Haworthia correcta corrected and how it impacts upon the names H. picta and H. emelyae.

Almost weekly pictures of Haworthia bayeri are posted on Internet Haworthia discussion groups labelled ‘Haworthia correcta’. It seems that the ‘correcta’ label found particular appeal in Japan as many Japanese Haworthia collections still contain H. bayeri plants labelled as H. correcta.  However, the photograph below is of a plant corresponding fully to the original description and photo of the type plant of Haworthia correcta. If you find this confusing or surprizing, read the text below.

The origins of the name ‘Haworthia correcta’ Poelln.

·         Firstly, the name Haworthia correcta was originally applied to the specimen Triebner 978 which clearly represents the species we currently refer to as Haworthia emelyae /H. picta/ also H. tricolor) . The name ‘correcta’ was applied as correction to replace the name ‘blackburniae’ which had been used already at the time.

A photo of the original publication of H. blackburniae in Kakteenkunde. On the right is the enlarged and clearer photo of the Triebner 978 plant.  

The picture above shows the original Triebner 978 plant that had been collected by Mrs E. Blackburn near Calitzdorp and which was published in 1937 as Haworthia blackburniae by Von Poellnitz in Kakteenkunde (9):132.

Soon afterwards Von Poellnitz realized that W.F. Barker had published the name Haworthia blackburniae for another Haworthia species only a few months earlier. W.F. Barkers’ H. blackburniae is the grass-like leaved species we still recognize today. The latter also grows near Calitzdorp. Von Poellnitz then corrected the error by renaming the Triebner 978 specimen Haworthia correcta in Feddes Repertorium 43 page 103 in 1938.

There should be little doubt with anyone familiar with these plants that the Triebner 978 specimen was a plant of the species we now refer to as H. picta/ emelyae/ tricolor. The black and white photograph of Triebner 978 shows a rather poorly cultivated specimen clumsily potted and protruding above ground but the shape of the leaves are clearly that of H. picta/ emelyae with flecked and very subtly pimpled upper windows bordered by toothless margins and opaque leaf-sides. Most characteristic is the upward-curving sharp leaf-tips ending in a sharp bristle. 

Why then, may one ask, don’t we currently refer to H. picta/ emelyae as H. correcta and how on earth did Haworthia bayeri get mixed up in the mess?

The confusion seemed to have originated with Col. C. L. Scott who initially referred to the plants we know today as H. bayeri as H. willowmorensis V. Poelln. but later he became convinced that the original collection of H. correcta was near Uniondale and proposed that H. correcta should be the correct name for these plants. Scott wrote that Mrs Blackburn had indicated to him that the original collection of H. correcta/ willowmorensis was at Uniondale.

In addition, he also suggested that the name H. emelyae be discarded upon grounds that it was insufficiently known and of doubtful origin and without exact locality.

The confusion was then strengthened and continued by M.B. Bayer who strongly defended the name H. emelyae and explained in a 1979 article in the National Cactus and Succulent Journal, 34:28 that G. G. Smith’s records indicate that his G.G. Smith 5437 ‘H. emelyae’ had been collected by a Mrs Le Roux of Vanwyksdorp who then gave it to Mrs Emely Ferguson who passed it on to Smith. Bayer published a photo of the latter G.G. Smith 5437 specimen with the article and apparently he could not see that the photograph of the G.G. Smith 5437 specimen was the same type of plant as the Triebner 978 ( H. correcta) specimen. He even argued that perhaps the latter was a form of H. turgida. This is actually very ironic, since the original H. emelyae (Long 322) specimen looks far more similar to H. turgida than the H. correcta Triebner 978 specimen. 

The original H. emelyae specimen Long 322

However, perhaps his confusion was influenced by the fact that the old Fourcade photographs that were taken in 1941 included photos of plants that are clearly H. turgida and one (Fourcade 242) was labelled “H. correcta, Riversdale’ while two other photos also of H. turgida are labelled ‘H. emelyae, Riversdale, ex Ferguson’ and another ‘H. emelyae , Gamka River ex Geldenhuys’ ( Fourcade 144). Bayer also mentioned a photo by Dr G.J. Broekhuisen in the Fouche collection involving the same misidentification.

