Table of Contents


The intractable problem of look-alikes in Haworthia. (2001)

The classification of Haworthia and particularly the sub-genus Haworthia is fraught with difficulty, because it is so difficult to circumscribe species either in writing or pictorially.  The solution I have followed is to recognise species as geographic systems, knowing that there are continuities which can only be resolved where the systems co-exist as apparently independent entities.  Even this is difficult because it is actually seldom that true co-existence occurs.  Usually when two species (even of different sub-genera) occur in close proximity, they occupy different habitats.  In some such cases it is possible to reasonably conclude that the differences in appearance are only at the level induced by that difference in habitat, or at a higher level at which they can be taken to be discrete systems.  With the small qualitative differences that actually determine these subjective judgements, there seems to be little that can be done to quantify them.

In this article I will just discuss a few examples which I can support with photographic evidence, and inform readers that there is far more extensive published and unpublished manuscript and photographic evidence available.

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A shadow of the past – Haworthia arachnoidea again. (1999)

M.B.Bayer, 16 Hope St., Cape Town

In the welter of words that has arisen around the enigmatic enigma, it has occurred to me that this information may help bring some perspicacity to the way we think about Haworthia and names.  Somehow or other I have forgotten to examine how Col. Scott came to apply the name arachnoidea in the way he did.  It is really curious that the whole story is so intricately woven in the rise and fall of my own career, and shows how the greater wheels of politics and economics grind down the least of us.

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Haworthia cymbiformis var. reddii (Scott) Bayer – a test of an hypothesis. (1997)

M.B. Bayer, with acknowledgment to P.V. Bruyns and J.D. Venter.

It is unfortunate when a situation arises where individuals compete to provide a classification for a group of plants.  The normal process for aspiring taxonomists is to determine what needs to be done that is not being done, and which attracts and interests them and so select a group to study.  There are probably not many instances where different people have worked comfortably together to explore and resolve the taxonomy of any plant group.  The objective of this article is to show how that it should be possible to look rationally and objectively at a problem and produce a solution which can be taken forward in the same way.

I think it is understood in the taxonomic fraternity that one of the main aims of a classification is that it must presume to account for all of the plants in the group in question.  Is this physically possible?  Nobody in the least familiar with Haworthia has any doubt that the territory to be covered for a study of the genus is unbelievably big.  The nature of habitats and size of populations, coupled with intrinsic variability and the sometimes cryptic nature of many of the plants make it not only possible but probable, that exploration of even a relatively small geographical area may miss something important.  This complexity in the field is not unique to Haworthia.  A classification therefore can never be considered to be complete and is only an hypothesis based on what is known.  For that which is at the time unknown, it should be assumptive and predictive.  It is further necessary that the classification meets the needs of a general group of people who will use it.  The nature of these needs is in a large part already expressed in the preceding attempts to classify the group and in the literature associated therewith.  A classification is important in the way it allows of generalisation, extrapolation to hitherto unknown collections and for communication.

The test of the hypothesis contained in the classification is the subsequent successful identification of plants by means of the key provided and also by the incorporation of new data into the structure of the classification.  It can also be tested by the ease with which people communicate about the components of the classification, and, of course, whether it comes to be generally accepted at all.  The strongest and most practical test is its acceptance by curators of herbaria and the way it is used to store and retrieve data in an herbarium.

In the case of plants popular in horticulture and with the general public (such as orchids and succulents) there is often controversy over their classification.  The reason for this controversy is that, because of their popularity with the general public, untrained and non‑professional people are drawn into the process of classification and identification.  Their only justification for this is their own enthusiasm and interest in the subject which they feel generates new and previously unrecorded information which they perceive a real need to express.  It should be recognised that they do not necessarily make any more or fewer mistakes than professionals working on obscure groups or at levels of classification (or sophistication) beyond the reach and interest of the layman.  There are also many cases where so-called ‘amateurs’ have made contributions unsurpassed by professionals.  It should also be noted that many classifications by professionals may very seldom come under any kind of practical and proper scrutiny because those plant groups do not attract the attention of anybody else.  Errors, inconsistencies and absurdities remain undetected.  The professional also goes to the outer limits of his intellect where he/she is just as error‑prone as any other person operating at their extreme.  Both classes of enthusiasts ‑‑ the professional and the layman ‑‑ need to draw on some other wisdom to know (probably) what is right and what is wrong.

One of the particular problems faced by both professional botanists and laymen in a popular group of plants, is the profusion of material that comes to be passed around in the horticultural trade without any information on its origin and frequently under the wrong name.  This considerably confuses the picture and this confusion is difficult to dispel without reference to populations in the field.

A further problem, again experienced by anyone who does not have extensive experience in the field (and indeed of pattern recognition generally, and not only in living systems), is the quite extraordinary variability of taxa like Haworthia.  The degree of variation is not consistent for species or for populations.  In extreme cases, where vegetative propagation has occurred, there may indeed be virtually no variation (eg H. reinwardtii); and at the other, hardly two clones in a population are identical.  There are no quantum steps where categories like sub-species, varieties etc. have consistent and invariable connotation.  The more fundamental and philosophical concept of even the species becomes questionable.

Haworthia has been one case where conflicting views have produced a fair amount of difference of opinion and acrimony among authors, and subsequent confusion in the minds of the audience that need the classification to serve their interest.  At present there are two classifications available for Haworthia, the one by C.L. Scott (Scott 1985) and the other by M.B. Bayer (Bayer 1982).  Neither has proved unassailable and both have shortcomings.  Particular shortcomings of both treatments are that they did not address typification, they did not comprehensively cite herbarium specimens and they did not provide credible identification keys.

In Haworthia the classifications are largely artificial because there are no definite morphological discontinuities between the different species recognised. This is why I have said elsewhere that a truly objective botanical classification would probably reduce the numbers of species to about half of that recognised even by myself.  For such an objective classification a key could perhaps be provided.  A key was provided in the older Handbooks (e.g. Bayer 1982) but my new classification will not provide a key.  The reasons for this are very obvious in my handbooks and in most of my writing on the subject since 1971:-

(1) there are really not enough tangible characters on which to build a key.

(2) where two keys (Scott 1985, Bayer 1982) have been provided, I have no knowledge that anyone has been able to prove their worth or make anything out of them.

Out of about five published reviews of the two accounts by Scott and Bayer, three were quite ambivalent:  they did not attempt to test the classifications and did not espouse either.  Since a reliable and useful key cannot be constructed, I have concluded that photographs and distribution information are the simplest, most reliable and most direct route to obtaining an identification.  The herbarium specimens in the three main South African herbaria follow the revised scheme (Bayer, in ms.) but this could be happenstance rather than cognitive intention.

Part of my strategy in the Handbook (Bayer 1982) was to retain species and varietal names even if the indications were that their status may have been weak.  There were two reasons for this.  Firstly, classification is also a communication process and I tried to match my classification to what I felt was the mood of the day.  Secondly I tried to avoid, where possible, dramatic change which may have had to be reversed, and where there was uncertainty of some kind.  Thirdly I retained names where I felt they had value in terms of the information portrayed if not as substantial taxonomic elements.  Whether or not I succeeded is beside the point because classification is an ongoing event, based on a sample that is known, on how well it is known and unfortunately on personal perceptions too.

The description of Haworthia reddii (Scott 1994) provides me with an opportunity to evaluate the respective hypotheses of Bayer (1982) and Scott (1985).  This account should also be a guide to aspiring taxonomists in the group who may be tempted to start at their own levels of knowledge and competence, rather than properly build on historical fact.

The population upon which H. reddii is based is referred to in the New Haworthia Handbook (Bayer 1982, p.30) under H. batesiana, as follows ‑ “… a collection from Klipplaat northwest of Cathcart is clearly comparable.  However, the plants there are too robust to be regarded as H. batesiana and it appears that there is a tendency towards H. cymbiformis“.

Scott did not seem to make the connection between this reference and the plants collected by Dr Reddi and himself at the same place which had in the meantime become better known as Waterdown Dam.  This is unfortunate because he does mention both H. batesiana and H. cymbiformis as possible relatives of his new species, and it would have been significant if this was an independent and credible observation.

In 1982, H. batesiana was not well known and there were very few pointers to the reality of its existence.  Since then there has been another collection from the Valley of Desolation to confirm its existence there, as well as two collections by P.V. Bruyns from the Kamdeboo Mountains and another from the Tandjiesberg.  These are both in the greater Graaff‑Reinet area.  From observations on these collections (and several others pertaining to H. archeri), it seems batesiana must be incorporated in H. marumiana as suggested in 1982.  Furthermore, the concept of that species needs also to be broadened to include H. archeri and relevant collections (Bayer in ms.).

In Bayer (Haworthiad, 1996) I wrote with reference to H. reddii ‑ “At the time I commented on the Waterdown plants there was some doubt about the existence, whereabouts and whatever of H. batesiana.  Since that time there have been any number of collections which fairly conclusively support its inclusion in H. marumiana.  There is, so far as I know, still nothing to show that marumiana comes far enough east to support speculation of linkage with cymbiformis via reddii.  The area NW of Cathcart to Tarkastad has not been fine‑combed by any collector and it probably would better be regarded as an under‑collected region.  Furthermore, the distance from Cathcart to Tarkastad is considerably less than Tarkastad to Beaufort West and Prince Albert (at the western known limits of marumiana).  There are plants in the upper Kei collected by Peter Bruyns which may strengthen the view that reddii is associated with cymbiformis.  In which case it may be sensible to consider it with the var. lepida.  My inclination is to put it with marumiana“.

It is quite obvious from Bayer (1982) that at the time I did not want to commit myself to a decision on the collection from Waterdown Dam.  I did not regard it as substantial enough as a single population to justify formal description and was fairly sure that it would fit into either of two already described species.  One of these was batesiana, which I suspected would prove to fit into marumiana.  The other was cymbiformis.  At the time the odds were heavily against the latter because it was not known at all from the Kei River valley, and only slightly better for the former.  The nearest populations included the missing H. lepida and a collection of my own from near that site and both of these came from the middle reaches of the Fish River which is rather far to the south.  However there were two collections from much further to the east in the Transkei to hint at a more extensive distribution for H. cymbiformis.

