Common Ice-plant (Mesembryanthemum crystallinum), a dew-spangled exotic relative of Australia’s friendly native pigfaces.
The name ‘Ice-plant’ refers to the prominent bladder cells which store water and cover its stems and fruit. The species thrives in dry saline environments, not only forming thick mats but concentrating salt in its annual foliage which goes on to ‘fertilise’ surrounding soils, raising salt and nitrate levels and excluding native and exotic competitors.
The common ice-plant originates in pre-colonial populations in Southern Africa and the eastern Mediterranean, a disjuncture that apparently reflects past arid periods across Africa’s tropics. The possibility that the plant was distributed in pre-colonial trade networks does not seem to have been considered by biogeographers, despite its use in pre-industrial soap-making.
Loudon (1830) recorded that the Common Ice-plant entered British horticultural trade as a 1727 import from Greece. Brought to Australia as an ornamental selection, it was widely discussed in early horticultural columns here, but it may have been simultaneously introduced as a contaminant of shipping ballast. Early naturalisation sites in South Australia reported by PM Kloot in 1983 may illustrate both pathways: the Torrens estuary (Reedbeds) hosted a number of prominent early homesteads, including the property of Charles Sturt; while Spencer Gulf jetties like Port Germein became key grain ports.
Late 19th c. interest in the plant’s agricultural value saw it sown across SE Australia’s arid interior. In Victoria, the species was collected from the Wimmera in 1892, and near Horsham in 1903. Within Melbourne, it was collected in 1943 from dunes near the rifle range at Williamstown, and although the plant is widespread within Victoria’s inland grain belt, records within the metro are all from coastal sites around Port Phillip Bay.
The photographed plants form an extensive inland infestation not previously recorded, on embankments associated with the Old Western Highway west of Melton.