Jade (Crassula ovata), a staple succulent of topiary and floriculture, and a relatively unusual adventive colonist of rock exposures in Melbourne’s coastal and riparian hinterlands.
Like many of our cultivated succulents, Jade was exported from Southern Africa by the colonial horticultural trade. In Mediterranean climates, the species can be spread into environmental areas through intentionally discarded garden waste or from windblown bits of stem or leaves.
Although in its native range Jade produces large quantities of small seed suitable to windblown dispersal, there seems to be an environmental incompatibility in pollination or germination that prevents the plants from becoming more invasive in Australia and other overseas locations where they have established as adventives.
In Melbourne, Jade can be found growing in discrete clusters alongside suburban railway lines, presumably from equal measures of dumped garden waste and freelance beautification works. However, the species has been collected just twice here in adventive circumstances, both in the last few decades: at Sandringham and on Moonee Ponds Creek. The photographed plants are on Darebin Creek, very well established on consolidated stone rubble reinforcement below a gabion retaining wall.