Mimosa pudica also called sensitive plant, sleepy plant and the touch-me-not,is a perennial herb often grown for its curiosity value: the compound leaves fold inward and droop when touched or shaken, due to evolution from predators, re-opening minutes later. The species is native to South America and Central America. but now It has been introduced to many other regions and is regarded as an invasive species in Tanzania,SouthAsia and South East Asia and many Pacific Islands.[7] It is regarded as invasive in parts of Australia and is a declared weed in the Northern Territory,[11] and Western Australia although not naturalized there.[12] It has also been introduced to Nigeria, Seychelles, Mauritius and East Asia but is not regarded as invasive in those places. It grows mostly in shady areas, under trees or shrubs.
Mimosa pudica is well known for its rapid plant movement. Like a number of other plant species, it undergoes changes in leaf orientation termed "sleep" or nyctinastic movement. The foliage closes during darkness and reopens in light.[4]The leaves also close under various other stimuli, such as touching, warming, blowing, or shaking. These types of movements have been termed seismonastic movements. The movement occurs when specific regions of cells lose turgor pressure, which is the force that is applied onto the cell wall by water within the cell vacuoles and other cell contents. When the plant is disturbed, specific regions on the stems are stimulated to release chemicals including potassium ions which force water out of the cell vacuoles and the water diffuses out of the cells, producing a loss of cell pressure and cell collapse; this differential turgidity between different regions of cells results in the closing of the leaflets and the collapse of the leaf petiole. This characteristic is quite common within the Mimosoideae subfamily of the legume family, Fabaceae. The stimulus can also be transmitted to neighboring leaves. It is not