What’s in a Name?!

[SpikyMike]

New to this forum and BCSS. HI.

Trying to get my head around taxonomy. Have been looking at Llifle.com. Seems a great resource. But am puzzled re names. For example as far as I can see ppl refer to Domino cactus as [i]Echinopsis subdenudata[/i]. But on Llife it says Accepted scientific name is [i]Echinopsis[/i] [i]ancistrophora[/i]. So what name should one go for? Who decides what is [i]accepted[/i] or not? I know the name is not what’s so important. It’s the beauty of the plants that count. But interested what the experts think. Cheers

[Phil_SK]

They've picked a reference book and are using that as a basis for their list of accepted names.

[rodsmith]

Over the years many species have been moved from one genera to another, on what might be considered the whim of plant scientists (in some cases with good reason). A prime example is the genus Lobivia, which was originally used to classify many cacti that originated in Bolivia (Lobivia is an anagram of Bolivia). Some years ago the genus Lobivia was moved en bloc to Echinopsis. However many growers (including me) still use the original name, which can lead to confusion. More recently, DNA testing is being used to determine the true family relationship of our plants and this could result in changes to genera classification.

[cactuspip]

Another problem is there are "splitters" and "lumpers".
Splitters tend to see every small variation in plants as the evidence to give separate names and so salami-chop species to give a plethora of names.
Lumpers take an opposite view and seek to allow for natural variation in nature to reduce the number of names.

Generally I tend to label plants with what is accepted by the majority of sensible growers. If you change labels every time a revision occurs you end up confused and with piles of labels!

A good example is Notocactus becoming Parodia. Most people would not argue one way or the other.

[KarlR]

Is DaveW still banned? He'd say that splitting and lumping comes and goes as the big «fashion» of the day. And that any name validly published is perfectly fine. Which is right, of course. Although I think it makes the most sense to use the most commonly and widely accepted names - at least if you're not used to any «older» names.

Currently, sites like llifle uses David Hunt's system of taxonomy to say what is the accepted name. His may be the most accepted taxonomy used in scientific papers and sites like llifle (as well as the basis for the CITES Cactaceae Checklist), but it's far from the only one. Joel Lodé recently released a huge tome on taxonomy of the Cactaceae based mostly on collated genetic studies over the past two decades. His taxonomy is almost diametrically opposed to that of Hunt's. Where Hunt's taxonomy is largely that of the «lumper», Lodé's is more that of the «splitter».

Newer genetic studies do show that e.g. Rebutia cannot include Aylostera, and that Hunt's view of a very large Echinopsis genus isn't really working unless it's expanded even further. I believe Hunt is working on an update or a new version of his New Cactus Lexicon, and I would expect to see far less lumping in that. Most of the newer genetic studies I've seen seem to favour more rather than fewer genera within the cactus family.

One big problem for the taxonomists trying to create an overall taxonomy for the whole family is that they simply cannot be familiar enough with all the genera to not make oversimplifications based largely on cultivated material instead of habitat field studies. Usually, scientists specialising in one genus will accept more species and varieties than someone more superficially acquainted with the genus.

[rodsmith]

Is DaveW still banned?

I didn't know he was banned. For what reason? He is one of our most prolific posters.

[KarlR]

I didn't know he was banned. For what reason? He is one of our most prolific posters.

He had a bit of a disagreement with ragamala over Brexit, and didn't quite heed Bill's warning to leave it be. Hopefully he'll be back again soon. Anyway, we should stay on topic, so probably best to leave it at that.

[D^L]

Cactuspip makes a good point that there are different opinions, to split or lump or...
Partly this depends on what you want the name to tell you. Biologists probably have different priorities to most cultivators. Most cultivators want the plant they buy to look like the nice one they saw in the book, the one with the long red spines.
Frankly given the variability of the plants this can be difficult to achieve. From a biologists' point of view this might drive towards lumping, since it is hard to draw lines between the different populations. For a grower though I would err on the side of keeping the splitter names rather than making a difficult situation even worse by ascribing a single name to very different plants.
None of this is perfect, just suggesting you hang onto split names rather than renaming to a large "lumped" name.
Looking further abroad, lumping lots of populations with small differences into one broad species is probably bad for concervation. Concervation strategies use the species (or subspecies) name as the determinator. If the species is widespread there is no protection for each unique population. If each population has a name they are now rare and may gain some measure of protection.
Cheers
David Lambie
Bristol

[SpikyMike]

Wow! Great series of very thoughtful posts! Lots of reference to genera. I’m also intrigued by how species even within same genus can morph taxonomically. My rudimentary understanding of a unique species is that it differs from other species by generally not being able to interbreed between species and produce viable offspring (interbreed = cross-pollinate in plant speak). But am I right in understanding - eg in Echinopsis sps. They can readily cross-pollinate between two distinct species within the same genus? I guess it all illustrates how complex and fascinating evolution is - a continuum- not a binary!

