Spider-nest Haworthia species in nature and cultivation.

Spider-nest Haworthias as pets

by Jay Vannini

*Haworthia decipiens var. cyanea* from Eastern and Western Cape Provinces. Shown growing in a 5”/13 cm terracotta pot. During summer the leaves on this plant exhibit a very saturated blue green cast. Author’s plant and image.

The influences that smaller succulents such as miniature cacti, stonecrops, tabletop aloes and haworthias have had on the popularity of ornamental horticulture are remarkable, persistent, and far-reaching. Visually attractive exotic succulents are a common gateway drug for novice indoor plant collectors everywhere. In conversations I have had with many homemakers, hobbyists, and hardcore plant collectors over the decades, almost all could trace their interests in specialty plants back to early impulse acquisitions of potted succulents at garden centers or supermarket plant stands. Barring the odd anti-succulent grumps here and there these plants’ aesthetic appeal is universal.

Haworthias (including three genera of Asphodelaceae or Xanthorrhoeaceae depending on the source) are easily recognized mainstream miniature succulents that are prized for their attractive leaves and plant forms. This Alooid genus and other close relatives formerly treated as Haworthia species are endemic to semi-arid regions of southern Africa, especially the coastal areas of the Eastern, Western, and inland Northern Cape Provinces of South Africa. They are terrestrial and lithophytic xerophytes that are well-camouflaged and especially cryptic when ensconced in pockets of soil or humus in rock crevices.

As currently defined by more conservative botanists in South Africa, Haworthia includes just over three dozen accepted species (Bayer, 1999; Bayer, 2008 in Schulz, 2009; Smith et al., 2017), more than 250 synonymized taxa, and a few dozen unresolved names (The Plant List, 2022). There are also many more-or-less accepted varietal names as well whose numbers remain in flux as the taxonomic debate over their validity continues.

In contrast with the prevailing South African perspective, one Japanese haworthia specialist, Masahiko Hayashi, speculates that the genus may include over 600 mostly microendemic species (Schulz, 2009). Because of this, a casual examination of online lists of plants offered by Japanese succulent nurseries will reveal many, many dozens of Haworthia “species” whose names are unfamiliar to succulent growers in the west. Automated internet plant checklists such as “World Flora Online” accept the validity of most of Hayashi’s self-published Haworthia species (diagnosed in “Haworthia Study”), adding to the confusion by listing over 150 accepted binomials. Also, see Breuer (1998) for an older, exhaustive treatment of a bewildering muddle of taxa, some of which were resurrected from von Poellnitz’s descriptions of Haworthia novelties published from 1929 to 1940 (see “References Cited” for more on this).

Inflorescence of *Haworthia rossouwii* with open flowers visible lower. Many haworthias has similar looking green-striped corollas. Author’s plant and image.

Precise locality data and plant morphology are considered critical to identifying many wild origin haworthias with a high level of confidence (Bayer, 1999; Bayer & Loucka 2013-2021). The relative uniformity of their inflorescences and generally plain, striped flowers makes them less useful as key characters than in many other plant groups. More than a few succulent collectors have remarked on how challenging it can be to identify certain haworthia taxa that lack documented geographical provenance and often prioritize plants of known provenance. Indeed, a cynical argument can be made that if their place of origin is absolutely necessary to identify them with any certainty, even 37 or 38 species is still far too many and that most haworthia populations may deserve subspecific, natural hybrid or varietal rank of a far lower number of readily identifiable species.

Some commonly cultivated species that were formerly included in the genus were segregated into Tulista (formerly subgenus Robustipedunculares), with four or five species like T. pumila (Rowley 2013; Manning et al., 2014; Smith et al., 2017 and 2018), and Haworthiopsis (formerly subgenus Hexangulares) with 18 species (Rowley 2013; Manning et al., 2014), including the also popular H. venosa. Even though both were formerly accepted subgenera (Bayer, 1999; Manning et al., 2014), and despite reasonable arguments in favor of, and molecular work supporting their separation from Haworthia, these nomenclatural changes remain largely ignored by most nurseries–even some well-known ones–and hobbyists, apparently due to sheer obstinance (pers. obs.).

