Distribution: Occurring chiefly east of the Cascades crest in Washington; southern British Columbia to California, east across much of North America to northeastern North America.

Habitat: Marshes and shores of streams and lakes; tolerant of alkali.

Flowers: June-August

Origin: Native

Growth Duration: Perennial

Conservation Status: Not of concern

Pollination: Flies, wasps

Perennial herbs from tuberous rhizomes, the simple or branched, square stem 2-8 dm. tall, with spreading hairs on the angles.

Leaves opposite, all cauline, glabrous or scabrous above and glabrous below, numerous, 3.5-10 cm. long and 0.6-3.5 cm. broad, oblong-lanceolate, coarsely and evenly serrate, nearly sessile.

Flowers sessile, verticillate in the axils of scarcely reduced leaves; calyx with 5 firm, narrow, sharp-pointed lobes; corolla white, 3-5 mm. long, about equally 4-lobed; fertile stamens 2, barely exerted, sterile stamens 2, small, club-shaped; style 2-parted; ovary 2-celled, superior.

Nutlets 4, the outer apical margin truncate and irregularly toothed.