Field numbers

In my collection I have found that there are two plants that have Michel Lacoste field numbers - M.camptrotricha (listed as ML481) and M. coahuilensis (listed as ML563). Does that mean that my plants can be labelled with those field numbers or is it possible that they are variations of the specimens to which the field numbers were given? The source of my information is the Field Numbers search engine on www.mammillarias.net under Michel Lacoste.



If this is the case, can I label other plants that may appear with field numbers or is that dangerous to do in case it isn't accurate?

Field numbers are probably the best way of labeling your plants, in my view, so yes, add them to your labels.
What a Mammillaria is called (species, subspecies / variety, form) is a subject on which many botanists and collectors have waxed lyrical for many years. The classifications (Hunt, Luthy, Reppenhagen....) vary to some extent, and whichever you decide to follow will almost certainly change.
The one thing that shouldn't change is the plant and where it was found - hence the significance of a field number. The only caveat I'd make is the same as with any species - the "truest" plant is one grown from habitat collected seed. It is illegal to export habitat collected cacti from Mexico, and the same, I think, goes for habitat collected seed. However it is possible to export seed from Mexico under an export license. Most of what we see with field numbers will have been grown from habitat collected seed, we have to assume legally, and we can but hope that it has been bred true.
Some botanists prefer the concept of a species group - encompassing many existing names, and qualifying this name with either a field collection number, a field location, or sometimes a name used to refer to its original name, most recently suggested to use these as cultivar names. Gordon Rowley has written recently in the UK based Mammillaria Society Journal on this topic.
Personally, as well as just enjoying prowing these plants, I like to know where my plants came from, and I like to be able to understand the relationships between different species or forms. But I do know that as we are talking about a living thing, there will be variations, often between plants separated only by a few miles or kilometres. Some plants seem to be more variable in form than others, perhaps because of different environments, or because they are more recently evolved perhaps, and probbaly still evolving. Whether these different forms are given different names seems to be a matter of how significant the botanist consider the differences are. And different botanists don't always agree, hence the plethora of names. Some people seem to "take sides" rather strogly, but I think that's rather unneccessary, the plant itself doesn't change!

Thanks for that Chris. However, I have now found a problem with M. senilis, in that it seems to have three field numbers from Lacoste. ML580A, 580B and 583!
I see the same rings true for other species that I don't have such as densispina. Now that is confusing for someone like me who is already struggling to get his head round all this naming and numbering stuff! Perhaps I should just leave well alone!

Marty, there should not really be a struggle. But the recording by people in the field isn't always consistent. In most cases a field number refers to a location and a specific plant(s). Sometimes several collections are made from a single field location, so you could get for example a Mammillaria and also an Echeveria with the same field collection numbers.
In the case of M. senilis 580a and 580b are from the same location 6-8km E of Canoas, Durango, so I suspect that Michel initially named the plants he found as 580, and then realised he had two which might have looked a little different, so split the number, rather than renumber the following plants. ML583 is from a slightly diferent location between 1-13km E of Canoas.

The struggle would be knowing which number to give a plant if there are slight variations in the plants themselves Chris. How do I know if my M senilis is the same as a 580A, 580B or a 583? That's what I mean by struggling to know which number to give. Maybe I'll stay away from that after all! LOL

Oh I see what you mean! OK, well it is very simple - if your plant isn't labelled with a field collection number when you buy it, then you simply cannot give it one subsequently. Your plant may very well be a perfectly genuine descendant of a field collected plant or field collected seed, but unless it bears that number you can't relate it to any specific location.
If you are serious about buildinga documented collection, then every plant you buy or seed you germinate should come with that number. But if you just like growing the plants, then you will have a wider choice of source for your plants.
I developed quite a large collection without worrying too much about field numbers, and it is only as I have learnt more about the plants that I have realised how variable some of them can be, and that if you grow several plants with the same name they can look different, and its useful therefore to know wher ethey came from. I'm now trying to add only plants fwith field numbers. Even reputable suppliers can get their names wrong, so its not infallable. I recently bought a plant which had a Lau collection number, but that number referred to a very different Mammillaria. Luckily I knew what the plant should look like and so questioned the file dnumber, and found it had been wrongly documented by the seed supplier. Most times though the field number is right, but the name might be wrong. Look at the thread here on Mammillaria saetigera to see an example of a very reputable seed supplier who appears to have mis-named a plant.
However, as I know you are developing a collection, don;t let this discussion put you off - at the end of the day its growing the plants well that is the best thing, and when they reward you with flowers and nicely shaped plants with great spines.

Most definitely Chris. I am excited every evening when i get home from work and find new developments on my plants. Tonight for example, my purple flowered zeilmanniana has a bud almost ready to open and my camptotricha has a white flower opening beneath the birds nest of spines. My giselae has a new flush of buds as does my glassii, so it seems there's always something of interest. I was only sking about the names and field number stuff to see if I could make head or tail of it all, but it seems that maybe, I'm still too much of a beginner to get those issues straight in my head!
My wife said a strange thing to me tonight too. She said that she takes back the comment she made to me a year ago when she declard that cacti are boring and don't do anything! Now I think she is growing rather fond of my little babies! She gets almost as excited as I do when a new bud emerges or a plant produces another offset or something!

Its a great time of year, Marty. I'm happy that your wife is also enjoying - its the only time of the year that my wife says anything complimentary about my plants - and then she follows that up by...she'd prefer orchids or fuschias!
To close off the field number question, if your plant hasn't a field number when you buy it, you can't add one later. The field number is supposed to indicate a true line of descent from a habitat plant or habitat seed.
The only way of trying to see which field number your plant look slike - and even if you are confident it's a match, you can't label it as such - is to go back top the original description or field notes of the collector. Michel Lacoste wrote a series of Field Notes for the Mammillaria Society, publsihed in its journals in the 80's, but I don't think they are written elsewhere and not yet scanned or electronicised in any way. Now there's an idea.....

I plan to join the Mammillaria society later in the month Chris, so I will have the benefit of the articles and stuff from their journals too, which I'm sure will mention the subject of field numbers occasionally! I understand what you say though and it is as I originally suspected. I now realise that every M giselae can't be a giselae ML677, so I won't persue that line of thought anymore! Thank you for being so patient with me while it finally sank into the old grey matter though!