 

Fourcade photos: ‘H. emelyae, Ferguson, Riversdale’ 1941 ( left), ‘H. correcta, Riversdale’ centre and ‘H. emelyae, Geldenhuys, Gamka River’ 1941 on the right. All are various forms of H. turgida.

It should also be pointed out here that at the time Bayer’s focus seems to have been fairly undefined and sketchy as he did not see H. emelyae (incorporating H. picta ) and H. bayeri as separate elements. In the above-mentioned 1979 article in the National Cactus and Succulent Journal he published photos of H. bayeri from Dysselsdorp as well as H. bayeri from Uniondale both labelled ‘H. emelyae’.

As a result of M. B. Bayer’s failure to recognize the differences between H. bayeri and the H. picta-type emelyae , people inevitably started using the most conveniently available name to differentiate the bayeri type, which was Col Scott’s name ‘H. correcta’. So that is how it happened that the name H. correcta became such a widespread label to indicate H. bayeri.

Only in 1997 did J.D. Venter and S.A. Hammer correct the situation by giving H. bayeri separate species status. 

Haworthia bayeri ( Uniondale form) in cultivation.

Let us take a brief but more detailed look at the various elements involved in the complicated confusion surrounding the names Haworthia correcta and Haworthia emelyae.

Several names got dragged into the confusion and these were H. blackburniae, H. correcta, H. emelyae, H. willowmorensis, H. emelyae var beukmanii , H. turgida, H. ryderiana, H. picta and recently the name H. tricolor was also added to the list.

Both H. correcta and H. blackburniae have been explained and illustrated above, so there is no need to re-discus them below.

Haworthia willowmorensis V. Poeln.

The original photo and description of the plant that Von Poellnitz described as H. willowmorensis strongly suggests a variant of H. mirabilis (Published in Feddes Rep. 41 in 1937).Firstly the plant’s leaves are less strongly recurved than found in any H. picta or H. bayeri forms. The leaves are described as green above and greenish red below and the lower leaf surfaces are described to have “oblong tubercles arranged in longitudinal rows from the middle to the tip”. Furthermore, the leaf edges and keels are described having minute teeth.

 

Triebner 840, the type plant of H. willowmorensis that appeared with the original publication of the species.

All these features suggest H. mirabilis, however the locality was erroneously given as “Willowmore, collected by Mrs Helm”. No specimens of these plants have ever been found near Willowmore and remain extremely unlikely to have come from that area.

Typical H. mirabilis in habitat between Greyton and Genadendal, north of Caledon.

In an article in ALOE 11(4) 1973 : 42-44, Colonel Scott gave the name ‘willowmorensis’ prominence by publishing a full re-description of it based upon plants he had found near Uniondale and which he then believed to be H. willowmorensis. The description that Col.  Scott published differed totally from the original description and he simply used the name ‘willowmorensis’ and applied it to his own description of the plants (H. bayeri) that he had found at Uniondale and which to him was a close enough locality to Willowmore to justify the identification. In fact, today it is known that a form of H. bayeri actually does occur much closer to Willowmore on Vaalkrantz farm, within a stone-throw from H. comptoniana .

It should perhaps also be mentioned that Colonel Scott’s initial concept of H. willowmorensis incorporated H. correcta V. Poelln. and  H.  atrofusca G.G. Smith. as synonyms of H. willowmorensis and he gave the distribution to include localities like Willowmore (= H. bayeri) ,Uniondale (= H. bayeri), Oudtshoorn ( =H. bayeri ), Springfontein (= H. breueri or H. multifolia, presumably) towards Barrydale and Riversdale (= H. atrofusca).

Haworthia emelyae var beukmanii Poeln.

