Distribution: Widely distributed on both sides of the Cascades crest in Washington; Alaska to Oregon, east to Alberta, Montana and Wyoming.
Habitat: Marshes, ditches, and wet low places, from low to middle elevations in the mountains.
Conservation Status: Not of concern
Stout perennials, often glaucous, 5-20 dm. tall, the stems solitary or few from a tuberous-thickened and chambered base, with several of the roots thickened as well.
Leaves basal and cauline, 1-3 times ternate-pinnate, with lance-linear to lance-ovate, serrate leaflets 3-10 cm. long and 6-35 cm. wide, the primary lateral veins directed to the marginal sinuses.
Compound umbels several, the rays 2-6 cm. long; involucre wanting; involucel of several narrow bractlets; calyx teeth evident; petals 5, white.
Stylopodium depressed; fruit glabrous, orbicular, 2-4 mm. long, the thickened ribs wider than the often darkened intervals.
EXTREMELY TOXIC EVEN IN SMALL AMOUNTS WHEN INGESTED BY HUMANS AND LIVESTOCK.