Panicum niihauense is a rare species of grass known by the common names lau 'ehu and Niihau panicgrass. It is endemic to Hawaii, where it has been found on the islands of Niihau and Kauai. It has not been observed on Niihau since 1949, and there are fewer than 40 individuals remaining on Kauai, not counting a few individuals that have been deliberately planted in appropriate habitat. The grass is a federally listed endangered species of the United States.