The singular foliage of this common annual herb is sensitive to the touch, and if roughly handled, or threshed with the foot, the numerous leaflets close together after the fashion of a fan, or remotely suggesting the operation of the shutters of a blind. They also close at night, and are thus said to "sleep." This leafy plant is small and branching, and grows only from six to fifteen inches high, in dry fields and sandy wastes, where it often forms large patches. The alternating leaves are compounded of from twelve to forty-four blunt pointed and narrow-oblong leaflets, which are arranged in opposite pairs. The small, short-stemmed flowers have five spreading yellow petals and are borne in clusters of twos or threes in the axils of the leaves. They have five stamens, and the fruit matures in a small, hairy pod. This species is found from July to October, from Maine to Georgia, and west to Indiana, Kansas, and Texas.