Mammillaria dioica

There are many forms of this variable species. This is one that I had from a British grower, Graham Charles, with a field collection number I don't recognise, PH265.1 Anyone know it?
This form has stayed small and round, and has flowered well each year I have had it - as you can see from the seed pods. But I wouldn't be sure that the seeds would bred true and I have 3 or 4 other forms. I'll post some others when their flowers are well open.
The flowers are rather different to my other plants, which are much less white, more yellow with more obvious red striping, but it is within the limits of the description.

This a very unusual and interesting form Chris. The flowers are different an bigger and the compact growth is also unusual too for a dioica. If there is seed in the pods, I will give it a try

OK, I'll check tomorrow morning and bring some if there is.

Thanks Chris,

This is my dioica L 06:

Chris,
your dioica is a goodridgei.
There must be made a mistake by the person who found this plant.

I'm not quite so sure about this, Hugo, but I don't have a firm position.
M. goodridgei is found mainly on Isla Cedros, but the description suggests that it is also found on neighbouring islands and on the mainland nearby. However, Pilbeam says in his book, that "an area that I was taken to on the mainland where this species was believed to grow revealed only plants with more in common with M. dioica".
The descriptions of dioica and goodridgei appear to overlap significantly, and I have to say that having looked at these in some detail, I have some difficulty in seeing exactly how they differ, other than the descriptions in Craig say that dioica has axils with sparse wool and 5-15 bristles as long as the tubercles, whereas goodridgei is described in that work (and this is reproduced in Pilbeam) as having sparse wool but no bristles. My PH285 plant does not have bristles in the axils. On that basis and the whiter flower, it should be goodridgei, except that it seems to have fewer stigma lobes than the 6 of the description. But then dioica is alos supposed to have 5-6 stigma lobes. So I'd tend to agree, despite John Pilbeam's comment - and the fact that I don't know where he was taken.
BUT.....a more typical dioica is shown in the photo below of another plant in my collection, M. dioica BOVE25. I can't see any real evidence on this plant of either wool or bristles in the axils. But the flower is just so typical to me of dioica, that I can't even think it is anything else.
If you then remove sparse wool and bristles as being the defining characteristic of dioica, then we are back to square one - what are the characteristics that separate these two species. Does goodridge remain as a name of the island form only, and all mainline forms are under dioica, or do we need a rather tighter description of dioica?

????

Your last pic is certainly a dioica, Chris. But if you look at the flowershape, the flower format and the stigma lobes and the globular form of the plant on your PH picture, it is not a dioica.

Hugo, you are quite right to point these out, and I do agree with you on the flower - even though I can't reconcile the stigma lobe mismatch. But dioica can be globes as well....this photo of a plant I saw in Southern California.

Ok Chris,
Bring your plant with this weekend, but keep an eye on it or it could be dissapear in ( Hamme) Belgium.