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Overview

Distribution

National Distribution

Canada

Origin: Exotic

Regularity: Regularly occurring

Currently: Unknown/Undetermined

Confidence: Confident

United States

Origin: Exotic

Regularity: Regularly occurring

Currently: Unknown/Undetermined

Confidence: Confident

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Physical Description

Morphology

Description

Perennials, 30–150 cm. Stems 1–few, erect or ascending, openly branched distally, villous to scabrous with septate hairs and loosely tomentose, ± glabrate. Leaves: basal and proximal cauline petiolate, blades oblanceolate or elliptic, 5–25 cm, margins entire or shallowly dentate to irregularly pinnately lobed; distal cauline sessile, not decurrent, gradually smaller, blades linear to lanceolate, entire or dentate. Heads discoid, in few-headed corymbiform arrays, borne on leafy-bracted peduncles. Involucres ovoid to campanulate or hemispheric, 15–l8 mm, usually ± as wide as high. Principal phyllaries: bodies lanceolate to ovate, loosely tomentose or glabrous, bases usually ± concealed by expanded appendages, appendages erect, overlapping, dark brown to black, flat, margins pectinately dissected into numerous wiry lobes. Inner phyllaries: tips truncate, irregularly dentate or lobed. Florets 40–100+, all fertile; corollas purple (rarely white), 15–18 mm. Cypselae tan, 2.5–3 mm, finely hairy; pappi of many blackish , unequal, sometimes deciduous bristles 0.5–1 mm. 2n = 22, 44.
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Diagnostic Description

Synonym

Centaurea jacea Linnaeus subsp. nigra (Linnaeus) Bonnier & Layens; C. nemoralis Jordan
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Ecology

Associations

In Great Britain and/or Ireland:
Foodplant / internal feeder
larva of Acanthiophilus helianthi feeds within capitulum of Centaurea nigra
Other: sole host/prey

Foodplant / internal feeder
larva of Acinia corniculata feeds within capitulum? of Centaurea nigra
Remarks: Other: uncertain

Foodplant / parasite
sporangium of Bremia lactucae parasitises live leaf of Centaurea nigra
Remarks: season: 9-10
Other: minor host/prey

Foodplant / internal feeder
larva of Chaetorellia jaceae feeds within capitulum of Centaurea nigra
Other: major host/prey

Foodplant / internal feeder
larva of Chaetostomella cylindrica feeds within capitulum of Centaurea nigra
Other: major host/prey

Foodplant / sap sucker
nymph of Eurygaster maura sucks sap of Centaurea nigra
Other: minor host/prey

Foodplant / parasite
Golovinomyces cichoracearum parasitises live Centaurea nigra
Other: major host/prey

Foodplant / saprobe
stalked apothecium of Hymenoscyphus limonium is saprobic on dead, fallen, covered by grass stem of Centaurea nigra
Remarks: season: 10-11
Other: major host/prey

Foodplant / saprobe
immersed pseudothecium of Kalmusia clivensis is saprobic on dead stem of Centaurea nigra
Remarks: season: 5-6

Foodplant / miner
larva of Liriomyza centaureae mines leaf of Centaurea nigra
Other: sole host/prey

Plant / resting place / within
puparium of Melanagromyza dettmeri may be found in stem of Centaurea nigra

Foodplant / saprobe
sessile apothecium of Mollisia coerulans is saprobic on dead stem of Centaurea nigra
Remarks: season: 4-6
Other: minor host/prey

Foodplant / internal feeder
larva of Napomyza hirticornis feeds within stem of Centaurea nigra

Foodplant / sap sucker
adult of Oncotylus viridiflavus sucks sap of capitulum of Centaurea nigra

Foodplant / feeds on
larva of Paroxyna misella feeds on Centaurea nigra
Remarks: Other: uncertain

Foodplant / saprobe
effuse colony of Phragmocephala dematiaceous anamorph of Phragmocephala elliptica is saprobic on dead stem of Centaurea nigra
Remarks: season: 4-10

Plant / resting place / within
puparium of Phytomyza autumnalis may be found in leaf-mine of Centaurea nigra