In the short additional notes to his description of Haworthia emelyae, Von Poellnitz mentioned that “our new species must be compared to H. willowmorensis Poelln., H. ryderiana Poeln. and H. whitesloaneana Poelln.”

As mentioned above, Von Poellnitz’s original description and accompanying photo of H. willowmorensis was clearly that of H. mirabilis. So, Von Poellnitz’s concept of H. emelyae was evidently much closer to a H. mirabilis -type of plant than to the H. picta kind. This also explains why he published H. picta only a year after H. willowmorensis as a totally different species and in his notes he did not compare it to H. emelyae at all.

A few years later during 1940, Von Poellnitz also published a variant of H. emelyae, the variety beukmanii in Feddes Rep. 49: 29.

The description, photos and locality of this variety indicate without any doubt the plants we know today as Haworthia mirabilis var beukmanii. 

Long 555 , the original specimens of H. emelyae var beukmanii.

This close association between the name H. emelyae and H. mirabilis was further supported by J. R. Brown who published an amended description of Haworthia emelyae in Cactus & Succulent Journal (USA) 37:114.  Both the photo and description of J.R. Brown’s H. emelyae also indicate a form of H. mirabilis and in the same article Brown also deals with H. emelyae var beukmanii and mentions that “ Haworthia emelyae and the var. beukmanii are very similar, the distinction mainly based on the crowded tubercles on the back of the leaves and the somewhat larger size of var beukmanii.”

H. turgida Haw. and H. ryderiana Poelln.

It was mentioned above that the photo of the original Long 322 specimen of H. emelyae does seem to correspond more closely to H. turgida than to the general H. picta type plant. It was also mentioned above that the 1941 Fourcade photographs of ‘H. emelyae’ are clearly H. turgida and another, Fourcade 242 labelled “H. correcta, Riversdale’ is also H. turgida. Two other old photos also of H. turgida are labelled ‘H. emelyae, Riversdale, ex Ferguson’ and another ‘H. emelyae , Gamka River ex Geldenhuys’ ( Fourcade 144).

It is in particular Haworthia turgida var suberecta that corresponds most closely to the Long 322 photo of H. emelyae. 

Haworthia turgida var suberecta at Brandwag. The plants are very variable, ranging from solitary to clustering, long-leaved to short-leaved, rosettes with few leaves to others with more, etc. A selection effort at this locality may yield plants that come much closer in appearance to the Long 322 specimen of H. emelyae than the one in the picture above.

Haworthia turgida is of course a very variable element mostly confined to almost vertical hillsides and it seems to be somewhat connected throughout its range to a few slightly larger and solitary-growing species found on the flats and gentle slopes of low hills. Around Riversdale H. turgida links with H. retusa and in areas it appears to be a clustering cliff-dwelling variety of H. retusa. Eastwards there is an undeniable link to the H. turgida/ asperata-type plants on the steep hills west of Herbertsdale and the H. pygmaea var argenteo-maculosa plants on the coastal flats and further east there is the H. turgida var suberecta around Brandwag and Hartenbos dam which also links somewhat to H. pygmaea var argenteo-maculosa. 

Haworthia turgida/ asperata from Towerlands, west of Herbertsdale. Another H. turgida-like element quite comparable to the original description of H. emelyae.

The H. turgida-like Long 322 plant almost appears as if it could well be a similar cliff-dwelling element linked to H. picta. But this is pure speculation, of course, as no such population is known to date. It remains a distinct possibility that somewhere along some steep banks of the Gamka-, Wabooms- or Gouritz rivers such a turgida-like link to H. picta may hide un-rediscovered.

The H. emelyae type plant Long 322 in the centre compared in black and white pictures to H. turgida var suberecta from Brandwag ( left) and MBB 7105 from N/E Ouvloere on the right.

Haworthia ryderiana Poelln. was described in 1937 in Desert Plant Life 9:103 from a plant sent to Kew by Mrs Ryder of Durns, England and Von Poellnitz compared it to his H. emelyae, H. willowmorensis , H. cuspidata ( presumably H. turgida or a form of H. retusa) and H. mirabilis.

