Distribution: Occurring on both sides of the Cascades crest in Washington; Alaska to California, east across North America to the Atlantic Coast.

Habitat: Stream banks, marshes and peat bogs, mostly in the mountains, but descending to sea level west of the Cascades.

Flowers: July-September

Origin: Native

Growth Duration: Perennial

Conservation Status: Not of concern

Pollination: Flies, wasps

Herbaceous, puberulent perennial from tubers with very slender rhizomes and stolons, the stems usually simple, 1-4 dm. tall.

Leaves opposite, nearly glabrous, all cauline and not much reduced upward, 2-8 cm. long and 0.6-3 cm. wide, narrowed to a short petiole, the margins coarsely and irregularly serrate-dentate.

Flowers in tight whorls in the leaf axils, sessile; calyx small, soft, obscurely nerved, the 5 ovate teeth acutish; corolla white or pinkish, 2.5-3.5 mm. long, surpassing the calyx, 4-lobed, nearly regular, the tube short; stamens 2, the upper pair (of the usual 4) obsolete.

Nutlets 4, the outer top margin toothed.