Sagittaria teres- Quill-leaved Arrowhead Nymphoides cordata
This is a big-time state and global rarity, an S1 G3. Endangered in NJ. I think its global range is only 4 states and it's endangered in 3 of them and rare in the other. This lovely little aquatic plant is pretty uncommon in NJ, usually found along the coastal plain. It is an S3 G5.