Description: Erect glabrous annual or possibly biennial herbs with slender 4-angular stems, often much-branched.
Leaves ± sessile, the lowest often forming a basal rosette, opposite and becoming smaller below inflorescence.
Flowers in compound cymes; mostly 5-merous. Calyx tube usually 5-lobed, persistent in fruit. Corolla reddish or pink [or yellow], persistent in fruit; tube cylindrical; lobes 5, spreading. Stamens usually 5, inserted in the throat of the corolla-tube; anthers ± twisted after the pollen is shed. Ovary 1-locular; stigma ± 2-lobed.
Capsule narrow-oblong, enclosed in or slightly exceeding the persistent calyx and corolla.
Distribution and occurrence: World: c. 45 species, widespread in northern & southern temperate regions, except Africa. Australia: 4 species (3 species naturalized, 1 species native), all States.
Text by G. J. Harden
Taxon concept:
| | Key to the species | |
| 1 | Basal rosette of leaves absent or weakly developed; corolla lobes 3–5 mm long; calyx mostly 6–8 mm long, usually at least two-thirds the length of corolla tube | Centaurium tenuiflorum |
| Basal rosette of leaves present and distinct; corolla lobes 5–6 mm long; calyx mostly 4–6 mm long, less than two-thirds the length of corolla tube | Centaurium erythraea |
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