ID Please

[TheBelmontRooster]

I just brought this pot of three cactus home. The label just says "CACTUS". Each one is approximately 1 1/4" tall x 1 1/2" wide.

[Caudexguy99]

Could be Mammillaria longimamma

[A1essandro]

I don't think so. I think it's Mammillaria compressa or similar to it.

[anttisepp]

M carnea aff IMHO

[DaveW]

One of the magnimamma/compressa group as Alexander says (I think carnea is a member of that group?). Not Mammillaria longimamma, which as the name suggests has very long tubercles.

[TheBelmontRooster]

This cactus has 5 whitish radial spines and 1 darker central spine. Photo shown for the "former" Mammillaria compressa f. bermalensis on Llifle (Encyclopedia of Life) looks like this plant. Description says it has 3-5 central spines and 1-3 radials... Even the photo looks like the opposite. Maybe it was written backwards by accident. Of course, Mammillaria compressa f. bermalensis is considered a synonym of Mammillaria compressa even though there is more than one variation... Hopefully someday "those in charge" of modern taxonomy will realize the importance of intraspecific names and show their acceptance. Mammillaria compressa, the species, is described as having 4-6 radial spines and usually no central spine, and the axils have wool and bristles... Although these three plants are likely "juvenile" and will change somewhat as they grow.

I also considered Coryphantha ottonis, but they have more radial spines and grooved tubercles...

I am going to post photos of my older Mammillaria hahniana and two cactus I recently brought home that were unlabeled... To get your opinions... They look different but there are similarities but nothing like the old one... Hmmm...

[DaveW]

Infraspecific names can be important if they are discrete populations in habitat. However many infraspecific names have been created for imported plants where the person naming them had no idea of the population variation in habitat.

Most original descriptions and the deposit of the type species were made on just one or two plants, therefore giving no indication of the population variability in habitat. Hence counting spines and giving any slight variation another infraspecific name does not always represent the habitat population. Many plants in cultivation have now become merely cultivars and no longer really representative of the habitat population.

I remember when I started in the 1960's we used to use the current books to identify plants and if it had two central spines it was "bispinosa" but if three it was "bispinosa v. trispinosa". Now with so many amateurs going to habitat we have learnt there can be considerable variation in a population with bi and tri spined plants within a foot or so of each other. Therefore counting spines is now only an indication of what species it may actually be and not a definitive identification. In variable populations you could erect numerous minor varieties on spine count as happened through ignorance of the population variability in the past. Sometimes the same applies to flower colour in some habitat populations.

Mammillaria hahniana is a case in point. Even the type form varies in the amount of hair it produces and even the former hairless forms which were regarded as distinct species in the past have now been reduced to subspecies under it.

http://mammillaria.net/oldweb/mammofmonth-Sep08.htm

http://mammillaria.net/oldweb/mammofmonth-Oct08.htm

You also may find Mammillaria compressa here, plus other Mammillaria's.

http://mammillaria.net/oldweb/motms.htm

As said above, many cultivated plants have now become horticultural clones and many amateurs find it hard to accept any new imported variants from the original habitat population as the same species. In the past, and still to a certain extent today, collectors in habitat tend to pick the most attractive plants from the population, or take seed from them and do not take a representative sample of the population. Also in cultivation nurserymen tent to breed from the most attractive forms which sell best, therefore the plants in cultivation become even less representative of plants in habitat.

[TheBelmontRooster]

Thank you DaveW. I really appreciate it. I posted photos of the Mammillaria as well.

[DaveW]

I decided to edit my post so it makes sense to others who read it.

Lonnie PM'd me to say he had found a plant he thought fitted his plant which was a Mammillaria from Tlayecac Morales, Mexico . However since looking at his plant above again I don't think it is.

Did your plant come with any name or number on it Lonnie? The plant you quote as being similar from Tlayecac is Mammillaria multiseta as this link says:-

https://mammillaria.forumotion.net/t241 ... 1-tlayecac

Chris Davies who identified it in the link is the Chairman of the British Mammillaria Society.

I think I am back to my original guess of one of the Mammillaris compressa/magnimamma group

You can find the group classifications here if you look for the ones with Mammillaria compressa or magnimama in them and then compare the other species listed.

http://www.mammillarias.net/wordpress_u ... %20More%20

[TheBelmontRooster]

I agree it probably M. compressa from the photo and description on Llifle of M. compressa f. bernalensis. Which is a synonym of M. compressa. I think the descriptions of the radial spines and central spines on the website are backward, though.

I didn't ever think it was an M. tlayecac because I thought it was a made up name. The number associated with the collection ( Rep 831 Tlayecac) is for an observation I presume and is for M. multiseta which became a synonym of M. karwinskiana. I have an M. karwinskiana in my collection and it certainly doesn't match this plant...

All I know is that the three plants in the pot I brought home resemble the photo on the Llifle (Encyclopedia of Living Forms) website labeled Mammillaria compressa f. bernalensis is a synonym of M. compressa. The intraspecific name was apparently not validly published.

Interestingly, though, the man named Werner Reppenhagen is the man who collected Rep. 831 and decided it is/was Mammillaria multiseta which is apparently a synonym of M. karwinskiana. I have a nice M. karwinskiana in my collection... Mr. Reppenhagednamed and described M. bernalensis and M. compressa f. bernalensis and they are not associated with Rep. 831. It is crazy that Rep. 831 has gotten screwed up with the name on the web and by growers and retailers as Mammillaria tlayecac that looks similar to the plant I brought home...

I realize my plants are likely VERY small compared to the specimens used to write descriptions from. They have some growing to do and are likely to grow longer spines, get a little wooly, etc. I believe my plants are a "variation" of Mammillaria compressa and are likely as described as M. bernalensis/M. compressa f. bernalensis...

I have 40-50 different species of cactus in my small collection and I write about them on my website The Belmont Rooster... I understand taxonomy, and all the confusing wording but I have to explain descriptions on my site in layman's terms... I am hoping to educate the public with correct plant names and not necessarily the names that come with plants that are bought at retail stores... Explaining why intraspecific names are not "accepted" when their descriptions further describe the plant at a different level is sometimes difficult... Which means sometimes I have to describe the "synonym" rather than the accepted species. That is fine, as I am told, because the synonym (intraspecific name) was also validly published.

[DaveW]

Classification is merely a matter of opinion Lonnie even for botanists and not holy writ. All that is asked is that the name be validly published according to the "Rules", then you can use any valid name or classification you like.

Seemingly M. bernalensis was validly published as LLifle gives:-

Mammillaria bernalensis Repp. Gattung Mammill. nach dem Heutigen Stand Meines Wissens 1988 151 (1989)

However he does not indicate that the transfer to a form of compressa was later made since he does not indicate the name of the person making the transfer. If Repenhagen himself had legitimately made the transfer after first publishing as M. bernalensis it would be listed as M. compressa f. bernalensis (Repp) Repp and the transfer publication cited.

Kew only lists it as a published species without listing any transfer to M. compressa. Therefore M. compressa f. bernalensis is a nomen nudum since the transfer to forma has never been legitimately made since many evidently think M. bernalensis is simply just a synonym of M. compressa and not worth distinguishing at subspecific level anyway given the amount of variation within M. compressa itself.

http://powo.science.kew.org/taxon/urn:l ... s:314823-2

Evidently the type species of Mammillaria bernalensis is deposited at Zurich herbarium, therefore complies with the "Rules" on publication.

https://www.ipni.org/n/314823-2