Potamogeton epihydrus is a species of aquatic plant known by the common name ribbonleaf pondweed. It is native to much of North America, where it grows in water bodies such as ponds, lakes, ditches, and slow-moving streams. This is a perennial herb producing a narrow, compressed stem branching to a maximum length which may exceed one meter. It has two types of leaf. Submersed leaves are up to 25 centimeters long but not more than one wide, linear in shape and ribbonlike. Leaves that grow to float on the surface are shorter and wider, up to 8 centimeters long and 3 wide. They are borne on long petioles. The inflorescence is a small spike of flowers that arises from the water on a peduncle.