The importance of standardized nomenclature is well estab-lished in medicine, even if it does not always extend to botanical nomenclature. Singh and Ferguson (2009) recognize the necessity of standardized definitions for improving the quality of critical care clinical trials. Biological taxonomy is now ruled by the principle of monophyly (a group that includes its ancestor and all of its descendants). Failure to consider monophyly in defining groups is a problem not only for taxonomy but for medicine. For example, the American–European Consensus Conference defini-tion of acute respiratory distress syndrome is a heterogeneous disease (Phua et al., 2008). In taxonomic terms, it is not mono-phyletic. They argue that the heterogeneous definition could negatively influence the outcome of clinical research as well as patient management.