The drainage system of the Kei river and its tributaries is a highly dissected landscape and the terrain is rugged and steep.  There are many rocky cliff faces which undoubtedly harbour Haworthias.  It will be a very difficult task to thoroughly investigate even a small proportion of possible Haworthia sites.  (I did at one time point at the possible significance of river drainage systems regarding species, but it is self‑evident that geographical features of any kind will influence distributions and breeding systems.).  Nevertheless, some collections have now been made from which a clearer picture begins to emerge.

The first interesting collections relevant to the ‘reddii‘ problem were collected by P.V. Bruyns at Inverbolo and Inversomo on the Kei River east of Cathcart.  These were of H. cymbiformis and established for the first time the existence of this species on the Kei River.  He also collected what purports to be H. marumiana var. marumiana in several places north of Queenstown, near to Sterkstroom (in an area which, like Waterdown Dam, is also drained by an upper tributary of the Black Kei).  This indicates that H. marumiana also occurs much further east than previously thought.  These collections have rather attenuate, strongly spined leaves and are highly marked with translucence between the dense reticulation.

In December 1996, I was fortunate that P.V. Bruyns was able to accompany me on a collecting trip to the Eastern Cape and one of our objectives was the upper Black Kei.  It is a tributary of the Black Kei on which the Waterdown Dam was built and the relative location of the populations discussed can be seen on the accompanying map.  We were also helped and motivated by a very old specimen in the Pretoria Herbarium collected by Galpin, which I only became aware of earlier in the year and which indicated the occurrence of plants related to H. cymbiformis and ‘reddii‘ southeast of Queenstown.

We travelled on a road running northeast from Cathcart in the direction of the Galpin site, but stopped at the bridge over the Black Kei on the farm Turnstream.  Peter did the climbing of the huge south‑facing cliff there and came back with several clones of reddii‑like plants.  At the same time I found H. bolusii var. blackbeardiana at the eastern base of the same cliff.  We then turned back and travelled eastward along the river to the base of a still higher west‑facing cliff on the farm Highclere.  Peter again did the very strenuous climbing and again returned with a few clones which he described as difficult to reach on the vertical cliff face.

Peter’s earlier collection along the lower Kei at Inversomo is still further to the south and east.  He also collected H. bolusii var. blackbeardiana at this site.

We took the opportunity to revisit the Waterdown Dam on the way home.  I was really surprised to find the south‑facing cliff alongside the dam clothed with huge numbers of plants.  Although H. marumiana is also a clump‑former, these larger clumps were at lower altitude and much more accessible than H. marumiana usually is.  Some of the plants had very distinctive translucent dots and lines while others are unmarked and uniformly opaque with a faint reticulate patterning on the leaves.  The floral characters mentioned by Scott are not definitive although the flowers do appear to have strongly coloured veins.  We also noted the presence at Waterdown Dam of H. bolusii var. blackbeardiana.  The repeated presence of this species may be important in the context of co‑occurrence which forms the basis of my hypothesis relating geographical distribution to the species concept.  It is only slightly relevant to this article but it is critical to a broader understanding of the genus [1].

The offsets we collected from Turnstream, Highclere and Waterdown Dam have taken several months under relatively low light to grow out enough to make useful comment.  At the moment it is extremely difficult to see any difference between three distinct clones from Turnstream and the collection made on the same trip from Waterdown Dam.  I put it like this because the Waterdown plants are quite variable as to the translucent patterning on the leaves.  This may be almost absent, or the margins may be translucent, or the face of the leaves may be quite heavily marked with a series of elongated translucent dots or short lines.  (It should be noted that in H. cymbiformis as a whole, there is a vast range of translucent patterning, from virtually absent, to only translucent leaf‑margins, to massive reticulate or dotted translucence).  The Turnstream collection comprises a very small sample (smaller than I would have liked, and I would have preferred to have seen the plants in situ if I had been fit enough to do so) but the plants are virtually identical in both shape and size to those Waterdown plants which lack the translucent markings.  The colour is also the same rather opaque mid‑green.  The leaves are sub‑cylindrical, or flatter and slightly recurved with a faint darker reticulation similar to that in H. marumiana var. batesiana, and which is also often evident in H. cymbiformis.  The leaf margins in both the Turnstream and Waterdown collections are relatively smooth with evidence of more spination in a few clones of the bigger Waterdown sample.  This spination is not comparable with that of the Andriesberg collections.

The Highclere plants looked slightly different at the time of collection.  They were bigger, paler in colour and less opaque.  The margins were also more heavily spined.  I relate these plants to a wider concept of H. cymbiformis var. setulifera V.Poelln.  It seems extremely improbable in the context of Haworthia, that these two populations at Turnstream and Highclere could be different species and I cannot harbour any question of this kind.

The Inverbolo and Inversomo plants have been in cultivation for more than eight years and, as they were also grown under brighter light, a straight comparison is perhaps unwise.  In comparison with the Turnstream and Waterdown plants they have relatively short obtuse leaves and form tighter smaller rosettes, the coloration is more intense, slightly more glaucous, and the reticulation, opaqueness and/or translucence in either of the two clones (the sample is too small) representing this collection is practically the same.  I included this collection among the specimens of H. cymbiformis var. setulifera, which is indicative of the compounding difficulty of making decisions, already difficult, below species level.

These three collections taken together seem to show a definite and tangible connection between the Waterdown Dam plants on the upper reaches of the Black Kei, through the collection at Turnstream and the herbarium collection of Galpin’s, to H. cymbiformis as represented by the Highclere collection and also the Inverbolo and Inversomo collections further to the south.

The connection to H. marumiana is weaker.  As one moves northeastwards from Tarkastad, populations of H. marumiana retain their more plentiful and rather slender leaves and do not tend to become more like the Waterdown collections or like H. cymbiformis.  The translucence becomes denser and the plants more spinescent.  Collections from the western Karoo (Sutherland, Merweville and Carnarvon by Bruyns and Bayer) which enforce the inclusion of H. archeri under marumiana, weaken the argument to include reddii there too.  In particular, forms of H. marumiana var. batesiana which do bear resemblance to the Waterdown Dam collections occur only very far to the west around Graaff-Reinet.  The clinal trend in this species from Tarkastad northeastward, is thus rather away from a resemblance to the Waterdown Dam plants than towards it.  Thus, if one is to seek continuity of variation, the Waterdown Dam populations do not form part of the series exhibited by H. marumiana but fit into the series of variants now known in H. cymbiformis along the upper reaches of the Kei River.

In 1982 I postulated that there were two species viz. H. batesiana and H. cymbiformis, involved in an assessment of the Waterdown Dam collections and was unable to fit it conclusively into either of these.  Nevertheless, I was convinced that it could be accommodated here and this was, and has been, the prediction of my classification hypothesis.

More recent collections (mostly by P.V. Bruyns) have filled in much detail in the distributions of both H. cymbiformis and H. marumiana that was, at that time, unknown.  These have indicated that H. batesiana and H. archeri can be included in a broader concept of H. marumiana (also as predicted), and they have amplified the known information on H. cymbiformis.  This new information shows that, if the species concepts of geographical continuity and co‑occurrence are followed, ‘reddii‘ is not a discrete new element standing outside of known and variable species.  My prediction that it should not be accommodated in H. batesiana (i.e. H. marumiana) seems to be correct, and our investigations seem to confirm rather that it is an integral part of H. cymbiformis.     The important fact then is that recognition as a distinct species is not warranted, and it can adequately be discussed and classified in terms of the structure of the Haworthia Handbooks.  The hypothesis has not been disproved and there is a rational basis for development of a still better understanding.

An important implication has been that if reddii and similar individual populations are to be treated as distinct species, then each new discovery of which there could be many, will require a new name and the system will become increasingly disordered and fail.  Evidence of exactly this problem is presented by the descriptions of H. batteniae, H. pringlei, H. joeyae, H. venusta and H. mcmurtryi all of which can similarly be accommodated within other variable species.  As far as variability is concerned, the plants from Waterdown Dam, and other populations now associated with them, are not exceptional.  If we had to continue naming each apparently different element like this, we would end up with a structure that has no coherence, no predictive element and no value in the sense that botanical classification is required to express ‘pattern’ and carry information generally.  Such a system may work for the collector in that he may have a name for a particular clone or set of clones, but have no wider or deeper meaning.  Many people may be comfortable with and feel justified in using Scott’s treatment.  Nevertheless, such an approach simply does not accommodate the incredible variation within the genus.

Because of the conflicting views that seem to be an inevitable part of the process of plant classification, many commentators have said that it is not a science but an art.  However, this conflict should not be there.  The essence of science is replication i.e. the deduction of conclusions (for example, a classification) from experiments (for example, observations on plants) which should be repeatable.  In my work on Haworthia, I have been very conscious of the historic conflict in the genus, the need for credibility, and the responsibility attached to making public statements.  Unfortunately, while I may have made mistakes, other authors seem to be less conscientious.  Therefore the presentation of differing taxonomic treatments requires the reader to discriminate between them.  This demands of the reader that he consider carefully the evidence put forward by authors and then discriminate for himself which author has concluded correctly.  Most readers are not prepared to go to this amount of trouble and would rather declare the taxonomy of the group concerned to be ‘controversial’.  This is unfair to all authors and also to other readers as it discounts the effort and sacrifice these people put into collecting and communicating information.  The opinion that taxonomy is an art with little relevance to the enjoyment of the plants themselves, stems from intellectual laziness and ignorance.  It belies the fact that the mere conveyance of a name, which can be forgotten in the very same moment, satisfies some deep psychological need.  The audience also has the responsibility to think analytically and critically about what is laid before them.  Otherwise they may get a meaningless classification that they have earned, but which is just another yoke around the neck of others who may be striving for the light.

