Distribution: Widely distributed throughout Washington; occurring throughout North America except for southeastern and lower Midwest of U.S.
Habitat: Moist areas, low to mid-elevations.
Conservation Status: Not of concern
Robust, single-stemmed perennial from a taproot or a cluster of fibrous roots, 1-3 m. tall.
Leaves large, once ternate, with broad, petiolate, coarsely-toothed and palmately-lobed leaflets 1-3 dm. long and wide, the lateral ones narrower than the central, thinly woolly on the lower surface; petioles sheathing and expanded.
Inflorescence of compound umbels on terminal and axillary peduncles, the terminal umbel 1-2 dm. wide; rays mostly 15-30, up to 10 cm. long; involucre of 5-10 deciduous, narrow bracts, 0.5-2 cm. long; involucel of similar bractlets; pedicels 8-20 mm. long; calyx teeth obsolete, flowers white.
Fruit obovate, 7-12 mm. long and 5-9 mm. wide, strongly flattened dorsally, nearly glabrous, the dorsal ribs narrow, the lateral ones broadly winged.