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

Centaurea diffusa Lam.
diffuse knapweed
Asteraceae (Aster family)

Introduction to Vascular Plants

© Bryan Kelly-McArthur  Email the photographer   (Photo ID #72692)

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Distribution of Centaurea diffusa
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Species Information

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General:
Annual, biennial or short-lived perennial herb from a taproot; stems erect, branched, sparsely hairy, 10-60 cm tall.
Leaves:
Basal leaves pinnately divided into linear segments, broadly lanceolate in outline, 3.5-20 cm long, 0.5-3.5 cm wide, grey-green, lightly dense-hairy, soon deciduous; stem leaves similar, reduced upwards.
Flowers:
Heads discoid, numerous, solitary at the end of diffuse branches; disk flowers usually creamish, sometimes purplish or pinkish; involucres 8-10 mm tall; involucral bracts broadly lanceolate, leathery, glabrous, with weak spines on the margins, the tips with 1.5-4 mm long spines.
Fruits:
Achenes glabrous; pappus lacking or of minute bristles up to 1 mm long.

Source: The Illustrated Flora of British Columbia

Habitat / Range

Dry roadsides, disturbed areas, overgrazed grasslands and shrublands in the steppe and lower montane zones; common in S BC east of the Coast-Cascade Mountains; introduced from the E Mediterranean region.

Source: The Illustrated Flora of British Columbia

Ecology

Ecological Framework for Centaurea diffusa

The table below shows the species-specific information calculated from
original data (BEC database) provided by the BC Ministry of Forests and Range.
(Updated August, 2013)
Site Information
 Value / Class

Minimum

Average

Maximum
Elevation (metres) 260 603 1772
Slope Gradient (%) 0 23 80
Aspect (degrees)
[0 - N; 90 - E; 180 - S; 270 - W] 		0 204 360
Soil Moisture Regime (SMR)
[0 - very xeric; 4 - mesic;
8 - hydric] 		0 2 5
Modal Nutrient Regime
Class		 C
Number of field plots
 species was recorded in:		 214
Modal BEC Zone Class
 PP
All BEC Zones (# of stations/zone) species was recorded in: BG(62), ICH(9), IDF(58), PP(75)

Climate

The climate type for this species, as reported in the: "British Columbia plant species codes and selected attributes. Version 6 Database" (Meidinger et al. 2008), is not evaluated, unknown or variable.

Synonyms and Alternate Names

Acosta diffusa (Lam.) Soják

Taxonomic and Nomenclatural Links

Flora North America treatment for Asteraceae
 Flora North America treatment for Centaurea diffusa
Genetic information (NCBI Taxonomy Database)
 International Plant Names Index
 Taxonomic Information from the World Flora Online
 Integrated Taxonomic Information System

Additional Photo Sources

Images From CalPhoto
UT Austin's Native Plant Database
 Google Image Search
 Flickr Image Search

General References

Google Scholar Search
Family References
 General Botanical References for BC
Recommended citation: Author, Date. Page title. In Klinkenberg, Brian. (Editor) 2020. E-Flora BC: Electronic Atlas of the Plants of British Columbia [eflora.bc.ca]. Lab for Advanced Spatial Analysis, Department of Geography, University of British Columbia, Vancouver. [Accessed: 2024-07-17 4:37:53 AM ]
Disclaimer: The information contained in the E-Flora atlas pages is derived from expert sources as cited in each section. This information is scientifically based. E-Flora also acts as a portal to other sites via deep links. As always, users should refer to the original sources for complete information. E-Flora BC is not responsible for the accuracy or completeness of the original information.
© E-Flora BC: An initiative of the Spatial Data Lab, Department of Geography UBC, and the UBC Herbarium.