Gasteria langebergensis
Introduction
Gasteria langbergensis is a cluster-forming, leaf succulent with oblong, flattened, slightly wrinkled leaves in two opposite rows (distichous) and bearing an inflorescence with orange-pink flowers in late winter. It grows in dry Succulent Karoo vegetation, on the lower slopes of the Langeberg, between Worcester and Robertson, in the Western Cape. The flowers are edible. It is best cultivated in containers.
Fig. 1. Gasteria. langebergensis from the Langvlei Quarry. Illustration by Jeanette Loedolff.
Description
Description
The plants are acaulescent, at first solitary but proliferating from the base to form clusters of 5 to 10 heads, about 90–150 mm tall and up to 180–240 mm in diameter. The roots are succulent, 3–4 mm in diameter. The leaves, 8–12 per rosette, grow in two opposite rows (distichous) and are linear-lanceolate, 80–120 mm long, 22–27 mm broad at base, ascending spreading, the lower leaves becoming spreading. The upper surface is flat, becoming canaliculated in dry conditions during summer, convex when turgid, plane towards apex, matt dull green, becoming reddish during the dry season, densely white-spotted in obscure transverse bands. The lower surface convex, rough to the touch (asperulous) and its margin is somewhat wrinkled in outline, armed with very small, leathery teeth (denticulate). The leaf tip is acute, sometimes acuminate, the tip bearing a hard short point (mucronate), the latter often slightly off-center. The juvenile leaves are similar in shape to adult leaves.
The inflorescence is elongated and semi scandent, 650–840 mm long, supported by the nurse shrub, the raceme about 390–410 mm long, bearing 28–34 flowers with up to 8 flowers open at the same time. The flowers are arranged in one plane, pointing in the same direction (secund). The bracts are linear triangular-acuminate, 9–10 mm long, as long as the pedicels, the base clasping. The stalk of the inflorescence is rounded (biconvex) at base, 4 mm in diameter. The flower (perianth) is oblong, gently curved, 20 mm long, with a stipe (stipitate) that is 2 mm long. The flower base is swollen (gasteriform) for half of its length, the segments fused for their greater length, except for the perianth apices and margins of the inner 3 segments, the distal portion cylindrical for about 10 mm, 4 mm in diameter. The lower and upper half inflated to about 5–6 mm in diameter, dull orange-pink, upper half white with green striations; apices erect becoming erectly spreading, obtuse; margins of inner segments free and channeled, diverging gradually towards apex. Stamens 10–12 mm long; anthers about 2×1 mm, included or shortly exserted. Ovary oblong, 8×3.5 mm, green; style 10 mm long, stigma included or shortly exserted, curved upwards, minute. Capsule and seed: not known. Flowering time is in winter (June to July in the southern Hemisphere).
Fig. 2. Gasteria langebergensis in habitat at the Langvlei Quarry, north of Rooiberg.
Conservation Status
Status
Plants are rare and range-restricted, and the region is mined for its dolomitic limestone. Consequently it is assessed as Endangered (EN) in the Red List of South African Plants.
Fig. 3. Langvlei Quarry, Buitenstekloof, the habitat of Gasteria langebergensis.
Distribution and habitat
Distribution description
Gasteria langebergensis grows in the Breede River Valley, in a small region between Worcester and Robertson, on the lower, south-facing slopes of the Langeberg. The geology consists of shales and dolomite of the Malmesbury Group.
On the lower mountain slopes of the Langeberg at Buitenstekloof, G. langebergensis grows on soils mainly derived from Malmesbury Group (Noree Formation dolomite and shale) and, to a lesser extent on quartzitic sandstone of the Table Mountain Group. On the southern foothills of the Rooiberg, G. langebergensis grows on shales of the Bokkeveld Group.
Gasteria langebergensis grows in succulent-rich Robertson Karoo vegetation, which is part of the Rainshadow Valley Karoo of the greater Succulent Karoo Biome (Mucina & Rutherford, 2006). It is found in a rocky terrain with scattered shrubs, including Carissa haematocarpa, Euclea undulata and Searsia undulata, small trees of Olea europaea subsp. africana and associated succulents include Haworthia reticulata, Aloe microstigma, Adromischus maculatus, A. filicaulis subsp. marlothii, Antimima sp., Lampranthus haworthii, Sarcostemma viminale, Cotyledon orbiculata var. orbiculata, Crassula atropurpurea, C. perforata, C. rupestris and C. anso-lerouxiae, Euphorbia burmannii and Pelargonium alternans.
The climate of the Robertson Karoo is consists of hot, dry summers with maximum temperatures above 30 degrees centigrade and short, moist, cool winters. If frost occurs, it is very light. Rainfall is mainly during winter but some rain can also occur in spring or autumn, associated with thunder showers. The rainfall is between 200 and 300 mm per annum (May to September). The advantage of rainfall in the winter is that the moisture persists for much longer. G. langebergensis grows in localized populations at an altitude of about 3–400 m.
Fig. 4. The habitat of Gasteria langebergensis at Langvlei Quarry. Note the dolomite rocks and Aloe microstigma.
Derivation of name and historical aspects
History
Bruce Bayer, former Curator of the Karoo National Botanical Garden, was the first to collect this plant from Buitenstekloof, northwest of Robertson. Since its naming as a new variety of G. disticha by the author in 2007, nuclear DNA investigation by Zonneveld showed that it is more closely related to the G. carinata complex and G. retusa than it is to G. disticha and suggested its separation from the latter species and consequently it was raised to an independent species in 2019 in the British succulent plant journal Bradleya. (Van Jaarsveld et al. 2019).
