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HAWORTHIA TRUNCATA (Perdetande) Guest column by Theo Heijnsdijk

Guest column by Theo Heijnsdijk

Succulent fanciers usually are not impressed by Haworthia flowers. On a wispy stalk there are a number of insignificant, mostly dirty white flowers. In H. truncata, the flowers have brownish longitudinal stripes. How different things become when you look at one of those flowers in close-up (fig. 1).

Fig. 1 Close-up of a flower of Haworthia truncata

The petals end in gracefully curly transparent slips and the ensemble is reminiscent of a majestic flying swan.
In nature the pollination of the tubular flowers is often done by bee species with extra-long mouthparts. Honey suckers (the African counterpart of the hummingbird) also play a role in pollination.

Haworthia truncata was found in April 1909 by a certain Miss L. Britten on a farm 7 miles from the town of Oudtshoorn in the Little Karoo (Western Cape, South Africa). In 1910, the description by botanist Selmar Schönland appeared in the South African magazine ‘Transactions of the Royal Society of South Africa’. The accompanying plate shows the plant with detailed drawings of the various parts (see fig. 2).

Fig. 2 The plate accompanying the description by Schönland in Transactions of the Royal Society of South Africa (1910).

The formal description is followed by Schönland’s reflection on the morphology and anatomy of this special plant.
Karl von Poellnitz distinguished three forms of H. truncata in 1938: fa. normalis, fa. crassa with thicker and less flat leaves and fa. tenuis which remains much smaller. The latter was described as a variety by M.B. Bayer in 1976.
According to current taxonomic insights, these different names are unjustified and one name is sufficient for all the varieties and forms mentioned: H. truncata subsp. truncata. The closely related H. maughanii is seen as another subspecies: H. truncata subsp. maughanii.

Haworthia truncata is an outsider among the Haworthias. To begin with, the species differs from the standard Haworthia in that the leaves are not arranged in a rosette but are aligned (see fig. 3).

Fig. 3 Seedling of Haworthia truncata (Vanwykskraal) in cultivation.

In addition, the leaves, which are almost completely hidden in the ground, are flattened at the top (but with some differences in height) and all at about the same level so that it looks like they have been cut off with a blunt knife just above the ground (truncata means shortened). The cross-section is almost rectangular, so that the whole plant (sideways) is reminiscent of a fan or a multi-armed candlestick. The upright truncated leaves have earned the plant the name ‘Perdetande‘ (Horse Teeth) in South Africa. In Schönland’s drawing (fig. 2) the leaves do not have that typically rectangular shape, but are more similar to the leaves of H. maughanii.
To prevent the growing plant from protruding above the ground, there is another special faculty. The roots have transverse grooves that allow them to contract and thus bring down the plant body. Pretty much like an earthworm can contract.
Schönland explains that the plant, of which only the top of the leaves is visible, looks like a collection of pebbles and therefore does not stand out. In other words: it is a mimicry plant that in this way tries to protect itself from being eaten by animals. In order to receive enough light for assimilation, the leaf surface is somewhat transparent so that the light can penetrate to the assimilating tissue located on the inside of the leaf. This means that H. truncata can be counted among the so-called window plants, which we find mainly in the mesems. Think of Fenestraria, Frithia and several Lithops and Conophytum species. Schönland believes that this type of Southern African plant species that grow in full sun should in fact physiologically be considered to be shade plants.

In South Africa, they use different wording for all this.
In the question and answer section ‘Vra vir Ernst’ of a South African newspaper, I found the following description of H. truncata by Ernst van Jaarsveld:
‟In nature, the Horse Teeth are found in the Klein Karoo, especially in the Oudtshoorn district. They grow partly under bushes in stony conglomerate soil. Only the blunt leaf tips stick out of the ground, like horse teeth. They are difficult to spot and adapted to the arid environment. The leaves like those of beeskloutjies (little cow hoofs = Lithops spp.) are translucent green. In times of drought, the leaves shrink, and the dust covers the plants until they are almost invisible to humans.”