A deservedly popular and widely cultivated rosetted succulent, *Tulista pumila*, formerly known as *Haworthia pumil*a, from the Western Cape Province. Author’s plant and image.

Several haworthias with fenestrated or rugose leaves–notably H. mirabilis, H. retusa and Tulista pumila–have been in cultivation for just over 200 years following collections made on the Cape by Karl Thunberg, Francis Masson, and other early botanical explorers (Rowley in Jacobsen, 1960; Rowley, 1997). Haworthias, together with cacti and aloes, were among the first ornamental succulents to become popular with wealthy European gardeners in the late eighteenth and early nineteenth centuries (Rowley, 1997).

Their current popularity in eastern Asia–especially Korea and Japan–as well as other countries has led to a flurry of breeding and laboratory activity that has produced ever more colorful, eccentric looking and expensive cultivars. These are typically propagated via leaf pulls, offsets and plant tissue culture (PTC). At one end of the interest spectrum, some haworthia fanatics around the world maintain hundreds of these often individually unique, man-made chimeras on their windowsills or on tables under specialty LED or other high output grow lights.

Common hybrid and “zebra” haworthias have been a mainstay of the windowsill succulent trade for decades (Graf, 1980; Rowley, 1978; Schulz, 2009). That said, established vegetative propagules of some of the rarest, most coveted Haworthia cultivars now fetch thousands of dollars (eBay plant listings 2020-2022; pers. obs.). While very much a matter of personal taste and recognizing that many of these complex hybrids and quirky cultivars are undeniably pretty, they are of little interest to me and will not be discussed further in this article.

The other camp is represented by equally dedicated haworthia species collectors who have amassed serious research or hobby collections of well-documented, provenanced specimens with collector numbers and locality data, often including dozens of individuals of a species representing a sample of the morphological variation occurring at a single origin in South Africa. Online images of some of these collections in Europe show impressively staged semi-detached greenhouses with large numbers of haworthias grown to perfection in serried rows; all grown in uniformly sized square plastic pots, often from wild-origin seed.

Very much like living stones such as conophytums and lithops (Aizoaceae), haworthias’ very small to small mature sizes (usually under 5”/13 cm in diameter) and morphological diversity from locality to locality or even within specific geographic populations make them compelling plants for single genus collectors. The literature dealing with this group is surprisingly vast, usually well-illustrated, and dates back centuries in some cases. They have their own national clubs together with The Haworthia Society for an international audience, a respected journal (Haworthiad), as well as many online fora and chat groups dedicated to their cultivation.

There are excellent images posted online of plants in nature by haworthia fanciers who travel to South Africa on a more or less regular basis, some of whom provide detailed locality and ecological information for the populations photographed. The images of haworthias taken in situ by Kobus Venter that are shown in Bayer (1999) are also beautifully rendered.

Spider-nest haworthias

*Haworthia arachnoidea* var. scabrispina. Plant grown by Ron Parsons, author’s image.

I lump the following species under this heading, which is a translation of the Afrikaans common name, “spinnekopnes”, of the widespread Haworthia arachnoidea (I. Latti, in Operation Wildflower, 2022). Spiders, including baboon and trapdoor spiders (Theraphosidae and Ctenizidae), are called spinnekop in Afrikaans. The resemblance of many of the “bristly” haworthias to web-lined terrestrial spider burrows accounts for this moniker (see left).

Haworthia arachnoidea*, H. aristata, H. bolusii*, H. cooperi*, H. cummingii, H. decipiens*, H. devriesii, H. elizeae, H. erii, H. floccosa, H. gracilis*, H. herbacea*, H. jansenvillensis, H. lockwoodii, H. marumiana, H. monticola*, H. mucronata*, H. nortieri*, H. odetteae, H. outeniquensis, H. semiviva, H. serrata, H. specksii, H. tretyrensis and H. vlokii.

This list includes 25 accepted species. Some are far less “spider-nesty-looking” than others. All asterisked names also have currently recognized varieties. Those highlighted in bold text are grown by the author.

Despite their apparent fierce armament and unlike many small aloes, the marginal and apical spines on all these species are fairly soft, even feather-like in some, to the touch.

