Rubber Bush – Calotropis procera
Habit: Shrub with large waxy leaves and large green seed pods. Flowers are white and purple. People get rashes from the milky sap.
Spread: Seed pods easily float. Feathery seeds spread by wind and water.
Rubber bush can grow up to 4m high. It can get thick at the base and sprawl out or grow in a cluster, out-competing and pushing out native plants. This plant does have some level of toxicity to stock however some limited grazing does occur. This plant easily penetrates areas that have a history of disturbances and loss of vegetative cover through fire or overgrazing. This photo was taken at Windjana Gorge, where rubber bush is found growing in association with other weeds including Stinking Passion Vine.
The attractive purple flowers and large leathery blue grey leaves are possible reasons for this plants originally introduction as an ornamental. It was also reportedly used as a filler for camel packsaddles earlier last century.
Rubber bush is advantaged in its wide ranging dispersal by the production of many feathery seeds that are able to float in the wind and travel via water.
Prior to opening, the air-filled seed pods are able to float and disperse through floodwaters, rivers and oceans.
As evidence of the dispersal capabilities of Rubber bush, and its tolerance of a range of growing conditions; an infestation of this plant was located along a remote Northern Kimberley Beach (Betram Cove near Koolama Bay).