Distribution: Occurring on both sides of the Cascades crest in Washington; Alaska to California, east to the northern Great Plains and further eastward to northeastern North America.
Habitat: In shallow water or wet mud of rivers, lakes, and ponds at low to middle elevations.
Flowers: June-October
Origin: Native
Growth Duration: Annual, Perennial
Conservation Status: Not of concern
Tiny, glabrous, scapose perennial, with fibrous roots from a small crown.
Leaves all basal, entire, the blades narrowly elliptic, 5-18 mm. long and 2-7 mm. wide, with long, slender petioles, up to 8 cm. long.
Flowers usually solitary on long, slender, lax scapes, or sometimes in a cluster on short pedicels, in a whorl of leaves at the top of a naked stem; calyx 5-toothed, 2-3 mm. high; corolla white or pinkish, inconspicuous, the tube about equal to the calyx, the 5 lobes short and spreading; stamens 4; stigma capitate.
Capsule 2-3.5 mm. high, 1-celled toward the tip.
PNW Herbaria: Specimen records of Limosella aquatica in the Consortium of Pacific Northwest Herbaria database
WA Flora Checklist: Limosella aquatica checklist entry
OregonFlora: Limosella aquatica information
E-Flora BC: Limosella aquatica atlas page
CalPhotos: Limosella aquatica photos