NEW THOUGHTS ON THE QUALITATIVE LAWS OF T HE VEGETAL FIELD AND THEIR HEURISTIC VALUE

As in quantitative laws of classic physics, the qualitative laws of th e vegetal world (botany, plant sociology) constitute preferential brid ges between some areas a priori without report (flora, vegetation on o ne hand, ecology, geography, dynamics... on the other hand). One gives an inventory of these multiple laws and one shows how it is possible to use them to acquire various informations from limited data. These l aws have therefore a high heuristic value, intervening for example in the elaboration of synsystematic keys and in <<paleo-plant sociology>> .