Bulbine sceletium
Introduction
Bulbine sceletium is a cliff-squatting, aloe-like plant with sparingly branched rosettes of soft, pale green, striated leaves and solitary inflorescences of yellow flowers in spring. The older leaves dry into papery, skeleton-like remains that persist on the plant. It grows wild on cliffs along both the Mzimvubu River and the Great Fish River in the Eastern Cape, South Africa. Best grown in containers and hanging baskets.
Fig. 1 Bulbine sceletium in flower, drawn by botanical artist, Barbara Pretorius.
Description
Description
The plants are fragile, softly succulent, solitary, sometimes branching from the base, forming decumbent rosettes up to 300 mm in diameter. The stems 15–20 mm in diameter and up to 50 mm long, with persistent, thin, papery remains of leaves and leaf bases. The roots are grey-brown, fleshy, terete, ± 1.5–2.0 mm diameter. Each rosette consists of about 10–12 functional leaves, initially ascending to ascending-spreading, ovate to broadly ovate, 150–300 × 70–140 mm, the leaf tip (apex) acuminate, ending in a short, firm point (mucronate), shallowly to deeply channelled, convex to rounded below, greyish-green and fragile, smooth, striate. The leaf margins are minutely hairy (ciliate).
Fig. 2 A leaf of Bulbine sceletium, note the minute cilia along the margin as well as the striate semi-translucent pale grey green leaves.
The inflorescence about 250–450 mm long, densely flowered in upper third; raceme up to 170–220 mm long; peduncle up to 15 × 7 mm diameter at base, biconvex. The floral bracts are linear, up to 4 × 3 mm, acuminate, clasping; the flower stalks (pedicles) 12–16 mm long. The flowers (perianth) stellate, ± 25 mm diameter; tepals yellow with greenish yellow median stripes, apices drawn to a sharp point (acute to subacute). The outer tepals are narrowly lanceolate, up to 12 × 3 mm; the inner tepals lanceolate, 11 × 4.5 mm. The stamens (male parts) up to 8 mm long, bearded in central part, with hairs 1–1.5 mm long. Ovary (female part) rounded (globose), up to 2 mm diameter The style erect, 7 mm long. The fruiting capsule 5 × 4 mm and the seeds 2 × 1.5 mm, pale grey, angular, surface minutely pitted (foveate). Flowering is in late spring, from October to November.
Fig. 3 Bulbine sceletium flowering at Babylonstoren Farm.
Conservation Status
Status
Bulbine sceletium has not yet been assessed for the Red List of South African Plants. Although it is only known from two river systems, it is well protected by its difficult to reach cliff habitat, consequently, it can be regarded as not threatened.
Fig. 4 Great Fish River at Langkrans (Hunts Hoek, Outspan), habitat of Bulbine sceletium, where plants were found growing on cliffs and ledges.
Distribution and habitat
Distribution description
Only known from the Mzimvubu and Great Fish River Systems in the Eastern Cape, Bulbine sceletium plants were found growing on shady to sunny, sandstone cliffs (Beaufort sandstones, Adelaide subgroup), on ledges, among moss and lichens.
The vegetation of the Great Fish River consists of dry Buffalo Thicket (Albany Thicket Biome) (Mucina et al. 2006). Succulents and bulbous plants are very prominent in its habitat and include: Agapanthus praecox, Albuca batteniana, Aloe pluridens, Aloiampelos ciliaris, Bowiea volubilis, Bulbine latifolia, Coleus madagascariensis, Delosperma laxipetalum, D. stenandrum and D. tradescantioides, Ceropegia stapeliiformis, Cotyledon, petiolaris, C. velutina and C. woodii, Crassula lactea, C. nemorosa, C. orbicularis, C. intermedia, C. perforata, C. spathulata and C. cordata, Curio ficoides, Cyphostemma cirrhosum, Dracaena aletriformis, Fockea edulis, Haemanthus albiflos, Haworthia cymbiformis, Senecio angulatus, S. macroglossus and S. voigtii, Crassothonna capensis, Othonna triplinervia, Peperomia blanda, Pelargonium inquinans, Plectranthus verticillatus, Portulacaria afra and Tetradenia barberae. Bulbine sceletium grows together with (sympatric) B. latifolia, also large robust plants.
Plants were also found along the Mzimvubu River Waterfall to the north-east, growing on a south facing cliff face in Eastern Valley Bushveld (Mucina 2006). Bulbine sceletium grows on Beaufort shale cliffs and associated succulents includes Gasteria loedolffiae, Portulacaria afra, Crassula perforata, Adromischus cristatus subsp. mzimvubuensis and Caputia medley-woodii.
Fig. 5 The habitat of Bulbine sceletium at the Mzimvubu River waterfall, where plants were seen growing on the sheer cliff face.
Derivation of name and historical aspects
History
Bulbine sceletium was named in 2022 by Adam Harrower and the author in the yearbook of the British Cactus and Succulent Society, Bradleya. The specific name pertains to the leaves, which characteristically dry into thin, papery skeletons.
Bulbine sceletium was found on two rubber canoe expeditions to the Eastern Cape. It was first recorded from near the waterfall at the Mzimbubu River in April 2002 and in April 2015 it was found on the Great Fish River. It was during the Great Fish River expedition that a large population of Bulbine sceletium was found at Langkrans (Outspan, Hunts Hoek) on the steep, south-facing cliffs and slopes. Plants were grown on at Babylonstoren Farm and when they came into flower the species was illustrated by the botanical artist Barbara Pretorius.
