Centaurea melitensis
Bruce N. Newhouse

Flora of Oregon

Plants annual, 1–10 dm.

Stems branched above, sparsely tomentose, gland-dotted.

Leaves villous, thinly to densely tomentose, gland-dotted; basal and lower cauline blades oblong to oblanceolate, 2–15 cm, margins dentate, pinnately lobed or entire, petiolate to tapering at base; upper cauline blades linear to oblong, 1–5 cm, bases decurrent, margins dentate to entire.

Inflorescences 1–few in corymb-like arrays or heads solitary.

Heads disciform.

Involucres ovoid, 8–15 mm.

Phyllaries outer ovate, bases spiny-fringed, surfaces tomentose to glabrate, central spines slender, 5–10 mm, often purple; inner entire, acute or spine-tipped.

Florets yellow; sterile florets ? fertile florets; fertile florets 10–14 mm.

Fruits 2.5–3 mm, white or light brown, finely hairy; pappi of unequal, white bristles, 1.5–3 mm.

2n=24.

Disturbed areas, roadsides, open woods, fields, pastures. Flowering May–Jul. 0–700 m. CR, ECas, Est, Sisk, WV. CA, ID, NV, WA; scattered in North America; Africa, Asia, Europe. Exotic.

Flora of North America

as described under Centaurea melitensis

Annuals, 10-100 cm, herbage loosely gray-tomentose and villous with jointed multicellular hairs, sometimes minutely scabrous, minutely resin-gland-dotted. Stems 1-few, few-many branched distally. Leaves: basal and proximal cauline petiolate or tapering to base, usually absent at anthesis, blades oblong to oblanceolate, 2-15 cm, margins entire to dentate or pinnately lobed; cauline long-decurrent, blades linear to oblong or oblanceolate, 1-5 cm, entire or dentate. Heads disciform, 1-few at branch tips, borne singly or in open leafy corymbiform arrays, sometimes clustered in distal axils, sessile or pedunculate. Involucres ovoid, 10-15 mm, loosely cobwebby-tomentose or becoming glabrous. Principal phyllaries: bodies ± stramineous, ovate, appendages purplish, spiny-fringed at base, each tipped by slender spine 5-10 mm. Inner phyllaries: appendages entire, acute or spine-tipped. Florets many; corollas yellow, those of sterile florets 10-12 mm, slender, inconspicuous, those of fertile florets 10-12 mm. Cypselae dull white or light brown, ca. 2.5 mm, finely hairy; pappi of many white, unequal, stiff bristles 2.5-3 mm. 2n = 24.Flowering mostly spring-summer (Apr-Jul). Roadsides, fields, pine-oak woodlands, chaparral, agricultural areas; 0-1500 m; widely introduced; B.C.; Ala., Ariz., Calif., Ga., Idaho, Ill., Mass., Miss., Mo., Nev., N.J., N.Mex., Oreg., Pa., Tex., Utah, Wash., Wis.; Mexico (Baja California); Europe; Asia; Africa.Centaurea melitensis is native to the Mediterranean region. It is listed as a noxious weed in New Mexico.

Photo images

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Herbarium specimens

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