Floating Pondweed (Potamogeton natans)

Floating pondweed has both submersed and floating leaves but the submersed leaves are very narrow and appear to consist only of an elongate petiole or midrib with out a blade (see top photo). Floating leaves are elliptical to ovate and 1-8 inches long. There is a pronounced mid leaf vein with finer parallel veins on either side.