Based on traditional taxonomic treatments and recent molecular phylogenies of the genus, mine is an admittedly artificial grouping that includes some locally endemic species that are not necessarily genetically very close to others on the list (Bayer, 1999; Manning et al., 2014). Many Haworthia species are morphologically variable–often considerably so–from site to site (Bayer, 1999; Bayer & Loucka 2013-2021). Because of this not all the species are uniformly “cobwebbed”, especially when the plants are well-watered and their leaves are turgid. Some individuals or localized forms are glabrous, even among normally bristly-leaved species such as H. arachnoidea and H. gracilis (Bayer, 1999; Schulz, 2009). Others have forms with conspicuously fenestrated leaves (i.e., with translucent windows), while many varieties show none. Most of the more attractive species have very high leaf numbers, soft spine-edged leaves and congested rosettes, especially during dry spells.

These plants are excellent examples of convergent evolution that parallels some specialized cacti (Malik et al., 2016), with their numerous narrow leaves and networking spines combining to greatly increase leaf surface area. This is likely an adaptation to optimize dew and fog harvest in their subhumid habitats (Martorell & Eczurra, 2007). Their barely emergent habit, small size and effective camouflage also help to hide them from native and introduced grazing ungulates.

They occur on soil types ranging from light clays and well-drained coastal soils through to rocky substrates and both acid to calcareous substrates. Some species are solitary or develop a single offset over time; others offset freely and can form extensive colonies in only in a few years (Bayer, 1999; Schulz, 1999).

All the spider-nest species were formerly placed in subgenus Haworthia prior to recent split into three genera. When sectional placements were more popular these plants were included in aptly named sections Arachnoideae and Denticulatae as in a review of their taxonomic history published in Jacobsen (1960). Some were earlier assigned to section Setato-Araneae = “bristly spiders” in the 1930s by German authority on African leaf succulents, Dr. Baron Karl von Poellnitz (Jacobsen, 1960; Breuer, 1998)

*Haworthia cooperi* var. cooperi (?), cultivated outdoors in coastal northern California with winter leaves fully distended following two months of heavy rain. As the leaves lose turgidity and the rosettes in-fold this plant has a much better resemblance to wild plants of this variety. Author’s plant and image.

Individual variation, environmental (esp. edaphic) influences, their known promiscuity and likely wild hybridization along with subsequent introgression resulting in hybrid swarms apparently make it very challenging to bring order to the group. Indeed, that haworthias continue to defy every attempt to permit some sort of “final word” on their taxonomy is evident by a comparison of those contained in recognized authority Bruce Bayer’s 1999 monograph and its updates through 2008 with those listed in online species checklists such as “World Flora Online” and “The Plant List”.

Some are obviously in error here, although apparently not in doubt.

“There has been a large degree of excessive, illegal and disconcertingly self-interested collecting which has made and will make no contribution to the scientific and herbarium record. Whatever growers and collectors have to say about nomenclature and much of the necessity and nonsense that goes with it, this is what provides the reference framework for all their communication.” (Bayer, 1999).

The blizzard of names used in the trade can be very confusing to novices and experts alike. It is clearly in succulent nurseries’ monetary interests to foster the notion of sky-high species and varietal diversity in Haworthia so that they can market more forms to those collectors who need to have “every one” (Shultz, 2009).

And then there are just good old-fashioned changes in taxonomic opinions. One good example of tangled haworthia nomenclature applies to a handsome plant first published as Haworthia xiphiophylla in Flora Capensis in 1897 by John Gilbert Baker. It was described from a living plant collected in 1895 and grown at Kew. It is variously known–depending on the authority–as Haworthia arachnoidea var. xiphiophylla (Baker) Halda by “The Plant List” and M.B. Bayer in his 1999 book, later H. decipiens var. xiphiophylla (Baker) M. B. Bayer and the South African National Biodiversity Institute-SANBI, and H. xiphiophylla Baker (in commerce). Older names also include H. setata var. xiphiophylla (Baker) Poelln.

