Distribution: Widely distributed on both sides of the Cascades crest in Washington; Alaska to California, east across much of North America to the Atlantic Coast.
Habitat: Streams, lakes, ponds, wet ditches, wetlands, and cattle ponds.
Growth Duration: Perennial
Conservation Status: Not of concern
Aquatic, scapose perennials, the scapes up to 12 dm. tall, longer than the leaves.
Leaves all basal, long-petiolate, the blades broadly lanceolate to ovate, 5-15 cm. broad, rounded to cordate at the base.
Flowers in much-compounded, bracteate, terminal panicles, the panicles branches in 2-6 whorles along the axis, the lower branches with 2 or more secondary branchlets or pedicles; sepals 3, 3-4 mm. long, greenish; petals 3, white, 4-6 mm. long; stamens 6, opposite the petals; pistils 10-20 in a single whorl; styles 0.4-0.8 mm. long, stout, slightly curved, somewhat lateral on the ovary, persistent.
Achenes obovate, 2.5-3 mm. long.
PNW Herbaria: Specimen records of Alisma triviale in the Consortium of Pacific Northwest Herbaria database.
WA Flora Checklist: Alisma triviale checklist entry.
OregonFlora: Alisma triviale information.
E-Flora BC: Alisma triviale atlas page.
CalPhotos: Alisma triviale photos.
USDA Plants: Alisma triviale information.