I wrote an short article on my plant for the British Mammillaria Society journal, which is included below. I asked for comments, and I received a couple of responses, and I have noted them below the main text.
Unusual or uncommon Mammillaria “names” – Part 2 – Mammillaria francinii DC445
A plant that has recently flowered for the first time in my collection is Mammillaria francinii DC445. I acquired this plant from Havering Cactus Mart quite a number of years ago, and it has slowly grown from a small seedling into its current 3½ inch pot.
It was the flower that prompted my attention, as this plant is otherwise fairly unremarkable. I have it placed close to Mammillaria wagneriana, to which it bears a fair similarity. It has 6-8 radial spines, of which the upper two are very short, the side radials longer and the lowest spines are the longest. It has mostly just one central spine, which is fairly erect. The flowers are relatively large, white with a very strong and wide midstripe, reminiscent of a flower of a Mammillaria blossfeldiana. In this flower, however, the stigma is typically 4 lobed and pink, rising nearly up to the length of the petals, the stamens being only half its length.
Its origins are to me rather shrouded in mystery. There are plants available for sale today from a couple of German nurseries, and seed is also available. The Field Collection number DC445 is one that I cannot trace. Ralph Martin’s database doesn’t list this, and the internet searches for both M. francinii and DC445 reveal very little of relevance. It isn’t listed in “A new review of Mammillaria Names” nor does it appear to feature in John Pilbeam’s “Mammillaria”
It would be good to clear up this “mystery” plant, and to know where it was collected from, by whom, and to confirm my tentative identification as synonymous, albeit a little different, with M. wagneriana.
The replies I received were from Bob Stanley, who said he also has M. francinii, and tells me that DC is Dennis Cowper, and it is supposed to come from Fresnillo, Coahuila. However he goes on to say that he can’t find a Fresnillo in Coahuila, and wonders if it is the Fresnillo in Zacatecas. This is M. wagneriana territory, but he also compares the flower of M. wagneriana to M. pettersonii, and there is a distribution area of M. pettersonii in Zacatecas. David Hunt only provisionally accepts M. wagneriana whilst comparing it to M. pettersonii.
Here's my plant again, just taken this year, the other photo is last year's, but this is just a little out of focus, but hopefully clear enough.