Haworthia retusa var. turgida
Introduction
Haworthia retusa var. turgida is a dwarf, cluster-forming, cliff-hugger, with numerous, small rosettes of light green to reddish succulent leaves, often as thick as they are broad, and a solitary inflorescence bearing white flowers in summer and early autumn. It is very variable and widespread, on cliffs along the Langeberg Mountains in the Western Cape. Best grown in containers.
Fig. 1. A close-up of a cluster of the the Langeberg cliff haworthia (Haworthia retusa var. turgida) in a container at Kirstenbosch; plant collected from a cliff in Tradouw Pass, Langeberg, Western Cape.
Description
Description
Plants dwarf-sized, rosulate, prolific from the base, forming dense, rounded clusters consisting of up to 25 heads or more. Rosettes 20–30(–80) mm in diameter. Roots grey, terete. Leaves 20 to 40, firm, oblanceolate, almost recurved or somewhat retuse (shallowly notched) at apices, turgid, ascending-spreading, with some translucent reticulation (network-like patterns); upper side flat to convex, lower surface rounded, surface smooth, bright green, becoming pinkish green to purplish green during dry periods; margin entire or with soft sparse spines; apex obtuse or acute (shiny and pellucid), mucronate. Inflorescence racemose, up to 200 mm long, 10–20-flowered in distal half; bracts white, clasping, up to 3 mm long, ovate-acuminate; pedicels 2 mm long. Perianth tubular, curved, ascending-spreading, 15 mm long, white with purplish green mid-stripe. Flowering is mainly from midsummer until early autumn (February–April, southern Hemisphere).
Fig. 2. A close-up of cluster of the the Langeberg cliff haworthia (Haworthia retusa var. turgida), growing in habitat during the dry season.
Conservation Status
Status
Occurring on sheer cliffs in the Langeberg Mountains of the Western Cape, plants are well protected by their difficult to reach habitat, and its distribution falls within a greater conservation region. Consequently, it is not threatened, and is classified as Least Concern (LC) (Raimondo et al. 2009).
Distribution and habitat
Distribution description
Haworthia retusa var. turgida occurs mostly in river valleys of the Langeberg Mountains from Heidelberg in the east to Barrydale in the west. Mainly confined to quarzitic sandstone cliffs (all aspects), but more so on open, shady, south-facing aspects at an altitude of 500–1 500 m. Plants are rooted in crevices, where they proliferate and fill the crevices, the cluster size often depending on the growing space allowed by the crevice. Temperatures are high in summer (28–40°C). Winters are cooler but frost is absent. Rainfall occurs throughout the year but more so in winter, 250–500 mm per annum, in the form of thunder showers or cyclonic winter rain.
It occurs on the higher mountains on quarzitic sandstone (Peninsula Formation, Cape Supergroup), but also on lower lying shale and mudstone (Ceres Group, Bokkeveld Formation) of the same supergroup. Substrate has many ledges, crevices and fissures, ideal for establishment of plants.
The associated vegetation consists of South Langeberg Sandstone Fynbos and Southern Cape Valley Thicket of the Thicket Biome (Mucina et al. 2006). Associated cremnophytes include: Cotyledon eliseae, Cotyledon orbiculata, Crassula perforata, Crassula rupestris, Drimia anomala and Albuca longibracteata.
Fig. 3. (LEFT) Cliffs in the Tradouw Pass, Langeberg Mountains, habitat of Haworthia retusa var. turgida. (RIGHT) A group of the Langeberg cliff haworthia (Haworthia retusa var. turgida) filling a ledge on a cliff in the Tradouw Pass.
Derivation of name and historical aspects
History
This plant was named Haworthia turgida by Adrian Haworth, British succulent student, in 1819. The genus Haworthia was created by Henri Auguste Duval in 1809 and named after him. This species name means ‘turgid’ or ‘swollen’ and pertains to the swollen look of its leaves and indeed, after sufficient rainfall or watering, the leaves become very turgid. Bruce Bayer, after considering all the populations and varieties known to him came to the conclusion that H turgida belongs in H. retusa. Consequently, in 2011 he transferred H. turgida to H. retusa and this species is now known as Haworthia retusa var. turgida. The species name retusa means ‘with leaf-tips bent back like a thumb’.
Haworthia turgida was an extremely variable taxon (genotypic variation), with many local variants. Bayer (1999) recognised three varieties, var. turgida, var. longibracteata and var. suberecta, all of which are now also recognised as varieties of Haworthia retusa. The var. suberecta does not occur in cliff habitats and has distinctly retuse leaves with markings. The var. longibracteata is much larger, occurring on steep, rocky slopes near Still Bay.
The genetic variability or plasticity of these plants reflects their ability to adapt to local conditions and colonise new habitats, should the opportunity arise.
Haworthia retusa var. turgida is related to H. mirabilis, H. reticulata and H. herbacea, all of them usually confined to flat or hilly terrain, usually well camouflaged, with a sunken growth and inconspicuous. They often occur under the protection of thorny nurse shrubs and their leaves have a firmer texture.
