The solitary pistillate flower is carried to the surface of the water on a long peduncle (which becomes spiraled in age). Staminate plants produce a large number of flowers, borne densely in a spathe on a short peduncle (sometimes as long as 33 cm). These staminate flowers are released under water, the perianth tightly closed and hence containing a gaseous bubble; at the surface, the perianth opens, acting as a sail. The staminate flowers drift upon the surface of the water, and when one reaches the dimple formed by a pistillate flower at the surface, it slides quickly to it and pollination occurs—barely above the surface of the water.
The characteristic three-zoned appearance of the leaves of Vallisneria will distinguish it from other plants that may produce rosettes of ribbon-like submersed leaves. The leaves of Potamogeton epihydrus are similarly three-zoned, but are shorter and alternate.
All species found in Vallisneria
MICHIGAN FLORA ONLINE. A. A. Reznicek, E. G. Voss, & B. S. Walters. February 2011. University of Michigan. Web. June 17, 2019. https://michiganflora.net/genus.aspx?id=Vallisneria.