Authors like J.R. Brown, M.B. Bayer and C.L. Scott all rejected the name H. ryderiana as ‘species non statis cognitae’ while Ingo Breuer claims that it was possibly a garden hybrid.

Fact remains, the photo and description of H. ryderiana are more similar to H. turgida than to a H. picta type plant.

H. picta Poelln.

As a result of the foggy and complicated origins of the name H. emelyae, many collectors and Haworthia enthusiasts have been using the name H. picta during recent times. Ingo Breuer also gave it preference and it is indeed a handy, descriptive and unambiguous label for the glabrous brown-green plants with flecked windows and sharply pointed leaves.

H. picta Poelln. was originally published in 1938 in *Feddes Rep. 44:133 from a specimen numbered Triebner 1063 which had also been collected by Mrs S. Blackburn and with habitat data mentioning “Moeras River near Little Brak River”.

Triebner 1036, the Type plant of H. picta.

It remains a mystery that H. picta was published during the same year as H. correcta and only a year after H. emelyae and H. willowmorensis, so Von Poellnitz dealt with all these specimens over the time period of a number of months and yet they seemed to him to be different enough to publish them as separate species.

However, at least in the case of H. picta, Von Poellnitz had more or less correct habitat data (although Moeras River is much closer to Oudtshoorn than to Little Brak River) and the photo and description published with the article on H. picta in Desert Plant Life 10:127 match the plants known to occur near Moeras River, south of Oudtshoorn.

H. tricolor I. Breuer and H. janvlokii I. Breuer

As mentioned, one of the authors who also decided that the name H. emelyae was not justified to uphold and preferred to recognise H. picta is Ingo Breuer. In 2004 Ingo went ahead and added two varieties to H. picta : H. picta var janvlokii and H. picta var tricolor.

Ingo Breuer is an excellent researcher and archivist who had sorted through all available old literature and assembled and organized all these historical names and descriptions into two tremendously convenient and invaluable volumes ‘The World of Haworthias’ (1999).

As taxonomist Ingo Breuer also attempted the very brave effort in subsequent books to re-evaluate the many species described by Dr Hayashi and integrate these with the drastic reductionist approach of M.B. Bayer. The solution that Breuer used to achieve this without having to re-describe and officially re-combine the many Hayashi species as subspecies or varieties, he came up with the concept of Aggregate groupings. This implied that he abandoned all previous subspecies and variety rankings and made ‘species’ the end status.

That is how it happened that in his 2010 species list H. comptoniana, H. tricolor and H. janvlokii became species under his ‘Aggregate Picta’.

H. janvlokii is the very smooth-leaved and slightly larger-sized variant growing on the hills east of the Kammanassie Dam. It is in many aspects transitional towards H. comptoniana. 

A plant of ‘H. tricolor’ Breuer in habitat near Assegaaibosch, east of Vanwyksdorp. This is also the locality of M.B. Bayer’s Epitype for ‘H. emelyae’.

H. tricolor refers to the population on the foothills of the Rooiberg east of Vanwyksdorp and south of Calitzdorp. As mentioned above, this might have been the original locality of H. correcta and it is also the locality of M.B. Bayer’s designated *epitype for H. emelyae. The G.G. Smith 5437 specimen mentioned above under H. correcta seems also to have been from this locality. With other words, Breuer’s H. tricolor involves the exact same locality and plants as Bayer’s epitype for H. emelyae.

So what then, one may ask, should be done about the name H. emelyae that still seems to enjoy frequent use as a result of M.B. Bayer’s persistent application of the name?

Haworthia emelyae V. Poelln.

                The logical thing to do is simply to take a look at the original description of Haworthia emelyae . Ideally the whole original description needs to be reprinted here, but that will burden the reader with tedious evaluation, so let us just look at some of the most relevant features:

                The plant size is given as 40 mm in diameter, which is smaller than the regular H. picta type plant that is on average 70 mm (and up to 90 mm) wide. The average solitary H. turgida plant is 40 mm in diameter though.

