black knapweed USDA PLANTS Symbol: CENI2
U.S. Nativity: Exotic
Habit: Forbs/Herbs
Centaurea nigra L.

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Taxonomic Rank: Magnoliopsida: Asterales: Asteraceae
Synonym(s): black knapweed
Native Range: Europe (BAIL);

Appearance
Centaurea nigra is a perennial plant that can grow from 1-3 ft. (0.3-0.9 m) tall.
Foliage
Leaves, near the base, are petiolate, oblanceolate, shallowly dentate and 2-10 in. (5-25 cm) long. As leaves move up the stem, they become smaller, sessile, linear, and entire.
Flowers
Flowering occurs from June to October, when purple (rarely white) flowers appear in heads at the tips of the branches.
Fruit
Fruit is a tan, hairy achene 0.08-0.12 in. (2-3 mm) long, may have a small, dark pappus.
Ecological Threat
Centaurea nigra is native to Europe and was first found in the United States in 1895 in Pullman, Washington. Preferred habitat includes roadsides, waste places, fields and clearings.

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


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

Plant(s);
Bruce Ackley, The Ohio State University, Bugwood.org
Additional Resolutions & Image Usage

Plant(s);
Bruce Ackley, The Ohio State University, Bugwood.org
Additional Resolutions & Image Usage

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

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

Flower(s); all flowers same length
Joseph M. DiTomaso, University of California - Davis, Bugwood.org
Additional Resolutions & Image Usage

Seed(s);
Bruce Ackley, The Ohio State University, Bugwood.org
Additional Resolutions & Image Usage

Seed(s);
Bruce Ackley, The Ohio 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.


Invasive Listing Sources:
Faith Campbell, 1998
Pacific Northwest Exotic Pest Plant Council, 1998