diffuse knapweed USDA PLANTS Symbol: CEDI3
U.S. Nativity: Exotic
Habit: Forbs/Herbs
Centaurea diffusa Lam.

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Taxonomic Rank: Magnoliopsida: Asterales: Asteraceae
Synonym(s): white knapweed
Native Range: Temp. Asia, Europe (GRIN);

Appearance
Centaurea diffusa is a biennial, annual, or short-lived perennial that is 8-40 in. (20.3-101.6 cm) tall.
Foliage
The leaves are stalked and lobed. The leaves become smaller and less divided as they move up the stem.
Flowers
Flowering occurs from July to September. White flowers develop in urn-shaped heads, in clusters, at the ends of the branches. The heads are subtended by leathery bracts. The lower and middle bracts have brown margins with spines at the tips.
Fruit
Seeds are achenes, 0.08-0.12 in. (2-3 mm) long with a plume of bristle-like hairs.
Ecological Threat
This species prefers well drained soils, gravel pits, trails, pastures and roadsides.

Identification, Biology, Control and Management Resources

Selected Images from Invasive.orgView All Images at Invasive.org


Plant(s);
Sara Rosenthal, USDA Agricultural Research Service, Bugwood.org
Additional Resolutions & Image Usage

Plant(s);
Cindy Roche, , Bugwood.org
Additional Resolutions & Image Usage

Flower(s);
Steve Dewey, Utah State University, Bugwood.org
Additional Resolutions & Image Usage

Flower(s);
Steve Dewey, Utah State University, Bugwood.org
Additional Resolutions & Image Usage

Flower(s);
USDA APHIS PPQ - Oxford, North Carolina , USDA APHIS PPQ, Bugwood.org
Additional Resolutions & Image Usage

Flower(s);
Cindy Roche, , Bugwood.org
Additional Resolutions & Image Usage

Flower(s); Close-up view of a flower head and flower bud of diffuse knapweed (Centaurea diffusa), showing the spiny bracts.
L.L. Berry, , Bugwood.org
Additional Resolutions & Image Usage

Seedling(s);
Joseph M. DiTomaso, University of California - Davis, Bugwood.org
Additional Resolutions & Image Usage

Plant(s);
Steve Dewey, Utah State University, Bugwood.org
Additional Resolutions & Image Usage

EDDMapS Distribution:
This map is incomplete and is based only on current site and county level reports made by experts and records obtained from USDA Plants Database. For more information, visit www.eddmaps.org
 


State(s) Where Reported invasive.
Based on state level agency and organization lists of invasive plants from WeedUS database.

U.S. National Parks where reported invasive:
Craters of the Moon National Monument (Idaho)
Dinosaur National Monument (Colorado)
Grand Canyon National Park (Arizona)
Rocky Mountains National Park (Colorado)
Yellowstone National Park (Wyoming)



Invasive Listing Sources:
California Invasive Plant Council
Faith Campbell, 1998
Jil M. Swearingen, Survey of invasive plants occurring on National Park Service lands, 2000-2007
John Randall, The Nature Conservancy, Survey of TNC Preserves, 1995.
Pacific Northwest Exotic Pest Plant Council, 1998