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.

Leaves mostly emersed or the blades floating, but sometimes submerged; emersed leaves with sagittate blades 1-12 cm. long and up to 6 cm. broad; floating leaves linear or ovate; submerged leaves linear, up to 4 dm. long and 2-10 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.

Flowers in whorles of 3 in bracteate racemes, the bracts lanceolate, 5-30 mm. long; lower whorles pistillate, the pedicles 5-20 mm. long, ascending, longer in the staminate flowers in the upper whorles;

sepals 3, 5-8 mm. long, persistent;

petals 3, white, longer than the sepals;

stamens 15-25;

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.

Achenes 2-2.5 mm. long, winged, the stylar beak straight, 0.2-0.4 mm. long.