First described as Mammillaria chionocephala by J A Purpus in 1906, it remained as such for almost 100 years before David Hunt reduced it to a subspecies of M. formosa in Mammillaria Postscripts 7 in 1998. In cultivation it can also be found under the synonym of M. ritteriana.
Its type locality is the Sierra de Parras, Coahuila, Mexico, a location of many cactus species. It can be found over a wide distribution range including the states of Nuevo León, Coahuila and Durango, from an altitude of 1,450–2,400m.
It is a solitary headed plant unlike the other subspecies, M. formosa subsp. formosa and M. formosa subsp. microthele and will, in time, produce a white woolly head over a foot (0.3m) tall. In John Pilbeam’s Mammillaria book the flowers are described as pale rose-pink to white.
The very attractive form shown in these photos is P283, which is a collection made by J Piltz of the Kakteen-Piltz nursery in Germany. The outer petals are rose-pink while the inside is a creamy-white.
Mark McCormack
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