Exploring Alternative Systems of Classification

Classification involves the development of a system of naming clades that can represent evolutionary relationships accurately and concisely. Using the acid-loving heath plants (Ericales) as an example, one can explore the application of different classification methods. The Linnean system of naming retains the traditional hierarchical framework (named ranks) and allows for the application of many cuqently used names. The "phylogenetic systematic" approach recommends the removal of an absolute hierarchy but allows retention of traditionally used endings such as -aceae. Historical usage of these names can lead to confusion when the names are used within a discussion or text, especially when a cladogram is not presented at the same time. Another method is suggested that removes the Linnean endings and adds the same ending (ina) to all clade names. This effectively eliminates absolute rank and clearly indicates that the group name represents a clade. The names used in this method and the "phylogenetic systematic" method do not indicate relative rank. Numbering systems and indentation are two ways in which relative rank has been conveyed. Indented lists have been the preferred method, often in combination with suffixes that indicate absolute rank. If absolute rank is eliminated, relative rank can still be reflected by indentation as in the "phylogenetic systematic" method. Relative rank can be conveyed by always presenting a cladogram in conjunction with a classification. In practice, relative rank is also effectively communicated within the context of discussion, thus a precise system of indicating relative rank within a formal classification may not be necessary.