UW Burke Herbarium species comparison

Leaves mostly emersed, but often submerged and the blades floating;

blades sagittate or hastate, up to 2.5 dm. long and nearly as broad; submerged leaves sometimes bladeless and greatly elongate, 4-10 mm. broad.

Flowers in 2-8 whorles of 3 in bracteate racemes, the bracts 5-10 mm. long, blunt, hooded; pedicles 1-5 cm. long, ascending, in both the pistillate flowers (lower whorles) and staminate flowers.(upper whorles), or the plants sometimes monoecious;

sepals 3, 5-10 mm. long, persistent;

petals 3, white, twice as long as the sepals;

stamens more than 20;

pistils many on a globose receptacle.

Achenes 2.5-4 mm. long, winged, with a stylar beak strongly up-turned, 0.5-1.5 mm. long.