Isoetes engelmannii A. Br. - Appalachian Quillwort, Engelmann's Quillwort
This species has also been historically reported from unspecified localities in Mercer Co., NJ; and Bronx Co., NY; not reported from our area since circa 1973.
This species is probably still extant in our area. Due to its diminutive stature, its emergent/submerged habitat, and often encountered sterile state (megaspores required for positive id), it has probably been overlooked.