Floating leaves are firm, green, elliptic, 1 to 3 inches long, up to ¾ inch wide, and rounded to bluntly pointed at the tip.
Submersed leaves are alternate on opposite sides of the stem (2-ranked), bright green to reddish, linear and ribbon-like, 2 to 8 inches long, 3/8 inch wide, bluntly to sharply pointed at the tip, and stalkless. Excerpted from: https://www.minnesotawildflowers.info/aquatic/ribbon-leaf-pondweed.
Floating and submerged leaves of ribbon-leaf pondweed, Dolloff Cove. Photo by Don Yurewicz
Floating and submerged leaves of ribbon-leaf pondweed, Dolloff Cove. Photo by Don Yurewicz