Yucca nana

[Tim Ingram]

Bob - very lovely painting! The past secretary of our local AGS Group was a fine botanical artist and we are aiming to display her work at the Spring Alpine Show we hold in Kent. It is a marvellous talent.

[Booker]

Another example of Cindy's magnificent artwork, Bob?  ... but what a legacy!

[Nold]

Yes, sorry, I forgot to mention that. She was working on a large drawing for an exhibit at RBG Kew.

Bob

[DesertZone]

Here is a couple.

[DesertZone]

Bob - very lovely painting!

I agree.

[Nold]

As far as I can tell, the only place where Yucca nana is accepted is in Hochstaetter's books. On the other hand, the only treatment of Yucca that I know that is the result of going out into the wild and looking at as many yuccas as possible, is also by Hochstaetter.
I noticed he was dismissed as a "hobbyist" in some publications, but who else has done as much field work? Especially in such as messy genus as Yucca, I would think that field work outweighed studying herbarium specimens in every respect. (I could be wrong.)

If you look at treatments of Yucca in various floras you will find almost no agreement at all as to the distribution of a number of species, not to mention reports that species grow in places where, in fact, they do not grow.

Bob

[Weiser]

If you look at treatments of Yucca in various floras you will find almost no agreement at all as to the distribution of a number of species, not to mention reports that species grow in places where, in fact, they do not grow.
Bob

I don't see this situation changing for the better. Field botanists and regional herbariums are finding it hard to get funding for projects and operations.The lion's share of current funding is being funneled into the genetic profiling of the plant kingdom. How is a geneticist sitting in an office even aware of what a species is supposed to look like, let alone be able to say were it's habitat begins and ends. How is he going to be able to tell the subtle differences, between varieties of a species, since they only test a very small portion of a specie's, genetic code in the first place? There seems to a push to make every species into a bar code, that you can scan with a hand held tricorder and positively identify. I don't see that happening any time in the foreseeable future. There are way too many plant species to begin dealing with. There are many university botany programs that have dropped their taxonomy classes in favor of genetic research. Were will the future taxonomists come from? Who will update the treatments and back them up with vouchered specimens?  With the climate changes predicted in the future, who is going to do the field research required to monitor the changes?
Lots of questions unanswered , but money talks!!

[Nold]

I don't see this situation changing for the better.

Cactus are a complete mess. Some species have 25 synonyms.
I don't find any treatment that recognizes Opuntia debreczyi (nor, for that matter, O. rhodantha). You probably couldn't find two botanists who even agree on what constitutes a species, let alone whether or not a specimen represents a species.

It wouldn't really matter except for the very real possibility of buying the same plant over and over again, but with a different name each time.

Bob

[Weiser]

Cactus are a complete mess. Some species have 25 synonyms.
I don't find any treatment that recognizes Opuntia debreczyi (nor, for that matter, O. rhodantha). You probably couldn't find two botanists who even agree on what constitutes a species, let alone whether or not a specimen represents a species.

I agree that cactus are a mess and Opuntias the worst of the lot!! Yes there is a lot of doubt out there about the validity of debreczyi. Rhodantha as a group needs study, to see if it has valid varietal standing.

Here in a somewhat lengthy write up on the "species concept" that I found a good read.

The concept of a species is a surprisingly difficult concept, perhaps because it is so basic to our understanding of the world. After all, virtually the first question most people ask is "what is it?"

That "what is it" concept is designed to group things into similar and different categories. Those categories can vary enormously. Sometimes they are more specific than a "species". For example, a Golden Delicious apple is different from a Macintosh apple is different from a Winesap. Sometimes less specific. "hardwood" vs. "softwood".

In modern biology, we not only have the concept "within group" vs. "different group", but we have added the concept first of grouping at different levels "Cactus" vs. "Opuntia" vs. "Opuntia fragilis" vs. "Opuntia fragilis. var. brachyarthra" , and we have added the concept of reproductive isolation at the species level. In other words, we want to believe that species X every individual within the species is capable of producing offspring with any other individual, at least of a different gender, and that species X individuals cannot produce offspring with members of another species. And, of course, this concept works reasonably well for many groups. Robins don't have babies with scarlet tanagers, and with only a few exceptions (chihuahuas and St. Bernards) individuals within a species can produce offspring with another individual in that species.

