A few other forummembers and I had have the luck to visit Herr Plein's collection last weekend. Together with herr Rogozinski's collection is it the place to be for every Mammillaria lover. A short impression:
Chris Davies is asking Herr Plein were a particularly specie of Mammillaria is growing. W. Plein is showing him the right direction:
The real M. prolifera ssp. arachnoidea from the type plant Of David Hunt: H 8598 from Antiguo Morelos, Tamaulipas.
A huge M. morganiana, often mislabeled in collections, but this is a real one
A very nice specimen of M. lanigera
Mammillaria elegans v. teyuca
A serie of M. tesopacensis