                The leaves of H. emelyae are described as being green in colour, oblong in general shape, broad at the base, erect or little spreading, with the leaf-tips ‘obliquely truncate’ and the leaf margins and keel having ‘minute, somewhat confluent teeth’. The triangular leaf-top (end area) is described to have ‘somewhat pellucid tubercles which are sharply pointed on the younger leaves’ and the window area has ‘three longer and fewer shorter lines of which only the middle one reaches the tip’.

                When above description is compared to the general H. picta type of plant, the following differences stand out:  the H. picta plants have darker more brown-green leaves, not erectly spreading but strongly recurved, the leaf margins have no teeth. On the rae occasion when teeth are present they are extremely inhibited and hardly visible. In H. picta type plants there are no sharply pointed tubercles on the young leaves and although the window area does have lines these are often not clearly visible, being somewhat obscured being crowded by dense flecking.

Most important also, are the sharp acuminate leaf-tips of H. picta plants ending in a frequently upward-curving end bristle.

It remains very difficult to believe that the Long 322 specimen was indeed a form of the H. picta type plants and if it was, it was definitely a drastically untypical plant of smaller size, with unusually blunt leaf-tips, semi-erect leaves, almost un-flecked windows and with the very rare occurrence of having a few minute suppressed teeth along the margins and keel near the leaf-tips.

It is obviously very different from the G.G. Smith 5473 specimen from the well-known Rooiberg locality, 25km east of Vanwyksdorp (the locality for M.B. Bayer’s designated epitype) and it remains rather inconceivable that the Long 322 specimen came from there.

It is marginally easier to accept that if the Long 322 specimen was indeed a H. picta kind of plant collected near Vanwyksdorp, that it could have come from the Arrievlakte locality  a few kilometres south of the latter town.

The Arrievlakte form of H. picta/emelyae in habitat.

The Arrievlakte population of H. picta/’ emelyae’ is somewhat different in certain respects and both the plants and locality differ from all other known populations of the species.

These Arrievlakte plants grow in a very arid situation on shale scattered with quartzite and amongst dwarf succulents like Gibbaeum dispar, Crassula columnaris and Avonia papyraceae. The haworthias at this locality are extremely well camouflaged, being dull reddish-ochre to dark brown in colour in the wild and blending very well with the soil colour. 

The dark Arrievlakte form of H. picta/’emelyae’ in cultivation.

It is particularly in cultivation that these Arrievlakte plants most display their distinctness by having a much darker, almost black-green colour and less dense and variegated flecking in the leaf windows. Of all the known forms of H. picta/’emelyae’, these Arrievlakte plants are perhaps slightly closer in appearance to the Long 322 specimen, provided one allows for rather bold and rough comparison.

Conclusive comments:

Not everybody’s interpretation of the old photos and descriptions may agree but even dogged devotees of the name emelyae must agree that it remains a slightly uncomfortable fit, almost like the old joke of the guy who wore a poorly constructed suit but if he lifted one shoulder and walked with a limp, the suit seemed to fit fine.

However, the problem is that if one does decide to discard the name H. emelyae like Col Scott who declared it as “of doubtful origin and without exact locality” then the next name with priority would be H. correcta….. Remember that the name H. emelyae was published in 1937 in * Feddes Rep number 42, while H. correcta was published in 1938 in Feddes Rep number 43 and H. picta also in 1938 but in Feddes Rep number 44. This means that the name H. correcta has a very slight priority over H. picta.

In practical terms, however, it would take many years and lots of quarrelling  amongst Haworthia authors, students and enthusiasts to accept the name H. correcta as replacement for H. picta/ emelyae , particularly in view of the fact that many collectors still have H. bayeri labelled as H. correcta !

