Neptunia lutea, the yellow-puff, is a trailing, vine-like perennial plant of the legume family Fabaeceae. Its stems are covered with soft spines, but is not nearly as prickly as its cousin, the sensitive brier (Mimosa nuttallii). This plant grows best in full sun to partial shade. It inhabits the various soils of forest margins, the openings of thickets, roadsides, prairies and pastures. Like the related sensitive plant and sensitive brier, the leaves of this plant exhibit rapid plant movement. They will close upon touch, as well as at night and during periods of cloudy weather.