Mammillaria gigantea AvZ 399

ELK 2014 -Directly from the Collector this AvZ 399
labelled Mammillaria gigantea AvZ 399 - Ojo Caliente - San Luis Potosì - Mexico





Could there be something wrong?
The flower is not greenish/yellow...







...

Hi maurillio,

Looks like the right plant, but as you say the flower colour appears to be wrong. Did the collector choose this one maybe because it was white flowered? Or has he not been very careful with his subsequent cultivation and allowed some cross pollination? Time will tell, the fruit should be dull pink, with brown seed.

This AvZ plant could be M. saint-pieana. If his Ojo Caliente is the village near Santa Maria del Rio, then that would fit, because M. saint-pieana grows in the Santa Maria del Rio region. Your plant does not look like the typical gigantea. But in nature, there are no strict boundaries, and then it is often difficult to identify a plant which does not completely fit the picture of the original description.
Your plant could also be a form of M. magnimamma. Not so far from Santa Maria del Rio, somewhat east of San Luis Potosí, I found plants which I found difficult to identify. I named them M. magnimamma WTH 1093, but M. saint-pieana could also be an option.
In Reppenhagen's 2-volume book, he shows a photo of M. gigantea with pale-white flowers.

Wolter ten Hoeve.

Isn't saint- pieana supposed to have pink flowers though?

Both Backeberg and Reppenhagen write with regard to the flower: weisslich, i.e. whitish.

Wolter.

Looking at the photo and description of saint-pieana from Chris and the same photo of maurillio's plant in that blog of 2010,still showing on this site, to me there seems to be a discrepancy with the shape and number of spines between the two to consider maurillio's plant saint-pieana.

The description which Chris has given is not the one of Backeberg, but the modified description of Reppenhagen. Backeberg states that the location of M. saint-pieana is not known and that it was probably collected by Schwarz: "Mexiko (ohne genaueren Standort, wahrscheinlich von Schwarz gesammelt)".
Reppenhagen then assigned M. saint-pieana status to the plants which he found near Santa Maria del Rio. Ojo Caliente, the site for the AvZ plant, is only 5 km north of Santa Maria del Rio.

On the forum at https://mammillaria.forumotion.net/t1320-mammillaria-saint-pieana?highlight=saint you can find photos of plants which I found at just one location of about 300 by 200 meters in that region, 5 km east of Santa Maria del Rio. There is quite some variability in these plants, but they grow considerably bigger than Reppenhagen states in his book.
Individual heads of M. magnimamma stay small, and they form offsets. In contrast, individual heads of M. gigantea grow very big, and they hardly form offsets. Therefore, I can understand Hunt's opinion that M. saint-pieana is a form of M. gigantea (which actually does not grow so far away, 50 km south of Santa Mario del Rio you reach M. gigantea territory). Yet, to me it is different enough to warrant a special status.

Let's wait and see what this AvZ plant looks like when it grows bigger.

Wolter.

We will wait and see