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Mimosa pigra


Mimosa grows into a bush that may be a few metres tall

Mimosa grows into a bush that may be a few metres tall

Mimosa pigra, also known as giant sensitive plant, is a native of tropical America, but it is not clear how it came to be introduced into Australia. For nearly 100 years, this species was isolated to small communities in and around Darwin. During the 1970s, it suddenly spread to many of the river systems of the Northern Territory. It now covers more than 50,000 hectares and poses a serious threat to Kakadu National Park.

Another introduced species, the Asian water buffalo, made this spread possible. It was introduced into Australia to provide meat and hides. Huge herds of wild water buffalo ate and trampled virtually all palatable vegetation on the floodplains of the Adelaide River, so that the abnormal floods of the mid-1970s deposited vast quantities of giant sensitive plant seed onto a ready made seedbed which was almost devoid of competing vegetation.

Mimosa pigra is now well established in the rangelands of the Northern Territory and continues to spread further every wet season. The spread of mimosa is enhanced by the lack of natural predators and its ability to produce an enormous number of seeds.

Impact on environment

Mimosa pigra grows rapidly, can withstand drought and its seed can float. The seed is mainly spread by floodwaters, so it can establish dense prickly thickets along watercourses and on floodplains. These impenetrable thickets inhibit access to waterways, smother pastures and alter the natural ecology in conservation areas.

To see a recent list of research on Mimosa pigra click here .