Discussion
Combining a multi-treatment greenhouse experiment with global-scale field observations, we disentangled the main sources of intraspecific trait variation for the short-lived herb Plantago lanceolata . Expression of functional traits along environmental gradients in the field was retained to some extent in the greenhouse, indicative of population genetic differentiation. However, while reproductive traits (biomass-corrected probability of flowering and fecundity) showed similar effects of source environment across exposure treatments, vegetative traits (biomass, specific leaf area and root:shoot ratio) showed more plastic responses and some contrasting effects of source and exposure environments. These results imply a higher predictability of genetic differentiation from field observations in reproductive than vegetative traits.