Gasteria langebergensis grows in close proximity to G. disticha, which is widespread on the lower flats below the obvious geological fault line at Buitenstekloof. G. retusa also grows in the same general region and is also found only on Malmesbury shale outcrops to the northwest, the latter with leaves which are distinctly tuberculate. G. disticha is larger with broader leaves but with the same type of leaf epidermal texture as G. langebergensis.
Ecology
Ecology
Gasteria differs from the closely related aloes in its defensive strategies. Aloes are generally much larger and conspicuous, their spiny, firm and very bitter tasting leaves ensure an effective defense to cope with predators. Gasterias are smaller and inconspicuous, with brittle leaves which are not bitter; they defend themselves using a different strategy, by making use of passive resistance and camouflage. They are usually difficult to detect, growing in the dappled shade of shrubs, termed nurse shrubs.
When plants are damaged by porcupine or rock rabbit predation, leaves or leaf fragments that are left lying on the ground will spontaneously root, proliferating from its base to form new clusters. This method of vegetative propagation is often seen in its habitat and can be found throughout the Succulent Karoo, Albany Thicket as well as the Savanna Biomes.
The succulent leaves of Gasteria langebergensis become turgid after rain in the winter months. This moisture-conserving strategy is essential for its survival during the long, dry summer months.
Growing below a Carissa haematocarpa nurse shrub also has its advantages. This nurse shrub not only provides shade during the long, hot, sunny days but the very thorny nature of the nurse shrub also protects the succulent plants growing below its canopy from plant predators.
Fig. 5. Gasteria langebergensis growing in the shade of a nurse shrub, in habitat at Langvlei Quarry.
The semi-scandent inflorescence is supported by branches of its nurse shrub (Carissa haematocarpa). The inflorescence appears in winter and the upper parts are usually exposed above the canopy of the nurse shrub; thus they are clearly visible to and pollinated by local sunbirds.
Uses
Use
Apart from its horticultural uses, the flowers of this species are edible; they are locally known as oukossie, harvested in spring and cooked up in a meaty stew.
Figure 6. Gasteria langebergensis plants growing at Babylonstoren Farm. Note the long drooping inflorescence.
Growing Gasteria langebergensis
Grow
Gasteria langebergensis is easily cultivated, either in containers or rockeries. A Mediterranean-type climate is the best. Locally in South Africa, it can be grown in a succulent karoo garden (Van Jaarsveld 2010). Care should be taken that the soil is well-drained and that the plants have some protection against the sun. The plants prefer a shale-derived soil but sand, gravel and ample lime should be added. The plants will benefit from ample compost or an organic liquid fertiliser, which can be added one a year. Plants grow well in containers, which can be placed on a shady windowsill or stoep. Water sparingly during winter and less so during summer.
Propagation is both by division, leaf cuttings or seed. Sow seed in spring or summer, in a well-drained, sandy mixture. Cover the seed with a thin layer of sand. Protect from full sun and keep moist. Germination is within about 3 weeks. The young plants are slow-growing and can be planted into individual containers when large enough to handle. Divide plants when necessary.
Leaf cuttings can be made at any time of the year. Preferably, remove a lower leaf by firmly holding the plant down with the one hand and remove the leaf with a twist from the other hand, or simply cut it near the base. Allow for about 3 weeks for the cutting to heal and plant by placing the leaf flat on the ground but with the lower portion partially covered in soil. Rooting is usually rapid and when rooted, the leaf will become turgid. Young plants will proliferate from its base but leave undisturbed until large enough to handle, (about 1 year).
References
- Keyser, N. 1997. Geological Map of the Republic of South Africa and the Kingdoms of Lesotho and Swaziland. Council for Geoscience, Pretoria.
- Mucina, L. & Rutherford, M.C. (eds) 2006. The vegetation of South Africa, Lesotho and Swaziland. Strelitzia 19. South African National Biodiversity Institute, Pretoria.
- Van Jaarsveld, E.J. 1994. Gasterias of South Africa. A new revision of a major succulent group. Fernwood Press in association with the National Botanical Institute, Cape Town.
- Van Jaarsveld, E.J. 2007. The genus Gasteria, a synoptic review new taxa and combinations. Aloe 44(4): 84–103.
- Van Jaarsveld, E. 2000. Wonderful waterwise gardening: a regional guide to indigenous gardening in South Africa. Tafelberg Publishers, Cape Town.
- Van Jaarsveld, E.J. 2012. Gasteria disticha (L.) Haw. (Asphodelaceae). PlantZAfrica. Online. http://pza.sanbi.org/gasteria-disticha.
- Van Jaarsveld, E.J., B.J. M. Zonneveld & D.V. Tribble. 2019. Gasteria langebergensis, a new status for a Gasteria from the Western Cape, South África. Bradleya 37: 167-171.
- Van Jaarsveld, E.J., Raimondo, D. & von Staden, L. 2015. Gasteria disticha (L.) Haw. var. langebergensis Van Jaarsv. National Assessment: Red List of South African Plants version 2020.1. Accessed on 2021/11/11
- Zonneveld, B.J.M. & Van Jaarsveld, E.J. 2005. Taxonomic implications of genome size for all species of the genus Gasteria Duval (Aloaceae). Plant Systematics and Evolution 251: 217–227.
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
November 2021
Plant Attributes:
Plant Type: Succulent
SA Distribution: Western Cape
Soil type: Sandy, Loam
Flowering season: Winter
PH: Acid, Alkaline, Neutral
Flower colour: Green, Pink, Orange
Aspect: Shade, Morning Sun (Semi Shade), Afternoon Sun (Semi Shade)
Gardening skill: Average
Special Features:
Attracts birds
Drought resistant
Good potplant
Indoor plant
Edible plant
Horticultural zones
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