Annual or biennial, slightly aromatic herb, from a taproot; stems erect, grooved, glabrous, branched above, 0.3-2.0 (rarely 3.0) m tall.
Stem leaves pinnately to bipinnately cut, glabrous, stalked, the segments lanceolate and sharp-toothed, 5-15 cm long.
Heads discoid, numerous in a compact spikelike inflorescence, short-stalked; involucres hemispheric, 2-3 mm tall; involucral bracts glabrous, the outer ones narrow and green, the inner with only a green midrib and broad, thin, dry, slightly papery margins; receptacles glabrous; female flowers fertile; disk flowers fertile.
Achenes 4-5-nerved, glabrous.
If more than one illustration is available for a species (e.g., separate illustrations were provided for two subspecies) then links to the separate images will be provided below. Note that individual subspecies or varietal illustrations are not always available.
Illustration Source: The Illustrated Flora of British Columbia