Carpobrotus muirii
Introduction
The Albertinia sour fig is a mat-forming leaf succulent from sandy regions near Albertinia in the Western Cape. It is the smallest of the species of Carpobrotus and has narrow linear leaves, bright purplish-pink flowers in late spring and fruits that are edible and taste similar to the sour fig (C. edulis). Easily propagated by cuttings and best for Fynbos and Strandveld gardens, planted on embankments and good for binding loose sand.
Fig. 1. A close-up of the Carpobrotus muirii flower in late spring at Babylonstoren Farm, ex Resiesbaan Siding, Albertinia, Western Cape.
Description
Description
Procumbent, mat-forming, hairless (glabrous), densely branched succulents with stems 1-1.5 m long and with branches 5-7 mm diameter and biconvex. The roots are fibrous. The younger branches maroon-red coloured by the pigment betanin, remaining procumbent, becoming greyish brown as they mature. Shorter, scimitar-shaped shoots appear from the leaf axils. The leaves are fleshy, trigonous, linear and slightly sickle-shaped, laterally flattened, 45-65 x 4 mm, the lateral keel 4-6 mm in diameter, green, sometimes tinged reddish. The nodes about 13-25 mm apart and with a smooth surface. The leaf surface is smooth, the leaf tip acute, and bearing a prominent little point (mucro). The flowers are solitary, 60-90 mm in diameter, pointing upwards, the flower stalks (pedicels) about 30-40 mm long; sepals 5, unequal 12-20 mm long. The flower petals, in 2-3 series, linear and purplish pink, 25-30 x 2 mm. The filaments, in 2-3 series, pale pink or whitish, 7-10 mm. The anthers yellow. The stigmas 15-17 mm, yellowish green, awl shaped. The fruits at first cup-shaped, later almost round (sub-globose), 12-15 mm long, 20-35 mm in diameter. The fruit is at first green, becoming wrinkled and grey-brown when mature. Flowering is mainly in winter and spring (September to November).
Fig. 2. An illustration by Mary Page of Carpobrotus muirii published in the Contributions of the Bolus Herbarium.
Conservation Status
Status
Carpobrotus muirii is a rare species and a range-restricted habitat specialist that is assessed as Near Threatened on the Red List of South African Plants, because its population and habitat are decreasing due to ongoing coastal development, wheat cultivation and invasive alien plants (Raimondo et al 2009).
Fig. 3. Carpobrotus muirii in habitat near Resiesbaan Siding, Albertinia, growing among the thatching reed, Thamnochortus insignis gonnabos, Passerina vulgaris and blombos, Metalasia muricata, with evidence of mole-rat activity nearby.
Distribution and habitat
Distribution description
Capobrotus muirii is a Sand Fynbos endemic from the south-eastern part of the Western Cape from Stilbaai to De Hoop in the Albertinia District, growing in lowland areas at altitudes of 150 to about 200 m above sea level and within 10 km of the coast. Plants grow in Albertinia Sand Fynbos in flat to hilly terrain among thatching reed (Thamnochortus insignis) and are locally abundant. Near Resiesbaan Siding, Albertinia, Carpobrotus muirii shares its habitat with the thatching reed (Thamnochortus insignis), Osteospermum moniliferum (= Chrysanthemoides monilifera), skilpadbessie (Muraltia spinosa = Nylandtia spinosa), gonnabos (Passerina corymbosa = P. vulgaris), blombos (Metalasia muricata), sour fig (Carpobrotus edulis), Lampranthus fergusoniae and Crassula nudicaulis. The geology consists of sandy flats and hills, derived from sandstone of the Table Mountain Group (Cape Supergroup). Rainfall can occur at any time of the year, usually frontal systems in the winter and convectional rain in summer. Rainfall is estimated between 400-500 mm per annum.
Fig. 4. A close-up of Carpobrotus muirii in habitat near Resiesbaan Siding, Albertinia.
