HYDRODYNAMIC MODELING STUDY OF ANGIOSPERM LEAF VENATION TYPES

The morphology of leaf venation has been studied repeatedly and variou s systems have been proposed for the classification of the observed le af venation patterns. Almost nothing is known, however, about the func tional properties of the various venation types. Using a computer mode lling approach we analysed the water transport properties of typical c raspedodromous and brochidodromous venation patterns. The water transp ort through the leaf and the veins was modelled as a fluid flow throug h a porous medium and the mathematical model was solved with the Finit e Element Method. The simulations illustrate that the leaf margin repr esents a critical region in terms of water supply. The results provide a plausible functional explanation for three well known phenomena: 1) the correlation between craspedodromous venation and the formation of leaf teeth; 2) the fact that craspedodromous venation is more common in temperate than in tropical regions and 3) the fact that xeromorphic leaves tend to have more closed venation.