Isoetes melanospora, commonly known as black-spored quillwort or black-spored Merlin's grass, is a rare and endangered aquatic pteridophyte endemic to the U.S. states of Georgia and South Carolina. It grows exclusively in shallow, temporary pools on granite outcrops, often with only 2 cm of soil. 11 populations are known to exist in Georgia, while only one has been recorded in South Carolina, though this population is believed to be extirpated. The number of sites has dropped from 18 following its discovery due to habitat destruction caused by quarrying, trash dumping and trampling. New leaves quickly sprout after fall and winter rains, but during the dry summer months these typically shrivel.