Principles and Concepts in the Classification of Higher Taxa
Despite the very great interest shown by botanists during the last 100 years in the “phylogenetic classification” of the Flowering Plants, much more attention seems to have been paid to the phylogenetic components of such schemes (despite the lack of adequate evidence) than to their taxonomic/classificatory components (for which much evidence is available). There is in fact an inbuilt conflict involved in constructing a scheme that attempts to express both the dynamic/historical phylogenetic component and a static horizontal present day classification, which makes most of the conventional phylogenetic tree-like diagrams conceptually suspect.
In the Flowering Plants, only the classes and families are widely accepted whereas there are numerous plausible ordinal classifications. The kind of questions we have to ask in the case of higher categories and taxa such as the subclass and order are: are the criteria to be primarily phylogenetic, or taxonomic in the sense of aiming at better circumscriptions of the taxa, greater predictive value, stability, etc.? Only when we have answered these and similar questions can we decide whether we should be aiming at cladogenetic schemes or anagenetic grades or an explicit combination of both.
KeywordsFossil Record Calcium Oxalate High Taxon Fossil Pollen Phylogenetic Classification
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