Hello, I am interested in identification of this cactus. I have only recently become interested in succulents and cactus and it appears there is a massive variation in types and some only vary physically ever so slightly. Can anyone help?
Looks like Organ Pipe Cactus (Stenocereus thurberi). edit - Didn't notice you were in Australia. not sure what it is.
as you browse through images of columnar cacti, remember that and the shape and spacing of the aeroles is diagnostic as well as the number of vertical ribs. The random changes in the diameter of the column has to do with growth cycles so is not diagnostic.
I understand that Cereus hildmannianus var. uruguayanus is the correct identification of this common and easily grown large cactus, though for a great many years it was wrongly known as C. peruvianus.
The name Cereus peruvianus has been applied to both C. hildmannianus and C. repandus which are both recognized as legitimate species today. The trouble is, neither of them resemble the many plants that we see labeled as Cereus peruvianus. Therefore the logical conclusion would be that these plants are simply not properly identified and through due diligence, we should be able to find their true name. Yet what we find is that the best choice of names turns out to be Cereus peruvianus! Sound absurd? That's because it is. It is my belief that these cacti are almost certainly a product of cultivation and do not exist in the wild. http://www.cactiguide.com/article/?article=article3.php
Why so? Cereus peruvianus (L.) Mill. [1768] long predates Cereus hildmannianus K.Schum [1860], let alone its var. uruguayanus (R.Kiesling) N.P.Taylor [1988], so Miller's name can't be a synonym of the other. Given its long history in cultivation, it is surely likely that the current cultivated material is directly vegetatively propagated from the same plant that Linnaeus and Miller had, rather than a recent discovery.
Ron - that's an interesting article, though it seems to leave a degree of doubt. Must confess I was relying largely on Anderson's The cactus family (2001) which includes in the synonymy of C. hildmannianus - "Cactus peruvianus Linnaeus 1753, Cereus peruvianus (Linnaeus) P. Miller, misapplied: see under C. repandus" Turning to C. repandus, I find its author citation is also (Linnaeus) P. Miller, based on Cactus repandus Linnaeus 1753. If you look in Linnaeus's Species Plantarum you will see (http://www.biodiversitylibrary.org/item/13829#page/479/mode/1up) they are named on the same page, with repandus 2 entries before peruvianus. I'm not sure exactly what the rule is when 2 Linnaean names published at same time and place are now regarded as synonyms (another example is Duranta erecta and D. repens), but better minds than mine have looked at this problem. Anderson refers to a 1992 article on Cereus by the Kew botanist Taylor, in which this problem is addressed. Taylor later (2004) co-wrote the monographic Cacti of eastern Brazil, which I dipped into once in a bookshop to see what they said on this question. It seemed from the key to Cereus that another possible identification of our plant could be C. jamacaru, based on mode of fruit splitting. Michael - I did not say that C. peruvianus is a synonym of C. hildmannianus, rather it's a case of misapplication of a name, moreover a name which has been relegated to the synonymy of an equally old name - as I have tried to explain above. As for Daiv Freeman's belief that "these cacti are almost certainly a product of cultivation and do not exist in the wild", I'm not sure what evidence he would base that on. The common cactus in question is apparently true-breeding, thus unlikely to be a hybrid (unless allopolyploid). See this Flickr shot from Rio Grande do Sul, where it appears to be growing in the wild. https://www.flickr.com/photos/97300...1hs-56kE1Z-4eZd8t-dFyMrh-58Eb7W-73MwJk-9T7WTD Admittedly it has slightly longer spines than most of the cultivated specimens and the outer tepals are a brighter red, but one should allow for variation within a species.
