Isoetes tuckermanii A. Br. ex Engelm. - Tuckerman's Quillwort
This species is also reported from unspecified localities in northern NJ.
This species is possibly more common than the map would indicate. Due to its diminutive stature, its emergent/submerged habitat, and often encountered sterile state (megaspores required for positive id), it is possibly under-reported/collected.