Chamaecrista nictitans

Chamaecrista nictitans, the sensitive cassia, sensitive partridge pea, small partridge pea or wild sensitive plant, is a herbaceous species of legume widely distributed through the temperate and tropical Americas. It is an annual plant capable of rapid plant movement—its leaflets fold together when touched. However, a population at Haleakala National Park on the island of Maui, Hawaii, was reported as not being sensitive to touch. It is similar to Chamaecrista fasciculata except that the leaves are generally smaller, it is less robust, and the flowers are smaller and inconspicuous. Chamaecrista nictitans is undesirable as a forage or hay but can be used for both in subtropical areas....read more on Wikipedia.