Volume 2, Chapter 12:- Haworthia rossouwii VPoelln. and the demise of H. serrata Bayer

This appeared as an article in ALOE 38:31 (2001).  Unfortunately there was a problem with illustrations and captions and these are corrected here.  A comment is also added as an addendum to respond to criticism by I.Breuer published in Alsterworthia 2:13(2002).

I described Haworthia serrata in 1973 (Jl S.AFr.Bot.39:249, see Figs.1) from Oudekraal, southwest of Heidelberg.  I commented then on the wisdom of describing a new species when “the recognition, estimation of taxonomic rank and circumscription of elements in Haworthia…” was so problematic.  The new species was said to resemble H. emelyae var. multifolia (Figs.2).  In respect of its distribution, I said it was closest to H. heidelbergensis at Heidelberg (Figs.3 JDV87/1) and as at Matjestoon (Fig.4 JDV87/3), and also to H. sublimpidula at Swellendam (now known to be H. floribunda var. major (Fig.5 MBB6859, taxonomically with little connection to H. rossouwii).  The implication was that it could have been taxonomically related to those elements in terms of geographic distribution.  I was still puzzled by the relationships of H. serrata when I wrote (New Haworthia Handbook :55, 1982) that collections by C.Burgers from the Coastal Limestones might throw more light on the matter (Fig.6 MBB6985 H. mirabilis var. calcarea).

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Volume 5, Chapter 8:- An extension of H. rossouwii

What always comes to mind as I travel through the countryside is the realization of just how much there is to explore.  It takes only an hour of driving from Cape Town to get to the start of Haworthia habitats from any of the three main routes inland.  The roads do not always take in the best routes in respect of suitable or inviting habitats to explore, and besides there is the question of landownership and permission for access.  In recent months my wife and I decided to really make an issue of new exploration and investing time and energy in contacting landowners and looking at places that we have ignored before because of access difficulties.  The result has been a massive set of new finds in respect of populations not previously known to us.  Having other interests such as in Drosanthemum and chameleons has also led us into places we might not have otherwise ventured.

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Volume 5, Chapter 13:- A February 2009 Miscellany

7807 H.minima.  Swartrug, SE Heidelberg. 002

This chapter is based on recent field exploration and embroiders around many aspects of Haworthia species discussed in earlier chapters.  What should be striking is that new populations follow the very predictable geographic pattern that all my earlier exploration has exposed and in my estimation confirm in every way what I consider a sound and satisfactory taxonomic solution and help explain its limitations.

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Haworthia flowers – some comments as a character source, Appendix 10

Appendix 10 to Vol. 8 Haworthia UpdateAn additional report on Haworthia mirabilis and Haworthia rossouwii ‘minor’, Rooivlei and Brakkloof, N and, NNE Bredasdorp.

The previous report indicated the necessity for further exploration of Rooivlei.  I had observed H. mirabilis, but not reported it in Update 3, at Brakkloof to the west in 2004.  So the object of this appendix is to remedy this oversight and to also cover more area of Rooivlei.  At Brakkloof there are several small remnants of rocky shale and we located several populations, while at Rooivlei we actually explored the very western boundary.  This constitutes the same topographical area as the Rooivlei populations but the plants we observed were factually on Brakkloof.   

The populations reported on here are:-

  1. 6537 H. mirabilis, Groudini, W Napier
  2. 7285 H. mirabilis, Brakkloof 3
  3. 8046 H. mirabilis, Brakkloof 2
  4. 8047 H. mirabilis, Brakkloof 1
  5. 8048 H. mirabilis, W Rooivlei 1
  6. 8049 H. mirabilis, W Rooivlei 2
  7. 8050 H. mirabilis, W Rooivlei 3
  8. 8051 H. mirabilis, E Rooivlei
  9. 8045+ H. rossouwii ‘minor’, NW type locality
  10. 8052 H. mirabilis, S.Welgegund
  11. 8053 H. mirabilis, Welgegund SE 8052

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Mystery – part 27, West of Riversdale

77. 2019.8.12, MBB7776 between Riversdale and Heidelberg – Coming to the end of the first chapter of my story. Lets now try something while we contemplate the reality of the difference between mutica and retusa. What are these next 8 plants? I suggest that they are H. mutica – but it is your opinion that matters now. What do you think?

Let me just add something about this DNA sequencing stuff. The technocrats assume that if they have a sample labelled H. retusa, it comes from an entity that truly exists and can be labelled so conveniently. In the one exercise I was involved in I attempted to get the dudes to replicate. How far it got I do not know beyond the first sequencing run presenting some very uncomfortable results. My comments and questions got me thrown out of the project.

Lawrence Loucka: ‘Replicate’ is a statistics term that means to use multiple samples, make multiple readings, to determine variation within (not between) populations. Because of time and expense botanical DNA studies have generally had insufficient sample sizes to be statistically significant. But costs are coming down and quality is improving.

