonomic work in which he will add descriptions for each species. Perhaps this might be the best version of cactus taxonomy we'll have for a very long time once it is finished, but I'm sure there will be lots of disagreement.

For my own part I pick and choose a bit based on what I personally feel "seems" right. It works for me, but as I grew up after Backeberg "went out of fashion" I find it a bit difficult to get used to some of the old genus names that have largely been out of use for a long time.
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Re: Taxonomy of cacti

Post by el48tel »

As a newbie I have followed the thread with interest. I was beginning to become very puzzled and confused as I was trying to find specific plants on the Web, in the cactus nursery, and in reference books. So now I do my research with a little more sceptical care because I have looked to purchase certain plants only to meet chaos in the nomenclature.
So I've nearly totally gone back to ..... if I like it when I see it I'll buy it.
Endeavouring to grow Aylostera, Echinocereus, Echinopsis, Gymnocalycium, Matucana, Rebutia, and Sulcorebutia. Fallen out of love with Lithops and aggravated by Aeoniums.
Currently being wooed by Haworthia, attempting hybridisation, and enticed by Mesembs.
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Re: Taxonomy of cacti

Post by Paul D »

A thorny subject for which there is a great deal of heated argument. But the fact is, there is no correct answer. The concept of "species" does not fit very well with the plants we like to grow, most of which are undergoing evolutionary radiation; and on top of this, there are several different ways of interpreting most taxonomic results, depending on the weighting put on different features / genes, the particular plants chosen, and (dare I say) the predilections of the researchers.
Luckily when most revisions are made, an explanation is given, so we can read up on it and make up our own minds.
Regarding Aylostera, for me (not being a taxonomist), the argument made by Mosti, Bandera & Papini in 2011 were plausible and seem to be generally accepted by some growers and botanists, so that's the revision I'm currently sticking with as far as Rebutia / Aylostera / Mediolobivia are concerned. But I accept that many might disagree. The name is nevertheless just a convenient label- for me the field collection number is more important, when it gives the location where the plant grows, the habitat, who collected it, when it was collected, and refers to a particular package of genes. To this end, it is a disaster when people selectively breed, cross-breed, select sports, take seed from plants where cross-fertilisation was not prevented, etc. and then give the progeny the same field collection number as the parent.
Paul in North-east Scotland (Grampian Branch BCSS)
National Collection Rebutia, Aylostera & Weingartia (inc. Sulcorebutia). Also growing a mixture including Ferocactus, Gymnocalycium, Lobivia, Mammillaria, Lithops, Gasteria, Haworthia.
http://www.rebutia.org.uk
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