Gratiola amphiantha is a rare species of flowering plant known by the common names little amphianthus, pool sprite and snorkelwort. It was previously the only species in the monotypic genus Amphianthus, but it was moved to genus Gratiola after genetic analysis in 2008. It is native to the Piedmont region of the southeastern United States, with a center of distribution in Georgia. It occurs in Alabama and South Carolina as well. It is limited to granite outcrops, a high-biodiversity habitat type that is threatened by activities such as quarrying, off-road vehicles, and trash and debris dumping. It is a federally listed threatened species.