Rhynchospora knieskernii is a rare species of sedge known by the common name Knieskern's beaksedge. It is endemic to the state of New Jersey in the United States, where it occurs naturallyin the Pine Barrens. Reports have cited it present in Delaware as well, but these populations appear to have been introduced. It is threatened by the destruction and degradation of its habitat. It is a federally listed threatened species of the United States. In 2007 there were 45 occurrences of the plant, but few of these have been surveyed recently enough to confirm the presence of the plant.