Sensitive plant

It is known by numerous common names including sensitive plant, Mimosa pudica, prayer plant and touch me not. In the evening the leaflets will fold together and the whole leaf droops downward. It then re-opens at sunrise. This type of motion has been termed nyctinastic movement. The leaves also close up under various other stimuli, such as touching, warming, or shaking.
Today while I was walking in the park outside the apartment I saw this strange plant.