XVI International Botanical Congess

It is well known that the discovery of new characters can change the position of a taxon in a system completely and entails shifts in its former hierarchical level and size. Consequently, taxonomists think that some data may be better than others and be used for the testing of previously segregated groups. However such an activity is not exactly the testing because simply new taxonomic hypotheses on the basis of different sets of characters are created. The problem is the choice between competitive hypotheses. In Ascomycetes, the situation is complicated by numerous parallel characters and is aggravated by fruitless taxonomic debates. The most notoriously known striving for the character set instead of a single difference may lead to the creation of very artificial groups after the unification of taxa with similar inner polymorphism.