In addition, the description and photo of the Triebner 978 specimen of H. correcta have been studied by all Haworthia authors to date and somehow none of them seemed to have been nearly as convinced as I am that the plant is indeed of the H. picta type, so perhaps in view of this persistent cloud of distorted doubt and misinterpretation, the name correcta should also be totally discarded. Besides, there is, like in the case of H. emelyae, also no preserved specimen or precise locality.

Therefore, the advantages of applying the name H. picta are numerous as there are no doubts regarding the precise features and locality. Furthermore, the name ‘picta’ is very suitable and descriptive of these plants and the Moerasrivier area is also reasonably central within the distribution range of the species and it is quite suitable to consider the Moerasrivier plants as typical.

Consequently the best solution seems to be to use the name H. picta, as many people have already been doing.

……………………………………………….

*Epitype-  An epitype is a specimen or illustration selected to serve as an interpretative type when the holotype, lectotype, or previously designated neotype, or all original material associated with a validly published name, is demonstrably ambiguous and cannot be critically identified for purposes of the precise application of the name of a taxon.

* Feddes Rep – Feddes repertorium specierum novarum regni vegetabilis.

Chronological summary:

* 1937 – W.F. Barker published Haworthia blackburniae in the Journal of South African Botany 3:93. The type specimen ( Reynolds1842) was collected by Mrs Blackburn south of Calitzdorp and sent to Dr Reynolds. This is the thin grass-like leaved plant known today as H. blackburniae.

* 1937 – Later that year Von poellnitz also published a plant named H. blackburniae in Kakteenkunde 9:132, but his description and photo of the plant (Triebner 978) matches that of what is known today as H. emelyae/picta/tricolor. The Triebner 978 specimen was also collected by Mrs Blackburn, near Calitzdorp. 

* 1937 -Also during the same year Von Poellnitz published Haworthia emelyae in Feddes Rep 42) from a plant received from F.R. Long that originally came from Mrs Emely Ferguson but without exact locality.

* 1937 – A plant that seems to match our current understanding of Haworthia mirabilis was also published in the same year by Von Poellnitz as Haworthia willowmorensis. The plant (Triebner 840) came ex Mrs Helm reportedly from Willowmore, but the locality must certainly have been an error.

* 1938 – Von Poellnitz has since discovered that the name H. blacburniae had been used before his publication, so he simply corrected the error by replacing the name for the Triebner 978 specimen with H. correcta in Feddes Rep 43.

1938- Later the same year Von Poellnitz also published Haworthia picta in Feddes Rep 44 from Triebner 1063, also originally sent to Triebner by Mrs S. Blackburn and reported from Moeras River area. Somehow Von Poellnitz could not see that this H. picta plant was the same species as his H. correcta.

* 1940 – Von Poellnitz published the Long 555 specimen from Caledon area as Haworthia emelyae var beukmanii in Feddes Rep 49. This is the same plant known today from the Caledon area as H. mirabilis var beukmanii.

* 1965 – J.R. Brown publishes an amended description of Haworthia emelyae in Cactus & Succulent Journal (USA) 37:114. Both the photo and description of J.R. Brown’s H. emelyae indicate a form of H. mirabilis.

* 1973 – Colonel C.L. Scott wrote in ALOE 11(4) that he had learnt from Mrs S. Blackburn that the original plant of H. correcta had been collected near Uniondale. He then concluded that H. correcta must be synonymous with Haworthia willowmorensis with Uniondale being not too far from Willowmore and no plants matching H. willowmorensis to be found in the Willowmore area. Col. Scott then went ahead and simply ignored the original description and picture of H. willowmorensis and re-described H. willowmorensis according to the Uniondale plants and even added a photo of the Uniondale plant (known today as H. bayeri) labelled H. willowmorensis.