Haworthia truncata remained rare in European collections for quite some time after its discovery in 1909. In the Dutch monthly magazine ‘Succulenta’ it was first written about only in 1932 by the then widely known G.D. Duursma:
“Haworthia truncata Schönl. is a welcome addition of recent years, predestined to become so popular that it will soon be present in many collections.”

Cultivating the species is not particularly difficult. In South Africa, the plant grows and flowers in the rainy season. That’s in September and October. It makes sense to maintain this growing period in the northern hemisphere as well. This means that the plant should receive as much light as possible in these months and be watered regularly. In our climate, growth usually takes place in spring too. In the summer months, shade should be provided in the heat of the day and just enough water should be given to prevent the plant from drying out. The pot should not be too large, because then the soil may remain wet for too long after watering, resulting in rot. In literature it is reported several times that the roots periodically die and that the plant then quickly makes new roots in fresh soil. Like all plants of the Western Cape, the species is not sensitive to cold.

As a rough estimate, H. truncata grows at less than 10 localities in the vicinity of Oudtshoorn and west of it near Calitzdorp. Well-known locations are Dysselsdorp and De Rust, both east of Oudshoorn.

Fig. 4 Haworthia truncata near Dysseldorp (photo Coby Keizer).

Fig. 4 shows a group on a flat hilltop west of Dysselsdorp. The plants there occur generally in full sun but sometimes also under bushes. The soil is sandy and mixed with large and small stones.
Other succulents Coby has seen there are Cotyledon orbiculata, Aloe humilis and Aloe humilis hybrid (humilis x microstigma), Anacampseros arachnoides, Crassula capitella ssp.thyrsiflora, Crassula subacaulis, Duvalia species, Quaqua spec., Stapelia spec, Gasteria spec, various mesems and caudiciform plants. A true paradise for succulent fanciers.
Between Dysselsdorp and Kammanassie Dam (about 10 km to the south), a small variation occurs in which the leaf edges usually have small, pointed protrusions reminiscent of hairs. This form was described by German Ingo Breuer as var. minor (fig. 5, photo Robert Wellens). Later on, Breuer elevated this variety to a separate species: H. papillaris.

Fig. 5 Haworthia truncata var. minor VA 6718 (photo Robert Wellens).

At Van Wykskraal, about 5 km from Dysselsdorp, a natural hybrid with H. arachnoidea seems to grow.

The populations have suffered severely from the collecting frenzy of succulent lovers and traders. In addition, there is habitat destruction due to increasing urbanization of the area. On the Red List of endangered South African plants, the species has been given the status ‘vulnerable’.

In addition to the natural hybrids, there are countless artificial ones, often with variegated leaves or different folds of the leaf surface. Worth mentioning is the hybrid “Lime Green” (fig. 6, photo Robert Wellens), probably a cross with H. cuspidata, although H. cymbiformis is also considered to be a possible parent.

Fig. 6 Haworthia ‟Lime Green” (photo Robert Wellens).

Of H. maughanii (fig. 7-9) only one locality, south of Calitzdorp, is known. The area is less than 1 km². Here too, a lot of damage has been done by succulent hunters and there is also damage from ostriches trampling the plants. All this has led to the status of ‘Critically Endangered’ for this species. The habitat of this species partly overlaps with that of the form of H. truncata which was described as fa. crassa and there are all kinds of natural hybrids in this area.

Fig. 7 A seedling of Haworthia maughanii (H. truncata ssp. maughanii) in cultivation.

Fig. 8 Haw. truncata v. maughanii in habitat. Photo Frans Noltee

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Fig. 9 Haw. truncata v. maughanii in habitat. Photo Frans Noltee

Literature:
–Duursma, G.D. (1932) Haworthia truncata, Succulenta 14 (7): 169-172.
–Jaarsveld, E. van (2001). Vra vir Ernst, Lastige molkrieke en die biologiese bekamping van plae, Die Burger, Kultuurkroniek, http://152.111.1.87/argief/berigte/dieburger/2001/09/08/4/19.html
–Schönland, S. (1910). On some points in the morphology and biology of a new species of Haworthia, Transactions of the Royal Society of South Africa 1 (2): 391-394.
–Red list of South African Plants, http://redlist.sanbi.org/genus.php?genus=2215

First published in Succulenta 93, 2014-2. Translated from Dutch by Frans Noltee.