    [1]  My classification hypothesis is built on a definition of species which pre-supposes that they are ‘continuous genetically and morphologically in space and/or time’ (Bayer 1982).  Therefore the prediction then is that not only is it probable that H. cymbiformis and H. marumiana will eventually found to be continuous in geographic space, but it is probable that they will also be found to be continuous with H. bolusii.  The entire hypothesis should fit within the framework of taxonomic botany, whatever the level of expertise, and satisfy the requirements of scientific discipline.  Any two people should come to the same conclusion.  If there is conflict there is error.

Gravitational collapse and black holes in Haworthia (1997)

Bruce Bayer
29 Weltevreden Str., Paarl, 7646 South Africa.

I think Haworthia is a gremlin genus.  For some reason or other the rays of clear thought and good sense become distorted and bent as they pass by.  Is it perhaps a black-hole that takes nothing in but easily lets nonsense out?  In making the following comments I try to take into account how the black-hole affects me.  I ask myself what causes this gravitational warp, because you cannot dabble in Haworthia and not know that you are a potential Haworth, Resende, Uitewaal, Smith, Baker, Von Poellnitz, Scott, Bayer and/or Simple controversial Simon.  As a holist, I have been tempted to ascribe ‘warp’ to some sort of homeopathic toxic ingredient in the plants themselves.  However, the inescapable truth is that it lies in human weaknesses such as ego, ignorance, envy and other lesser virtues.  These warp factors also influence this response to Haworthiad 11, No.1:-

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Fundamentals as I see them (1997)

I commented rather defensively, harshly and disparagingly on Ingo Breuer’s article in Haworthiad 10:1, and now here is Haworthiad 10.2 with the second part.  There are also three good letters responding to my request for comment on the requirements for another handbook.

In my frustration with the other authors who also write about Haworthia, it has become obvious to me that I have to look at my own motive and what reward I seek.  H. Jacobsen wrote an article (C&SJ(US) 46:230, 1974) entitled ‘Why I wrote books’, but it disappointed me as I do not think he addressed the issue very well.  He cited talent as one motive for writing and, as a second and only alternative, the professional scientist writing in pursuit of his own perfection.  I do not think that either of these are correct.

It is generally acknowledged that in life we try to create an impression.  Calvin (of Calvin and Hobbs) put it ‘God put me on earth to accomplish a certain number of things..’.  Here we have two other views.  Surely another is simply to earn a living, and there are probably more.

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Haworthia History – Zurich (1997)


The history of this succulent genus is an interesting one as it has its roots in the earliest botanical exploration of the Cape.  Haworthia were included in the first collections of plants when the main concern of botanical collections was medicinal and culinary use of plants.  Haworthia were depicted by several different artists in the late 17th and early 18th century.  These early illustrations were surprisingly good and can be interpreted according to present understanding.  The fact that they have been the object of much confusion is really attributable to the inherent difficulty in understanding the genus and its component species, rather than to poor quality of the illustration.

The genus is not easily separated into separate and easily distinguishable species and the history is correspondingly confused.  Although there are some earlier illustrations, it is the illustrations in Caspar Commelin’s ‘Horti Medici Amstelodamensis in 1701 that form the basis of the taxonomic record.

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Natural Variation and Species Delimitation in Haworthia Duval. – Part 6. HAWORTHIA MACULATA (V. Poelln.) Bayer. (1987)

Printed in British Cactus and Succulent Journal 5:13 (1987)
Part 6. HAWORTHIA MACULATA (V. Poelln.) Bayer.
M. B. Bayer, National Botanic Gardens of South Africa, Karoo Gardens, Worcester.

Haworthia maculata (V. Poelln.) Bayer. Haworthia Handbook: 130 (1976);  New Haworthia Handbook: 43 (1982);  J. W. Pilbeam, Haworthia and Astroloba: 89 (1983).  H. schuldtiana var. maculata v. Poelin. in Feddes Repert. Spec. Nov. 49: 25 (1940).  Type: Cape; in the neighbourhood of Worcester, Swellendam, Bredasdorp and Caledon. Major H. Venter No. 6a. No specimen preserved.  Neotype: Cape- 3319 (Worcester): Worcester District, H. Venter No. 6a in G. G. Smith 3912 (NBG)

scans 005

Rosette stemless, 30-70mm in diameter, up to 60 leaves.  Stem thick, white-fleshed, non-fibrous, 1/3 diameter of rosette, never elongate, slowly proliferous from base.  Roots thick, white-fleshed, non-fibrous.  Leaves erect, spreading, slightly incurved at tips, up to 60mm long, 12mm broad, 8mm thick, ovate-lanceolate acuminate, aristate with bristle up to 5mm long, seldom setiferous, green to grey-green, purplish- green in sun, lines distinct with pronounced small longitudinal transparent areas on upper surface, lower surface heavily mottled or with longitudinal markings, spots occasionally with small hairs, face slightly concave at base, convex-turgid towards upper 1/4, back convex, frequently with second keel or with double row of spines on keel, margins sub-acute, lightly spined, spines white, up to 0.5mm long to 1mm apart.  Perianth white, yellowish-green inside, nerves pinkish-brown outside, pinkish inside at tips, tube ascending curved, up to 16mm long, obclavate, bluntly triangular at base, 4.5mm across reducing to 3mm, segments free, regularly stellate, inner lower segments incurved along upper margin.  Buds biarcuate, bifid at tips.  Flowering Oct-Dec.

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Haworthia and Nomenclatural Confusion (1987)

Printed in British Cactus and Succulent Journal 4:45 (1987).

Haworthia is indeed a popular genus which seems to inspire a great deal of controversy and confusion.  One would have to be very thick-skinned to be able to ignore past history and not plead for forgiveness for similar transgression.  I was just busy trying to clarify, in my own clouded mind, the problem of H. pumila (L.) Duval, when I saw Will Tjaden’s little article on the subject in this journal (3:88, 1985).  Gordon Rowley in the same issue reviews the recent books on Haworthia and also mentions the H. pumila versus H. margaritifera debate.  Coming so soon on the heels of Fearn versus Cole and Walker versus Bruyns, it would be insensible for Bayer to take up the cudgels against anyone.

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Haworthia – Confusion Reigns Again (1986)

Printed in Excelsa 12:91 (1986)

Haworthia is a genus plagued by confusion of one kind or another and it seems now impossible to write about these plants without casting doubts on someone’s integrity or sanity.  The problem in the genus is not simply that there are very few herbarium specimens, or adequate descriptions and illustrations by which the various species can be typified. The various elements in the field are so continuously variable that it is difficult to decide where one species begins and another ends – but not so difficult.  There is some straightforward confusion as in the case of Haworthia margaritifera (L.)Haw. where Wijnands shows that H. pumila (L.)Duval is incorrect.  (Excuse my nomenclature – but this means it is incorrect for the species to which Duval attached the name [H. herbacea] – it is correct for the species to which Scott attached the name).

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Observations on the G. G. Smith Collection of Haworthia. (1982)

Printed  in National Cactus and Succulent Journal 37:105(1982).

G.G.Smith’s collection of Haworthia was donated to Kirstenbosch and the Compton Herbarium in 1950, together with an ostensible manuscript of a monograph, his basic collecting record, various catalogues of literature and odd notes.  However, there was no indication of Smith’s overall view on the classification of Haworthia, or of any intention he had for the genus at the time he abandoned work on it.  On his death in February 1976, Dr M. Courtenay-Latimer obtained many remaining papers from his home, and also the Compton Herbarium became the repository on permanent loan of the entire collection belonging to the East London Museum.  Among the papers are an immense number of detailed drawings by Dr Courteney-Latimer of the kind which were used to illustrate Smith’s publications, as well as very detailed assessments of ‘species’.  Smith accessioned all his plants individually and each plant was assessed on virtually every measurable character.  It appears that Smith first considered whether a new taxon was indicated or not, and then made these numerical assessments against plants which either were, or were considered to be, existing taxa.

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Natural Variation and Species Delimitation in Haworthia Duval. – Part 5. HAWORTHIA ANGUSTIFOLIA Haworth. (1981)

Printed in National Cactus and Succulent Journal, 37:31(1981).
M. B. Bayer, National Botanic Gardens of South Africa, Karoo Gardens, Worcester.

Haworthia angustifolia was described by Haworth in Philosophical Magazine in 1825 as follows:- “(slender leaved) leaves lorate attenuate, curved, widely recurved, wholly green, apex nearly keeled, keel armed with small closely spaced teeth from point of emergence.  Similar to H. chloracantha Haw., but smaller, leaves narrower, more recurved and longer, 3-4 inches long, convex below, flat above, soft elevated longitudinal lines in the middle, marginal teeth small and barely visible to the eye”.

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Looking for Haworthias (1980)

Printed in Calandrimia, Succulent Publication, South Australia. :57 (1980).
M.B. Bayer, Worcester, South Africa

