Delimitation of the Major Taxa of the Higher Cycadophytina: Theoretical Criteria Versus Taxonomic Practice

Abstract

The application of other than strictly morphological criteria in attempts towards producing a “phylogenetic” classification of the Flowering Plants is clearly unsound as long as the fundamental morphological interpretation of certain magnoliophytic features remains unsettled. Such “established” notions as gymnospermy versus angiospermy, the nature of the functional reproductive units, the sporophyll concept, the assumed primacy of phaneranthy and the entomophilous syndrome (including the sex distribution), etc., which postulates primarily decide the basic framework for the taxonomic arrangement in a system, may well be antiquated. A greater heterogeneity among the major taxa of the magnoliophytic assembly is in better agreement with the available evidence and finds some support when additional taxonomic criteria are applied. It is to be expected that appreciable advances will result from such ancillary criteria if applied to a framework based on a neological approach of the phylogeny and morphology of the Magnoliophyta founded upon alternative assumptions concerning their original anthomorphology and palaeoecology. The present author is entirely in favour of the application of evidence from all sources potentially providing useful taxonomic pointers, but does not believe that such data can be decisive for the delimitation and placing of higher taxa among the Angiosperms until some agreement concerning several fundamental, morphological concepts has been attained. This inevitably involves phylogenetic speculations concerning the nature and morphology of the early magnoliophytes which already require the application of some additional criteria such as palaeoecological evidence and certain palaeo-botanic clues.