A taxonomic revision of native New Zealand Plantago (Plantaginaceae)

Species delimitation is challenging in New Zealand Plantago because of a complex polyploid evolutionary history, few taxonomically useful characters due to reduced habit and wind-pollinated flowers, and phenotypic plasticity. To clarify species limits and revise the taxonomy of this group, analyses of novel morphological data were undertaken and evaluated alongside previously published studies of chromosome number, amplified fragment length polymorphisms, molecular phylogenetics, molecular cytogenetics and morphology. All 11 native species of Plantago recognised here are endemic to New Zealand, except Plantago triantha which is also native to Tasmania, Australia. In contrast to previous treatments, Plantago picta is recognised here at the species rank, Plantago masoniae is treated as a synonym of Plantago triandra, and one new 16-ploid species, Plantago udicola Meudt & Garn.-Jones, is formally described. Seed number and shape, scape, bract and sepal vestiture, and number of flowers and spikes are particularly important characters for species delimitation.