Centaurea jacea L.
brown knapweed (brownray knapweed)
Asteraceae (Aster family)
Introduction to Vascular Plants
brown knapweed (brownray knapweed)
Asteraceae (Aster family)
Introduction to Vascular Plants
Species Information
General:
Perennial herb from a taproot; stems erect, branched, glabrous or somewhat woolly or cobwebby, 0.1-1.2 m tall.
Leaves:
Basal leaves oblanceolate or narrowly elliptic, long-stalked, toothed or shallowly lobed to entire, hairy above and below, the blade up to 15 cm long and 3 cm wide; stem leaves reduced and becoming unstalked upward.
Flowers:
Heads discoid, few to several, solitary at the ends of erect branches; disk flowers rose to purple, rarely white, the marginal ones enlarged and conspicuous; involucres 15-20 mm tall, nearly as wide; involucral bracts with enlarged, broad, rounded, papery, tattered, tan to dark brown appendages at the tips, these wider than the bracts.
Fruits:
Achenes light brown with a few lighter longitudinal lines, 3-3.5 mm long; pappus lacking.
Illustration
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
Habitat and Range
Mesic to dry roadsides and fields in the montane zone; rare in WC BC, known recently only from the Smithers area; introduced from Europe.Status Information
Taxonomic Keys
There are twelve species of Centaurea reported from British Columbia and many are very similar in appearance. Identification is made primarily on the morphology of the involucral bracts and bract appendages. This species may be separated from others by the following key characters: purplish flowers (rarely yellow); comb-like involucral bracts that are tattered and nearly entire to the base and which have conspicuous flagged tips that are broader than the base; involucral bract appendages that are papery and tattered (not dark and comb-like); stem leave simple, at most coarsely toothed, lobed or pinnately cut below.
Source: Illustrated Flora of British Columbia, 1998 (volume 1). |