Mimosa ( Mimosa pigra ), also known as the giant sensitive plant, was deliberately introduced to the Northern Territory in the late 1800s as an ornamental curiosity, according to the Northern Territory Government . Up to 140,000 hectares of land are now estimated to be affected. Up to 4.6 million hectares of Australian land are considered at risk of infestation.
Sometimes a plant that looks interesting can end up becoming a huge headache.
Mimosa is native to tropical America, ranging from Mexico to northern Argentina . Its fern-like leaves close when touched, and its fluffy round flower heads are pink to mauve. But the plant is also spiny. It is well established in many river systems across the Top End, including the Daly, Mary and Adelaide rivers. Two known outbreaks are outside the territory. One is at Lake Proserpine in eastern Queensland, and the other is near Kununurra in Western Australia. Both outbreaks are actively managed. Mimosa is a Weed of National Significance. A statutory weed management plan outlines the legal control requirements. Control methods include herbicides, hand pulling, bulldozing and fire. Biological control is also being tried. There has been a wide range of projects involving Indigenous land managers, the pastoral sector and the Territory Government. Everyday habits also count. The government advises people to remove mud, which can carry seeds, from boats and vehicles before traveling to a new area and to avoid driving through infested areas. If you fish, boat, or travel through wetland country, those are simple habits worth keeping.
Adult plants are shrubs, branching, up to 6 meters high. Each flower head has up to 100 little flowers. The Northern Territory Government explains that up to 140,000 hectares of land in the territory are already impacted. That’s 10 percent of the territory’s wetlands. Mimosa has invaded 15 catchments and three islands. Since the start of mimosa biocontrol research in 1979, a total of 15 agents have been released, including 13 insects and two fungal pathogens.
The government says that, under the right conditions, mimosa can form dense, thorny thickets dominated by a single species. The government says mimosa could spread through wetland areas across northern Australia . Currently, nine are actively working to reduce the growth, spread and seed production of mimosa, and the government says some have been very successful.
