| Carpobrotus edulis | |
|---|---|
| Carpobrotus edulis, West Coast National Park, South Africa | |
| Scientific classification | |
| Kingdom: | Plantae |
| (unranked): | Angiosperms |
| (unranked): | Eudicots |
| (unranked): | Core eudicots |
| Order: | Caryophyllales |
| Family: | Aizoaceae |
| Genus: | Carpobrotus |
| Species: | C. edulis |
| Binomial name | |
| Carpobrotus edulis (L.) N.E. Br |
|
Carpobrotus edulis is native to South Africa. It is also known as ice plant, Highway Ice Plant, Pigface or Hottentot Fig and in South Africa as the Sour Fig (Suurvy; earlier: Hotnosvy), on account of its edible fruit.
It was previously classified in genus Mesembryanthemum and is sometimes referred to by this name.
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Carpobrotus edulis is a creeping, mat-forming succulent species and member of the Stone Plant family Aizoaceae, one of about 30 species in the genus Carpobrotus.
Carpobrotus edulis is easily confused with its close relative, the more diminutive and less aggressive Carpobrotus chilensis (sea fig), and the two species hybridize readily throughout their ranges in California. The large 2.5-to-6-inch-diameter (63 to 150 mm) flowers of C. edulis are yellow or light pink, whereas the smaller, 1.5-to-2.5-inch-diameter (38 to 63 mm) C. chilensis flowers are deep magenta.
The Sour Fig grows on coastal and inland slopes from Namaqualand in the Northern Cape through the Western Cape to the Eastern Cape. It is often seen as a pioneer in disturbed sites.
Leaves are eaten by tortoises. Puff-adders and other snakes such as the Cape Cobra are often found in Carpobrotus clumps where they ambush the small rodents that are attracted by the fruits. Flowers are pollinated by solitary bees, honey bees, carpenter bees and many beetle species. Flowers are eaten by antelopes and baboons. The clumps provide shelter for snails, lizards and skinks. Fruits are eaten by baboons, rodents, porcupines, antelopes and people, who also disperse the seeds.[1]
Ice plants grow year round, with individual shoot segments growing more than three feet (1 m) per year (D’Antonio 1990b). Ice plants can grow to at least 165 feet (50 m) in diameter. Flowering occurs almost year round, beginning in February in southern California and continuing through fall in northern California, with flowers present for at least a few months in any given population. Seed production is high, with hundreds of seeds produced in each fruit. The fruit is edible. In South Africa the Sour Fig's ripe fruit are gathered and either eaten fresh or made into a very tart jam.
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 share a similar climate. The ice plant has escaped from cultivation and has become an invasive species. The ice plant poses a serious ecological problem, forming vast monospecific zones, lowering biodiversity, and competing directly with several threatened or endangered plant species for nutrients, water, light, and space. [2]
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.
On the Mediterranean coast, Carpobrotus has spread out rapidly and now parts of the coastline are completely covered by this invasive species. Moreover, it has been shown that another invasive species, the black rat, enhances the spreading of the ice plant through its feaces.[3] As the ice plant represents a food resource for the rat, the invasive species benefit from each other (invasive mutualism).
In New Zealand C. edulis and its hybrids are classed as unwanted organisms and are listed on the National Pest Plant Accord.[4]
In the early 1900s C. edulis was brought to California from South Africa to stabilize soil along railroad tracks and was later put to use by Caltrans for similar purposes. 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 magenta or yellow flowers, and resistance to some harsh coastal climatic conditions (salt) have also made it a favoured 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.
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, California, 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 approximately 500 feet (150 m)
It needs well-drained soil, a sunny position and room to spread. It is an excellent evergreen drought-, and wind-resistant groundcover that can be planted on flat, sandy ground, on loose sand dunes, gravelly gardens, lime-rich and brackish soils as well as in containers, rockeries, embankments and will cascade over terrace walls.
Its leaves are edible, as are its fruit, as with other some members of the Aizoaceae family. It was used in California to stabilize soil around railroad tracks, as discussed above.