alpine knapweed USDA PLANTS Symbol: CENI3
U.S. Nativity: Exotic
Habit: Forbs/Herbs
Centaurea nigrescens Willd

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Taxonomic Rank: Magnoliopsida: Asterales: Asteraceae
Synonym(s): Tyrol knapweed, short-fringed knapweed, vochin knapweed
Native Range: temp. Asia & Europe (GRIN);

Appearance
Centaurea nigrescens is a perennial herb with erect, branched, glabrous or somewhat long-hairy stems that grows 1.3-3.2 ft. (0.4-1.0 m) tall.
Foliage
Stems are erect or ascending, openly branched distally, villous to scabrous with septate hairs and loosely tomentose. Leaves are basal and proximal cauline, petiolate, blades oblanceolate or elliptic, 2-10 in. (5-25 cm) long, margins entire or shallowly dentate to irregularly pinnately lobed; distal cauline sessile, not decurrent, blades linear to lanceolate, gradually smaller, entire or dentate.
Flowers
Flowers are radiant or discoid, in few-headed corymbiform arrays, borne on leafy-bracted peduncles. The involucres are 0.6-0.7 in. (15-18 mm), subcylindric to ovoid or campanulate, usually longer than wide, even when pressed. Flowering summer-fall (Jun-Oct).
Fruit
Fruit are gray to light brown, 0.09-0.11 in. (2.5-3 mm) long, and finely hairy. The seeds are small, 0.02-0.04 in. (0.5-1 mm) long, and darkly colored.
Ecological Threat
Centaurea nigrescens can be found in disturbed areas including along roadsides, fields, pastures, and waste areas. It is native to Europe.

Identification, Biology, Control and Management Resources

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


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

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

Plant(s);
Eric Coombs, Oregon Department of Agriculture, Bugwood.org
Additional Resolutions & Image Usage

Plant(s); hybrid of meadow knapweed and yellow starthistle
Eric Coombs, Oregon Department of Agriculture, 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
Faith Campbell, 1998
Faith Campbell, 1998
John Randall, The Nature Conservancy, Survey of TNC Preserves, 1995.
Mid-Atlantic Exotic Pest Plant Council, 2005
Pacific Northwest Exotic Pest Plant Council, 1998