Sparganium chlorocarpum?
Please help with identification of this palnt from Ontario. Leaves.6-7 mm wide, about 35 cm long, triangular (only very end -few cms - flatitsh), slightly dilated at base, very soft but erect. First head is supra-axilary, next is terminal spike - axilary with 3 femin.heads about 20-25 mm wide. Diameter of plant base (above roots) about 8-10mm wide. Tepals a bit wider at the ends.