Derivation of name and historical aspects
History
Carpobrotus muirii was first collected by John Muir (1874-1947) a Scottish physician and naturalist who came to the Cape in 1896. John had a keen interest in botany and contributed to our knowledge of the flora of the Riversdale district. He collected his plant specimens near Zoutpan, and he deposited his herbarium specimen in the Bolus Herbarium. It was then named by Louisa Bolus in 1922 in the Annals of the Bolus Herbarium as Mesembryanthemum muirii. She aptly named it after John Muir. In 1925, the British botanist N.E. Brown published his newly created genus Carpobrotus in the Gardeners Chronicle in 1925. Louisa Bolus then transferred this species to its rightful place within Carpobrotus in 1927. C. muirii belongs to the mesemb family (Aizoaceae), the largest succulent family in South Africa, and is one of 7 species of Carpobrotus and is easily distinguished by its smaller, very narrow leaves only 4-6 mm thick. The genus Carpobrotus was revised by Walter Wisura and Hugh Glen in the Contributions of the Bolus Herbarium in 1993, recognizing 7 species. Carpobrotus edulis, is the most common and widely spread in the Western Cape and shares its habitat with C. muirii.
Fig. 5. A close-up and side-view of the flower of Carpobrotus muirii growing at Babylonstoren Farm, ex Resiesbaan Siding, Albertinia, Western Cape.
Ecology
Ecology
This Albertinia sourfig grows wild in Fynbos vegetation. It is confined to the sandy flats near Albertinia mostly associated with the thatching reed (Thamnochortus insignis). It is a trailing and mat-forming, long-lived perennial rooting at the nodes. The succulent leaves enable the plant to withstand periods of drought. The leaves and young stems turn reddish to yellowish in the summer due to the betanin pigment which slows down photosynthesis. Stems and leaves are soft and flaccid, a character that can be viewed as an adaptation to the soft sand. Plants increase vegetatively, the branches (vegetative growth) rooting where they touch the soil, an efficient vegetative dispersal survival on these nutrient poor sandy flats. Mole-rat activity in its habitat causes continual disturbance and recycling of organic material, which is beneficial to the vegetation.
Fig. 6. A close-up of the Carpobrotus muirii flower, in late spring, showing the stamens and stigma and a visiting bee.
The flowers are produced on new growth towards the branch tips. The purplish-pink colour is conspicuous, maximising visibility, and the flowers are pollinated by bees, and other insects. Flowering time is in spring (from September until November in the southern hemisphere), ensuring a long and continual seed supply. The fruits develop during summer, ripening in February, and the seeds are dispersed by animals and humans that eat the fruits. Unlike Carpobrotus deliciosus and C. quadrifidus, which are consumed fresh, the fruits of C. muirii, C. acinaciformis and C. edulis have a long shelf life and have to mature, becoming rounded wrinkled and brownish, and then only when fully mature are they ready for consumption. Unlike many other mesembs, the seeds are small and embedded in mucilage and when consumed they pass through the animal’s gut and when later excreted, have been efficiently scarified and when landing on sandy soil with the right conditions, will germinate within 3 weeks.
Fig. 7. Close-up of a developing fruit of Carpobrotus muirii, in December, growing in the Babylonstoren Farm Garden.
Uses
Use
Carpobrotus muirii fruits are annually collected in summer, when mature, when they are rounded wrinkled and brownish. They can be eaten fresh when mature or prepared as a jam. Fruits are popular in jam making and are sold in Cape Town vegetable markets. Mature fruits have a long shelf life. This plant is also ornamental, water-wise and a useful sand binder, ideal for sandy coastal gardens.
Fig. 8. Carpobrotus muirii growing in the Babylonstoren Farm Garden, in late spring.
Growing Carpobrotus muirii
Grow
The Albertinia sour fig (Carpobrotus muirii) is a mat-forming, attractive and easily grown succulent ornamental. The leaves are often tinged reddish. The bright purplish-pink flowers appear during spring (from September until November). Useful as a sand-binding ground cover in coastal gardens. The runners, as with the other species of sour fig (Carpobrotus), can be planted in-situ in its required position and kept moist until rooted.