Frithia pulchra (Guest column by Theo Heijnsdijk)

The first record
In January 1906, Ms. Olive Nation found a peculiar little plant. It was growing “on the top of the Magaliesberg, 5500 ft.”, near Rustenburg (South Africa). Today, that area belongs to the Northwest province, but at that time it was part of the now-defunct Transvaal province. She sent the plant to Kew Botanic Gardens near London for identification. Unfortunately, it did not survive the trip, but from the remnants, Kew botanist N.E. Brown deducted that it had to be a new species. Ms. Nation died not long afterward and attempts to get more specimens came to nothing.

“It bears a flower so it must be a plant”
Until in 1924 Mr. and Mrs. Dobie, who lived in the same area, on a Sunday hike in the mountains, suddenly saw reddish-purple flowers that seemed to grow directly from crevices in the rocks. Upon further examination, the flowers were found to be attached to small plants, consisting of 6 to12 short rods that were almost completely covered by the flowers. “Here’s something for your collection. It bears a flower so it must be a plant, Mr. Dobie is believed to have told his wife.

The first description
Mrs. Dobie sent a specimen to Frank Frith (1872 – 1954) in Johannesburg, a botanist who worked for the South African railways. Frith also came looking for it himself and he submitted some of the collected plants for the ‘South African Rockery’ of the Wembley Exhibition of 1924 (a kind of World Exhibition).
On December 10, 1924, Frith wrote to Mrs. Dobie:

That professor was the famous Nicholas Edward Brown, who worked in Kew from1873 until his death in 1934. In the 1920’s he separated many genera from the ever-expanding genus Mesembryanthemum. In the identification key he published in the journal ‘Gardeners’ Chronicle’ in November 1925, the generic name Frithia first appears. The description of the only species in that genus, F. pulchra, followed in 1926. He named the genus Frithia, to honor Frank Frith. In view of the above, it would have made more sense to call it Dobiea. The species name pulchra, by the way, is derived from the Latin pulcher = beautiful.
The original material collected and supplied by Frith is still present in Kew’s herbarium (fig. 1).

Fig. 1. Kew’s herbarium sheet with the original material collected by Frith in 1924.

Brown added an exclamation mark after his remark that the flowers of this plant lasted for up to three weeks.

The first published image
The oldest image known to me appeared in 1927 as record 275 in the seventh part of the magazine ‘The Flowering Plants of South Africa’ (fig. 2).

Fig. 2. Plate 275 of ‘The flowering plants of South Africa’ from 1927.

This magazine, published annually since1921 and edited by I.B. Pole-Evans, is reminiscent of the well-known ‘Curtis’s Botanical Magazine’: always a botanical drawing with many details on a full page, followed by a text of 1 to 2 pages. In this way, 40 plants were depicted and discussed each year. F. pulchra’s drawing was created by botanical artist Beatrice Orchard Carter; the text accompanying the image is by Louisa Bolus.

Rapid integration
Amazingly, the species – of which only one locality was recorded at the time – quickly became widely known. As early as 1927, a slide of a F. pulchra in bloom was displayed at a meeting of the ‘s Gravenhage (Netherlands) branch of the succulent plant lovers’ association Succulenta. In 1928, Mr. E.J. Labarre (member of Succulenta since its inception in 1919) wrote an article in the weekly magazine ‘Onze Tuinen’ about Frithia. He had received plants from Mrs. Dobie himself and donated a seed tray full of them to the Botanic Garden of Amsterdam. In the same year, an article by the same writer appeared in the monthly magazine ‘Succulenta’, titled “The Frithia blooms!” with a picture of another seed pan, this time with flowering plants. With this exhibit, Mr. Labarre won a certificate of merit at the show of the Amsterdam Hortus. He added: ‘The finder, Mrs. Dobie, has always called them ‘Fairy Elephants’ Feet’. Isn’t that a suitable name for those who are romantically inclined?”
The name Fairy Elephants’ Feet is still used. In South Africa the plant is also referred to as ‘Bobbejaanvingers’ (a bobbejaan is a baboon), ‘glasies’ (glasses), ‘toontjies’ (toes) and ‘Baby Toes’. Also called ‘Purple Baby Toes’ to distinguish it from the Fenestraria’s, which look like it and are also called ‘Baby Toes’ but have white or yellow flowers.

