India, Oct. 20 -- Sometimes a plant that looks interesting can end up becoming a huge headache. According to the Northern Territory Government, 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. 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.

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. Adult plants are shrubs, branching, up to 6 meters high. Each flower head has up to 1...