Foodplant / parasite
mostly hypophyllous uredium of Puccinia calcitrapae parasitises live leaf of Centaurea nigra
Other: major host/prey

Foodplant / parasite
pycnium of Puccinia dioicae var. arenariicola parasitises live Centaurea nigra

Foodplant / parasite
uredium of Puccinia hieracii var. hieracii parasitises live leaf of Centaurea nigra
Other: minor host/prey

Foodplant / saprobe
erumpent apothecium of Pyrenopeziza adenostylidis is saprobic on dead stem of Centaurea nigra
Remarks: season: 5-11

Foodplant / spot causer
usually hypophyllous colony of Ramularia anamorph of Ramularia triboutiana causes spots on live leaf of Centaurea nigra

Foodplant / saprobe
gregarious, black pycnidium of Rhabdospora coelomycetous anamorph of Rhabdospora coriacea is saprobic on dead, silvery-grey-spotted stem of Centaurea nigra

Foodplant / shot hole causer
punctiform pycnidium of Septoria coelomycetous anamorph of Septoria centaureae causes shot holes on fading leaf of Centaurea nigra
Remarks: season: 8-9

Foodplant / saprobe
colony of Stachybotrys dematiaceous anamorph of Stachybotrys dichroa is saprobic on dead stem of Centaurea nigra
Remarks: season: 4-9

Foodplant / saprobe
fruitbody of Subulicystidium longisporum is saprobic on dead, decayed stem of Centaurea nigra
Other: minor host/prey

Foodplant / saprobe
sessile apothecium of Unguicularia incarnatina is saprobic on dead stem of Centaurea nigra
Remarks: season: 4-7

Foodplant / gall
larva of Urophora jaceana causes gall of receptacle of Centaurea nigra
Remarks: season: -9
Other: major host/prey

Foodplant / gall
larva of Urophora quadrifasciata causes gall of capitulum of Centaurea nigra
Other: major host/prey

Foodplant / internal feeder
larva of Xyphosia miliaria feeds within capitulum of Centaurea nigra
Other: unusual host/prey

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Molecular Biology and Genetics

Molecular Biology

Barcode data: Centaurea nigra

The following is a representative barcode sequence, the centroid of all available sequences for this species.


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Statistics of barcoding coverage: Centaurea nigra

Barcode of Life Data Systems (BOLDS) Stats
Public Records: 12
Specimens with Barcodes: 14
Species With Barcodes: 1
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Conservation

Conservation Status

National NatureServe Conservation Status

Canada

Rounded National Status Rank: NNA - Not Applicable

United States

Rounded National Status Rank: NNA - Not Applicable

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NatureServe Conservation Status

Rounded Global Status Rank: GNR - Not Yet Ranked

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Wikipedia

Centaurea nigra

illustration
Meadow Brown butterfly on knapweed

Centaurea nigra is a species of flowering plant in the daisy family known by the common names Lesser Knapweed, Common Knapweed and Black Knapweed. A local vernacular name is Hardheads.

It is native to Europe but it is known on other continents as an introduced species and often a noxious weed.

Description[edit]

It is a perennial herb growing up to about a metre in height.

The leaves are up to 25 centimetres long, usually deeply lobed, and hairy. The lower leaves are stalked, whilst the upper ones are stalkless.

The inflorescence contains a few flower heads, each a hemisphere of black or brown bristly phyllaries. The head bears many small bright purple flowers. The fruit is a tan, hairy achene 2 or 3 millimetres long, sometimes with a tiny, dark pappus. Flowers July until September.[1] flowers sometimes are yellow, or white

Wildlife value[edit]

Important for Gatekeeper butterfly, Goldfinch, Honey bee, Large skipper, Lime-speck pug moth, Meadow Brown, Painted lady, Peacock, Red admiral, Small copper, Small skipper

Similar species[edit]

Brown Knapweed Centaurea jacea is different in having pale brown bract appendages, no pappus. Flowers August until September.

References[edit]

  1. ^ Rose, Francis (1981). The Wild Flower Key. Frederick Warne & Co. pp. 386–387. ISBN 0-7232-2419-6. 
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Notes

Comments

Black knapweed is listed as a noxious weed in Colorado and Washington.
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