E-Flora BC: Electronic Atlas of the Flora of British Columbia

General:
Biennial or sometimes perennial herb from a taproot; stems erect, ridged, laxly branched, 0.2-1.8 m tall.

Leaves:
Basal leaves pinnately cut, linear, stalked; stem leaves becoming reduced and unstalked above.

Flowers:
Heads discoid, few to several, in a corymb-like arrangement at the ends of ascending branches; involucres 9-13 mm tall, 6-8 mm wide; involucral bracts oblong, grooved, membranous, the middle and outer ones bearing a relatively narrow, darkened comb-like tip; disk flowers purple to pinkish-purple, rarely white, the sterile marginal ones 18-20 mm long, enlarged at the tips with 5 narrow lobes, the central perfect ones 12-16 mm long.

Fruits:
Achenes dark grey to black, 2.5-3.5 mm long; pappus white, 0.5-2 mm long, rarely lacking.

Notes:
This species is sometimes difficult to separate from the closely related C. paniculata. The latter, however, has much stiffer, divergent branches that are often again branched with narrower heads.