Distribution: Widely distributed on both sides of the Cascades in Washington; Alaska to California, east across Canada and most of the United States to the Atlantic Coast.
Habitat: Common in lake and pond shore margins, riparian zones, wetlands, and other wet areas at low elevations.
Conservation Status: Not of concern
Aromatic, perennial herbs from creeping rhizomes, the square stems ascending to erect, pubescent, 2-8 dm. tall.
Leaves opposite, all cauline, short-petiolate, glabrous or hairy, 2-8 cm. long and 6-40 mm. wide, serrate, acuminate, narrowly ovate to rhombic-elliptic, with several pairs of lateral veins.
Flowers in compact verticels in the axils of the upper leaves, the verticels well separated; calyx pubescent, 2.5-3 mm. long, regular, 5-lobed, 10-nerved; corolla nearly regular, four-lobed, with a short tube, white to lavender or pink, 4-7 mm. long; stamens 4, equal, exerted; style 2-parted; ovary 2-celled, superior.