Pistillate Flower, Front View
5 Miles East, 4 Miles North of Hudson Bay on Fir River Road
Note the flower has only one stigma.
Sparganium emersum is similar to Sparganium angustifolium, especially when floating leaves are present. This population had emergent leaves in shallow water and floating leaves in the deeper portion. I have identified these plants as S. emersum because their features (except perhaps for beak length) match the description of S. emersum in the Flora of North America discussion (see here) of the differences between the two species. FNA states:
Sparganium emersum is easily confused with S. angustifolium, especially when floating leaves are present, but it is distinguished by its leaves which are triangulate at least at the base, by its often more numerous staminate heads, at least some of which are not contiguous, and by its greenish fruits with longer beaks.
FNA also notes that the entire S. emersum-S. angustifolium complex could perhaps be better treated as one variable species, S. angustifolium. In addition, FNA suggests that some characters of S. angustifolium might have been incorporated into S. emersum, and North American plants could be a stable hybrid that differs somewhat from S. emersum as it is known in Europe.
See here for a key to Saskatchewan Sparganium species created by Anna Leighton and found in Rushes, Bulrushes & Pondweeds plus the remaining Monocots of Saskatchewan by V.L. Harms, A.L. Leighton and M.A. Vetter).
Emersum: Answers to key questions in Rushes, Bulrushes & Pondweeds plus the remaining Monocots of Saskatchewan by V.L. Harms, A.L. Leighton and M.A. Vetter leading to this species. The answers are in the order you would normally work through the key.