Distribution: Introduced in the Pacific Coast states, Montana, and some Eastern states
Habitat: Uncommon in streams, ponds and ditches
Flowers: May - August
Origin: Introduced from Europe
Conservation Status: Not of concern
Small aquatic herbs, the stems 3-15 cm. long, aquatic to terrestrial; leaf bases joined by small, winged ridges.
Leaves from linear and 1-nerved to broadly obovate-spatulate and 3- to 5-nerved, and nearly 1 cm. broad.
Flowers imperfect, sessile in the leaf axils, each consisting of a single pistil or 1 stamen or both; styles 2, distinct, 1-3 mm. long, reflexed to erect, deciduous; floral bracts conspicuous, white.
Carpels 2, round to oblong-oval, 1-1.5 mm. long, conspicuously wing-margined all around.