This month's Mammillaria is rather a mystery. It is shown in the collection of W. Plein.

Mammillaria fertilis is a long known name, having been originated by Hildmann in 1898. It seems that no location data was mentioned about this plant when its description was made by Schumann in Gesamtbeschreibung Kakteen 530. 1898.

Craig also includes a description in his book, of an offsetting plant, globose to short cylindric, central spines 1-2 golden brown, somewhat bent, and 8 - 10 white acicular spines.

Both the description  of Schumann and that Craig (possibly simply beingtaken from this) refer to some white wool at first on areoles and in axils, although this is not evident on the plant pictured above. So there has to be some uncertainty here.

The name Mammillaria fertilis was consigned to synonymy with Mammillaria backebergiana although it is not clear whether Backeberg actually knew the plant at the time. It has also been said that this plant is a somewhat monstrose form of M. backebergiana.

Whatever the truth is we probably shall never know, as the plant does not appear to have been discovered again in the wild. Those few plants in cultivation today have a somewhat uncertain pedigree, although the continental European focus might suggest that they are descendants of Hildmann's original plant.

I offer this uncertain plant as this month's Mammillaria of the Month simply because of its mysterious history.