Fig. 6 Adam Harrower observing a plant of Bulbine sceletium in its native habitat at Langkrans (Hunts Hoek, Outspan), Great Fish River.
The Great Fish River enters the Indian Ocean about 60 km south-east of Makhanda. It originates along the southern escarpment mountains between Graaff-Reinet, Cradock and Middelburg. The Great Fish River according to Raper (1987) is a translation of the Khoekhoen name Oub, meaning ‘fish’. It was known by the Portuguese as Rio de Infante. Mzimvubu is Xhosa meaning ‘the home of the hippo’. The Mzimvubu River originates in the Drakensberg where Lesotho, Eastern Cape and KwaZulu-Natal meet, and enters the Indian Ocean at Port Saint Johns. Incidentally, it was on the Great Fish River rubber canoe expedition, when the type specimens were collected, that the rubber canoe was attacked by a female Hippo, a near escape for the authors.
Bulbine sceletium differs from other cliff-dwelling species by its solitary, decumbent rosettes of broad, thin and softly succulent, striate, grey-green leaves, which dry out as a persistent, thin skeleton starting at the leaf tips. Its seed is also distinct, angular, with a pale grey, distinctly pitted (foveate) epidermis . The plants grow solitary but rosettes may rarely grow side shoots.
Fig. 7 Bulbine sceletium in habitat, note the persistent, dry papery remains of its leaves.
Ecology
Ecology
Plants have soft, fragile leaves and grow in the relative safety of the cliff-face environment, free from larger herbivores and also partially protected from fires. Bulbine sceletium flowers during late spring, and the flowers are pollinated by insects. The fruiting capsules ripen shortly after flowering, during summer, and the light, angular seeds are dispersed by wind. The succulent nature of the plant (leaves, stems, roots) enables the plant to cope during the dry season.
Fig. 8 Bulbine sceletium in habitat on a cliff face, Great Fish River.
Uses
Use
No medicinal or cultural uses have been recorded.
Growing Bulbine sceletium
Grow
Bulbine sceletium is easily grown from seed. It makes an interesting pot plant and is ideal for hanging baskets. It can also be grown as a garden plant but is best for gardens along the subtropical coast.
Fig. 9 Bulbine sceletium in cultivation in the Babylonstoren Succulent Collection.
Plants grow relatively fast. The soil should be sandy and well-drained, as is found in its natural habitat, e.g. 2 parts sand, 1 part compost and 1 part garden loam. They react well to an organic fertiliser. In the garden, plant it on a shady embankment. As a pot plant it is best on a balcony or windowsill. During the summer months, its growing season, the plant should be regularly watered.
Sow seed in summer in a sandy medium. First moisten the substrate with fine rose. Sow the seed and cover lightly with a thin layer of sand. Keep moist and in a shady area. Germination is usually within 3 weeks and the young seedlings are slow growing. Transplant seedlings to individual containers once large enough to handle.
Plants are relatively disease free but snails can cause a problem.
References
- Mucina, L. & Rutherford, M.C. (eds) 2006. The vegetation of South Africa, Lesotho and Swaziland. Strelitzia 19. South African National Biodiversity Institute, Pretoria.
- Nienaber, G.S. & Raper, P.E. 1983. Hottentot (Hhoekhoen). Place names of southern Africa. Onomastic Research Centre, Butterworth Publishers, Durban/ Pretoria.
- Raper, R.E. 1987. Dictionary of Southern African Place Names. Lowry Publishers, Johannesburg.
- Van Jaarsveld, E.J. & Forster, P.I. 2019. Bulbine. In U. Eggli & Nyffeler (Editors) Illustrated handbook of Succulent Plants, Volume 1: 713-738. Monocotyledons (Agavaceae to Asphodelaceae), Second Edition. Springer, Germany.
- Van Jaarsveld, E.J. & Harrower, A. 2022. Bulbine sceletium, a new cliff-dwelling Bulbine species (Asphodelaceae) from the Eastern Cape. Bradleya 40: 137–143.
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
October 2022
Acknowledgements: the author thanks botanical artist Barbara Pretorius (Hermanus, Western Cape) for her water-colour illustrations of Bulbine sceletium (Fig1) from plants grown at Babylonstoren Farm, Simondium; Koos Bekker, owner of Babylonstoren Farm for support; colleagues Adam Harrower, Werner Voigt (Kirstenbosch National Botanical Garden) and Ricardo Riddles (Karoo Desert National Botanical Garden, Worcester) for their support in the field on the Great Fish River expedition; and Phakamani Xaba (Kirstenbosch National Botanical Garden) for support on the Mzimvubu River rubber canoe expedition.
Plant Attributes:
Plant Type: Succulent
SA Distribution: Eastern Cape
Soil type: Sandy, Loam
Flowering season: Spring, Early Summer
PH: Acid, Neutral
Flower colour: Yellow
Aspect: Shade, Morning Sun (Semi Shade), Afternoon Sun (Semi Shade)
Gardening skill: Easy
Special Features:
Drought resistant
Good potplant
Feeds honeybees
Horticultural zones
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