Centaurea solstitialis

Linnaeus

Sp. Pl. 2: 917. 1753.

Common names: Yellow or Barnaby star-thistle St. Barnaby’s thistle centauré du solstice
IntroducedIllustrated
Treatment appears in FNA Volume 19. Treatment on page 193. Mentioned on page 183.

Annuals, 10–100 cm. Stems simple or often branched from base, forming rounded bushy plants, gray-tomentose. Leaves gray-tomentose and scabrous to short-bristly; basal and proximal cauline petiolate or tapered to base, usually absent at anthesis, blades 5–15 cm, margins pinnately lobed or dissected; cauline long-decurrent, blades linear to oblong, 1–10 cm, entire. Heads disciform, borne singly or in open leafy arrays, long-pedunculate. Involucres ovoid, 13–17 mm, loosely cobwebby-tomentose or becoming glabrous. Principal phyllaries: bodies pale green, ovate, appendages stramineous to brown, each with palmately radiating cluster of spines, and stout central spine 10–25 mm. Inner phyllaries: appendages scarious, obtuse or abruptly spine-tipped. Florets many; corollas yellow, all ± equal, 13–20 mm; sterile florets slender, inconspicuous. Cypselae dimorphic, 2–3 mm, glabrous, outer dark-brown, without pappi, inner white or light-brown, mottled; pappi of many white, unequal bristles 2–4 mm, fine. 2n = 16.


Phenology: Flowering mostly summer–autumn (Jun–Oct), sometimes year-round in frostfree coastal habitats.
Habitat: Roadsides, fields, pastures, woodlands
Elevation: 0–2000 m

Distribution

V19-226-distribution-map.gif

Introduced; Widely, Alta., Man., Ont., Sask., Ariz., Calif., Colo., Conn., Del., Fla., Idaho, Ill., Ind., Iowa, Kans., Ky., Md., Mass., Mich., Minn., Mo., Mont., Nebr., Nev., N.H., N.J., N.Mex., N.Y., N.C., N.Dak., Ohio, Okla., Oreg., Pa., R.I., S.C., S.Dak., Tenn., Tex., Utah, Va., Wash., W.Va., Wis., Wyo., s Europe

Discussion

Centaurea solstitialis is a serious weed pest, especially in the western United States, where it has invaded millions of acres of rangelands, and it is listed as a noxious weed in eleven western states and two Canadian provinces. It is a strong competitor in infested areas, often forming dense colonies. It is very difficult to control or eradicate once it becomes established. In addition, yellow star-thistle is poisonous to horses; when ingested over a prolonged period it causes a neurological disorder called equine nigropallidal encephalomalacia, or “chewing disease.” Although its bitter taste and spiny heads usually deter grazing animals, horses sometimes will seek it out. Yellow star-thistle tends to spread in rangelands when more palatable plants are consumed.

Selected References

None.

Lower Taxa

None.

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

... more about "Centaurea solstitialis"
with fine , 1-celled hairs +  and glabrous +
scarious +
stramineous +  and brown +
erect;spreading +
spine-tipped +  and obtuse +
leafy +  and open +
indeterminate +  and determinate +
David J. Keil +  and Jörg Ochsmann +
Linnaeus +
decurrent +
Asteraceae tribe Cynareae +
compound +  and simple +
linear;oblong +
1 cm10 mm <br />0.01 m <br /> (10 cm100 mm <br />0.1 m <br />) +
pale green +
10-nerved or 20-nerved +  and rugose +
barbed +  and smooth +
0.2 cm2 mm <br />0.002 m <br /> (0.4 cm4 mm <br />0.004 m <br />) +
long-decurrent +
1 cm10 mm <br />0.01 m <br /> (2.5 cm25 mm <br />0.025 m <br />) +
Yellow or Barnaby star-thistle +, St. Barnaby’s thistle +  and centauré du solstice +
actinomorphic +
radial +  and bilateral +
inconspicuous +
expanded +  and slender +
1.3 cm13 mm <br />0.013 m <br /> (2 cm20 mm <br />0.02 m <br />) +
compressed +  and barrel--shaped +
fertile +  and bisexual +
Widely +, Alta. +, Man. +, Ont. +, Sask. +, Ariz. +, Calif. +, Colo. +, Conn. +, Del. +, Fla. +, Idaho +, Ill. +, Ind. +, Iowa +, Kans. +, Ky. +, Md. +, Mass. +, Mich. +, Minn. +, Mo. +, Mont. +, Nebr. +, Nev. +, N.H. +, N.J. +, N.Mex. +, N.Y. +, N.C. +, N.Dak. +, Ohio +, Okla. +, Oreg. +, Pa. +, R.I. +, S.C. +, S.Dak. +, Tenn. +, Tex. +, Utah +, Va. +, Wash. +, W.Va. +, Wis. +, Wyo. +  and s Europe +
0–2000 m +
glandular-punctate +
puberulent +, strigose +, villous +, tomentose +  and glabrous +
pistillate +, staminate +  and neuter +
inconspicuous +
slender +
winged +  and beaked +
dispersed +
Roadsides, fields, pastures, woodlands +
long-pedunculate +
in open leafy arrays +  and singly +
indeterminate +
each +  and sessile +
mottled +, light-brown +  and white +
glabrous +  and cobwebby-tomentose +
1.3 cm13 mm <br />0.013 m <br /> (1.7 cm17 mm <br />0.017 m <br />) +
sessile +  and petiolate +
cauline +  and basal +
scabrous +  and short-bristly +
acute +  and linear-oblong +
entire +  and dentate +
dissected +  and lobed +
2-carpellate +
persistent +
Flowering mostly summer–autumn (Jun–Oct), sometimes year-round in frostfree coastal habitats. +
rounded +
papillate +  and smooth +
distinct +  and fused +
flat;convex +
exalbuminous +
Introduced +  and Illustrated +
branched +  and simple +
spreading +, ascending +  and erect +
appendaged +  and truncate +
dilated +  and swollen +
enlarged +
Acosta +, Cnicus +, Grossheimia +, Jacea +  and Leucacantha +
Centaurea solstitialis +
Centaurea +
species +
tomentose +  and glabrous +
10 cm100 mm <br />0.1 m <br /> (100 cm1,000 mm <br />1 m <br />) +
tree +, vine +, shrub +  and subshrub +
15 +, 13 +, 12 +, 11 +, 10 +, 9 +  and 8 +