Occurrence in nature
The plant also became a popular species in South Africa itself. This is evident from a comprehensive report in ‘Succulenta’ (8 pages) of a trip by Mr. F.W. Reitz of Pretoria in1935 from his hometown to the Rustenburg Gorge. Below are some of the passages from his report:

Being a passionate succulent collector, I already consider myself owning an extensive collection of succulents and also some rare cacti. However, the heavy rains of last November have ruined all my Frithia pulchra, so I planned to search for some of those beautiful plants.

A little further, diagonally opposite Rustenburg Gorge, lives Mrs. Dobie, the discoverer of Frithia pulchra. I know her well and had promised her I would come and see her collection of rare succulents.

That fine rose flower on the crystal-white quartz grit was the purpose of our trip, Carefully I wiped away the gravel, and only then did the characteristic rods emerge, with their transparent windows that absorb the sunlight, since the plant itself does not expose itself in order to protect itself from the drought. With long spikes, which Mrs. Dobie had supplied, we managed to remove the plants from the crevices: it had to be done very carefully because they were well secured, and the Frithias are very delicate. When I removed the gravel over a greater surface, it turned out that the ground was literally dotted with Frithia pulchra, and that without realizing it, we had walked over them. But it is remarkable that only on those flats covered with fine gravel and in solid rocks this special succulent could be found. Dry, intensely dry, it has to be there. And the power of the sun at 4500 feet (1372 m) above sea level, where the average winter temperature is 58° F. (14 °C), the average summer temperature is 72° F (22 °C)., and the average annual rainfall is only 25 inches (635 mm), must be very strong.

The removal of these petite plants was not easy, but in the course of half an hour, we had more than 100 of them together. Carefully they were packed in a bag, and, glad to have achieved our goal, we made our way back.

Before packing the car and setting out on the return journey, I filled two flour bags with pure white quartz gravel. This came in handy, because I now keep my Frithia pulchra in a box, in which I have tried to imitate the natural conditions at the site on the mountain as faithfully as possible. Yet I have failed to keep the whole treasure alive. Within a week, about 50% of my Frithias suddenly dried up. The rest, on the other hand, is safe and sound. I am very satisfied with the result. Frithia pulchra possesses the same property as many other aristocratic plants, i.e. that they are very difficult to replant and very peculiar about unaccustomed living conditions: too much water, too rich soil and too little gravel can be the cause of Frithia pulchra’s death.

So much for Mr. Reitz’s account. This story clearly shows that you can easily overlook the plants.
In figure 3 we see what looks like a piece of land with some grassy plant growth. But in reality, it’s full of F. pulchra. Within the red circle, there are three clusters.

Fig. 3. Locality somewhere southeast of Rustenburg. In the indicated area there are 3 clusters of Frithia pulchra. Photo Werner du Toit

Figure 4 shows the same site with a corresponding circle.
Fig. 4. Many specimens of Frithia pulchra among quartz gravel and in crevices, with the same area encircled as in fig. 3. Photo Werner du Toit

These photos by Werner du Toit were taken on January 28, 2017, in the middle of the growing period. In the dry season (winter), the plant tissue contracts due to dehydration and so the plant bodies are even pulled completely into the ground. The quartz gravel in which the plants grow can become very hot in summer. In harsh winters it may freeze there. In summer it can rain heavily and the plants clearly enjoy that. Flowering in South Africa also takes place in summer (December through February).

