Ice Plant
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| Carpobrotus edulis (L.) N.E. Br | ||||||||||||||
The common name Ice Plant refers to Carpobrotus edulis, a creeping, mat-forming succulent species, and member of the Stone Plant family Aizoaceae, one of about 30 species in the genus Carpobrotus. It is also known as the Highway Ice Plant, Pigface or Hottentot Fig and in South Africa as the Sour Fig, on account of its edible fruit. It was previously classified in genus Mesembryanthemum and is sometimes referred to by this name.
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 flowers of C. edulis are yellow or light pink, whereas the smaller, 1.5 to 2.5 inch diameter C. chilensis flowers are deep magenta. Large cells in the leaves sparkle like granules of ice in the sun, giving the plant its common name. The common name "Ice Plant" is sometimes also used for other related plant species, including Delosperma cooperi and Lampranthus, which also belong to the plant family Aizoaceae and share in common a South African origin. The name is, unfortunately, used for plants in other families, as well, including Sedum spectabile (Crassulaceae).
The Ice Plant is a native of South Africa. 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.
In several parts of the world, notably Australia, California and the Mediterranean, all of which share a similar Mediterranean 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 (State Resources Agency 1990).
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.
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.
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).
Close-up of the ice plant blossom.
White blossomed ice plants.
White flower with red-tinted leaves.
Pink blossomed Carpobrotus edulis
