Melocactus ernestii ?

[hlchang]

Is this Melocactus M. ernestii? Looked up the many types of Melocactus , not sure if this is M. Azureus , curvispina or ernestii . Your assistance will be much appreciated.

[greenknight]

I'd rule out ernestii, it has long spines. Hard to be sure, but azureus looks like a good possibility.

[jp29]

I would say most likely M. neryi or M. salvadorensis possibly M. zehntneri - M. azureus has white fruit.
It is often hard to differentiate cultivated Melocactus because their growth forms in containers (their naturally wide-spreading and much branched root systems being constrained) are sometimes quite different from plants in the wild.


M. neryi


M. salvadorensis


M. zehntneri

[greenknight]

I found collection notes for M. azureus, said the fruits could be red or white - though in most of the pictures I found with fruit they were pale pink. The cephalium is darker than on the azureus I looked at, though, the ones above do look closer, zehntneri is as close as anything I've seen. It is hard to tell, though.

[jp29]

I found collection notes for M. azureus, said the fruits could be red or white - though in most of the pictures I found with fruit they were pale pink. The cephalium is darker than on the azureus I looked at, though, the ones above do look closer, zehntneri is as close as anything I've seen. It is hard to tell, though.

Yes, you are right - I should have said "mostly white" fruit. In their description for this species Taylor & Zappi report "Fruit entirely white, slightly pinkish at apex or pale pink throughout .....", and indeed I have produced seedlings that bore pinkiish fruit when they matured. I have not encountered a Melocactus azureus with red fruit. As the specific name implies this Melocactus is characterized by an epidermis that is predominently blue - in various degrees of intensity. I have always selected the plants with the most intense or uniform blue coloration from my seedlings flats to grow on to maturity as can be seen in the following pics: