Hottentot-fig
Flower of Carpobrotus edulis
Scientific classification Edit this classification
Kingdom: Plantae
Clade: Tracheophytes
Clade: Angiosperms
Clade: Eudicots
Order: Caryophyllales
Family: Aizoaceae
Genus: Carpobrotus
Species:
C. edulis
Binomial name
Carpobrotus edulis
Synonyms

Mesembryanthemum edule L

Carpobrotus edulis is a ground-creeping plant with succulent leaves in the genus Carpobrotus, native to South Africa. Its common names include hottentot-fig,[1][2][3][4] sour fig, ice plant or highway ice plant.

Description

Carpobrotus edulis is a creeping, mat-forming succulent species. It grows year round, with individual shoot segments growing more than 1 m (3 ft) per year. It can grow to at least 50 m (165 ft) in diameter. The leaves are a dull-green or yellow-green colour. They are only very slightly curved and have serrated sides near the tips.[5]

The yellow flowers are produced from April to October, and range from 6.4 to 15.2 centimetres (2+1⁄2 to 6 inches) in diameter.[6] Two of the calyx lobes are longer, extending further than the petals. The flowers open in the morning in bright sunlight and close at night.[7] The receptacle is somewhat wedge-shaped, tapering down to the pedicel.[8] The fruit is multi-chambered, ripening from green to yellow.[6]

The species is easily confused with its close relatives, including the more diminutive and less aggressive Carpobrotus chilensis (sea fig), with which it hybridizes readily. C. edulis can, however, be distinguished from most of its relatives by the size and yellow colour of its flowers. The smaller flowers of C. chilensis, 3.8 to 6.4 cm (1+1⁄2 to 2+1⁄2 in) in diameter, are deep magenta.

Chemistry

C. edulis contains rutin, neohesperidin, hyperoside, catechin and ferulic acid; these contribute to the antibacterial[9] properties of the plant. It also contains procyanidins and propelargonidins.[10]

Taxonomy

The species is a member of the fig-marigold family, Aizoaceae, one of about 30 species in the genus Carpobrotus. It was previously classified in Mesembryanthemum and is sometimes referred to as Mesembryanthemum edule.

Distribution and habitat

The sour fig grows on coastal and inland slopes in South Africa from Namaqualand in the Northern Cape through the Western Cape to the Eastern Cape. It is often seen as a pioneer on disturbed sites.

Ecology

The flowers are pollinated by solitary bees, honey bees, carpenter bees, and many beetle species. Leaves are eaten by tortoises. Flowers are eaten by antelopes and baboons. Fruits are eaten by baboons, rodents, porcupines, antelopes, who also disperse the seeds. The clumps provide shelter for snails, lizards, and skinks. Puff adders and other snakes, such as the Cape cobra, are often found in Carpobrotus clumps, where they ambush the small rodents attracted by the fruits.[7]

As an invasive species

Carpobrotus edulis has naturalised in many other regions throughout the world, and is an invasive species in several parts, notably Australia, California and the Mediterranean, all of which have similar climates. The ice plant has escaped from cultivation and has become invasive, posing a serious ecological problem by forming vast monospecific zones, lowering biodiversity, and competing directly with several threatened or endangered plant species for nutrients, water, light, and space.[11]

The success of Carpobrotus edulis as an invader can be attributed to several key adaptive mechanisms. The plant exhibits a high rate of clonal growth, a trait that is commonly associated with successful invasive species.[12][13] Invasive ice plant also displays high levels of phenotypic plasticity, allowing it to best integrate into varied environmental conditions such as coastal cliff ranges as well as nutrient-rich forests.[14] Such plasticity has raised concerns about its continual spread, especially in the face of changing climatic conditions.[15]

Through hybridization, invasive Carpobrotus edulis gains genetic diversity and novel traits that further enhance its adaptability.[16][17] The species readily engages in genetic exchanges with other Carpobrotus, such as Carpobrotus chilensis, leading to hybrid variants with unique genetic combinations that allow them to thrive and outcompete native flora.[16][18] Analysis of chloroplast DNA has revealed a large amount of genetic similarities between Carpobrotus edulis and Carpobrotus chilensis, indicating that the two may share a common ancestor.[17]

Found at Cape Angela in Bizerte, Tunisia, near the Mediterranean Sea

Ireland

Recorded as a garden escape from County Down,[19] in the south and east[20] and on the cliffs of Howth Head, County Dublin.[21]

Mediterranean

On the Mediterranean coast, Carpobrotus has spread out rapidly and now parts of the coastline are completely covered. Moreover, another invasive species, the black rat, has been shown to enhance the spreading of the ice plant through its feces.[22] As the ice plant represents a food resource for the rat, both benefit from each other which is referred to as invasive mutualism.

