Mammillaria rosensis

Mammillaria rosensis.

I found  a mammillaria rosensis in an old collection near Alessandria similar to a plant of Ento "Ennio Toso" Savona.


This is a note I found in the journal of the U.K. Mammillaria Society...
Habitat: San Juan de las Rosas, Queretaro, Mexico
Details of M.rosensis were asked for in the distribution notes. The most notable thing about this one is its very slow growth rate. Despite being a double headed plant it still only measures 1 3/8" across. In this respect it certainly takes after M.parkinsonii. The body is medium grey green,very flat in growth, with naked axils and almost naked areoles. The centrals, as yet two
up and down, acicular, straight, rough, 4-6mm long, the lower longer, with a yellow base, brown shaft, and dark brown tip. The number of radials has crept up from 14 to 20 now, acicular, thin, recurved, and somewhat bending, smooth,very short, l-3mm long, white with brown tip. The central spines are certainly not anywhere near purplish brown to black as suggested. I wish they were. It would make for a fine looking plant.

The replay to a MP by Chris Davies:
I think that this is a short spined form of M. parkinsonii. The flowers are right, the axils are woolly as in M. parkinsonii though I can't see enough in the photo to know if there are any bristles. San Juan de las Rosas is about 8 miles south west of Vizarron, so well in the distribution range for M. parkinsonii.

Hunt refers this to M. parkinsonii, as does Reppenhagen, so if these two are in agreement, I can't see any reason to disagree.

Whether it will dichotomise would be interesting, it doesn't seem to be doing so yet.

Hunt in his article in Bradleya 1986, says that is probably is M. parkinsonii, but could be related to M. formosa, which is an interesting view. I wonder where Ento's plant comes from, as the type collection apparently was not preserved, though that might just mean preserved in a herbarium, not in cultivation.

Field study needed!!

Chris Davies