Not to be semantically confused with: Annual Cornflower (Centaurea cyanus) nor with Perennial Cornflower (Centaurea montana) or Common Knapweed (Centaurea nigra) or Greater Knapweed (Centaurea scabiosa) or Lesser Knapweed (Centaurea nemoralis) (now known as Chalk Knapweed (Centaurea debeauxii)) [plants whose scientific names are similar, but which are in a totally different Family altogether, the Daisy & Dandelion Family (Asteraceae)].

Easily mis-identified as : Seaside Centaury but that has narrower and strap-shaped basal leaves as the main identifying feature.

Hybridizes with :

• Seaside Centaury (Centaurium littorale) to become Centaurium × intermedium which is found on the Sefton Coastline, on Walney Island and on the coast in Southern Anglesey.
• Lesser Centaury (Centaurium pulchellum) to become Centaurium erythreae × pulchellum which is found in very few hectads.

Some similarities to : Sticky Stork's-bill, Common Stork's-bill, Lesser Sea-spurrey and to Rock Sea-Spurrey which all have pink to lilac flowers with 5 petals that also happen to grow near the sea.

Many similarities to : besides other Centauries, the Gentians Autumn Gentian, Chiltern Gentian, Early Gentian and Dune Gentian all look very similar but have more purplish coloured flowers and at the centre of the flower a long fringed ring which are a lighter shade of mauve. Also, the anthers are not yellow in colour as they are for the other Centaury, Yellow Centaury (Cicendia filiformis) which are in differing Genera. Moreover, Yellow-wort has yellow flowers. The Gentians are in the same Family Gentianaceae as the Centauries and Yellow-wort.

Common Centaury is by far and away the most ubiquitous centaury. It grows up to 50cm high, but is very variable and can be as short as only 5cm in exposed places. Habitat is grassy places and grassy sand dunes. It hybridizes readily with Seaside Centaury (Centaurium littorale) and the hybrid is found extensively near the parents, especially on the Sefton Coastline.

For details of the sizes and differences between Common Centaury and they others, see the captions below the photos above.

The fruit is a cylindrical capsule.

SECOIRIDOIDS It contains the intensely bitter tasting  Secoiridoid Glycosides Gentiopicrin (aka Gentiopicroside), Centapicrin, Deacetylcentapicrin, Decentapicrin A, B, and C, Swertiamarin, Secologanin, Centauroside and Gentioflavoside. Lacking nitrogen, none of these compounds are alkaloids. Gentiopicrin has anti-malarial properties. Gentiopicroside inhibits Tumour Necrosis Factor (TNF) in laboratory conditions in mice. Dihydrocornin is also found in shrubs belonging to the Cornus Genus. Dihydrocornin also occurs in two members of the Cornus shrubs, or Dogwood. The parent ketone compound, Cornin was previously known as Verbenilin and found in Vervain. Both Cornin and Dihydrocornin are secoiridoid glycosides. Dihydrocornin is a potent anti-fungal compound. Apart from the aldehyde group, top centre, centauroside is a dimer.

PYRIDINE ALKALOIDS Common Centaury may also contain traces of the pyridine alkaloids Gentianine, Gentianidine and Gentioflavine, but these are controversial, possibly being isolation artefacts.

The tincture of Common Centaury is bitter and is used in non-alcoholic bitter tonics in Europe and in alcoholic Vermouth formulations, particularly in USA, but it is usually blended with other bitter components because it contributes very little flavour by itself. Maximum concentration used is very low at about 8ppm, and usually much lower at 2ppm.