Centaurea stoebe
Centaurea depressa
spotted knapweed
iranian knapweed, low cornflower
usually several–many from base, spreading, ± openly branched distally, loosely gray-tomentose.
± loosely gray-tomentose;
basal and proximal cauline petiolate, blades oblong, 5–10 cm, margins entire or pinnatifid with terminal segment largest, apices obtuse;
mid and distal cauline sessile, linear-lanceolate to oblong, blades usually not much smaller, entire, mucronate.
ovoid to campanulate, 15–20 mm.
25–35;
corollas of sterile florets spreading, dark blue, 25–30 mm, enlarged, those of fertile florets purple, ca. 15 mm.
bodies green, ovate (outer) to oblong (inner), glabrous, margins and erect appendages silvery white to brown, scarious, fringed with slender teeth 1.5–2 mm.
radiant, borne singly, pedunculate.
brown, 4.5–6 mm, puberulent near attachment scar, otherwise glabrous;
pappi of outer series of unequal stiff bristles 2–8 mm, inner series of slender scales ca. 1.5 mm.
= 16 (Armenia).
Centaurea stoebe
Centaurea depressa
Subspecies 3 (1 in the flora).
Native to southeastern Europe, Centaurea stoebe has been introduced to the whole of Europe, as far north as southern Sweden.
The nomenclature of Centaurea stoebe in the broad sense has been a source of confusion in European literature for about 200 years. The names used in that group (C. stoebe, C. rhenana, C. maculosa, C. biebersteinii) have been applied to different taxa by different authors with varying circumscriptions. Different species concepts were used in western and eastern Europe. Unfortunately this fact was not taken into account properly in the treatment by J. Dostál (1976).
Recent studies have shown that the American plants are identical with plants introduced to the whole of Europe (J. Ochsmann 2001). Subsp. micranthos, a tetraploid perennial, is clearly distinct from the diploid, biennial plants native to central Europe known as C. stoebe Linnaeus subsp. stoebe, C. rhenana Boreau, or C. maculosa Lamarck. In most American literature the name Centaurea maculosa Lamarck has been misapplied to C. stoebe subsp. micranthos. W. A. Weber (1987, 1990) treated this taxon as Acosta maculosa (Lamarck) Holub. The treatment of about 100 species of Centaurea sect. Acrolophus Cassini as the genus Acosta by J. Holub (1972) and others is supported by neither morphologic nor molecular characters and is not widely accepted in Europe.
(Discussion copyrighted by Flora of North America; reprinted with permission.)
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