Invasive Plants of California's Wildland

Crystalline iceplant (Mesembryanthemum crystallinum) is a succulent, low-growing herb spreading over ground with flat, fleshy leaves. Leaves and stems are covered with distinctive tiny, clear, blister-like out growths. Flowers are small (one-fifth of an inch across) and radial, with many narrow petals that range from white to pinkish, depend ing on the age of the flower. The stems can range from green to red and usually trail along the soil surface.

Crystalline iceplant occurs along the immediate coast from the San Francisco Bay region south into Baja California, Mexico. It can also be found on all the California Channel Islands (Junak et al. 1995, Munz 1974). A few plants have been observed up to eight miles (13 km) inland (Vivrette and Muller 1977). It is found primarily in saline soils on coastal strand, coastal sage scrub, coastal bluffs and cliffs, and other disturbed ground. It tolerates saline soils, but not frost.

Crystalline iceplant is native to South Africa and is thought to have been in troduced to California, perhaps as early as the 1500s, in sand used as ships' ballast. About fifty years ago, the California Department of Transportation began using iceplant for roadside landscaping and ero sion control. This practice was discontinued in 1969 when it was discovered that the plant was killed by hard freezes and not effec tive for erosion control on steeper slopes. Many homeowners still use iceplant as a groundcover or for erosion control (Moss 1994). The constant erosion of coastal bluffs creates an open habitat that encourages colonization and spread of iceplant, as does grazing disturbance in coastal grass lands.

Crystalline iceplant can invade coastal bluff areas and compete with native species. Because iceplant has an exceptional ability to absorb moisture from the soil, it can outcompete most other species for water. A high level of nitrate build-up has been found to occur underneath crystalline iceplants, and this can be detrimental to survival of grassland seedlings growing there. Accumulation and release of these salts by crystalline iceplant also prevents or retards reestablish ment of native species (Vivrette and Muller 1977).

Crystalline iceplant usually flowers from March to June, although, because germination is staggered, individual plants can be found flowering most of the year. Fruiting generally occurs from June to August, after which the plant gradually dries from the base upward, fruits being the last to dry (Vivrette and Muller 1977). Rabbits and mice aid in dispersal of seeds.

Seeds germinate with the first rains in autumn and with each succeeding rain or heavy fog. Seedlings continue rapid vegetative growth until spring. Vegetative stages are characterized by broad, flat leaves. Vegetative growth slows and then stops as the hot, dry summer season progresses.	(click on photos to view larger image)

Information specific to the control of crystalline iceplant is not available. Control techniques for Carpobrotus edulis, another invasive species in the same family (Aizoaceae) with similar growth form, would likely be effective.