[2] Molecular data show Littorella to be sister to the rest of the genus Plantago.

[2][3] Some researchers, particularly Rahn in the 1990s, have considered Littorella to be located within Plantago, but this does not seem to be required given the molecular data and a closer look at morphology.

Other considerations, such as the wider range and more frequent flowering of L. uniflora, also argue for separate species.

[2] The European species is found in a wide range of habitats, from arctic to Mediterranean.

The North and South American species are found in a more limited range of temperate climates.