Example of an area completely covered with ice plant on a French Mediterranean island, Bagaud island, in the Port-Cros National Park

New Zealand

In New Zealand forms monocultures and has taken over vast areas of coastal sand dune ecosystem. C. edulis and its hybrids are classed as unwanted organisms and are listed on the National Pest Plant Accord.[23]

United States

The ice plant forms large monospecific zones.

Although the ice plant may have arrived by ship as early as the 16th century,[24][25] C. edulis was actively introduced in the early 1900s to stabilize dunes[24] and soil along railroad tracks; it was later put to use by Caltrans for ground cover along freeway embankments.[24] Thousands of acres were planted in California until the 1970s. It easily spreads by seed (hundreds per fruit) and from segmentation (any shoot segment can produce roots). Its succulent foliage, bright yellow flowers, and resistance to some harsh coastal climatic conditions (salt) have also made it a favored garden plant. The ice plant was, for several decades, widely promoted as an ornamental plant, and it is still available at some nurseries. Ice plant foliage can turn a vibrant red to yellow in color. Despite its use as a soil stabilizer, it actually exacerbates and speeds up coastal erosion. It holds great masses of water in its leaves, and its roots are very shallow. In the rainy season, the added weight on unstable sandstone slopes and dunes increases the chances of slope collapse and landslides.

The ice plant is still abundant along highways, beaches, on military bases, and in other public and private landscapes. It spreads beyond landscape plantings and has invaded foredune, dune scrub, coastal bluff scrub, coastal prairie, and, most recently, maritime chaparral communities. In California, the ice plant is found in coastal habitats from north of Eureka, south at least as far as Rosarito in Baja California. It is intolerant of frost, and is not found far inland or at elevations greater than about 500 ft (150 m).

Flowering occurs almost year-round, beginning in February in southern California and continuing until the autumn in northern California, with flowers present for at least a few months in any given population.

Removal of plants

Control of ice plants can be attempted by pulling out individual plants by hand, or with the use of earth-moving machinery such as a skid-steer or tractor, though it is necessary to remove buried stems, and mulch the soil to prevent re-establishment. For chemical control, glyphosate herbicides are used. Because of the high water content of shoot tissues, burning of live or dead plants is not a useful method of control or disposal.

Uses

The fruit is edible[6] (as with some other members of the family Aizoaceae), as are its leaves. In South Africa the sour fig's ripe fruit are gathered and either eaten fresh or made into a very tart jam.

The different parts of C. edulis are used in different forms in traditional medicine, mainly in South Africa. Mostly, the fruits and flowers are eaten raw or cooked for fungal and bacterial infections. The leaves can be ingested orally for digestive problems or the juice can be sucked out to help a sore throat.[26] The juice can also be mixed into a lotion base and used for external issues such as ringworm, bruises, sunburns, and cracked lips.[26]