Santa Madre…

*Haworthia mucronata* var. inconfluens is sometimes treated as a full species, *H. inconfluen*s. While this species is usually glabrous, this plant form from Barrydale, Western Cape Province is toothy. Probably not coincidentally it strongly resembles the sympatric *H. arachnoidea var. nigricans*. Plant grown by Ron Parsons, author’s image.

Conservation status

Published reports indicate that little is known about the long-term viability of populations of a surprisingly large number (~20) of widely accepted Haworthia species that are still “Data Deficient”, including some of the spider-nest forms. From this specific group, one is designated “Rare” (H. vlockii), two are considered “Threatened” (H. lockwoodii and H. outeniquensis) and one “Endangered” (H. aristata). Habitat loss or degradation due to urbanization or expansion of the agricultural frontier, fuelwood collection that removes critical scrub cover, road building, climate change and–albeit to a lesser degree–illegal collection of wild plants of some taxa–are all cited as current threats (fide SANBI’s PlantZAfrica website).

A young *Haworthia vlockii* (JDV 93-2) from Groot Swartberg, Western Cape Province is an uncommonly cultivated species currently considered to be rare in nature. Shown growing in a 3.5”/9 cm terracotta pot. Author’s plant and image.

While under far less of a threat of local extirpation by poaching than localized types of Aizoaceae, some wild haworthias also face ongoing commercial collecting pressure from EU and Asia-based succulent plant smugglers that sometimes leverage messaging apps to exploit economically vulnerable local counterparts (Trenchard, 2021). All commercially valuable miniature species of Cape succulent flora, including certain haworthias, are now squarely in the cross-hairs of the global wild plant poaching trade, especially in the EU and Asia (Trenchard, 2021).

It is undeniable that the better Japanese and Korean succulent growers are admired for their horticultural talent and considerable attention to detail. Many produce impeccable looking plants. Demand for artificially propagated Korean origin stonecrops and Alooids is high around the world right now, especially in the PRC and the U.S. (Margulies, 2020; pers. obs.). Leaving legal domestic production in nurseries aside, very high demand in eastern Asia for illegally wild collected miniature succulents is leaving holes in fragile desert and other xeric ecosystems across the globe (Nuwer, 2021; US Department of Justice, 2022). To be fair, U.S., Czech and Russian collectors have also been arrested in South Africa, Arizona, and Texas in recent years for poaching threatened succulent plants so there is plenty of blame to go around (Jordaan, 2020; Nuward, 2021; Trenchard, 2021).

This is not a recent phenomenon.

Again, in the Bayer monograph on haworthias published more than two decades (!) ago: “There is a lot of evidence to suggest that field collected plants (haworthias) are being commercially exploited. Two kinds of people are responsible - those who physically remove the plants from the field, and those who eagerly and irresponsibly buy or receive such plants…However, by far the greatest change and losses I have observed in the field are those directly attributable to physical damage and destruction of habitat. Nevertheless, the potential for such loss should never be construed as an excuse to remove plants from habitat: That simply ensures non-survival.”

Despite its ferociously prickly aspect, the spines on this *Haworthia herbacea* var. herbacea from Western Cape Province are actually soft and pliable. At larger sizes, this is one of the nicer species for display. Shown growing in a 5”/13 cm terracotta pot. Author’s plant and image.

Cultivation

Attracted by their deceptively fearsome looks and compact size, I assembled a small collection of these species five years ago and have added a few plants since. The haworthias that I grow all mature at small rosette diameters; ~one to three inches or three to eight cm. I grow them on a long, south-southeast facing windowsill in my study in the San Francisco Bay Area in California as well as on an eastern facing terrace outside that is open to the sky.

Superb drainage makes for ease of culture, especially if grown in plastic containers. Although some growers successfully cultivate them in pure horticultural grade pumice, I add very small volumes (~10% by weight) of a peat-based substrate such as Pro-Mix X to improve moisture retention and cationic exchange capacity (CEC). I also add small amounts of dolomitic limestone (calcium magnesium carbonate) as a buffer, and pelleted gypsum (calcium sulfate dihydrate) to compensate for mineral deficiencies in my tap water together with a time release prilled fertilizer such as 180-day nutricote custom blended to 15-9-11 + micros.