Stephen Boisvert: Replication just means to repeat the experiment or measurement and get the same result. It can be completely meaningless if you don’t satisfy the requirements for philosophical validity – face validity – construct validity or logical validity – predictive, concurrent, discriminant and convergent. Looks like Bruce’s complaint here is with construct validity, concurrent and discriminant/convergent.

The first issue is a bit more complicated. It’s conceptual at the level of what you think a “species” is. Botany (and zoology) has a strange history on this with one with their notion of Type plants (and animals) where a single instance is held as the defacto species standard and entails a whole host of problematic philosophical assumptions (like a platonic ideal form or aristotelian essentialism) which never quite fit the real physical world or the use of concepts in language and has huge sampling problems (one individual chosen to represent a purported population is extremely problematic to say the least). Still I believe if you clearly articulate your assumptions regardless of your philosophical positions on concepts (platonic idealism, aristotelian essentialism, Wittgensteinian familial resemblance and so on) you should be able to produce useful and communicable knowledge. The big problem is being clear enough both in your own head and in your writing about your assumptions which is difficult because of lot of this is stuff we learn and know at an implicit rather than explicit level. You see this when people can identify and distinguish plants but if you ask them how they differentiate they sometimes can’t tell you. They just know implicitly without explicit rules.

Bruce Bayer: Stephen – I truly appreciate your comments. I have been criticized because I many times cannot identify a Haworthia unless I know where it comes from. Written descriptions are fairly useless with many examples to demonstrate the fact. How do you describe the variation in a population when it is difficult to describe a single plant? No matter how unclear the head, the fact is as you see in these last pictures posted, plants from quite different populations (too often identified as different species) can be identical. What really bothers me is that other peoples heads are not clear enough to grasp this statement. I have been pondering explaining my expressed discomfort with the Haworthiopsis paper in Phytotaxa where my discomfort is seen as a personal attack on the authors.

Ronel Kloppers and Sean Gildenhuys have written an outstanding paper with respect to nomenclature and technicality of taxonomy, but which I regard as weak in both scientific method and “philosophy of concepts”. I am hesitant to deal with the issue because I am not in their intellectual league and not in the least sure where my convictions stem from! I am however extremely concerned that the methodology successful perhaps in Haworthiopsis will be a total disaster if applied to Haworthia stricto sensu.


This next set is just another lot from the same place west of Riversdale. Silly me. I think the first would fit comfortably with H. mutica and these now with H. retusa.

Early on in this series I started by going north and west from the Duiwenhoks River south of Heidelberg, and moved west to H. mutica. Now I skip four very relevant populations and travel eastwards. What is happening is we are going to H. retusa. It will take us across area already covered in detail in the Updates under the cover of mutica var nigra. [1] After that north-east of Riversdale to Kruisriver, further east to the Platkop area, to east Albertinia, to the Gouritz and H. pygmaea. There are three directions northwards to H. emelyae untouched and two southwards that link mirabilis and retusa.

Volume 2, Chapter 6:- How to understand Haworthia mutica var. nigra
Volume 5, Chapter 10:- Haworthia ‘enigma’ and H. mutica var nigra
Volume 7, Chapter 1:- Haworthia retusa ‘nigra’ – Another grand finale.

78. 2019.8.14, MBB7794 – SE Heidelberg. Unfortunately I do not have pictures of one population that used to be closer to Heidelberg that would also have been instructive. 7794 is one of 3 populations, one of which is commonly known. I would refer to these as mirabiloid retusa.

Mystery – part 28, H. rossouwii

79. 2019.8.14 – I think I am going to abandon the topic of “species”.

This is H. rossouwii from a place new to me sw Heidelberg.

Funny that one plant that seemed to me to be a significant variant, was also the target for a browser.

Steven Molteno: Interesting that the one “marginata-form” plant was grazed. Bristles, like tubercles, could be evolved for defensive camouflage reasons, in the dappled light of a nurse bush. Breaking up the appearance, like the stripes on a zebra?

80. 2019.8.15, MBB7732 – From south of the locality for the original and erroneous H. serrata. It does occur further north near the N2 and might still be found at Koppies. Here it is among dense grass and so very vulnerable to fire as what decimated the Koppies population.

81. 2019.8.16, MBB7803 S. Heidelberg – H. rossouwii is a strange species because it has a few populations near Bredsadorp and a few SW Heidleberg. The plants very similar. But there are oddities on the outskirts of the distribution. This is a small form south of Heidelberg in three population, two of which are probably close enough to be considered as one.

Some more MBB7803 from S Heidelberg. There are no doubt two ways of approaching this. Simply giving them a new name or trying to fit them to existing. The latter is what I try to do – so just follow this little story and see what follows. Even if we go to the large hadron collider we still may not find an answer.

82. 2019.8.18 – Unfortunately I do not have pictures for what I eventually called H. rossouwii var calcarea – an oddity from the De Hoop Reserve, but this is another oddity from the limestones just east of Bredasdorp. I ended up with this as a rossouwii variant as well for lack of any better idea. The east end of the limestones towards Potberg provides its own complications that better involve H. variegata.