Stuckenia is a small genus recently segregated from Potamogeton.
1. Fruit 2.2–3 mm long, beakless (with merely a wart-like apex, the broad stigma sessile); leaves rounded, ± blunt, or obtuse, often with a tiny notch, at the tip [30–40×].
1. Fruit (2.5–) 3–4.5 mm long, not including a tiny beak (the short style persistent as a beak toward one side of end of fruit) leaves mostly sharp-pointed (the younger ones tapering slenderly to a point; older ones often more abruptly pointed).
All species found in Stuckenia
MICHIGAN FLORA ONLINE. A. A. Reznicek, E. G. Voss, & B. S. Walters. February 2011. University of Michigan. Web. March 29, 2017. http://michiganflora.net/genus.aspx?id=Stuckenia.