alpine knapweed, Tyrol knapweed

Centaurea nigrescens Willd

Description from Invasive.org

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.

Resources


Selected Images from Invasive.org

View 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

Distribution