Distribution: Occurring chiefly east of the Cascades crest in Washington; widely distributed throughout much of North America.
Habitat: In or along slow-moving streams in the lowlands.
Origin: Introduced from Europe
Conservation Status: Not of concern
Glabrous, short-lived perennial from fibrous roots, the stems usually erect, 2-10 dm. tall.
Leaves opposite, sessile and clasping, elliptic-ovate to elliptic-oblong, 2-10 cm. long and 0.7-5 cm. wide, sharply serrate to entire.
Inflorescence of many-flowered racemes on long peduncles arising in the leaf axils; calyx of 4 highly variable sepals; corolla blue, rotate, 4-lobed, the upper lobe the largest, about 5 mm. wide; style 1.5-2.5 mm. long; pedicels up-curved, 3-8 mm. long; stamens 2.
Capsule swollen, 2.5-4 mm. high and wide, scarcely notched.