Best for fynbos and other warm temperate Mediterranean climate gardens, grown in sandy soil (Van Jaarsveld 2010). Outside its habitat, it is best grown in containers under controlled conditions in a greenhouse. In temperate climates the plant can be moved out of doors for the summer period. The plant grows naturally on mineral-poor, acidic, sandstone-derived soil. When grown in containers it is best to re-pot every second year. When the plant becomes untidy, refresh from cuttings.
Propagate from cuttings or seed.
Propagate from stem cuttings at any time of the year but best from spring to autumn rooting as growth is faster. Take cuttings about 10 to 15 cm in length. Remove the lower leaves and plant the stems to a depth of about 1-5 cm in a sandy soil mixture. Keep moist until well rooted. Rooting will take place within 3 weeks.
Plants grow well in a general succulent mixture, such as 2 parts sand, 1 part garden loam and 1 part peat or well broken down compost but good drainage is essential.
Sow seed in autumn or winter in shallow trays in a sandy soil. Cover the seed with a thin layer of sand (1-2 mm) and keep moist. The Kirstenbosch Smoke Plus Seed Primer (a smoke treatment) should enhance the germination process. Plants are fairly fast-growing and should flower during their first season.
References
- Bolus, H.M.L. 1923. Novitates Africanae. Annals of the Bolus Herbarium 3: 123-139.
- Bolus, H.M.L. 1927. Novitates Africanae. Annals of the Bolus Herbarium 4: 72-109.
- Bolus, H.M.L. 1928. Mesembryanthemum and some allied genera Part 1. University of Cape Town, Bolus Herbarium.
- Bolus, H.M.L. 1929. Notes on Mesembryanthemum and allied genera. Part 2. University of Cape Town.
- Brown, N.E. 1925. Mesembryanthemum and some new genera separated from it. The Gardeners’ Chronicle 78: 433.
- Clarke, H. & Charters, M. 2016. The illustrated dictionary of southern African plant names. Flora & Fauna Publications Trust, Jacana, Johannesburg.
- Hartmann, H.E.K. 1991. Mesembryanthema. In Systematics, Biology and Evolution of Some South African taxa. Contributions from the Bolus Herbarium 13. 75-157.
- Hartmann, H. 2001. Aizoaceae A-E. In Eggli, U. & Hartmann, H.E.K. (eds.) Handbook of succulent plants. Springer, Heidelberg, New York
- Manning, J. & Goldblatt, P. 2012. Plants of the Greater Cape Floristic Region 1: the Core Cape Flora. Strelitzia 29. South African National Biodiversity Institute, Pretoria.
- 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.
- Van Jaarsveld, E.J. 2010. Waterwise gardening in South Africa and Namibia. Struik, Cape Town.
- Van Jaarsveld, E.J. & Pienaar, U. de V. 2004. Die Mittagsblumen Südafrikas. Les Mésembs d'Afrique du Sud. Edition Eugen Ulmer, Stuttgart (German), Paris (French).
- Wisura, W. & Glen, H.F. 1993. The South African species of Carpobrotus (Mesembryanthema, Aizoaceae). Studies on the Mesembryanthema (Aizoaceae). Contributions of the Bolus Herbarium 15:67-107.
Credits
Ernst van Jaarsveld
Kirstenbosch National Botanical Garden (Retired)
Babylonstoren Farm (Current)
Extraordinary senior lecturer and researcher,
Department of Biodiversity and Conservation, University of the Western Cape
April 2024
Plant Attributes:
Plant Type: Ground Cover, Succulent
SA Distribution: Western Cape
Soil type: Sandy
Flowering season: Spring
PH: Acid
Flower colour: Purple, Pink
Aspect: Full Sun
Gardening skill: Easy
Special Features:
Drought resistant
Edible plant
Feeds honeybees
Horticultural zones
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