Bright, filtered sunshine and judicious watering seems to produce uniformly good results with spider-nest haworthias in my care. They should be considered light feeders if natural proportions are desired. Higher light levels indoors (>1,500 fc) and sparse watering favor the development of tight rosettes and a nice touch of pink to reddish leaf color that is often a hallmark shown in photographs of plants in situ.

Rooted leaf pull from a *Haworthia decipiens* variety. Author’s image.

Some of the species or varieties are slow growing but all are generally easy to propagate from seed, offsets or rooting single leaf pulls taken from thickest leaves in the rosette.

For several reasons, I have always preferred Italian terracotta azalea or side vented orchid pots as containers for my specimen succulents. Like others, I use inert stone ground covers around the plants to prevent substrate from splashing back onto the leaves during watering. Everyone has their favorite top dressing for their aloes and haworthias. I prefer either coarse, well-washed river sand mixed with small pebbles or chipped slate as shown in images here.

Outdoors, a few species are tolerant of cold, wet coastal northern Californian winters and high late summer and fall temperatures as well.

Like other popular aloids in cultivation, haworthias and related genera are vulnerable to infestations of aloe mite (Aceria aloinus - Eriophidae; Fischel, 2020). Incoming plants should be quarantined for at least a couple months to ascertain that they are not showing indications of damage from this pest. Where permitted, preventive sprays of approved miticides in rotation are useful. Always follow local laws, label recommendations and use both common sense and protective gear when applying any agrochemical from any class.

On a scale of difficulty from one to 10, with a one being idiot-proof and a 10 being nigh-impossible to grow, I would rate spider-nest haworthias as a two or three. I find them pretty much maintenance-free, barring the need for careful seasonal watering and the odd dilute fertilizer drench every semester or so. I also keep a watchful eye out for mealybugs. Admittedly, I haven’t grown that many haworthias, but I have also never killed one either, something I wish I could claim about any other plant genus I have cultivated during my lifetime.

For indoor growers with limited space, together with tabletop aloe species and hybrids, this is a modestly priced, rewarding and pain-free group of plants to work with.

Many thanks to Ron Parsons for the loan of two of his very well-grown plants together with several key titles listed in the reference section below that are now out of print, expensive and very hard to find.

GALLERY

*Haworthia arachnoidea* var. *xiphiophylla* from Eastern Cape Province. This species is the original spider-nest haworthia. Author’s plant and image.

Two young *Haworthia bolusii var. bolusii* from Eastern Cape Province. Author’s plant and images.

A cluster of young *Haworthia cummingii* from the Eastern Cape Province. As watering intervals decrease from mid winter onward, these rosettes contract and assume a more typical look for the species. Author’s plant and image.

*Haworthia gracilis* var. tenera from the Eastern Cape Province. Author’s plant and image.

A compact, very attractive variety of Haworthia herbacea. This species is endemic to Western Cape Province. Author’s plant and image.

*Haworthia jansenvillensis*, a larger growing species (rosettes to 5”/13 cm in cultivation) closely related to the *H. decipiens* complex. Author’s plant and image.

Referenced Cited

Baker, J. G. 1897. In Flora Capensis: Being a Systematic Description of the Plants of the Cape Colony, Caffraria & Port Natal (and Neighboring Territories). Part III. L. Reeve & Co. London.

Bayer, B. 1999. Haworthia Revisited – A Revision of the Genus. Umdaus Press. Hatfield, South Africa. 250 pp.

Bayer, B. and L. M. Loucka. 2013-2021. Haworthia Updates. Thoughts and observations on the genus Haworthia. Link: https://haworthiaupdates.org

Breuer, I. 1998. The World of Haworthias. Volume 1. Ingo Breuer and AfM. Niederzier, Germany. Pg 1-340 + XII

Breuer, I. 2000. The World of Haworthias. Volume 2. Ingo Breuer and AfM. Niederzier, Germany. Pg 341-859 + XIII

Fischel, M. 2020. Aloe Mite, A Haworthiad Problem. Haworthiad. Vol. 34 (3). Pg 61-64.

Graf. A. B. 1980. Exotica Series 3. 10th Edition. Roehrs Company. East Rutherford, New Jersey. 1,837 pp with plates.

