Distribution: Occurring on both sides of the Cascades crest in Washington, but more common west of the crest; British Columbia to California, east to Idaho and Montana; also in eastern North America.
Habitat: Wetlands, lake and pond margins, irrigation ditches, backwaters, and other wet places where often disturbed; invasive.
Origin: Introduced from Eurasia
Conservation Status: Not of concern
Herbaceous perennial from short, thick rhizomes, forming dense clumps, the simple flowering stem up to 1 m. tall, leafy.
Basal leaves stiff, narrowly linear, 5-9 dm. long and 10-15 mm. broad; cauline leaves reduced upward.
Inflorescence branched, few to several flowered, 1.5-5 dm. long; flowers pale to deep yellow, purple-lined; pedicles up to 5 cm. long; perianth parts fused in a tube at the base, the tube about about 12 mm. long; sepals 3, obovate, spreading, about 5 cm. long; petals 3, much shorter and narrower than the sepals, upright; stamens 3, opposite the sepals; style branches 3, about 22 mm. long, with 2 terminal lobes less than as long; stigma triangular; ovary inferior.
Capsule 3-celled, leathery, 5-8 cm. long.