UW Burke Herbarium species comparison

Submerged leaves linear, 5-20 mm. long, thin, 1-nerved, with a slight notch at the tip; floating and emergent leaves broadly spatulate, up to 4 mm. broad, 3-nerved.

Emersed leaves linear, 1-nerved, 0.5-2.5 mm. long; floating and emergent leaves broadly obovate, 3-nerved, up to 1 cm. wide.

Flowers imperfect, sessile in the leaf axils, each consisting of a single pistil or 1 stamen or both;

styles 2, distinct, 1-2.5 mm. long, deciduous;

floral bracts present.

Flowers imperfect, sessile in the leaf axils, each consisting of a single pistil or 1 stamen or both;

styles 2, distinct, 1-5 mm. long, persistent;

floral bracts present.

Carpels 2, oblong-obovate, about 1 mm. long and 0.7 mm. broad, with pit-like markings in vertical lines.

Carpels 2, obovate, 0.7-1.2 mm. long and broad, wingless, pitted with small, shallow pits.