PALAEO-ECOPHYSIOLOGICAL PERSPECTIVES ON PLANT-RESPONSES TO GLOBAL CHANGE

Taxonomic classifications of plant species, based on morphological cha racteristics, provide a stable and robust approach for Inferring taxon omic and phylogenetic relationships between extant and extinct species . This implies that, although evolution is a continuous process for a species, there is no whole-scale change in those suites of morphologic al characteristics that define higher order (genus and greater) relati onships. Recent research suggests that a higher order characteristic s tomatal density - may reflect not only the atmospheric CO2 concentrati on during initial evolution, but may also strongly constrain the respo nses of higher order plant groups to future CO2-enrichment.