Sagittaria teres
Sagittaria teres, the quill-leaved arrowhead or slender arrowhead, is an aquatic plant species in the genus Sagittaria. It is a perennial herb up to tall. The leaves can grow both under and above the water. The flowers are white, up to in diameter, borne in one or more whorls on a stalk rising above the leaves.
It is native to the northeastern United States: Rhode Island, Massachusetts, New Hampshire, New York and New Jersey. It grows along the shores of lakes, marshes, and other wetlands, frequently those with acidic water such as Sphagnum bogs.