The attraction of Haworthias is their interesting diversity of leaf arrangement and form, as their flowers certainly do not attract attention.  My own interest in these plants owes itself certainly to my introduction to a plant then known as Haworthia chalwinii.  This is now know to be a variation of H coarctata in which the leaves are shorter and more closely adpressed to the stem than is normal.  Even now I am still impressed by the closely-incurved, tubercled leaves packed tightly above one another on a stem which may he up to 20 cm long.  Although I was scarcely 10 years old then, the memory of dense mats of H. cymbiformis on a riverine rock-face in the eastern Cape is still a strong one, but interest remained dominant until nearly twelve years later.  My father was stationed in the Natal Midlands and an uncle, who was a Health Inspector in the malaria areas of northern Natal, brought in an Haworthia from those parts.  J. R. Brown’s book…”Succulents for the Amateur” was one of my favourite books and by that stage would fall open at the section on Haworthias.  The picture of H. bolusii most impressed me and I felt that I knew enough then to recognise these plants from Natal as something new.  They seemed to me quite unlike H. limifolia which 1 knew from illustration, and I thought they should be described as a new species particularly to record the occurrence of the species in Natal.  Fortunately Dr. R.A.Dyer, Chief of the National Herbarium in Pretoria, persuaded me to be more moderate and the plant was eventually described as H. limifolia var gigantea.  . Dr. Dyer also suggested that it would be wise to investigate the species in the field and so launched a 5,000 km wild-goose chase across northern Natal, Zululand and Swaziland.  The only direct success my companion and I had was in meeting Captain D. R. Keith at Stegi on the eastern border of Swaziland.  He directed us to the bottom of the Umbuluzi Valley where we found H. limifolia growing in vast quantity on the shaded dry forest floor (On reflection I wonder why he did not direct us to his original farm Ravelston where the vars keithii and ubomboensis were found).   Although we found no other plants, we did find evidence of plants from as far afield as Paulpietersburg. Barberton, Gollell, Mozaan, Hluhluwe and even as far south as Stanger.  The plant is used by native witch-doctors and herbalists as a remedy for a variety of ailments and one recorded use is for the plants to be placed on the tops of the huts as a lightning deterrent.  Our collecting trip was thus highlighted by endless cross-examination of the rural blacks crying to locate where the plants could be found.  Neither of us had more than a smattering of the Zulu language and this was probably our main stumbling block to success.  On one occasion we were excitedly directed towards an unlikely looking hillside to find a police contingent waiting for us on our return to the vehicle.  Our ‘guide’ had taken us for communist agitators.  Another highlight was being marooned in the Umfolozi Game Reserve by flooded rivers.  Taking adantage of the forced respite, we thought we would explore the Reserve itself, famous as the then last resort of the white rhinoceros.  Our intrepid guide directed us off on a side road in search of the hotter-tempered black rhinoceros and we were soon axle-deep in thick black sticky mud.  The guide was most reluctant to get out of the car and help dig, push and curse while we tried to extract it from the mire.

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A Story of Haworthia Nitidula v. Poell. ( = H. mirabilis Haw.) (1980)

Previously published Cact S.Jl 52.1 1980
M. B. Bayer, Karoo Botanic Garden, National Botanic Gardens of South Africa

Haworthia nitidula was described by von Poellnitz in Desert Plant Life (11:192, 1939) from plants collected by Major H. Venter.  Venter was very generous with his localities and like most of his others, this no. 15 was also simply cited… “in the environs of Worcester, Swellendam, Caledon and Bredasdorp”.  This is an ideal example for demonstrating the problems of identification of haworthias and especially in the section Retusae Haworth.  J.R.Brown illustrated H. nitidula in the Cactus and Succulent Journal (18:89, 1946) but apart from this and the original illustration accompanying the description, the plant has not figured in the succulent literature.  In G.G.Smith’s records, the species and nine varieties are distinguished.  The interesting thing is that these varieties are drawn from three geographically separated species.  The object of this article is to present Smith’s photographs and notes of his “varieties” and discuss their actual position as they relate to distribution.

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Natural Variation and Species Delimitation in Haworthia Duval. – Part 4. HAWORTHIA EMELYAE von Poelln. and a new variety. (1979)

Printed in National Cactus and Succulent Journal, 34:28 (1979).
Part 4: HAWORTHIA EMELYAE von Poelln. and a new variety.
M. B. Bayer, National Botanic Gardens of South Africa, Karoo Gardens, Worcester.

The retention of the name H. emelyae v. Poelln. over H. picta v. Poelln. and H. correcta v. Poelln. is discussed.  There is also a discussion of the relationship of H. emelyae to H. comptoniana Smith. to H. springbokvlakensis Scott and to H. magnifica var. major (Smith) Bayer.  A new variety, H. emelyae var. multifolia is described.

Haworthia emelyae was described by von Poellnitz in 1937 and named in honour of Mrs Emely Ferguson whom von Poellnitz presumed to have been the collector.  Von Poellnitz related his new species to H. willowmorensis v. Poelln., to H. ryderiana v. Poelin. and to H. whitesloaneana V. Poelln..  None of these names is currently upheld (see Haworthia Handbook. Bayer, 1976) and it would be extremely difficult to form a picture of H. emelyae from any vision conjured up from the little tangible evidence associated with them.  Similarly the variety H. emelyae var. beukmannii v. Poelln. is known to be a variant of H. mirabilis Haw. (see Bayer, Excelsa 7: 37, 1977) and offers no solution to the problem.  There are three photographs supposedly of H. emelyae in the H. G. Fourcade photographic record of Major F. R. Long’s collection.  This record was compiled in 1940 and one would have expected less discrepancy at this distance in time than the three photographs actually project.  One photograph is of a plant sent in by a collector and recorded…”from the Gamka river, Calitzdorp”.  The plant is obviously H. turgida and comparable with the forms of that species from along the lower tributaries of the Gamka River (which actually becomes the Gouritz River after its confluence with the Olifants River in the Rooiberge to the north-east of Vanwyksdorp).  The second photograph is of a plant in the collection of W. R. van Ryneveld which is also clearly H. turgida comparable with the Lower Gouritz and Mossel Bay forms.  The third photograph is of a plant recorded as from Mrs E. Ferguson herself and this is unmistakably H. reticulata Haw.

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Haworthia mirabilis Haworth. (1977)

Printed in Excelsa 7::37 (1977).

Haworthia mirabilis was described by Haworth in 1804 from plants said to have been brought to England by the collector Francis Masson.  It could thus have originated from practically anywhere in the southern and south-western Cape.  Haworth referred to this species as the ‘rough cushion cushion’, and it was characterised by having retuse-deltoid leaves with ciliate-spinose margins and keels, the leaves being smooth on the face and the back surfaces almost tubercled and indistinctly reticulate.  There is no extant type specimen and only the brief original description, and illustrations in Curtis’ Botanical Magazine (t 1354, 1811) and in Salm-Dyck’s Aloe Monograph (s9, t 1, 1836-49) serve to identify and typify the species.

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The ‘Retuse’ Haworthias (1975)

Printed in Excelsa 5:83 (1975).
(This article was subsequent to the revision of the Retusae by C.L.Scott).

The 162 named species in the genus Haworthia Duval have been split into 20 sections of which Retusae Haworth is one.  The clearest and most obvious subdivision in Haworthia is into three subgenera which are based on both floral and vegetative characters.  The Retusae fall into the subgenus Haworthia which contains the soft- leaved stemless species in which the three outer petals of the flowers completely enclose the inner petals.  Division within this subgenus is the most difficult of the three and thus the composition of the section Retusae is understandably problematic.  The type species of the section is H. retusa (L.) Haw., so named on account of the fat, bent, thumblike leaves.  In theory this type of leaf should characterise all the other species in the section.  However, in the field it soon becomes apparent that apart from the difficulty in recognising and identifying “species” related to H. retusa, some of these related elements do not have retused leaves.  What then is the composition of the section Retusae and how can the individual species be recognised?  So far the only really satisfactory criterion we have is the geographic distribution and relationship of a large series of rather localised populations.  The individual plants in each of these populations differ to a greater or lesser degree from each other, and in similar manner, the populations differ from each other.  Thus we have variability within and between populations.  The composition of the Retusae is based here on visual assessment of the discontinuities of this variability, on geographic distribution, and on habitat.

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Haworthia Duv.: Section Retusae fide Scott — Additional Comment (1974)

Printed in Aloe 12:89 (1974).
M.B Bayer, Karoo Botanic Garden, Worcester.

The ‘retuse’ haworthias are among the most fascinating of the genus and therefore Colonel Scott’s recent revision is of particular interest.  This work…‘A revision of the genus Haworthia, Section Retusae” was published in ALOE, Dec.1973 and forms a new taxonomic record of the species involved.  The object of the present paper is to examine the validity of this record particularly in the light of past history of Haworthia.  A considerable literature on Haworthia is now available much of which points to the problems likely to be encountered in the group. Much of it also points to the consequences of inadequate species concepts for the group.

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Haworthias – small relatives of Aloe (1974)

Printed in Excelsa 4:17 (1974)


There are few succulent collections which do not include haworthias, although these small and insignificantly flowered plants are not good garden subjects.  Their size, and shade and shelter requirements make them better suited to intensive cultivation in raised containers under shelter.  Very popular with collectors especially prior to World War II, the decline in popularity can be attributed to various factors.  Although the genus is credited with some 160 species and more than 250 varieties, it is highly unlikely that more than 90 species and perhaps 10 sub-species would survive a critical revision.  Many species have been eliminated in recent years, but there are still many maintained only by the mystery of their origin.  Hybrids and ill-defined or inadequate species account for many superfluous names.  The result is an artificial pseudo-scientific system of nomenclature in which the classic binomial system is prostituted for a series of horticultural cultivars.

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Leaf spirals in Haworthia. (1973)

Printed in Aloe 11:31 (1973).
M. B. Bayer, Karoo Botanic Garden, Worcester.

The fascination of haworthia lies in the shape, arrangement, compact neatness and marking of the leaves.  With nearly 170 named species and over 200 varieties, the genus is unfortunately very confused as far as the application of these names is concerned.  Many of the species originally described by Haworth and Baker have not been recognised since, while in recent times new species have been described with little or no reference to occurrence, distribution and variation of existing or related species.  Obstacles in the way of better classification and recognition of the species are many, and include insufficient information on basic morphology.  Secondly, whatever morphological differences there might be between species are often difficult to rationalise and describe, and may even be difficult to perceive with the naked eye anyway.  A third difficulty is the whole question of framing an adequate species concept, or for that matter, a concept of sections.   There is at present even an illogical trend to ‘lump’ the genera Astroloba, Poellnitzia and Chortolirion, into Haworthia, showing that concepts at that level have not reached reasonable finality.  The removal of genera can be applauded for its broadmindedness, if singular lack of appreciation of (a) the criteria by which they can be recognised, or (b) the reasons why they were erected in the first place.  Such an approach must naturally descend to species level, and at a time when the birth pangs of ‘splitting’ and consolidation have barely started, can only lead to a loss of information.