References

  1. ↑ "Hottentots Fig - Flowers". Kruger Park. Retrieved 2021-12-26.
  2. ↑ "Carpobrotus edulis". Global Invasive Species Database (GISD).
  3. ↑ "Carpobrotus edulis" at the Encyclopedia of Life
  4. ↑ "Carpobrotus edulis (hottentot fig)". CABI Invasive Species Compendium. 2019-11-20. Retrieved 2021-12-26.
  5. ↑ "Medicinal plants of Fernkloof". Archived from the original on 2012-07-29.
  6. 1 2 3 Spellenberg, Richard (2001) [1979]. National Audubon Society Field Guide to North American Wildflowers: Western Region (rev ed.). Knopf. pp. 330–331. ISBN 978-0375402333.
  7. 1 2 "Carpobrotus edulis". www.plantzafrica.com.
  8. ↑ Wisura, W. & Glen, H.F. (1993). The South African species of Carpobrotus (Mesembryanthema-Aizoaceae). Contributions from the Bolus Herbarium 15:76–107.
  9. ↑ Purification and identification of active antibacterial components in Carpobrotusedulis L. Elmarie van der Watt and Johan C Pretorius, Journal of Ethnopharmacology, June 2001, Volume 76, Issue 1, pp. 87–91, doi:10.1016/S0378-8741(01)00197-0
  10. ↑ LC/ESI-MS/MS characterisation of procyanidins and propelargonidins responsible for the strong antioxidant activity of the edible halophyte Mesembryanthemum edule L. Hanen Falleh, Samia Oueslati, Sylvain Guyot, Alia Ben Dali, Christian Magné, Chedly Abdelly and Riadh Ksouri, doi:10.1016/j.foodchem.2011.02.049
  11. ↑ (State Resources Agency 1990).
  12. ↑ Portela, Rubén; Barreiro, Rodolfo; Roiloa, Sergio R. (January 2019). "Biomass partitioning in response to resources availability: A comparison between native and invaded ranges in the clonal invader Carpobrotus edulis". Plant Species Biology. 34 (1): 11–18. doi:10.1111/1442-1984.12228. ISSN 0913-557X.
  13. ↑ Song, Yao-Bin; Yu, Fei-Hai; Keser, Lidewij H.; Dawson, Wayne; Fischer, Markus; Dong, Ming; van Kleunen, Mark (February 2013). "United we stand, divided we fall: a meta-analysis of experiments on clonal integration and its relationship to invasiveness". Oecologia. 171 (2): 317–327. Bibcode:2013Oecol.171..317S. doi:10.1007/s00442-012-2430-9. ISSN 1432-1939. PMID 22915332. S2CID 2929123.
  14. ↑ Pérez-Diz, Marta; Rodríguez-Addesso, Berea; Hussain, Muhammad Iftikhar; Rodríguez, Jonatan; Novoa, Ana; González, Luís (2023-05-15). "Carbon and nitrogen stable isotope compositions provide new insights into the phenotypic plasticity of the invasive species Carpobrotus sp. pl. in different coastal habitats". Science of the Total Environment. 873: 162470. Bibcode:2023ScTEn.873p2470P. doi:10.1016/j.scitotenv.2023.162470. ISSN 0048-9697. PMID 36842586.
  15. ↑ G. Campoy, Josefina; Lema, Margarita; Fenollosa, Erola; Munné‐Bosch, Sergi; Retuerto, Rubén (October 2021). "Functional responses to climate change may increase invasive potential of Carpobrotus edulis". American Journal of Botany. 108 (10): 1902–1916. doi:10.1002/ajb2.1745. hdl:10347/29048. ISSN 0002-9122. PMID 34636413.
  16. 1 2 Suehs, C. M.; Affre, L.; Médail, F. (January 2004). "Invasion dynamics of two alien Carpobrotus (Aizoaceae) taxa on a Mediterranean island: I. Genetic diversity and introgression". Heredity. 92 (1): 31–40. doi:10.1038/sj.hdy.6800374. ISSN 1365-2540. PMID 14628076.
  17. 1 2 Schierenbeck, Kristina A.; Symonds, V. Vaughan; Gallagher, Kelly G.; Bell, Jeffrey (February 2005). "Genetic variation and phylogeographic analyses of two species of Carpobrotus and their hybrids in California". Molecular Ecology. 14 (2): 539–547. Bibcode:2005MolEc..14..539S. doi:10.1111/j.1365-294X.2005.02417.x. ISSN 0962-1083. PMID 15660944. S2CID 25384753.
  18. ↑ Ellstrand, Norman C.; Schierenbeck, Kristina A. (2000-06-20). "Hybridization as a stimulus for the evolution of invasiveness in plants?". Proceedings of the National Academy of Sciences. 97 (13): 7043–7050. Bibcode:2000PNAS...97.7043E. doi:10.1073/pnas.97.13.7043. ISSN 0027-8424. PMC 34382. PMID 10860969.
  19. ↑ Hackney, P., ed. (1992). Stewart & Corry's Flora of the North-east of Ireland (3rd ed.). Institute of Irish Studies The Queen's University of Belfast. ISBN 978-0853894469.
  20. ↑ Parnell, J. and Curtis, T. 2012 Webb's An Irish Flora. Cork University Press. ISBN 978-1859184783
  21. ↑ Dhuill, E.N. and Smyth, N. 2021. "Invasive non-native and alien garden escape plant species on the cliffs of Howth Head, Co. Dublin", Irish Naturalists' Journal 37(2) 102–110.
  22. ↑ "Carpobrotus edulis (succulent)". Global Invasive Species Database. ISSG. Archived from the original on 2006-09-28.
  23. ↑ "Iceplant". Biosecurity New Zealand. 22 October 2008. Archived from the original on 6 March 2012. Retrieved 6 May 2010.
  24. 1 2 3 Au, Leakhana. Carpobrotus edulis in California Coastal Plant Communities Archived December 24, 2013, at the Wayback Machine, Restoration and Reclamation Review, University of Minnesota, Vol. 6, No. 1, Fall 2000.
  25. ↑ "Hottentot Fig (Carpobrotus edulis)". Bureau of Land Management, Arcata Field Office. Archived from the original on 2015-06-18. Retrieved 10 October 2015.
  26. 1 2 "Carpobrotus edulis – Useful Tropical Plants". tropical.theferns.info. Retrieved 2020-11-09.
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