The Bases of Angiosperm Phylogeny: Vegetative Anatomy

Abstract

The principal characters of vegetative anatomy which are of phylogenetic significance at the higher levels in angiosperm systematics are defined and discussed in relation to their taxonomic distribution in the Takhtajan and the Cronquist systems of angiosperm classification.In absence of a complete fossil record, application of the phylogenetic method of association, correlation, and common ground plan are illustrated from anatomical data.Vegetative structure contains a wealth of potentially significant systematic information.However, only the evolutionary trends in the secondary xylem and the phylogenetic conclusions that have resulted from recognizing these trends, provide a firm basis of angiosperm phylogeny.In order for the phylogenetic significance of other vegetative anatomical characters to be fully realized, more comprehensive studies must be undertaken and new methodologies and approaches applied.For the most part, anatomical data support the phylogenetic conclusions of the Takhtajan and Cronquist systems of angiosperm classification at the higher taxonomic levels.However, the most reliable application of anatomical information remains in statements of negation of close relationship rather than positive assertions of close affinity.Anatomical characters have been employed for systematic purposes well over а hundred years.C. В.