Distribution: Occurring chiefly west of the Cascades crest in Washington; Alaska to California.
Habitat: Low elevation wet areas, often in standing water.
Conservation Status: Not of concern
Glabrous, weak, freely-branched perennial from fibrous roots, generally reclining and rooting at the nodes, the stem up to 1 m. long.
Leaves mostly bipinnate, the toothed to cleft leaflets 1.5-6 cm. long and 7-50 mm. wide, the primary lateral veins of the leaflets directed to the marginal teeth.
Inflorescence a compound umbel, the peduncles attached opposite the leaves; rays 10-20, 1.5-3 cm. long; involucre of a few narrow bracts or wanting; involucel of evident, narrow bractlets; calyx teeth evident, persistent; flowers white, the styles elongate.
Fruit glabrous, oblong, terete, truncate, 2.5-3.5 mm. long and 1.5-2 mm. wide, the conic stylopodium much smaller than the body of he fruit; the corky-thickened ribs much broader than the intervals.