The writer’s experience of the naming of Haworthias and also of other succulent plants, suggests strongly that species descriptions based on broad external appearances are often very inadequate.  Growing conditions including the influence of soil types, temperature, water and light may have such a strong influence on plant growth as to completely nullify the written description, particularly where based on single specimens as has so often been the case.  The object of this article is to discuss the leaf arrangement in Haworthia and its relationship to the general appearance of the plants.  As in many plants, the leaves are produced consecutively at the growing point of the plant, and are consequently arranged in a single continuous spiral about the stem (the genetic spiral).  Thus Aloe polyphylla is by no means unique with its leaf spirals.  When the leaf bases are wide and enfold the stem it is much easier to observe this spiralisation, but when narrowly attached on a broad stem it may be more difficult to detect.  Generally the leaf bases are not continuous as they are in A. broomii where the leaves may be detached from the plant in a long continuous ribbon.  The leaves are produced at a fairly constant angle subtended from the stem and the result is similar to that obtained say when an orchard is planted with the trees at equal distances in and between the rows – i.e. secondary rows are visible when the orchard is viewed from a different angle.   These secondary rows are called parastichies.  The very obvious 3- and 5-tier arrangement of the leaves in the Haworthia section Trifariae and in Astroloba are the result of secondary spiralisation and have long been recognised in taxonomy.  Similarly Haworthia retusa was originally defined as quinquefarious and H. truncata has always been distinguished by its distichous leaf arrangement.

Generally it seems in Haworthia that the twenty-second leaf is again approximately superposed over the first after 8 complete revolutions of the genetic spiral (leaf-divergence (8.360)/21=137 degrees).  However, in the Trifariae only three leaves are clearly visible when the plant is viewed from below and these leaves form the bases of the three secondary spirals which characterise the group.  The leaves are arranged in three tiers with the leaf sequences 1—4—7—10;

2—5—8—11; 3—6—9—12 (i.e. three parastichies).  The classic example of this trifarious arrangement is H. viscosa where every third leaf is superposed approximately over the first.  In the quinquefarious (5-tiered) spiral, the leaf sequence is 1—6—11—16; 2—7—12—17; 3—8—13—18; 4-9—14—19; 5—10—15—20 (five parastichies as in Astroloba), and in the octafarious 8-tiered) spiral 1—9—17—25; 2—10—18—26; 3—11 etc.

In long-stemmed species particularly, it is possible to see simultaneously the arrangement of leaves in tri-, quinque- or octafarious series e.g. in H. reinwardtiii and H. coarctata.  In the short-stemmed, broad- and few-leaved species such as H. retusa or H. pilifera (now H. cooperi), only the lower series are visible, whereas in the acaulescent, many-leaved species, the higher series may appear.  It may seem that the angle of divergence of the leaves from one plant of a species to another is a constant one.  This is not true for the writer has seen for example a single plant of H. rnargaritifera now (H. pumila) with 8 perfect vertical rows indicating a leaf-angle of 135°.  Normally in this species the parastichies 5 and 8 are seen ascending in opposite directions.  In H. tuberculata (now H. scabra) the leaves appear randomly arranged at some localities whereas at others the plants are either trifarious or both the 3 and 5 parastichies are apparent.  In H. viscosa one would expect that to achieve three near vertical leaf tiers, that the angle of leaf divergence must be 120°.  Actually the angles prove to be only complementary, being often on the order 135°, 115°, 110° – to the point that they can be accurately measured.  Similarly in a plant of H. sordida the angles were measured at 180°, 95°, 85°.  Despite the fact that no one angle is measurably the same as the next, the plants still age to maintain an orderly progession of leaves.  In H. truncata, which is distichous (and really only approximately so), the two rows of leaves are actually the consequence of a spiral arrangement in which the leaf angle is near to 180°.

In H. limifolia the average leaf angle is in the vicinity of 160° but this is by no means constant as Diagram 1 of the variety ubomboensis will show.  Some leaf pairs are almost opposed at 180° and the youngest 7 leaves have an average divergence of 170°.  What is perhaps important is that two parastichies are prominent – the primary counter spirals with the leaf sequences 1—3—5—7; 2—4—6—8.  The impossibility of accurately estimating the central axis in the plant from which to measure the angles of divergence must be stressed.  By counting the number of leaves in rotational sequence until a leaf directly above the first is reached, an estimate can be made; thus the ninth leaf above the first in 3 revolutions is the consequence of (3.360)/8= 135 degrees divergence.  Spiral patterning is also related to stem diameter in proportion to leaf thickness and width.  If the stem diameter is great and leaf width small then the higher parastichies will appear.  The relation of stem length to number and size of leaves will also affect spirals.  In H. reinwardtiii and H. coarctata, a complex notorious for its many varieties and forms, the two species with their discrete distribution ranges are separable almost only by the fact that the ratio of number of leaves to stem length differs.  Thus in H. reinwardtii the leaves are more densely compressed on the stem, there are more leaves per unit stem length and the angle of ascent of the genetic spiral is approximately half that in H. coarctata.  Oddly enough the longest stems observed in a recent field study were H. reinwardtii:  27 cm and H. coaretata: 49 cm.  An associated variable is the ratio of stem diameter to leaf width…1:1,7 in H. coarctata, and 1:1,16 in H. reinvardtii.

Diagram 1 illustrates the leaf arrangement in a single plant of H. limfolia var ubomboensis showing the two counter spirals very clearly.  Diagram 2 illustrates the situation in which a uniform leaf angle of 135° presents 8 vertical parastichies, and also how variations of 1—4° alter the entire conformation in only 3 revolutions of the genetic spiral.  At 139° five parastichies are becoming prominent which will reach the vertical at 144°, whereas at 131 °three parastichies will be dominant and reaching vertical at 120°.  A 1°  increase in leaf divergence will result in an 8° displacement at the ninth leaf.

A.H.Church in a fascinating book… “On the relation of phyllotaxis to mechanical laws” (1904), explains that there is a fundamental constant which determines leaf arrangements and spiralisation.  He defines this as the “bulk-ratio”, which is the ratio of the diameter of the leaf buds to the diameter of the stem at the point at which they are joined to it.  In this light, raw dimensions (especially from single plants) can be seen as only a fractional contribution to species descriptions.  Where even normal standards of biometry have been ignored it is even more important to appeal for a more realistic use of measurements.  While proportionate dimensions of leaves and stem (ratios between leaf width, leaf thickness and stem diameter, for example) may help to better describe a species, it does not mean that the basic problem of defining the species will be solved.  In Haworthia the populations are so localised and often so variable that recourse will have to be made to even more refined methods before a satisfactory species concept will be obtained.  It is unlikely that “bulk-ratio” will help solve any problems at species level, but there is no doubt that it can contribute to deciding limits of sections, subgenera and even genera. In the case of the two very closely related species H. maughanii and H. truncata, it would be very interesting to know why the leaves of the former species “spiral” and why in H. truncata they remain distichous.


Diagram 1. Leaf arrangement in Haworthia limifolia var. ubomboensis showing the two primary counter spirals.

Diagram 1. Leaf arrangement in Haworthia limifolia var. ubomboensis showing the two primary counter spirals.

Diagram 2. Representation of leaves diverging at an angle of 135° in which 8 leaf tiers are vertical and a 4° increase or decrease in leaf divergence to show the appearance of 5 and 3 parastichies respectively.

Diagram 2. Representation of leaves diverging at an angle of 135° in which 8 leaf tiers are vertical and a 4° increase or decrease in leaf divergence to show the appearance of 5 and 3 parastichies respectively.


Natural Variation and Species Delimitation in Haworthia Duval. – Part 3. HAWORTHIA REINWARDTII Haw. and HAWORTHIA COARCTATA Haw. (1973)

Printed in National Cactus and Succulent Journal, 28:80(1973).
M. B. Bayer, National Botanic Gardens of South Africa, Karoo Gardens, Worcester.

Abstract:  The names Haworthia reinwardtii Haworth and H. coarctata Haw. are upheld for two related species occumng in the Eastern Cape, South Africa.  The species names H. fulva Smith, H. musculina Smith, H. baccata Smith.  H. peacockii Baker and H. coarctatoides Resende et Viveiros are rejected as superfluous.  H. coarctata subsp. adelaidensis (Von Poellnitz) Bayer stat.nov., H. coartata subsp. coarctata var. greenii (Baker) Bayer stat.nov. and H. coarctata subsp. coarctata var. tenuis (Smith) Bayer stat.nov. are the only infra-taxa recognised.  The many varieties of H. reinwardtii previously upheld are, recognised as forms within the two accepted species. A map showing the distribution of the taxa is given.

Introduction:  Considerable doubt most exist that all the varieties of H. reinwardtii Haw. are really necessary.  Unfortunately such doubts are seldom associated with a rationalised expectation of what varietal differences should express.  It has already been shown that problems in Haworthia taxonomy can only be resolved by the adoption of a realistic species concept.  The object of this paper is to report on the field investigation into the distribution and variation of H. reinwardtiii and its allies, with observations on population structure within this complex.

The species involved in this study are all in the Section Coarctatae Berger, and include H. baccata Smith, H. coarctata Haw., H. coarctatoides Res. et Viveiros, H. fulva Smith. H. greenii Baker, H. musculina Smith, H. peacockii Bak., H. reinwardtii and varieties of these.  Apart from Smith’s species, original localities are not recorded.

Investigation:  Attention was confined to the Eastern Cape, in the area extending from Addo in the west to East London in the east, and from the southern sea coast to the Fish River in the north.  As for other species of Haworthia, it was found that plants are nearly always confined in small localised populations of varying densities.  No particular correlation of distribution with vegetation type or geological formation was observed, and plants were recorded from sea-level to 650m through four main vegetation types and three geological systems.  Distribution is primarily associated with rocky, well-drained situations and reduced competition from other vegetation.  This latter point is by no means always true, as for example H. reinwardtii var. tenuis Smith, growing in deep soils under a dense canopy of Valley Bushveld vegetation.  Similarly, as the name implies the origin of H. greenii var. silvicola Smith was also sylvan.  Fifty-three collections were made at different points throughout the area, paying particular attention to localities for recognised varieties where known.  Of these, only H. reinwardtii var. peddiensis Smith was not recollected.  In each case up to ten pieces of full- length leafy stem were collected from separate plants at each site.  Judgement of the taxonomic position is thus based on field impressions, collections made personally by the writer, twelve collections made by Mr F. J. Stayner, 31 single plant collections still extant in Smith’s collection after 30 years, and on herbarium specimens in the Albany Museum, Grahamstown, the Compton Herbarium, Kirstenbosch and the Bolus Herbarium, University of Cape Town.