Ecology
Ecology
Haworthia retusa var. turgida proliferates and grows in dense rosettes, the leaves ascending-spreading to almost recurved, with pellucid to distinctly translucent apices. This appears to be an adaptation to maximise distribution of light (longer and short rays) within the leaf tissue on the shady cliff face. The very swollen nature of the leaves reflects their ability to store moisture on the extremely dry, well-drained cliffs.
Fig. 4. A cluster of a few plants of the Langeberg cliff haworthia (Haworthia retusa var. turgida) shaded by grass, growing in the Tradouw Pass. Note the reddish-purple colour of the leaf and the large translucent windows.
The plants are tightly arranged, the leaves bright green to greyish green, becoming pinkish to purplish green under dry conditions, thus minimising absorption of light under dry conditions. Plants are long-lived, with soft leaves withering from the base. The leaves have a soft texture and are not armed, the margin varying from entire to softly spined. Compared to its relatives, there is a reduction in armament and camouflage, this is in response to its undisturbed cliff habitat, in contrast to theirs in the thorny but heavily grazed surrounding thicket vegetation.
The inflorescence is ascending to spreading, the corolla white, attracting a pollinating flying insect. The capsules release the seed in autumn, coinciding with the winter rainfall. Moisture is retained longer in the substrate during this cooler time of the year thus providing the best chance of germination. The seed is small and angular, ideal for establishment in crevices. The seed is light, shaken from the capsules, and dispersed by wind.
Haworthia retusa var. turgida suckers freely from the base, forming dense, rounded clusters. Continual sprouting from the base represents an efficient vegetative backup dispersal strategy for this harsh cliff-face environment. Detached clusters or heads will also root if they fall into a crevice.
Fig. 5. A rounded cluster of the the Langeberg cliff haworthia (Haworthia retusa var. turgida) growing in a crevice on a cliff on the Tradouw Pass, Langeberg, Western Cape.
Uses
Use
No medicinal or cultural uses have been recorded.
Growing Haworthia retusa var. turgida
Grow
Plants are easily cultivated and are popular pot plants throughout the world. They do well in containers and miniature gardens where conditions can be controlled. They grows best in dappled shade, in slightly acidic, sandy soil. Feed with organic fertiliser in autumn. Plants respond rapidly to watering, becoming turgid. Water should be provided throughout the year, but sparingly in summer.
Plants are easily propagated by division, in late summer. Plants divide rapidly, forming dense clusters.
Sow seed in autumn in a shallow tray in a sandy mixture (e.g. a mix of peat, sand and polystyrene) and keep moist. Germination is within 3 weeks and once large enough to handle, transfer to individual containers. Place container in a shady position but with full light. The south side of a building is ideal.
Plants are relatively disease free but aphids, slugs and snails can sometimes be a problem.
References
- Bayer, M.B. & Van Jaarsveld, E.J. 2001. Haworthia. In U. Eggli. (ed.), Illustrated handbook of succulent plants: Monocotyledons. Springer, Berlin.
- Bayer, M.B. & Manning, J.C. 2012. The Haworthia nomenclator: A list of accepted species with some guidelines for infraspecific names. Haworthia Updates. Online. https://haworthiaupdates.org/species-list/
- Bayer, M.B. 1999. Haworthia revisited, a revision of the genus. Umdaus Press, Hatfield.
- Bayer, M.B. 2011. That squadron of Haworthias from Albertinia eastwards. Haworthia Updates. 4 (1). Online. https://haworthiaupdates.org/2011/12/04/volume-4-chapter-1-that-squadron-of-haworthias-from-albertinia-eastwards/.
- Haworth, A. 1819. Supplementarum Plantarum Succulentarum. London.
- Mucina, L. & Rutherford, M.C. (eds) 2006. The vegetation of South Africa, Lesotho and Swaziland. Strelitzia 19. South African National Biodiversity Institute, Pretoria.
- Raimondo, D., Von Staden, L., Foden, W., Victor, J.E., Helme, N.A., Turner, R.C., Kamundi, D.A. & Manyama, P.A. (eds) 2009. Red list of South African plants. Strelitzia 25. South African National Biodiversity Institute, Pretoria.
- Scott, C.L. 1985. The genus Haworthia, a taxonomic revision. Aloe Books, Johannesburg.
Credits
Ernst van Jaarsveld
Kirstenbosch National Botanical Garden (Retired 2015)
Babylonstoren Farm
Extraordinary senior lecturer and researcher,
Department of Biodiversity and Conservation, University of the Western Cape
February 2022
Plant Attributes:
Plant Type: Succulent
SA Distribution: Western Cape
Soil type: Sandy
Flowering season: Spring, Early Summer
PH: Acid
Flower colour: White
Aspect: Shade, Morning Sun (Semi Shade), Afternoon Sun (Semi Shade)
Gardening skill: Easy
Special Features:
Drought resistant
Good potplant
Horticultural zones
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