Fig. 5. Frithia pulchra in bloom in habitat at the end of January. Photo Werner du Toit

Nature conservation
Fortunately, in these times people no longer work as described above by Mr. Reitz. On the IUCN Red List of Threatened Species, F. pulchra has the status of ‘vulnerable’. The distribution area is limited to a number of localities in the Magaliesberg region and is estimated to be less than 5 km². The biggest threat is illegal collection, but it is assumed that this has not had a major impact on the occurrence of the species. The populations are stable. The fact that the plant is easy to grow and that plants collected in the wild usually die may play a role in this. The area of the Magaliesberg is now a protected nature reserve, the Magaliesberg Protected Environment (MPE). It runs roughly from Rustenburg to Pretoria.

The genus Frithia
As mentioned above, the genus Frithia was established in1925. Today it is one of more than 120 genera in the Ruschioideae, one of the five subfamilies of the large family of Aizoaceae (the ice plant family). The grouping into genera is based, among other things, on the construction of the seed capsules and therefore not easy to understand for the average enthusiast. The genus Frithia however is easy to tell apart from the genus Fenestraria – which at first glance bears a lot of resemblance to Frithia – by the way the leaves are arranged. In Frithia, the leaf position is spiral, whereas in Fenestraria the leaves are placed crosswise. Also, in Fenestraria the leaf surface is smooth, whereas in Frithia it is divided into tiny lens-like structures (fig. 6 and fig. 7).

Fig. 6. In Frithia, the leaf surface is covered with lens-like structures. Photo Theo Heijnsdijk

Fig. 7. Six-week-old seedlings of Frithia pulchra. The first ‘rod’ with lens-like structure develops between the cotyledons. Photo Theo Heijnsdijk

In his 1925 description of both genera, Brown commented that the leaf surfaces do not contain chlorophyll. He indicated that you can easily ascertain this by cutting off the top of a leaf and looking at it against the light. This works, but it’s also quite destructive.

A second species
Brown knew one species: F. pulchra. In 1968 H.W. de Boer described in ’Succulenta’ some different plants that he had received from a C.G. Booker in Transvaal. The deviations concerned the much smaller leaves and flowers, the colour of the leaves (“rose-like greenish-brown”), and the colour of the flowers (white with the tips of the petals tinted rose-violet). The locality could not be established because Mr. Booker had since died. De Boer described this form as F. pulchra var. minor (= smaller). Because no material was deposited in a herbarium, the description is invalid. In the year 2000 Patricia Burgoyne et al. described the plant as a new species: Frithia humilis. According to the dictionaries, humilis means low or near the ground, but according to Burgoyne it is ‘smaller than others of its kind’. One of the photos accompanying the 1968 article by de Boer is now the lectotype of F. humilis.
Bronkhorstspruit, about 50 km east of Pretoria, is indicated as locality (fig. 8 and 9).

Fig. 8. Frithia humilis north of Bronkhorstspruit . Photo Sean Gildenhuys

Fig. 9. Frithia humilis north of or Bronkhorstspruit in bloom. Photo Sean Gildenhuys

It is worth noting that Louisa Bolus in ‘The Flowering Plants of South Africa’ mentions that the South African lawyer and plant collector Douglas Gilfinnan had already found F. pulchra at the place Witbank at the end of December 1905, just a few weeks before Mrs. Nation. That is about 200 km east of Rustenburg and about 40 km east of Bronkhorstspruit. This may also be F. humilis.

Cultivation
In cultivation, we grow Frithia pulchra with its leaves above the ground. The risk of rot is high if we don’t. The soil should be granular and well permeable with a small proportion of organic matter. Keep absolutely dry in winter. The plants will certainly start to shrivel then. In spring, light misting is recommended. Once the plants are filled out, you need to water them regularly. The plants should not start to shrivel during this time. Flowering time occurs with me in the Netherlands in June-July. It is wise to limit the amount of water afterward, because the growing period is rather short.

Fig. 10. Frithia pulchra flowering in cultivation. Photo Theo Heijnsdijk

Propagation by sowing works fine, but is also possible by cuttings. This is done by carefully dividing a rosette in half and planting the pieces after the wounds have dried. But don’t do this if it’s your only plant, as there’s a good chance of rot occurring.