Attention is drawn to specimens in the Bolus Herbarium; H. Viedge April 1927 from “Tabase’ near Umtata”, a sparsely tubercied and steeply spiralled plant like H. coarctata, R. C. Holmes August 1935 from ‘between Kei and Tsomo Rivers” which is akin to H.. attenuata Haw., and a glabrous leaf remnant, Pillans November 1906, from “between King Williamstown and Grahamstown”.  Neither of the latter specimens can be confidently allied to present known taxa, and the Umtata specimen in particular represents a complete contradiction in terms of the known distribution of the genus.

In the case of H. baccata. a thorough search was made in the Isidenge area of the Stutterheim district before concluding that the locality was a most improbable one.  It was subsequently learned from Mr W. E. Arrnstron (a well-known collector) that the plant had not been collected at Isidenge but in fact came from Frazers Camp near Grahamstossn.  The plant came in Smith’s possession at third-hand and there is thus reason to question the given locality.  Interpretation of observations presented here was subject to particular consideration of both phenotypic and genotypic variation.  Phenotypic variation is the outward appearance of the individual as it responds to factors in the environment.  Comparison of specimens collected from the same sites as plants growing in Smith’s collection showed surprisingly little differences.  Attenuation resulting from shading was seldom encountered and it was nearly always possible to observe plants at each locality in demonstrably steady growth states.  More difficult were certain localities where combinations of rock substrate and shade produced more variable growth conditions.

As far as the genotype – the fixed genetic basis of variability – is concerned, the problem also appears relatively slight, despite the high percentage of polyploidy noted by Riley (1968).  Riley suggested that polyploidy may account for the large number of taxonomic varieties in H. reinwardtii, or alternatively because differences between these are small, that they may have arisen as single gene mutants which have propagated vegetatively.  Riley and Mukurjee (1965) recorded 4 diploids, 8 tetraploids and 1 aneuploid.  These are H. fulva, H. reinwardtii vars. olivacea Smith, tenuis Smith, haworthia Res. (= reinwardtii) with 2n =14; H. baccata, H. musculina, H. greenii var. silvicola, H. reinwardtii vars. huntsdriftensis Smith, valida Smith and an unnamed variety with 2n=28:

and H. greenii forma pseudocoarcata (VP) Res. with 2n=28 and 30.  In 1962 (Riley,1968) these authors also recorded the aneuploid H. reinwardtii var. chalwinii (Marl. et Berg.) Res. with 2n=26.  Resende and Pinto-Lopes (1946) recorded the following: H. reinwardtii vars. adelaidensis VP., triebneri VP, minor Haw. and major Haw. 2n= 14:  H. reinwardtii vars. conspicua VP, fallax VP, haworthia, chalwinii, H. greenii forms greenii, minor and pseudocoarctata 2n =28:  H. reinwardtii var. archibaldiae VP 2N=21;  H. coarctata vars. coarctata, kraussii Res. and coarctatatoides Res. et Viv. nom. nud. 2n=42.

Where these records can be referred to field populations, it appears that diploids and polyploids are encountered across the range of the species complexes.  Thus polyploidy is not conclusively a basis of species or varietal differentiation in this group.  If it were so, one would expect some evidence of discrete sympatric populations – which is definitely not the case for example, at ‘Hopewell’, Bathurst. Here H. fulva, H. musculina and H. greenii var. silvicola all have their origin in the same close locality.  Smith’s field notes, in which he also recorded H. coarctata, H. chalwinii and H. reinwardtii from the same locality, put the three taxa into proper perspective.  Apart from the fact that H. musculina and H. greenii var. silvicola have been cited as tetraploids, as opposed to H. fulva which is diploid, these three taxa do not command separation if indeed recognition at the level of forms. H. coarctatoides is a nomen nudum for a plant said to be intermediate between H. reinwardtii and H. coarctata and can be rejected as a meaningless taxon.

Only one locality was found presenting any real evidence of two non.-interbreeding entities growing together.  This is at Hellspoort where one of these entities is allied to H. coarctata and may thus be hexaploid (or perhaps only tetraploid following Resende’s notes on the locality for H. greenii forma pseudocoartata at Alicedale, a plant which the writer allies with his interpretation of H. coarctata), and the other to H. reinwardtii var. adelaidensis which is diploid.  The latter variety can be shown to be correctly related to H. coartata at subspecies level.  An interesting point is the occurrence of sterile or at least partly sterile triploids in the H. reinwardtii vars. archibaldiae. chalumnensis Smith and peddiensis (Riley, private communication).  The writer particularly noted two populations in which it appeared that despite normal flowering, ovules were aborting.  This does bear on Riley and Majumdar’s (1966) statement that Haworthias usually propagate vegetatively.  While as a general stalement this is incorrect, it is clearly to some extent true for some species including H. reinwardtii and H. coarctata.  Vegetative reproduction could perhaps account for uniformity at different sites if populations had their origins in single clones, or alternatively one would expect more discontinuity where several genotypes were involved.  Variability at various sites and clinal trends across the distribution range, in the writers opinion,  tend to detract from vegetative propagation as a factor in population differentiation.  In support of this comment is the observation on locality restrictions where it is felt that movement of detached stems would surely lead to positive downward migration of populations.  Yet it is a feature of the species, particularly nearer Grahamstown and notwithstanding earlier comments, that they occupy elevated positions on edges of ridges and plateaus.  Nevertheless there is adequate evidence that vegetative propagation does occur especially under conditions of heavy grazing.

A final consideration is the exploratory work done by Riley and Isbell (1963) on paper chromatography in the Aloineae.  Here it was suggested by way of demonstration that H. fulva was close to H. greenii, that H. reinwardtii vars. tenuis. committeesensis Smith and possibly diminuta Smith were close, that H. reinwardtii vars. haworthii and chalwinii were similar, whereas the vars. archibaldiae, valida and H. baccata were different.  If H. baccata had originated at Frazer’s Camp, the chromatograph could have been expected to show affinity to H. reinwardtii var. diminuta.  Similarly on the basis of distribution and outward appearances, one would have expected diminuta to be at variance with, rather than relating to committeesensis and tenuis: the latter two also expectedly differing to some degree.

Results and Discussion:  The superficial impression that might be gained from the field is that a single species complex is involved.  However, three distinct entities, with the two larger of these exhibiting strong clinal trends, are apparent.  The two principal entities are regarded as H. coarctata and H. reinwardtii and it is rather surprising that there is a complete break in continuity between them despite their close affinity.  Conceptions based on past taxonomic treatment give no indication of this discontinuity, and varieties previously described under H. reinwardtii actually belong in H. coarctata as will be shown.  Even the older species H. chalwinii resolves under H. coarctata rather than H. reinwardtii as implemented by Resende.  Most existing taxa in the complex are based on size, density of leaf arrangement and on shape, size and arrangement of leaf tubercles.  That these criteria are inadequate is clear both front examining variability within and between populations. and from the relation of the described taxa to one another and to field populations.

In attempting to rationalise the discontinuity between eastern and western populations in the complex, it was concluded that the general difference as associated with the spiral arrangement of the leaves on the elongated stems – a principle of phyllotaxis elaborated by Church (1904).  (Church postulated that phyllotaxis is a result of fundamental growth processes and can be treated mathematically.)  It is this phenomenon of spiral series which provides the device by which the two entities can be consistently and satisfactorily differentiated.  By cutting the leaves at right-angles near (4mm) to the stem, these spiral rows (parastichies) can be more clearly observed.  In the entity H. coarctata there are apparently 2 spirals ascending in one direction with approximately 4.5 leaves per revolution, while in the reverse direction there are 3 spiral tiers with 7 leaves per revolution.  In the entity H. reinwardtii, 3 spirals with 7 leaves per revolution and 5 counter spirals with 11 leaves per revolution are seen.  In fact, in both entities the leaves are arranged in a single continuous spiral about the stem, so that cutting the leaves too close to the stem precludes the configuration stated here.  In both species, the leaves follow successively at an angle of approximately 137.5 degrees, so that the 22scd leaf in the spiral is again superposed over the first (the orthostichy) through 8 revolutions.  The difference in spiral patterning is thus apparently an artifact which is dependant on a number of variables.  These are: the ratio of stem diameter to leaf width, leaf thickness, degree to which the leaves are amplexicaul. (in effect Church’s ‘bulk ratio’), the degree of compression of the spirals on the stem, and the angles at which the leaves are subtended from the stem.  The ratios of stem diameter to leaf width in H. coarctata and H. reinwardtii are 1:1.7 and 1:1.16 respectively (see table 1).  The real nature of the spiralisation of leaves is shown in diagram I and 2.  In H. coarctata the tiers seen on the cut leaf sections are the 3 tiers of the secondary spiral (P2 on diagram) and the 2 tiers of the primary counter spiral (Cl).  In H. reinwardtii it is the 3 tiers of the secondary spiral and 5 tiers of the secondary counter spiral (C2) which are seen: the primary counter spiral ascending at such a shallow angle that the narrower leaf sections comprising it are taken for the primary spiral.  The angle of ascent of the primary spiral in H. reinwardtii is half that in H. coarctata, and it is interesting to note that the maximum stem length of 26cm observed in the field, was also almost half of the 47cm observed in H. coarctata.

It must be stressed that growing conditions may possibly affect the angles of ascent of the leaf spirals to some degree, so that thicker, fleshier leaves in a specimen of H. reinwardtii may produce a likeness to a specimen of H. coarctata grown under hardy conditions. In the writer’s experience of the plants in the field and under cultivation, the distinction between the two species on this basis is absolute, and it is confidently expected that a statistical evaluation of stem and leaf dimensions will verify this conclusion.  It should be noted that in the section Trifariae. the 3 leaf spirals are the secondary spirals (leaves 1-4-7- . . . ). In Astroloba and Poellnitzia, the 5 spirals are secondary counter spirals (leaves 1-6-11- . . . ).  A plant of H. margaritifera (L.) Duv. at the Karoo Garden has the leaves in 8 spirals – the tertiary spirals (1-9-17- . . .), while even the distichous leaves in H. truncata Schon. are arranged in a spiral series (the primary counter spiral!  The leaves are arranged spirally in all plants and whether the spirals impress visually or not depends on the width and thickness, curvature, nature of attachment, and density of the leaves on the plant stem.

