Distribution: Both sides of the Cascades in Washington; British Columbia south to California, east to Alberta and Utah.
Habitat: Stream banks, wet meadows, marshes and bottomlands, from the foothills and valleys to moderate elevations in the mountains.
Conservation Status: Not of concern
Robust perennial from a stout taproot, 5-20 dm. tall, mostly glabrous.
Leaves large, ternately-pinnately twice compound, the base of the petiole sheathing; leaflets ovate to lanceolate, pointed, 4-14 cm. long and 1.5-8 cm. wide, serrate or doubly serrate.
Compound umbels 2 or more, rays of the umbel 18-45, unequal, up to 8 cm. long; involucre wanting; involucels wanting, or a few inconspicuous bractlets; calyx obsolete; petals 5, white, glabrous.
Ovary inferior, 2-celled, glabrous, the stylopodium broadly conic; fruit broadly elliptic to orbicular, 4-7 cm. long and 4-5 mm. wide, with narrowly-winged dorsal ribs and lateral wings nearly as wide as the body.