Literature
Boer, H.W. de (1968). Frithia pulchra var. minor 47: 147.
Bolus, L. (1927) Frithia pulchra, The flowering plants of South Africa 7: text accompanying plate 275.
Brown, N.E. (1925). Mesembryanthemum and some new genera separated from it. The Gardeners’ chronicle 78: 433.
Brown, N.E. (1926). Ficoidaceae in J Burtt Davy, Manual of the Flowering Plants and Ferns of the Transvaal 1: 41, 162.
Burgoyne, P.M. & Smith, G.F. & Plessis, F. du. (2000). Notes on the genus Frithia (Mesembryanthemaceae) and the description of a new species, E humilis, in South Africa, Bothalia 30 (1): 1 – 7.
Labarre, E.J. (1928). De Frithia pulchra, of romantiek in de botanie, Onze tuinen 23 (6): 61.
Labarre, E.J. (1928). De Frithia bloeit!, Succulenta 10 (12): 215 – 219.
Reitz, F.W. (1935). Frithia pulchra, Succulenta 17 (6): 81 and 17 (7): 97.

First published in Succulenta 99 (2), 2020. Translated from the Dutch by F.N.

Bulbine mesembryanthoides (part 3 of 3)

Subspecies namaquensis differs from its sibling by having no more than two leaves, one of which is usually inconspicuous.
The inflorescence is shorter (5-10 cm tall) and always single and the filaments have a double tuft of hairs.
These plants occur only in the Northern Cape, from Springbok to the Richtersveld in gravelly places.

Bulbine mesembryanthoides (part 1 of 3)

If there were a list of favourite types of succulents, I’m sure the so-called window plants would rank very high. Most of these plants belong to the Aizoaceae (Mesembs), but they are also found in Bulbine and Haworthia.
When one looks up information on window leaves, one gets the impression they are all built on the same principle: the surface of the leaf tip lacks chlorophyll, the central parenchyma* reaches up to the epidermis and as a result of this combination, the leaf tip looks and acts like a window.
In a few cases however, the windows are formed differently.
It has taken me quite a while to find a place where this is described in a comprehensive as well as comprehensible way.
In Cactus & Succulent Journal (US) vol. 16, 1974, Werner Rauh published an article called Window-leaved succulents. He starts his explanation with a description of Haworthia obtusa (=cooperi) var. pilifera and uses more or less the following wording:
“The numerous fleshy leaves are nearly hidden in the substratum and we can only see the transparent, glass-like leaf tips, ending in a long hair. The transparence of the leaf tips is caused by a lack of chloroplasts**. We find the assimilation parenchyma only in the lower two thirds of the blades, but these leaf parts are not accessible to the light. The consequence of this anatomical structure is that light, necessary for assimilation, can reach the assimilation parenchyma only by passing the transparent windows. But the leaves of H. pilifera are not in the morphological sense true window leaves.”
He then moves on to Haworthia obtusa (=cooperi) var. dielsiana, saying:
” … the most remarkable feature is the behaviour of the leaves in the course of their development: young leaves are of the same shape as those of H. pilifera, but becoming older, the upper third of the lamina, which exceeds the soil surface, dies off, so that only the water parenchyma, covered by the shrunken epidermis is to be seen. The lower parts of the leaves with the assimilation parenchyma are hidden in the ground; sunlight can reach it only by passing through the water parenchyma.”
This is the same type of window formation we find in Bulbine mesembryanthoides. In Rauh’s words:
“Becoming older, the upper parts of the leaves die off, as in Haw. obtusa var. dielsiana and the result is the formation of a big window with a plane surface. The assimilating parenchyma is completely hidden in the substratum.”

We know that strong sunlight destroys the chlorophyll, which is essential for the plant’s metabolism.
Window-leaved plants are hidden in the ground (at least in the hot and dry season) and sunlight can reach the assimilation tissue only through the windows, passing through the water parenchyma. This filtering process protects the plants against very strong light.
In experiments carried out with Fenestraria, it was found that the light is reduced so much that the chloroplasts will not be damaged, but stays strong enough to allow sufficient assimilation and production of organic substance.

* parenchyma is the relatively undifferentiated tissue that makes up the bulk of many plant organs and is often used for storing of water or food.
** chloroplasts are the tiny parts within plant cells that contains chlorophyll.