The distribution of the principal entities recognised in the present study is shown in the accompanying map.  In H. coarctata, very large forms exist as populations in the vicinity of Patterson, Alicedale, Hellspoort and Fort Brown.  Intermediate forms occur south and west of Grahamstown. and smaller forms in the Bathurst-Alexandria area.  The Hopewell population is not such an extremely heterogenous one as earlier notes suggest, and localities on the Kowie River at Vaalvlei and at Blaauwkrantz Bridge near Manley Flats display perhaps greater variability.  H. reinwardtii var. tenuis represents a distinct discontinuity and is upheld in the species H. coarctata, in the absence of further known populations, at varietal level.  H. fulva, H. musculina and H. reinwardtii var. committeesensis do not represent marked discontinuities, and the same is true of H. reinwardtii var. chalwinii. The latter appears to be an admittedly rather di€tinctive form, but which appears in various population of H. coarctata including the entity tenuis.  H. greenii at Howiesonspoort is recorded as both tetraploid and aneuploid and is a notable variant although clear population discontinuity does not occur.  Its tetraploid state does not necessarily suggest taxonomic separation from the main body, H. coarcata, where diploid to hexaploid states are known.  H. peacockii with its submersed tubercies is considered to be a local variant at Howiesonspoort and is rejected taxonomicall, while H. greenii is upheld at varietal level only.  With the rejection of H. chalwinii at any level above that of forma, H. coarctatoides receives similar treatment. H. reinwardtii var. conspicua is rejected as a form of H. coarctata as many plants agreeing reasonably with Von. Poellnitz’ description were seen, but not constituting discrete populations.

H. reinwardtii var. huntsdriftensis Smith represents something of an anomaly.  In the Compton Herbarium, Smith 6818A from “n hill at top Hunt’s Drift, last cutting on west side of Fish River” is clearly H. coarctata, as is Smith 7105 – “top Hunt’s Drift, west side”.  Smith 6818 and 68l8B are from “on hill on top of Huntsdrift just before valley before Frazers Camp”, and these may be specimens of H. reinwardtii.  Smith 3849 “west side of Hunt’s Drift” is an isotype and Smith 7106 “top Huntsdrift near Frazers Camp” is very similar.  There is in all cases a lapse of 4-5 years between collection date and herbarium labeling except for Smith 7106, one year.  If Smith’s detailed locality for the variety “in hollow before last hill going up to last gate at top Hunt’s Drift” is correct, then plants collected by the writer at this locality are at variance with the described taxon.  Either this is due to (a) phenotypic changes brought about by cultivation—which is discounted, (b) errors between collection and recording – and there are six herbarium sheets involved, or (c) there is an additional point not located by the writer where H. coarctata is in close proximity to H. reinwardtii.

The question of phenotypic change is rejected as almost without exception herbarium specimens agree with current field collections.  Exceptions are one specimen labelled “25 miles from Port Alfred to Alexandria”, which is the actual distance between these towns; and the specimen agrees with plants of H. reinwardtii collected at a distance of about 5 miles along that road.  Another exception is Smith 7349 labeled “4-5 miles between Riebeek East and Alicedale” which is a blatant misfit, matching rather specimens from the eastern limits of the distribution of H. reinwardtii and Smith 5218, an isotype of H. reinwardtii var. riebeekensis Smith, labelled “4 miles before Riebeek East from Alicedale” whereas in Smith’s field book the locality is recorded “4.5 miles before Riebeek East from Carlisle Bridge”.  These few discrepancies in all the herbarium specimens (263 sheets) do not allow the supposition that either phenotypic change or incorrect labeling are responsible.  Plants which do match Smith’s description occur at Hunt’s Drift on the east bank, and it is likely that they are also found nearer Frazers Camp.  This may prove important in future studies on this group.  H. reinwardtii var. huntsdriftensis is considered to belong to H. coarctata.

H. reinwardtii var. bellula Smith is another anomaly, as a close search of the type locality, and near localities, failed to produce matching specimens.  What very small specimens were seen were taken to be suffering under adverse growth conditions, and the population at this locality falls into a series extending from Bothas Ridge and Queens Road northeast of Grahamstown, to Hellspoort and Riebeek East.  The Queens Road locality is the type locality for H. reinwardtii var. adelaidensis VP as pointed out to Smith by the finder, W. F. Armstrong.  This is one of Von Poellnitz’ unfortunate errors where a locality has been attributed to the collector’s address rather than to actual field origin.  At Hellpoort there is the case of a smaller, densely-leaved entity coexisting with a more typical population of H. coarctata, albeit not precise superimposition of locality. This fact coupled with morphological criteria, is the basis for recognition of the taxon H. coarctata. subspecies adelaidensis, which includes the populations from which the H. reinwardtii vars. bellula and riebeekensis were drawn.  In the latter case, Smith’s field notes were found to be confusing and the site at Willowfountain north of Riebeek East could only be located by cross reference to noted landmarks and two other species recorded from the near vicinity.

Generally in H. coarctata the tubercles are nearly smoothly rounded and smaller than in H. reinwardtii, where they are frequently large and flattened scale- like.  Also in H. coarctata there are more tubercles across the width of the leaf than in H. reinwardtii.  Between Salem and Alexandria, southwest of Grahamstown, there is one particular population of H. coartata with much larger tubercies and also very densely tubercled on the leaf face.  However, this is not clearly discontinuous if other populations are also considered and a new taxon is not proposed.

The distribution of H. reinwardtii can be traced from Kaysers Beach near East London, to a point west of Port Alfred, then northward to Frazers Camp and Coombs and eastward to Peddie.  Local populations appear to some extent more consistent than in H. coarctata but discontinuities are not readily discernible. H. reinwardtii var. major is a form which can be found at several localities, and H. reinwardtii var. chalumnensis is reasonably regarded as one of these.  H. reiiiwardtii vars fallax, valida. kafferdriftensis Smith, pulchra VP and grandicula Smith similarly have no reasonable basis on the grounds of population discontinuities.  The same is true of the var. peddiensis which, in the absence of field material, it was necessary to compare the described taxon and the living type with populations nearer to the Fish River.  H. reinwardtii vars. zebrina Smith and olivacea Smith are distinctive forms in a notably variable population and it cannot be considered that rank above forma is necessary or desirable.  In the case of H. reinwardtii vars.brevicula Smith and diminuta, the taxa are drawn effectively from the same population at Frazers Camp.  If it was necessary to apply an appellation to this fairly extensive population, perhaps the name H. reinwardtii var. minor Baker would be more appropriate at the extreme of a clinal trend in size-reduction from southeast to northwest.

In H. baccata the specimen Smith 3572 (NBG) is an isotype dated July 1944 and agrees reasonably with Smith’s illustration.  Another isotype, Smith 3572 (BOL) dated November 1945 does not agree with the previous specimen, but does conform with specimens from Frazers Camp.  As Armstrong, who knew the collector, Mr McClaren, maintains that H. baccata originated at this locality, the name is rejected as superfluous.  The locality of H. reinwardtii var. archibaldiae is, on the basis of specimens submitted to Smith by Miss G. V. Britten (of the Albany Museum, and a contemporary of Miss E. Archibald), taken to be at the Umtana River east of Wesley in the Peddie district.  Only four clones were located in a brief search at this site and this scarcity may be attributable to it being a sterile triploid.  Smith identified several plants from other localities as this taxon and Von Poellnitz also recorded two localities – the varietal rank is not upheld.

Conclusion:  The separation of H. reinwardtii and H. coarctata on the basis of morphological criteria, also satisfies geographical requirements.  Local populations in each species, and particularly in H. reinwardtii, tend to have distinctive facies but discontinuities between populations are seldom marked.  It is the writer’s opinion that colouration and general condition of the plants, imposed by local environmental conditions contribute greatly to this phenomenon of local ecotypes, obscuring more basic similarities between populations.  A key for separation of varieties, as presented by Von Poellnitz, may have been workable in a collection comprised only of those particular forms, but not as a basis for usefully or consistently distinguishing field collected material.  The diagnoses by which the described varieties of H. reinwardtii were to have been distinguished from one another can often be totally discredited by inherent variability at each point of origin.  It is a basic tenet of taxonomy that all individuals must be referrable to a species.  If lesser ranks are recognised in these species, it is logical to expect that in the same way individuals will all be referable to these categories and the parent species not treated as a repository for all forms which do not conveniently agree with descriptions.

Believing that the present exposition satisfies these requirements, the writer’s concept of H. coarctata and H. reinwardtii is as follows:-

Haworthia coarctata Haworth in Phil. Mag. 44: 301 (1.824).
Aloe coarctata (Haw.) S-D. Monogr. S6, f. 17 (1836-49).
Haworthia chalwinii Marl. et Berg. in Notizblau Berl. Bot. Gart. 4: 247 (1906).
Haworthia reinwardtii var. conspicua VP. in CJ. 5:31 (1936).
H. reinwardtii var. committeesensis Smith in Jl SA. Bot. 9:93 (1943).
H. fulva Smith in 15.4. Jl SA Bot. 9:101(1943).
H. greenii var. silvicola Smith in Jl SA.Bot. 9:103 (1943).
H. reinwardtii var. huntsdriftensis Smith in Jl.S.A. Bot. 10:14 (1944).
H. reinwardtii var. chalwinii (Marl. et Berg.) Resende et Pinto-Lopez in Port. Acta Biol. (B) 2:175 (1946).
H. coarctatoides Res. et Lopez nom. nud. in Port. Ada Dial. (A) 2:175 (1948).
H. musculina Smith in JS.A. Bot. 14:43 (1948).