[KarlR]

I agree with David that as a collector it makes more sense to keep the «splitter name» as it were, rather than a lumped name.

Take Rebutia pygmaea as an example. It was originally placed in Rebutia by Britton and Rose, I believe, before Krainz later put it in the genus Mediolobivia. Most later authors didn't favour that genus and kept pygmaea in Rebutia (including the genus Mediolobivia in Rebutia). Now, the latest genetic studies on Rebutia suggest that the genus Aylostera (included in Rebutia by most authors) cannot be included in Rebutia after all. And since Mediolobivia is closer to Aylostera than the now much more restricted Rebutia, authors such as Joel Lodé includes Mediolobivia in Aylostera, which means that Rebutia pygmaea is now Aylostera pygmaea.

Whatever you decide to call it, the "lumper" would be inclined to call every variety of R. pygmaea as simply R. pygmaea and be done with it. The "splitter", on the other hand, would likely opt to stick with the 20 or so varietal names described to the various populations of R. pygmaea. So that if you want to grow pygmaea var. minor or var. diersiana, or var. torquata you seek out those specific varieties and grow them, instead of sticking to that one form of pygmaea you have and call it a day. For the collector those names are extremely useful. Some might argue that it would be better to use field numbers or location names to describe the various forms rather than scientific names, but I think it is far easier to talk about various forms in terms of names rather than numbers.

For the taxonomist however, these varietal names mean little and probably just add noise to the picture. The problem for most collectors is when they go a bit overboard in lumping species and genera together in order to try and clarify the taxonomic picture. Hunt writes on Echinopsis in his New Cactus Lexicon that: "Current botanical opinion favours uniting several popularly recognized but closely interrelated genera under Echinopsis, pending a better understanding of the group as a whole." And just like that, the genera Lobivia, Trichocereus, Soehrensia, Helianthocereus, Setiechinopsis, Acanthocalycium, Chamaecereus and Pseudolobivia were now Echinopsis. Some of these genera were in little use and hardly missed, but the lumping of some of the others were harder to accept for many. With this large Echinopsis group most likely not being viable (not monophyletic unless further genera are added), I assume it will most likely be split up again if Hunt creates an update to his lexicon. In the meantime this lumping will most likely only have contributed to the chaos in these complicated genera.

Joel Lodé on the other hand, in his Taxonomy of the Cactaceae, keeps Echinopsis, Setiechinopsis, Acanthocalycium, Lobivia, Reicheocactus and Trichocereus of the above as accepted genera. Some might argue he goes too far in the other direction, but to me this is a much better approach while awaiting further, more detailed genetic studies. Lodé does the same with Hunt's expanded Parodia, Sclerocactus, Eriosyce, and others.

As for the species concept, it really doesn't work that way with cacti. A lot of cacti within genera (and across genera) will interbreed under artificial circumstances, although it's not as common in the wild. There are still hybrid populations though. Ariocarpus confusus may be a hybrid population between A. trigonus and A. retusus (although it may also be a separate species), and Turbinicarpus X mombergeri is a naturally occurring hybrid population between T. laui and T. pseudopectinatus. But all the Ariocarpus species can interbreed in cultivation, and most of the Turbinicarpus species can too. So that definition of what constitutes a species doesn't work for cacti.

Species in cacti are (currently) based mostly on morphology (including flower structure, seed structure etc.), distance between populations in habitat, and then perhaps on further distinguishing details like flowering season, substrate, altitude and so on. There are also a few species separated based on molecular studies - some species from the Echinocereus coccineus complex I think are now accepted as "good" species. Correct me if I'm wrong, but I believe E. transpecosensis and E. arizonicus are now accepted as "good" species? This is from memory, so take it with a slight pinch of salt in case I'm misremembering...