Genetic analysis revealed that Centaurium was polyphyletic, made up of plants that could be grouped into four clades.

Zeltnera and Centaurium species differ mostly in the morphology of the style and stigma, as well as the shape of the fruit capsule.

[1] Zeltnera can be subdivided into three groups, a division which is supported by DNA evidence but is most obvious in terms of geography.

The first group is distributed from British Columbia south through the West Coast of the United States and into Baja California.

[1] Genus Zeltnera was named for the Swiss botanists Louis and Nicole Zeltner, who have researched Centaurium and other gentians.