European centaury, petite-centaurée commune

Herbs annual or biennial, 3–60 cm. Stems 1–several, branching mostly above middle. Leaves: rosette of basal leaves usually present at flowering; blade ellip­tic to spatulate-obovate, 15–70 × 5–20 mm, apex rounded to subacute; cauline blades elliptic (proximal) to lanceolate or lin­ear (distal), 8–50 × 1–8 mm, apex obtuse to acute. Inflo­rescences dense, ± corymboid, dichasial cymes; flowers sessile or occasionally on pedicels to 2 mm. Flowers: calyx (2–)5–7 mm; corolla (6–)10–17 mm, lobes (3–)4–8 mm; anthers (1–)2–2.5 mm; stigmas ovate-elliptic. Seeds brown. 2n = 40 (Europe), 42 (Spain).

Flowering summer–early fall. Fields, roadsides, other open, disturbed habitats; 0–1000 m; introduced; Man., N.S., Ont., Que.; Calif., Idaho, Ind., La., Md., Mass., Mich., Mont., N.Y., N.C., Ohio, Oreg., Pa., Vt., Va., Wash.; Eurasia; introduced also in Central America, South America, Pacific Islands (New Zealand), Australia.

The name Centaurium minus Moench is a synonym of C. littorale (Turner) Gilmour but has often been misapplied to C. erythraea. Centaurium minus Garsault and C. umbellatum Gilibert are invalidly published names that have been applied to C. erythraea.

In the flora area, Centaurium erythraea appears to be represented only by what is called subsp. erythraea in more inclusive circumscriptions of the species, for example, A. Melderis (1972). The one chromosome count for a North American population is consistent with this interpretation.