Enum. Pl., 930. 1809
Annuals, 10–100 cm. Stems simple to openly branched, branches ascending, villous to hispid with septate hairs and loosely tomentose. Leaves ± villous to hispid with septate hairs, minutely resin-gland- dotted; basal winged-petiolate, blades oblong to oblanceolate, 10–15 cm, margins pinnately lobed, lobes acute, finely dentate; cauline sessile, long-decurrent with narrow wings, linear-oblong to oblanceolate, 1–6 cm, entire or distally serrate with short, spine-tipped teeth. Heads disciform, borne singly or in open, few-headed corymbiform arrays, long-pedunculate. Involucres ovoid, 12–30 mm, distally constricted. Principal phyllaries: bodies greenish or stramineous, ovate to elliptic, glabrous, appendages spreading to reflexed, brown to blackish purple, each with palmately radiating cluster of spines, central spine stout, 1–2.5 cm, base dark brown to black, distally stramineous. Inner phyllaries: appendages acute or spine-tipped. Florets many; corollas yellow, all ± equal, 25–35 mm; corollas of sterile florets slender, inconspicuous. Cypselae dark brown, 5–8 mm, glabrous; pappi of many, brown to blackish, unequal bristles 6–7 mm. 2n = 24.
Phenology: Flowering spring–summer (May–Jul).
Habitat: Disturbed sites, grasslands, woodlands, pastures, roadsides
Elevation: 0–300 m
Calif., sw Europe.
Centaurea sulphurea is considered to be a noxious weed by the state of California.