However, even though we've added that concept, in reality it is neither obeyed by many "species", nor is it measured by biologists attempting to define species. The oak tree in front of my house will happily try to have sex with almost anything, including my nose. Imagine, for example, if I tried to publish an article "Opuntia fragilis and Opuntia polyacantha naturally hybridize, and have numerous offspring in some parts of the world. Therefore, they should be lumped into one species..." And the inverse of the concept isn't even true, that within a species individuals should be capable of producing offspring. Opuntia fragilis, for example, won't let pollen from genetically similar individuals fertilize its eggs. Which leads to a real absurdity: two clones of Opuntia fragilis should be two different species???

Well, I'm digressing. But my first point is that the very concept of a "species" is a messy one, and those of us interested in cactus should know that the cacti are a great example of this messiness. Everyone should keep in mind that the very concept of a "species" is fragile in this group. Call it reticulate evolution, hybridization, morphological complexity ...

Second. We define species based on appearance (and now increasingly on rather arbitrary concepts of DNA).

Third. Without a touchstone of some external measurable reality to help us determine species, we are always going to have disagreements. Lumpers will lump, splitters will split. We can look for guidance in things like morphological variation, DNA variation, etc., but we are always going to hear "looks like ..." or "could be a hybrid" ...

Therefore. The very concept of a "correct" species nomenclature is rather arbitrary. I commend you for you desire to be accurate and up-to-date, and indeed I do the very same thing in the herbarium I curate for example. But think of the very concept of what some of your species of interest are ... think of that as a sort of extended conversation. Benson, sitting in the corner, remarks that it is X. Anderson disagrees. Dave Ferguson tells a long story about the last time he saw it, and thinks it is Z. This is why one of the most important pieces of a scientific name isn't the name at all, but the authorities at the end of the name. So when you see Opuntia fragilis (Nutt.) Haw. that is a sort of scientific shorthand saying "the group of plants that Nuttall described first, and called Cactus fragilis. Then later Haworth decided they really belong in a different genus, and moved them to Opuntia fragilis.

So. Enjoy your cactus. Keep track of who they are and where they are from. Love them (maybe not giving them hugs though). And remember that all of those names will persist as long as we keep records, so Cactus fragilis Nuttall and Opuntia fragilis (Nutt.) Haw. are both ways of referring to the same kind of plant. And remember that a species, and a species name, is a uniquely human concept. My Opuntia fragilis is trying hard to live and reproduce, and it doesn't care what species it is.

Well, I've rambled on far too long. Can you tell my students get really hung up on the species concept? And that I've been teaching long enough to get notices that I'm eligible to retire???

Dr. Eric Ribbens
Biology
Western Illinois University
Macomb, IL 61455

[Nold]

Cronquist was more succinct. "The smallest groups that are consistently and persistently distinct, and distinguishable by ordinary means."
Backeberg is said to have described a species from a moving train. (He was on the train.)
If you get seeds of Echinocereus triglochidiatus var. inermis, which is listed as an Endangered Species, you will get spineless plants, some with a few spines, and some indistinguishable from regular "trigs".
As you can see. (Sorry, leafage of Asphodeline damascena in the way.)

Bob

[Tim Ingram]

That was a really valuable discussion of the concept of 'species'. In one of my favourite books, 'The Living Garden' by E. J. Salisbury he prefaces his chapter on Plant Names with the saying 'Words are wise men's counters: they do but reckon by them, but they are the money of fools'. I imagine the implication is that there is a bit of the fool in all of us! There is a nice example with the same species that have a very wide range and will reproduce with adjacent populations right around their range, but those at opposite ends will not. I have learned recently that animals are much simpler in this regard than plants which have complex levels of polyploidy which makes sex even more tricky!

[Tim Ingram]

To get back to plants after that bit of philosophy - those yuccas in pots posted by Desert Zone are marvellous under whatever name! The biggest one must be quite an age.

[Nold]

I like the idea of yuccas in pots, too. That way you could move them to weed around them.

Here, you can get plants like that, imported from Texas. They're removed from the wild, growing on private land.
Of course there is a lot of controversy around this, but if you want a 3m tall Yucca faxoniana, you can get one.
Moving it, and digging the hole, are different stories.
Bob

[Weiser]

Here are a few photos of Yucca harrimaniae var. gilbertiana in bloom last summer.

[McDonough]

Beautiful plant John, the flower spike looks extra plump and showy emerging from the small leaf base.