7. 2019.5.19 – Perhaps I should have spelled out my hypothesis in the very beginning of this haworthia species mystery. This is that Haworthia was separable into morphological and numerically defined entities that would fit into a clearly defined set of species. A proviso being that the word species was defined as based on the ill-considered and untrue precept of non-interbreeding entities. The nature of variability coupled with this weak species definition result in the initial hypothesis to be totally false. Haworthia does not present such clearly defined entities and in fact there is a very variable set of elements that can only be recognised in respect of their general appearance and their geographic distribution and relationships. These are themselves mildly confounded. In fact, the issue was grossly confounded by the now established fact that Haworthia was, in reality, three very different genera.
When I dismantled G.G. Smith’s putative two-volume manuscript purporting to be a monograph, these three genera were split into 20 sections with specimens of many of the currently recognised species, represented in more than one. I never pretended to be the knight in shiny armour that was a going to slay that windmill of confusion and I put a great deal of effort into looking for someone who could and would. That never materialised.
From my personal perspective (isolated as I am from the popular literature of the last 5 years), all I can say is that there is a publication authored by myself and Dr. John Manning that reasonably presents the truth of Haworthia. It does not entirely do so as this series of posts will show.
Science as a real matter of inquiry, together with objectivity, rationality, logic and reason, are not strongly represented in the human endeavours that have been and are being made to properly understand the phenomenon of the Haworthia species that can be observed. There is no doubt that DNA sequencing offers the very best solution to the issue. My experience suggests that there is still some way to go before that goal is reached and it will not be done until the complexity of issues like this one are seen to be real and understood as they are.
This is the reference … Bayer, M. B. and J. C. Manning. 2012. A rationalization of names in Haworthia: a list of species with new combinations and new synonyms. Haworthia Update, Essays on Haworthia, vol. 7. Preston: Alsterworthia International.