Jacobsen, H. 1960 (English Edition). A Handbook of Succulent Plants. Blandford Press. London. Three volumes. 1,441 pg, 1,617 illustration and 3 maps.

Jordaan, N. 2020. American fined R500,00, banned from SA for ‘stealing’ protected plants. Sunday Times. https://www.timSpider-nest describes both their appearance and taxonomy.eslive.co.za/news/south-africa/2020-04-01-american-fined-r500000-banned-from-sa-for-stealing-protected-plants

Malik, F.T., R. M. Clement, D.T. Gethin, M. Kiernan, T. Goral, P. Griffiths, D. Beynon and A.R. Parker. 2016. Hierarchical structures of cactus spines that aid in the directional movement of dew droplets. Philosophical Transactions Royal Society A374. 2016.0110. Pp. 1-13.

Manning, J. C., J. C. Boatright, B. H. Daru, O. Maurin and M. van der Bank. 2014. A Molecular Phylogeny and Generic Classification of Asphodelaceae subfamily Alooideae: A Final Resolution of the Prickly Issue of Polyphyly in the Alooids? Systematic Botany, 39 (1): pp. 55-74

Margulies, J.D. 2020. Korean ‘Housewives’ and ‘Hipsters’ Are Not Driving a New Illicit Plant Trade: Complicating Consumer Motivations Behind an Emergent Wildlife Trade in Dudleya farinosa. Frontiers in Ecology and Evolution. 8:604921.

Martorell, C. and E. Eczurra. 2007. The narrow-leaf syndrome: A functional and evolutionary approach to the form of fog-harvesting rosette plants. Oecologia 151 (4):561-73.

Nuwer, R. 2021. Global Cactus Traffickers Are Cleaning Out the Deserts. New York Times. https://www.nytimes.com/2021/05/20/science/cactus-trafficking-chile.html

Operation Wildflower. 2022. Notes on Haworthia arachnoidea. https://www.operationwildflower.org.za/index.php/albums/haworthias/haworthia-arachnoidea-il-1-3129#joomimg

Poellnitz, K. von. 1929-1940. See pages 33-35 in the “Literature” section of Ingo Breuer’s “World of Haworthias, Vol. 1” for a complete list of Poellnitz’s many publications on haworthias, including 80 species descriptions of which about a dozen are still considered valid names. A very accomplished German botanist who met a tragic end during Allied force bombing of his home in 1945. Gordon Rowley has published a few short biographical sketches of Dr. Baron von Poellnitz, including one in “A History of Succulent Plants”. A thoughtfully composed tribute may be found here: http://australianportulaca.blogspot.com/2013/10/biography-of-dr-karl-von-poellnitz-1896.html

Rowley, G. 1978. The Illustrated Encyclopedia of Succulents. Salamander Books Limited, London. 256 pp.

Rowley, G. D. 1980. Name that Succulent. Stanley Thornes, Cheltenham, UK. 268 pp.

Rowley, G. D. 1997. A History of Succulent Plants. Strawberry Press, Mill Valley, California. 409 + XV pp.

Schulz, R. 2009. Haworthia for the Collector. Schulz Publishing. San Bruno, California. 239 pp.

Smith, G. F., E. Figueiredo and S. Molteno. 2017. A new combination in Tulista, T. kingiana (Asphodeloideae, Xanthorrhoeaceae/Alooideae, Asphodelaceae). Phytotaxa Vol. 297 No. 3.

Smith, G. F., E. Figueiredo and S. Molteno. 2018. A new combination in Tulista, T. minor (Alooideae, Asphodelaceae). Phytotaxa Vol. 364 No. 2.

Trenchard, Tommy. 2021. In South Africa, Poachers Now Traffic in Tiny Succulent Plants. New York Times, July 31, 2021. https://www.nytimes.com/2021/07/31/world/africa/south-africa-poachers-tiny-succulent-plants.html

U.S. Department of Justice-Central District of California. 2022. Korean National Sentenced to Two Years in Prison for Attempting to Illegally Export to Asia Poached Wild Succulent Plants. https://www.justice.gov/usao-cdca/pr/south-korean-national-sentenced-two-years-prison-attempting-illegally-export-asia