XVI International Botanical Congess

Phylogenetic analysis in systematics has accelerated dramatically in the past ten years. This has improved our knowledge about evolutionary relationships and promises to continue to provide significant insights in the future. As more details of plant phylogeny are learned, the challenge is to convey this information in a consistent and explicit form. The discovery of clades new to science is important and can reveal new insights into the process of evolution. The present system of nomenclature is not well suited to communicate these new discoveries and cannot accommodate the complexity of phylogenetic relationships. The principal problem with the current nomenclature is its emphasis on rank. The naming of newly discovered clades under the present system can cause a cascade of name changes at lower levels as taxa shift in rank. Clade names thus become unstable. In contrast, in phylogenetic nomenclature, clade names do not convey rank and are therefore not subject to change due to changes in rank.