Centaurea nigra

Linnaeus

Sp. Pl. 2: 911. 1753.

Common names: Black knapweed lesser knapweed centaurée noire
Introduced
Synonyms: Centaurea jacea subsp. nigra (Linnaeus) Bonnier & Layens Centaurea nemoralis Jordan
Treatment appears in FNA Volume 19. Treatment on page 187. Mentioned on page 184, 186, 188, 189.

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, 15–18 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.


Phenology: Flowering summer–fall (Jun–Oct).
Habitat: Roadsides, fields, clearings, waste areas
Elevation: 0–300 m

Distribution

V19-212-distribution-map.gif

Introduced; St. Pierre and Miquelon, B.C., N.B., Nfld. and Labr. (Nfld.), N.S., Ont., P.E.I., Que., Calif., Conn., Del., Idaho, Ill., Iowa, Ky., Maine, Md., Mass., Mich., Mo., Mont., N.H., N.J., N.Y., Ohio, Oreg., Pa., R.I., Vt., Va., Wash., W.Va., Wis., Europe

Discussion

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

Lower Taxa

None.

"fine" is not a number."fine" is not a number.

... more about "Centaurea nigra"
with fine , 1-celled hairs +  and glabrous +
scarious +
dark-brown +  and black +
less dentate or fringed linear +  and ovate +
indeterminate +  and determinate +
David J. Keil +  and Jörg Ochsmann +
Linnaeus +
decurrent +
Asteraceae tribe Cynareae +
compound +  and simple +
linear;lanceolate +
5 cm50 mm <br />0.05 m <br /> (25 cm250 mm <br />0.25 m <br />) +
glabrous +  and tomentose +
10-nerved or 20-nerved +  and rugose +
lanceolate;ovate +
barbed +  and smooth +
0.05 cm0.5 mm <br />5.0e-4 m <br /> (0.1 cm1 mm <br />0.001 m <br />) +
Black knapweed +, lesser knapweed +  and centaurée noire +
actinomorphic +
radial +  and bilateral +
white +  and blue pink purple or yellow +
inconspicuous +
expanded +  and slender +
1.5 cm15 mm <br />0.015 m <br /> (1.8 cm18 mm <br />0.018 m <br />) +
compressed +  and barrel--shaped +
fertile +  and bisexual +
St. Pierre and Miquelon +, B.C. +, N.B. +, Nfld. and Labr. (Nfld.) +, N.S. +, Ont. +, P.E.I. +, Que. +, Calif. +, Conn. +, Del. +, Idaho +, Ill. +, Iowa +, Ky. +, Maine +, Md. +, Mass. +, Mich. +, Mo. +, Mont. +, N.H. +, N.J. +, N.Y. +, Ohio +, Oreg. +, Pa. +, R.I. +, Vt. +, Va. +, Wash. +, W.Va. +, Wis. +  and Europe +
0–300 m +
glandular-punctate +
puberulent +, strigose +, villous +, tomentose +  and glabrous +
pistillate +, staminate +  and neuter +
winged +  and beaked +
dispersed +
Roadsides, fields, clearings, waste areas +
in corymbiform arrays +, singly +  and radiant +
indeterminate +
each +  and sessile +
ovoid;campanulate or hemispheric +
1.5 cm15 mm <br />0.015 m <br /> (1.8 cm18 mm <br />0.018 m <br />) +
sessile +  and petiolate +
cauline +  and basal +
acute +  and linear-oblong +
shallowly dentate to irregularly pinnately lobed +  and entire +
dissected +
2-carpellate +
persistent +
Flowering summer–fall (Jun–Oct). +
papillate +  and smooth +
distinct +  and fused +
flat;convex +
ockendon1969a +
exalbuminous +
Introduced +
ascending +  and erect +
1 +  and few +
appendaged +  and truncate +
dilated +  and swollen +
enlarged +
Centaurea jacea subsp. nigra +  and Centaurea nemoralis +
Centaurea nigra +
Centaurea +
species +
lobed +  and dentate +
tomentose +  and glabrous +
30 cm300 mm <br />0.3 m <br /> (150 cm1,500 mm <br />1.5 m <br />) +
tree +, vine +, shrub +  and subshrub +
15 +, 13 +, 12 +, 11 +, 10 +, 9 +  and 8 +