General:
Perennial herb from an elongated taproot, seldom thickened, surmounted by a simple branched crown or stem-base; stems or scapes solitary or few, erect, 10-80 cm tall, glabrous.

Leaves:
Mostly basal, pinnately compound, divided 1-3 times or, at the base, 2-3 times; stem leaves 1 or more on the middle or upper stem; ultimate leaf segments narrow and scarcely leaflike, usually less than 5 mm wide, finely hairy.

Flowers:
Inflorescence of compound umbels; flowers yellow, spokes of the umbel elongating unequally, 2-10 cm long; involucels present.

Fruits:
Oblong to broadly elliptic, 7-15 mm long, narrowly to very broadly winged, glabrous to minutely hairy or granular-roughened.

Notes:
Two subspecies occur in BC:

1. Fruits broadly elliptic, wings nearly or fully as wide as body; ultimate leaf segments linear................ ssp. platycarpum (Torr.) Cronq

1. Fruits usually relatively narrow, wings usually half as wide as body; ultimate leaf segments lanceolate..................... ssp. triternatum

Source:  The Illustrated Flora of British Columbia