1979 – M.B. Bayer adds to the confusion by publishing photos of the above-mentioned Uniondale plants as ‘Haworthia emelyae’ in his article ‘Natural Variation and Species Delimination in Haworthia Duval. Part 4: Haworthia emelyae Von Poelln. and a new variety’ in the National Cactus and Succulent Journal 34 (2). Bayer also considered H. picta as synonymous with H. emelyae and referred to the H. bayeri plants from Dysselsdorp and Uniondale as ‘more scabrid and with rounded leaf end areas’.

1985 – Colonel C.L. Scott’s book was published wherein he finally rejected the name H. willowmorensis and decided in favour of H. correcta. So, the beautiful colour photograph of H. bayeri in Col. Scott’s book is labelled H. correcta.

Therefore, as a result of M.B. Bayer’s refusal to see the dull-grey, scabrid and rounded-tipped leaved plants (H. bayeri) as different from H. emelyae ( including H. picta) , people started using Col. Scott’s name H. correcta to differentiate.

1979- J.D. Venter and S.A. Hammer finally corrected the situation by publishing the Uniondale, De Rust, Dysselsdorp, etc. area plants Haworthia bayeri in the Cactus and Succulent journal (U.S.A.) 69:75.

* 1999 – M.B. Bayer adjusted his view of H. emelyae to exclude H. bayeri and also designated a Epitype for H. emelyae from the Rooiberg, south of Calitzdorp (- Mrs Schnettler in KG335/71 (NBG).)

* 2004 – I. Breuer publishes two varieties of H. picta in Alsterworthia International Special Issue 7: 20 - 22. These were H. picta var janvlokii and H. picta var tricolor.

* 2010- Alsterworthia International publishes Ingo Breuer’s ‘The Genus Haworthia’ Book 1 wherein he does away with all ranks below species and his ‘Aggregate Picta’ then includes H. picta, H. comptoniana, H. tricolor and H. janvlokii.

References:

Bayer, M.B., 1979. Natural Variation and Species Delimination in Haworthia Duval. Part 4: Haworthia emelyae Von Poelln. and a new variety. National Cactus and Succulent Journal 34 (2): 28-31.

Bayer, M.B., 1999. Haworthia Revisited. Umdaus Press.

Breuer,I. 2000. The World of Haworthias Vol. 2. Arbeitskreis fur Mammillarienfreunde e.V. (AfM), Niederzier and Homburg/Saar.

Breuer, I. 2004. New Haworthia species/combinations published subsequent to Haworthia Revisited. Part 1. Alsterworthia International Special Issue 7 :3-33.

Breuer, I. 2010. The Genus Haworthia. Book 1.  Alsterworthia International.

Brown, J.R. 1965. H. emelyae. C & S Journal of America 37: 114.

Marx, Gerhard. 2009. Haworthia emelyae, the ‘Klein Karoo Kliprosie’. ALOE 46(4): 67-95.

Scott, C.L. 1973. A Revision of the Genus Haworthia, Section Retusae. ALOE 11 (4): 8-45.

Von Poellnitz, Karl. 1937. Neue Formen der Gattung Haworthia Duval. Kakteenkunde (9): 132-134.

Von Poellnitz, Karl. 1937. Zur Kenntnis von Haworthia Duval. Feddes repertorium specierum novarium regni vegetabilis 41: 216.

Von Poellnitz, Karl. 1937. Vier neue Haworthia-Arten . Feddes repertorium specierum novarium regni vegetabilis 42: 271.

Von Poellnitz, Karl. 1938 . Three Interesting Species of the Genus Haworthia Duval. Desert Plant life. July 1938 : 125-127.

Von Poellnitz, Karl. 1938. Haworthia Duval: Scabrae Berger, Retusae Haw and Coarctatae Berger. Feddes repertorium specierum novarium regni vegetabilis 43: 103.

Von Poellnitz, Karl. 1938. Neue formen der Gattung Haworthia Duval. Feddes repertorium specierum novarium regni vegetabilis 44: 133.

Von Poellnitz, Karl. 1940. Zur Kenntnis von Haworthia Duval. Feddes repertorium specierum novarium regni vegetabilis 49: 29.