Centaurea virgata var. squarrosa

Photo courtesy Joseph DiTomaso

Synonyms: Centaurea squarrosa Willd. is an illegally applied name according to the rules of the International Code of Botanical Nomenclature (Saint Louis Code) since the name Centaurea squarrosa Roth was previously applied to a different species. Centaurea virgata Lam. var. squarrosa (Willd.) Boiss. is a synonym of Centaurea squarrosa Willd. Some taxonomists are using the name C. triumfetti All. for diffuse knapweed. Some flora use C. virgata Lam. ssp. squarrosa (Willd.) Gugler, but the taxon was given variety ranking first.

Common names: squarrose knapweed

Centaurea virgata var. squarrosa (squarrose knapweed) is a perennial (family Asteraceae) found in the Klamath and Cascade Ranges, Modoc Plateau and northern Sierra Nevada Mountains of California. Squarrose knapweed favors disturbed open sites, including degraded rangeland, logged areas, grasslands and roadsides. Squarrose knapweed seed dispersal is enhanced by soil and water movement, and by clinging to humans and animals. Seed dispersal and reproduction can be limited by mowing or mechanical removal of plants before seed-set. Squarrose knapweed is a listed noxious weed in several western states.

Rating: Moderate

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