Mammillaria of the Month
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Mammillaria guelzowiana probably has the largest and showiest flowers of any Mammillaria species. When in full flush, the large flowers with their almost metallic sheen hide the plant body, which itself is not unattractive with its reddish-brown or yellow hooked central spines and hair-like radials.
It has been known for a long while, first described by Werdermann in 1928. However it seems to have been rather slow to become widespread in collections, and perhaps its recollection by Glass and Foster in 1968 marked the real start of its popularity.
It does cluster, although this seems to happen much later in its life, if indeed it gets that far. It has the reputation of being somewhat unpredictable if the growing conditions are not right. But with a really open compost and a light hand with the watering can or hose, it will make steady progress, and reward with its superb flowers.
There are three variants grown, and apart from the more usual form, the so called var. splendens has yellow spines, and the so called var. robustior with rather longer spines. It is likely however that these just mark what is a more variable species that was first appreciated, a not too uncommon matter with introductions from one specific locality.