CARBON INTEGRATION IN TWO PLANTAGO SPECIES

We measured the pattern of export of ¹⁴C-assimilate from reproductive spikes and leaves subtending spikes in Plantago aristata and P. virginica. In P. arislata, little ¹⁴carbon was exported to any other reproductive metamer (leaf + associated spike) from the leaf subtending a flowering spike. In P. virginica a large amount was exported. Thus, like clonal species, rosette species can vary in patterns of carbon integration among the repeated morphological subunits comprising an individual. When considered in the context of other studies, these data suggest that comparisons of carbon integration in species differing in morphological complexity would be useful in trying to understand the evolution of patterns of carbon integration in plants.