Plants with fibrous elongate leafy stems from 5 to 47cm long, overall diameter from 2 to 7cm; leaf length from 2.5 to 7.5cm, width from 1.0 to 2.4cm, thickness from 0.2 to 0.8cm;  ratio of stem diameter to leaf width in region of 1: 1.7; leaves ascending- spreading, multifarious incurved, broadly lanceolate to ovate-deltoid, broadly amplexicaul;  back of leaves rounded, slightly keeled above, beset with numerous small rounded tubercles;  face generally flat to concave, seldom tubercled.

Haworthia coarctata subsp. coarctata var. greenii (Baker) Bayer comb. nov. –
H. greenii Baker in Journ. Linn. Soc. 48:202 (1880).
H. peacockii Bak. in Journ. Linn. Soc. 48:202 1880.
Plants with stems up to 15 to 20cm long, overall diameter up to 5cm, tubercles mostly suppressed or absent.

Haworthia coarctata subsp. coarctata var. tenuis (Smith) Bayer comb. nov.
H. reinwardtii var. tenuis Smith in Jl.S.A.Bot. 14 :51 (1948).
Plants with narrow elongate stems up to 44cm. overall diameter 2.5cm, leaves up to 3.2cm long , 1cm wide.

Haworthia coarctata subsp. adelaidensis (VP) Bayer comb. nov.
H. reinwardtii var. adelaidensis VP in Succ. Afr. 3:82 (1943).
H. reinwardtii var. riebeekensis Smith in Jl. SA. Bot. 10:16 (1944).
H. reinwardtii var. bellula Smith in Jl.S.A.Bot. 11:70 (1945).
Plants with stems from 5 to 15cm long, overall diameter up to 3cm, leaf length 2.5 to 3.5cm, width 1.0 to l.lcm, thickness 0.2 to 0.3cm.  Leaves are proportionately longer and narrower than in type, while stems are more elongate and thinner overall than in corresponding specimens of H. reinwardtii.

Haworthia reinwardtii Haworth
Suppl P1. Succ., 57 (1819).
Aloe reinwardtii (Haw.) S-D. Monogr. S6, f16 (1836-49)..
H. baccata Smith in Jl.S.A. Bot. 10:20 (1944).
(Included in synonomy are the varieties of this species described at various times by Von Poellnitz, Smith and Resende which have not been located elsewhere.)

Plants with fibrous elongate leafy stems from 5 to 26cm long, overall diameter from 2.5 to 6cm, leaf length from 2 to 4.5cm. width from 0.7 to 1.5cm. thickness from 0.2 to 0.35cm;  ration of stem diameter to leaf width in region of 1:1.16.  Leaves ascending – spreading multifarious, incurved, lanceolate, narrowly amplexicaul;  back of leaves rounded, slightly keeled above, beset with large flattened scale-like white tubercles generally arranged in transverse rows, face flat, often sparsely tubercled.

(Note: It is proposed to maintain all specimens collected during the course of this investigation at the Karoo Botanic Garden, so that in due course the above classification can be verified or revised.  Floral morphology has not been considered as a source of characters as the similarity or floral structure in the subgenus Hexangulares Uitewaal suggests that a very meticulous, time-consuming study would be required to prove the worth as a taxonomic aid.  It is also suggested that the above arrangement based on vegetative characters may provide a working basis for further investigation in this complex.  For collectors it is suggested that deposed varieties be regarded as formae in the respective species, as there is no doubt that specimens such as ‘zebrina’ and ‘olivacea’ are striking collectors’ pieces.)

Acknowledgement:  The writer gratefully acknowledges the encouragement and assistance received from the Curator of the Karoo Garden, Mr F. J. Stayner, and also the assistance and hospitality of Mr D. A. Timm of Vaalvlei, Grahamstown, during the course of field work.

Literature cited:
Riley, H. P. The Nucleus, Seminar on Chromosomes (1968).
Riley,.H. P. and Mukurjee, D. The Nucleus 8:2 p. 149 (1965).
Riley, H. P. and Majumdar, S. K. Botanical Gazette 127:4 p. 239 (1966).
Resende and Pinto-Lopez, I. Port. Acta. Biol. (B) 2:178 (1946).

Fig. 1 Photograph of principal entities to show secondary spirals:- Left: KG 31/64 H. coarctata subsp. coarctata. Biaaukrantz Centre: KG 39/65 H. coarctata subsp. adelaidensis. Queens Road Right: GGS 7346 H. reinwardtii. east of Fish River
Fig. 1 Photograph of principal entities to show secondary spirals:-
Left: KG 31/64 H. coarctata subsp. coarctata. Biaaukrantz
Centre: KG 39/65 H. coarctata subsp. adelaidensis. Queens Road
Right: GGS 7346 H. reinwardtii. east of Fish River
Diagram 1. Diagram showing the different angles of the leaf spirals in (A) H. reinwardtii where the low angle of the secondary counter spiral approximates that of the primary spiral in (B) H. coarctata.
Diagram 1. Diagram showing the different angles of the leaf spirals in (A) H. reinwardtii where the low angle of the secondary counter spiral approximates that of the primary spiral in (B) H. coarctata.
Diagram 2. Diagram showing the position of the leaves relative to the stem axis and the spirals so formed. P2 - One of three secondary spirals Cl - One of two primary counter spirals 		C2 - One of five secondary counter spirals
Diagram 2. Diagram showing the position of the leaves relative to the stem axis and the spirals so formed.
P2 – One of three secondary spirals
Cl – One of two primary counter spirals
C2 – One of five secondary counter spirals
Diagram 3. Map showing the distribution of:- C - H. coarctata subspp. coarctata var coarctata Haw. CG - H. coarctata subspp. coarctata var greenii (Bak.) Bayer. CT - H. coartata subspp. coarctata var tenuis (Smith) Bayer. CA - H. coarctata subspp. adelaidensis (V Podia.) Bayer. R - H. reinwardtii Haw.
Diagram 3. Map showing the distribution of:-
C – H. coarctata subspp. coarctata var coarctata Haw.
CG – H. coarctata subspp. coarctata var greenii (Bak.) Bayer.
CT – H. coartata subspp. coarctata var tenuis (Smith) Bayer.
CA – H. coarctata subspp. adelaidensis (V Podia.) Bayer.
R – H. reinwardtii Haw.

Table 1.

Natural Variation and Species Delimitation in Haworthia Duval. – Part 2. HAWORTHIA HERBACEA (Miller) Stearn. (1972)

Printed in National Cactus and Succulent Journal, 27:51(1972).
Part  2. HAWORTHIA HERBACEA (Miller) Stearn.
M. B. Bayer, National Botanic Gardens of South Africa, Karoo Gardens, Worcester.

Abstract:  The application of the name Haworthia herbacea (Mill.) Stearn to field populations is discussed.  It is concluded that this name applies best to the predominant complex occurring in the western and south-western Robertson Karoo.  The species H. aegrota v Poelln., H. submaculata v Poelln., H. luteorosa Uitew. and the variety H. pallida var. paynei are shown to have their origin in the same complex, and are therefore reduced to synonymy.

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Natural Variation and Species Delimitation in Haworthia Duval. – Part 1. HAWORTHIA RETICULATA (Haw.) Haworth (1972)

Printed in National Cactus and Succulent Journal, 27:10(1972).
M. B. Bayer, National Botanic Gardens of South Africa, Karoo Gardens, Worcester.

Abstract:  The name Haworthia reticulata (Haw.) Haw. is upheld for a species occurring in close association with H. herhacea (Mill.) Stearn in the Robertson Karoo.  Evidence is presented to show that H. haageana v. Poelln., H. hurlingii v. Poelln. and H. intermedia v. Poelln., together with published varieties of these, have their origin in the same species complex.  These species are reduced to synonymy in the single species H. reticulata.  It is suggested that H. subregularis Baker may also be synonymous.

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Anguish Among the Haworthias. (1972)

Printed in Cactus and Succulent Journal of Great Britain, 1972.

M. B. Bayer, Karoo Botanic Garden, Worcester, South Africa

Confusion in nomenclature has robbed an attractive and interesting genus of much of its charm and enticement to the collector.  For the past few years considerable effort has been made at the Karoo Botanic Garden at Worcester, South Africa, into the investigation of Haworthia.  It has been disturbing to find the extent to which current nomenclature is at variance with the natural groups as they are found in the field.  Perhaps more disturbing is the difficulty which obviously lies in reducing the complex field relationships to an understandable and usable system of classification, Haworthia can clearly be divided into three subgenera on the basis of floral characters; these are the subgenus Haworthia in which the base of the floret is rounded-triangular and in which the outer three segments completely enclose the three inner ones, and the subgenera Hexangulares Uitewaal and Robustipedunculares  (Uitcw.) Bayer in which the floret base,is rounded-hexangular (the florets stipitate in the former) with the outer floral segments separated by the midribs of the inner segments.

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Changes in the genus Haworthia Duval. (1971)

Printed in Cactus and Succulent Journal (US), 43:157 (1971).

M.B.Bayer, National Botanic Gardens of South Africa, Karoo Garden, Worcester.

The genus Haworthia is sub-divided into twenty sections principally on leaf and growth habit.  The composition of the sections thus often bears little relation to the actual and natural affinities of the constituent species.  Sub-division of the genus on the basis of floral characters has been suggested by Uitewaal (1947) and reference should also be made to Berger (1908).  In Das Pflanzenreich, under the Section Margaritiferae, Berger particularly comments (citing N.E. Brown) on the problem of garden hybrids, and it is unfortunately true that many species are still recognized which have no real basis in field populations.  These inevitably obstruct attempts at presenting natural relationships, and hence also a desired aim of plant classification.  The inadequacies of leaf morphology as a basis for subdivision is particularly evident in a study of the species H. reticulata Haw., H. herbacea (Mill.) Stearn and H. schuldtiana var. maculata vPoelln..  These species are presently placed in the sections Muticae, Arachnoideae, and Retusae respectively, when in fact distribution, inherent variability, field hybridization and floral morphology demonstrate their unquestionable affinity.

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