Multivariate morphometric analyses of leaves from plants grown in the field and in the glasshouse indicate that Plantago tasmanica and P. daltonii are developmentally flexible, but their leaf forms remain distinct when the taxa are grown in common environments. No evidence of a geographical trend of leaf form was observed within or among taxa but leaf form appears to be correlated with local habitat conditions. Evidence from the morphometric data, together with preliminary seed germination experiments and qualitative characteristics, suggests that the varietal ranks of P. tasmanica var. tasmanica and var. archeri should be maintained but that P. daltoniiis specifically distinct. However, introgression probably occurs between the two species.