Principal Component Analysis, an ordination technique frequently ušed in phytosociological ecology, has been successfully applied in an attempt to consolidate unknown factors and processes responsible for influencing and modulating photosynthesis determining sugar beet leaf characteristics. Starting from a rough data matrix which consisted of the observed values of 18 cytological, anatomical and ecophysiological leaf parameters, measured in 32 leaf series, this technique calculated the co-ordinates of 32 entities with respect to a whole new set of principál axes. The ordination of all leaf entities was highly correlated with the relative increase of intemal (leaf) area, the total relative stomatal area and the chlorophyll a content. Since their arrangement on the main principál axis was also strongly determined by plant age, the conclusion could be drawn immediately that these three leaf parameters were significantly modulated by plant age. So, conclusions found in a rather subjective way were confirmed by this mathematical ordination technique.