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Published In: Species Plantarum 2: 911. 1753. (1 May 1753) (Sp. Pl.) Name publication detailView in BotanicusView in Biodiversity Heritage Library
 

Project Name Data (Last Modified On 8/11/2017)
Acceptance : Accepted
Project Data     (Last Modified On 7/9/2009)
Status: Introduced

 

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2. Centaurea cyanus L. (cornflower, bachelor’s button, blue bottle)

Pl. 252 d, e; Map 1041

Plants annual, with a taproot, pubescent with dense, woolly hairs when young (appearing pale or whitened), the pubescence often partially reduced to woolly or cobwebby tufts at maturity, at least the leaf undersurface remaining persistently woolly. Stems 20–120 cm long, erect or ascending, with ascending branches at or above the midpoint, angled and/or ridged but usually not winged. Leaves 4–13 cm long; basal and lower stem leaves with the blades mostly 2–5(–9) mm wide, linear or narrowly lanceolate, tapered to a sharply pointed tip, tapered gradually to a sessile or short-petiolate base, the margins entire or the basal leaves rarely with a few linear lobes (the leaves then wider); median and upper stem leaves somewhat reduced, mostly sessile, the base sometimes narrowly decurrent, the blades linear, entire. Heads solitary at the branch tips. Involucre 11–16 mm long, longer than wide (sometimes about as long as wide when pressed), more or less bell-shaped. Lower and median involucral bracts with the body ovate, the margins entire, the outer surface glabrous or finely woolly, not concealed by the appendages; the apical appendage not strongly differentiated, ascending, the broad, white or brownish- to purplish-tinged margins papery and with coarse, ascending, triangular teeth. Upper involucral bracts similar but oblong-lanceolate. Florets discoid, but the marginal florets raylike. Pappus of many unequal bristles, these 2–4 mm long, straw-colored to brown, usually persistent at fruiting. Corollas of discoid florets 10–15 mm long, those of raylike florets 20–25 mm long, blue or less commonly purple, pink, or white. Fruits 3.5–5.0 mm long, somewhat flattened, the attachment scar appearing lateral, the surface grayish brown to yellowish brown, brown or nearly black, with sometimes faint, lighter stripes, finely hairy. 2n=24. May–September.

Introduced, widely scattered in Missouri (native of Europe, Asia; introduced throughout the U.S. and Canada). Banks of rivers and ledges of bluffs; also fallow fields, railroads, roadsides, and open, disturbed areas.

Centaurea cyanus is a popular garden annual and a component of some wildflower seed mixes. Steyermark (1963) knew it from only ten widely scattered counties but suggested that it actually was present in most counties. Surprisingly, since that time, it has been collected in only a few additional counties.

 


 

 
 
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